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Sensory Disruption: Is Modern Living Killing Our Sense of Smell
... Rates of olfactory dysfunction are hard to calculate because it has not been considered part of routine clinical assessment nor is it treated when identified; however, frequency of the condition may be as high as 20 percent globally but there are major data gaps from the developing world [27]. The health impacts of smell loss include multiple negative physical, mental, and social health outcomes, but no systematic study has yet to examine the health impact from having a decreased sense of smell [28]. While sound and sight impairments have been the focus of both medical and basic research, little attention has been paid to olfaction and there are no preventions, treatments, or reversals available for those with dysfunction. ...
Modern lifestyles are disrupting the human senses-primarily sight, sound, and smell. Noise-induced hearing loss has been noted for centuries and increasing over time following the industrial era. From the mid-20thcentury, the numbers of individuals with myopia (the leading visual impairment) have been increasing globally. Historical evidence for olfactory dysfunction is not known but its etiological links to pollution suggest it increased following industrialization. Clinical interventions for sight and sound loss include preventative and corrective measures but none exist for olfactory dysfunction. Further, olfactory loss is linked to multiple negative health outcomes across physical, mental, and social domains. Due to the global rates of exposure to pollution, olfaction is a global health concern. The environmental injustice inherent in human society (locally and globally) results in inequitable risk for sensory loss by the most vulnerable populations and creates an even deeper gradient in health disparity. Situated within the environmental justice and health disparity literature, this paper introduces the termsensory inequityto describe variation in sensory environments based on socio-economic status (which is often entwined with race and education). A key challenge to risk management is awareness of sensory inequity experienced by vulnerable populations and incorporating that awareness into basic research and policy.
Mechanotransducer channels at the tips of sensory stereocilia of inner ear hair cells are gated by the tension of 'tip links' interconnecting stereocilia. To ensure maximal sensitivity, tip links are tensioned at rest, resulting in a continuous influx of Ca2+ into the cell. Here, we show that this constitutive Ca2+ influx, usually considered as potentially deleterious for hair cells, is in fact essential for stereocilia stability. In the auditory hair cells of young postnatal mice and rats, a reduction in mechanotransducer current, via pharmacological channel blockers or disruption of tip links, leads to stereocilia shape changes and shortening. These effects occur only in stereocilia that harbor mechanotransducer channels, recover upon blocker washout or tip link regeneration and can be replicated by manipulations of extracellular Ca2+ or intracellular Ca2+ buffering. Thus, our data provide the first experimental evidence for the dynamic control of stereocilia morphology by the mechanotransduction current.
In this article, the authors evaluate the possible roles of negative emotions and cognitions in the association between socioeconomic status (SES) and physical health, focusing on the outcomes of cardiovascular diseases and all-cause mortality. After reviewing the limited direct evidence, the authors examine indirect evidence showing that (a) SES relates to the targeted health outcomes, (b) SES relates to negative emotions and cognitions, and (c) negative emotions and cognitions relate to the targeted health outcomes. The authors present a general framework for understanding the roles of cognitiveemotional factors, suggesting that low-SES environments are stressful and reduce individuals' reserve capacity to manage stress, thereby increasing vulnerability to negative emotions and cognitions. The article concludes with suggestions for future research to better evaluate the proposed model.
Background:
Olfactory dysfunction is an increasingly recognised condition, associated with reduced quality of life and major health outcomes such as neurodegeneration and death. However, translational research in this field is limited by heterogeneity in methodological approach, including definitions of impairment, improvement and appropriate assessment techniques. Accordingly, effective treatments for smell loss are limited. In an effort to encourage high quality and comparable work in this field, among others, we propose the following ideas and recommendations. Whilst the full set of recommendations are outlined in the main document, points include the following: • Patients with suspected olfactory loss should undergo a full examination of the head and neck, including rigid nasal endoscopy with small diameter endoscopes. • Subjective olfactory assessment should not be undertaken in isolation, given its poor reliability. • Psychophysical assessment tools used in clinical and research settings should include reliable and validated tests of odour threshold, and/or one of odour identification or discrimination. • Comprehensive chemosensory assessment should include gustatory screening. • Smell training can be helpful in patients with olfactory loss of several aetiologies.
Conclusions:
We hope the current manuscript will encourage clinicians and researchers to adopt a common language, and in so doing, increase the methodological quality, consistency and generalisability of work in this field.
People struggle to name odors [1-4]. This has been attributed to a diminution of olfaction in trade-off to vision [5-10]. This presumption has been challenged recently by data from the hunter-gatherer Jahai who, unlike English speakers, find odors as easy to name as colors [4]. Is the superior olfactory performance among the Jahai because of their ecology (tropical rainforest), their language family (Aslian), or because of their subsistence (they are hunter-gatherers)? We provide novel evidence from the hunter-gatherer Semaq Beri and the non-hunter-gatherer (swidden-horticulturalist) Semelai that subsistence is the critical factor. Semaq Beri and Semelai speakers-who speak closely related languages and live in the tropical rainforest of the Malay Peninsula-took part in a controlled odor- and color-naming experiment. The swidden-horticulturalist Semelai found odors much more difficult to name than colors, replicating the typical Western finding. But for the hunter-gatherer Semaq Beri odor naming was as easy as color naming, suggesting that hunter-gatherer olfactory cognition is special.
Autism spectrum disorder (ASD) is characterized by impaired social communication, often attributed to misreading of emotional cues. Why individuals with ASD misread emotions remains unclear. Given that terrestrial mammals rely on their sense of smell to read conspecific emotions, we hypothesized that misreading of emotional cues in ASD partially reflects altered social chemosignaling. We found no difference between typically developed (TD) and cognitively able adults with ASD at explicit detection and perception of social chemosignals. Nevertheless, TD and ASD participants dissociated in their responses to subliminal presentation of these same compounds: the undetected 'smell of fear' (skydiver sweat) increased physiological arousal and reduced explicit and implicit measures of trust in TD but acted opposite in ASD participants. Moreover, two different undetected synthetic putative social chemosignals increased or decreased arousal in TD but acted opposite in ASD participants. These results implicate social chemosignaling as a sensory substrate of social impairment in ASD.
How wealth is distributed among households provides insight into the fundamental characters of societies and the opportunities they afford for social mobility. However, economic inequality has been hard to study in ancient societies for which we do not have written records, which adds to the challenge of placing current wealth disparities into a long-term perspective. Although various archaeological proxies for wealth, such as burial goods or exotic or expensive-to-manufacture goods in household assemblages, have been proposed, the first is not clearly connected with households, and the second is confounded by abandonment mode and other factors. As a result, numerous questions remain concerning the growth of wealth disparities, including their connection to the development of domesticated plants and animals and to increases in sociopolitical scale. Here we show that wealth disparities generally increased with the domestication of plants and animals and with increased sociopolitical scale, using Gini coefficients computed over the single consistent proxy of house-size distributions. However, unexpected differences in the responses of societies to these factors in North America and Mesoamerica, and in Eurasia, became evident after the end of the Neolithic period. We argue that the generally higher wealth disparities identified in post-Neolithic Eurasia were initially due to the greater availability of large mammals that could be domesticated, because they allowed more profitable agricultural extensification, and also eventually led to the development of a mounted warrior elite able to expand polities (political units that cohere via identity, ability to mobilize resources, or governance) to sizes that were not possible in North America and Mesoamerica before the arrival of Europeans. We anticipate that this analysis will stimulate other work to enlarge this sample to include societies in South America, Africa, South Asia and Oceania that were under-sampled or not included in this study.
Purpose
The aim of the study was a systematic review of refractive errors across the world according to the WHO regions.
Methods
To extract articles on the prevalence of refractive errors for this meta-analysis, international databases were searched from 1990 to 2016. The results of the retrieved studies were merged using a random effect model and reported as estimated pool prevalence (EPP) with 95% confidence interval (CI).
Results
In children, the EPP of myopia, hyperopia, and astigmatism was 11.7% (95% CI: 10.5–13.0), 4.6% (95% CI: 3.9–5.2), and 14.9% (95% CI: 12.7–17.1), respectively. The EPP of myopia ranged from 4.9% (95% CI: 1.6–8.1) in South–East Asia to 18.2% (95% CI: 10.9–25.5) in the Western Pacific region, the EPP of hyperopia ranged from 2.2% (95% CI: 1.2–3.3) in South-East Asia to 14.3% (95% CI: 13.4–15.2) in the Americas, and the EPP of astigmatism ranged from 9.8% in South-East Asia to 27.2% in the Americas. In adults, the EPP of myopia, hyperopia, and astigmatism was 26.5% (95% CI: 23.4–29.6), 30.9% (95% CI: 26.2–35.6), and 40.4% (95% CI: 34.3–46.6), respectively. The EPP of myopia ranged from 16.2% (95% CI: 15.6–16.8) in the Americas to 32.9% (95% CI: 25.1–40.7) in South-East Asia, the EPP of hyperopia ranged from 23.1% (95% CI: 6.1%–40.2%) in Europe to 38.6% (95% CI: 22.4–54.8) in Africa and 37.2% (95% CI: 25.3–49) in the Americas, and the EPP of astigmatism ranged from 11.4% (95% CI: 2.1–20.7) in Africa to 45.6% (95% CI: 44.1–47.1) in the Americas and 44.8% (95% CI: 36.6–53.1) in South-East Asia. The results of meta-regression showed that the prevalence of myopia increased from 1993 (10.4%) to 2016 (34.2%) (P = 0.097).
Conclusion
This report showed that astigmatism was the most common refractive errors in children and adults followed by hyperopia and myopia. The highest prevalence of myopia and astigmatism was seen in South-East Asian adults. The highest prevalence of hyperopia in children and adults was seen in the Americas.
Social signals are identified through processing in sensory systems to trigger appropriate behavioral responses. Social signals are received primarily in most mammals through the olfactory system. Individuals are recognized based on their unique blend of odorants. Such individual recognition is critical to distinguish familiar conspecifics from intruders and to recognize offspring. Social signals can also trigger stereotyped responses like mating behaviors. Specific sensory pathways for individual recognition and eliciting stereotyped responses have been identified both in the early olfactory system and its connected cortices. Oxytocin is emerging as a major state modulator of sensory processing with distinct functions in early and higher olfactory brain regions. The brain state induced through Oxytocin influences social perception. Oxytocin acting on different brain regions can promote either exploration and recognition towards same- or other-sex conspecifics, or association learning. Region-specific deletion of Oxytocin receptors suffices to disrupt these behaviors. Together, these recent insights highlight that Oxytocin’s function in social behaviors cannot be understood without considering its actions on sensory processing.
Primate trichromatic colour vision has been hypothesized to be well tuned for detecting variation in facial coloration, which could be due to selection on either signal wavelengths or the sensitivities of the photoreceptors themselves. We provide one of the first empirical tests of this idea by asking whether, when compared with other visual systems, the information obtained through primate trichromatic vision confers an improved ability to detect the changes in facial colour that female macaque monkeys exhibit when they are proceptive. We presented pairs of digital images of faces of the same monkey to human observers and asked them to select the proceptive face. We tested images that simulated what would be seen by common catarrhine trichromatic vision, two additional trichromatic conditions and three dichromatic conditions. Performance under conditions of common catarrhine trichromacy, and trichromacy with narrowly separated LM cone pigments (common in female platyrrhines), was better than for evenly spaced trichromacy or for any of the dichromatic conditions. These results suggest that primate trichromatic colour vision confers excellent ability to detect meaningful variation in primate face colour. This is consistent with the hypothesis that social information detection has acted on either primate signal spectral reflectance or photoreceptor spectral tuning, or both.
Significance
In the perpetual race between evolving organisms and pathogens, the human immune system has evolved to reduce the harm of infections. As part of such a system, avoidance of contagious individuals would increase biological fitness. The present study shows that we can detect both facial and olfactory cues of sickness in others just hours after experimental activation of their immune system. The study further demonstrates that multisensory integration of these olfactory and visual sickness cues is a crucial mechanism for how we detect and socially evaluate sick individuals. Thus, by motivating the avoidance of sick conspecifics, olfactory–visual cues, both in isolation and integrated, may be important parts of circuits handling imminent threats of contagion.
Primate color vision is based on two to three cone types in the retina, each expressing a different class of visual pigment, making them the only mammals that possess trichromacy. These pigment classes are the short wavelength-sensitive (SWS1) pigment and the long wavelength-sensitive (LWS) pigment, orthologues of the same pigments found in many other vertebrates, as well as the middle wavelength-sensitive (MWS) pigment, a paralogue to the LWS pigment. Trichromacy was achieved differently in Old World and New World primates. In Old World primates, a duplication of the LWS opsin gene occurred giving rise to a “red-sensitive” or L pigment and a “green-sensitive” or M pigment. Their corresponding L and M genes are adjacent on the X chromosome which, together with their high sequence homology, is the underlying cause for the high frequency of red-green color blindness seen in humans. In New World primates and prosimians, however, the mechanism leading to trichromacy, with one exception, is based on a single polymorphic LWS gene, from which different allelic variants encode pigments with differing spectral peaks. X chromosome inactivation limits expression to just one gene per photoreceptor meaning that trichromacy is only seen in females; while all male are red-green color blind. Despite several leading hypotheses, the reasons for the different evolutionary paths taken by Old and New World primates for trichromacy are still unclear and remain to be confirmed.
Social factors play a critical role in a panoply of health processes, including, as recently demonstrated, olfaction. Here, we investigated sex-dependent differences in the relationship between social lives and ability to identify odors in a large sample of nationally representative older US adults (n = 3005, National Social Life and Aging Project (NSHAP)). Social life was measured by the number of friends and close relatives as well as frequency of socializing. We here confirm the association between social lives and olfactory function and extend the notion by showing specifically that olfactory identification ability is modulated by sex in older adults. The connection between olfactory performance and social lives could reflect social modulation of aging as has been reported for health in general. Future studies are necessary to elucidate the precise mechanisms underlying this association and sex difference.
People with low-income often experience higher exposures to air pollutants. We compared the exposure to particulate matter (PM1, PM2.5 and PM10), Black Carbon (BC) and ultrafine particles (PNC; 0.02-1 µm) for typical commutes by car, bus and underground from 4 London areas with different levels of income deprivation (G1 to G4, from most to least deprived). The highest BC and PM concentrations were found in G1 while the highest PNC in G3. Lowest concentrations for all pollutants were observed in G2. We found no systematic relationship between income deprivation and pollutant concentrations, suggesting that differences between transport modes are a stronger influence. The underground showed the highest PM concentrations, followed by buses and a much lower concentrations in cars. BC concentrations in the underground were overestimated due to Fe interference. BC concentrations were also higher in buses than cars because of a lower infiltration of outside pollutants into the car cabin. PNCs were highest in buses, closely followed by cars, but lowest in underground due to the absence of combustion sources. Concentration in the road modes (car and bus) were governed by the traffic conditions (such as traffic flow interruptions) at the specific road section. Exposures were reduced in trains with non-openable windows compared to those with openable windows. People from lower income deprivation areas have a predominant use of car, receiving the lowest doses (RDD<1 µg h-1) during commute but generating the largest emissions per commuter. Conversely, commuters from higher income deprivation areas have a major reliance on the bus, receiving higher exposures (RDD between 1.52-3.49 µg h-1) while generating less emissions per person. These findings suggest an aspect of environmental injustice and a need to incorporate the socioeconomic dimension in life-course exposure assessments.
Facial color varies depending on emotional state, and emotions are often described in relation to facial color. In this study, we investigated whether the recognition of facial expressions was affected by facial color and vice versa. In the facial expression task, expression morph continua were employed: fear-anger and sadness-happiness. The morphed faces were presented in three different facial colors (bluish, neutral, and reddish color). Participants identified a facial expression between the two endpoints (e.g., fear or anger) regardless of its facial color. The results showed that the perception of facial expression was influenced by facial color. In the fear-anger morphs, intermediate morphs of reddish-colored and bluish colored faces had a greater tendency to be identified as angry faces and fearful faces, respectively. In the facial color task, two bluish-to-reddish colored face continua were presented in three different facial expressions (fear-neutral-anger and sadness-neutral-happiness). Participants judged whether the facial color was reddish or bluish regardless of its expression. The faces with sad expression tended to be identified as more bluish, while the faces with other expressions did not affect facial color judgment. These results suggest that an interactive but disproportionate relationship exists between facial color and expression in face perception.
Food choice and food intake are guided by both sensory and metabolic processes. The senses of taste and smell play a key role in the sensory effects on choice and intake. This article provides a comprehensive overview of, and will argue for, the differential role of smell and taste for eating behavior by focusing on appetite, choice, intake, and satiation.
The sense of smell mainly plays a priming role in eating behavior. It has been demonstrated that (orthonasal) odor exposure induces appetite specifically for the cued food. However, the influence of odors on food choice and intake is less clear, and may also depend on awareness or intensity of the odors, or personality traits of the participants. Taste on the other hand, has a clear role as a (macro)nutrient sensing system, during consumption. Together with texture, taste is responsible for eating rate, and thus in determining the oral exposure duration of food in the mouth, thereby contributing to satiation.
Results from these experimental studies should be taken to real-life situations, to assess longer-term effects on energy intake. With this knowledge, it will be possible to steer people’s eating behavior, as well as food product development, toward a less obesogenic society.
Americans live three years less than their counterparts in France or Sweden. Scottish men survive two years less than English men. Across Europe, women in the poorest communities live up to ten years less than those in the richest. Revealing gaps in life expectancy of up to 25 years between places just a few miles apart, this important book demonstrates that where you live can kill you.
Clare Bambra, a leading expert in public health, draws on case studies from across the globe to examine the social, environmental, economic and political causes of these health inequalities, how they have evolved over time and what they are like today.
Bambra concludes by considering how health divides might develop in the future and what should be done, so that where you live is not a matter of life and death.
Danny Dorling provides a foreword. - See more at: https://policypress.co.uk/health-divides#sthash.Y9Veeiqv.dpuf
Non-human primates evaluate food quality based on brightness of red and green shades of color, with red signaling higher energy or greater protein content in fruits and leafs. Despite the strong association between food and other sensory modalities, humans, too, estimate critical food features, such as calorie content, from vision. Previous research primarily focused on the e ects of color on taste/ avor identi cation and intensity judgments. However, whether evaluation of perceived calorie content
and arousal in humans are biased by color has received comparatively less attention. In this study we showed that color content of food images predicts arousal and perceived calorie content reported when viewing food even when confounding variables were controlled for. Speci cally, arousal positively co-varied with red-brightness, while green-brightness was negatively associated with arousal and perceived calorie content. This result holds for a large array of food comprising of natural food - where color likely predicts calorie content - and of transformed food where, instead, color is poorly diagnostic of energy content. Importantly, this pattern does not emerged with nonfood items. We conclude that in humans visual inspection of food is central to its evaluation and seems to partially engage the same basic system as non-human primates.
This article begins with a review and synthesis of some of the key theories, scholars, case examples, debates, methods, and (multiple) interpretations of environmental justice (EJ), as well as its expansion and globalization. We then look to some newly emerging themes, actions, and strategies for EJ and just sustainabilities. First, we look at the practices and materials of everyday life, illustrated by food and energy movements; second, the ongoing work on community and the importance of identity and attachment, informed by urban planning, food, and climate concerns; third, the growing interest in the relationship between human practices and communities and nonhuman nature. We also expand on the longstanding interest in just sustainabilities within this movement, illustrated by a wide range of concerns with food, energy, and climate justice. These new areas of work illustrate both recent developments and a set of paths forward for both the theory and practice of EJ. Expected final online publication date for the Annual Review of Environment and Resources Volume 41 is October 17, 2016. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
The U.S. NHANES included chemosensory assessments in the 2011–2014 protocol. We provide an overview of this protocol and 2012 olfactory exam findings. Of the 1818 NHANES participants aged ≥40 years, 1281 (70.5 %) completed the exam; non-participation mostly was due to time constraints. Health technicians administered an 8-item, forced-choice, odor identification task scored as normosmic (6–8 odors identified correctly) versus olfactory dysfunction, including hyposmic (4–5 correct) and anosmic/severe hyposmic (0–3 correct). Interviewers recorded self-reported smell alterations (during past year, since age 25, phantosmia), histories of sinonasal problems, xerostomia, dental extractions, head or facial trauma, and chemosensory-related treatment and changes in quality of life. Olfactory dysfunction was found in 12.4 % (13.3 million adults; 55 % males/45 % females) including 3.2 % anosmic/severe hyposmic (3.4 million; 74 % males/26 % females). Selected age-specific prevalences were 4.2 % (40–49 years), 12.7 % (60–69 years), and 39.4 % (80+ years). Among adults ≥70 years, misidentification rates for warning odors were 20.3 % for smoke and 31.3 % for natural gas. The highest sensitivity (correctly identifying dysfunction) and specificity (correctly identifying normosmia) of self-reported olfactory alteration was among anosmics/severe hyposmics (54.4 % and 78.1 %, respectively). In age- and sex-adjusted logistic regression analysis, risk factors of olfactory dysfunction were racial/ethnic minority, income-to-poverty ratio ≤ 1.1, education <high school, and heavy drinking. Moderate-to-vigorous physical activity reduced risk of impairment. Olfactory dysfunction is prevalent, particularly among older adults. Inexpensive, brief odor identification tests coupled with questions (smell problems past year, since age 25, phantosmia) could screen for marked dysfunction. Healthcare providers should be prepared to offer education on non-olfactory avoidance of hazardous events.
The exhibition of increasingly intensive and complex niche construction behaviors through time is a key
feature of human evolution, culminating in the advanced capacity for ecosystem engineering exhibited by
Homo sapiens. A crucial outcome of such behaviors has been the dramatic reshaping of the global biosphere,
a transformation whose early origins are increasingly apparent from cumulative archaeological and
paleoecological datasets. Such data suggest that, by the Late Pleistocene, humans had begun to engage in
activities that have led to alterations in the distributions of a vast array of species across most, if not all,
taxonomic groups. Changes to biodiversity have included extinctions, extirpations, and shifts in species
composition, diversity, and community structure. We outline key examples of these changes, highlighting
findings from the study of new datasets, like ancient DNA (aDNA), stable isotopes, and microfossils, as
well as the application of new statistical and computational methods to datasets that have accumulated
significantly in recent decades. We focus on four major phases that witnessed broad anthropogenic
alterations to biodiversity—the Late Pleistocene global human expansion, the Neolithic spread of agriculture,
the era of island colonization, and the emergence of early urbanized societies and commercial networks.
Archaeological evidence documents millennia of anthropogenic transformations that have created
novel ecosystems around the world. This record has implications for ecological and evolutionary research,
conservation strategies, and the maintenance of ecosystem services, pointing to a significant need for
broader cross-disciplinary engagement between archaeology and the biological and environmental sciences.
Human beings continuously emit chemicals into the air by breath and through the skin. In order to determine whether these emissions vary predictably in response to audiovisual stimuli, we have continuously monitored carbon dioxide and over one hundred volatile organic compounds in a cinema. It was found that many airborne chemicals in cinema air varied distinctively and reproducibly with time for a particular film, even in different screenings to different audiences. Application of scene labels and advanced data mining methods revealed that specific film events, namely “suspense” or “comedy” caused audiences to change their emission of specific chemicals. These event-type synchronous, broadcasted human chemosignals open the possibility for objective and non-invasive assessment of a human group response to stimuli by continuous measurement of chemicals in air. Such methods can be applied to research fields such as psychology and biology, and be valuable to industries such as film making and advertising.
Hearing loss is the third most common chronic physical condition in the United States, and is more prevalent than diabetes or cancer (1). Occupational hearing loss, primarily caused by high noise exposure, is the most common U.S. work-related illness (2). Approximately 22 million U.S. workers are exposed to hazardous occupational noise (3). CDC compared the prevalence of hearing impairment within nine U.S. industry sectors using 1,413,789 noise-exposed worker audiograms from CDC's National Institute for Occupational Safety and Health (NIOSH) Occupational Hearing Loss Surveillance Project (4). CDC estimated the prevalence at six hearing impairment levels, measured in the better ear, and the impact on quality of life expressed as annual disability-adjusted life years (DALYs), as defined by the 2013 Global Burden of Disease (GBD) Study (5). The mining sector had the highest prevalence of workers with any hearing impairment, and with moderate or worse impairment, followed by the construction and manufacturing sectors. Hearing loss prevention, and early detection and intervention to avoid additional hearing loss, are critical to preserve worker quality of life.
Purpose:
Myopia is a common cause of vision loss, with uncorrected myopia the leading cause of distance vision impairment globally. Individual studies show variations in the prevalence of myopia and high myopia between regions and ethnic groups, and there continues to be uncertainty regarding increasing prevalence of myopia.
Design:
Systematic review and meta-analysis.
Methods:
We performed a systematic review and meta-analysis of the prevalence of myopia and high myopia and estimated temporal trends from 2000 to 2050 using data published since 1995. The primary data were gathered into 5-year age groups from 0 to ≥100, in urban or rural populations in each country, standardized to definitions of myopia of -0.50 diopter (D) or less and of high myopia of -5.00 D or less, projected to the year 2010, then meta-analyzed within Global Burden of Disease (GBD) regions. Any urban or rural age group that lacked data in a GBD region took data from the most similar region. The prevalence data were combined with urbanization data and population data from United Nations Population Department (UNPD) to estimate the prevalence of myopia and high myopia in each country of the world. These estimates were combined with myopia change estimates over time derived from regression analysis of published evidence to project to each decade from 2000 through 2050.
Results:
We included data from 145 studies covering 2.1 million participants. We estimated 1406 million people with myopia (22.9% of the world population; 95% confidence interval [CI], 932-1932 million [15.2%-31.5%]) and 163 million people with high myopia (2.7% of the world population; 95% CI, 86-387 million [1.4%-6.3%]) in 2000. We predict by 2050 there will be 4758 million people with myopia (49.8% of the world population; 3620-6056 million [95% CI, 43.4%-55.7%]) and 938 million people with high myopia (9.8% of the world population; 479-2104 million [95% CI, 5.7%-19.4%]).
Conclusions:
Myopia and high myopia estimates from 2000 to 2050 suggest significant increases in prevalences globally, with implications for planning services, including managing and preventing myopia-related ocular complications and vision loss among almost 1 billion people with high myopia.
Background:
Olfactory loss is a challenging clinical problem with few proven therapeutic options. Early experimental results with olfactory training suggest that this novel therapy may be an effective intervention for olfactory dysfunction of multiple etiologies. The aim of this study was to systematically review currently available studies that assess the efficacy and outcomes of olfactory training in patients with olfactory loss.
Methods:
A comprehensive systematic literature review was performed with the assistance of a reference librarian using the PubMed, PsycInfo, Google Scholar, EMBASE, and Proquest databases. Eligible studies were extracted based on defined inclusion criteria and the effect of olfactory training on objective olfactory function was evaluated qualitatively and by meta-analysis.
Results:
A total of 10 studies with 639 patients were identified and systematically reviewed. Sufficient data for meta-analysis was available for 3 studies. Patients receiving olfactory training experienced a statistically significant improvement in the Threshold, Discrimination, Identification (TDI) score compared to control patients (mean difference [MD] 3.77; 95% confidence interval [CI], 2.28 to 5.26). Improvement in olfactory function was observed in discrimination (MD 1.92; 95% CI, 1.13 to 2.71) and identification (MD 1.61; 95% CI, 0.55 to 2.68), but not in olfactory thresholds (MD -0.01; 95% CI, -0.42 to 0.39).
Conclusion:
Olfactory training is a promising modality for the treatment of olfactory dysfunction. Results of this systematic review and meta-analysis suggest that it may be an effective treatment for olfactory dysfunction due to multiple etiologies. Additional high-quality studies are needed to define indications, outcomes, and duration of therapy for this novel therapy.
Perception and evaluation of objects are highly dependent on surrounding contexts. Threatening contexts enhance processing of faces. Because odors are assumed to deliver strong contextual information, the present study aimed at demonstrating 1) that odors can constitute threat and safety contexts, and 2) consequently modulate the processing of faces presented in these contexts. Therefore, previously neutral odors were used as contextual stimuli in a context conditioning paradigm, resulting in an olfactory anxiety and a safety context. Then, faces showing angry, neutral, or fearful expressions were presented within both contexts during a test phase to investigate the effects of threat versus safety contexts on face perception. The late positive potential (LPP) from the EEG, skin conductance level, and subjective ratings were recorded. Results reveal successful olfactory context conditioning as reflected in enhanced processing of the anxiety context, indicated by enhanced LPP after conditioning, increased skin conductance level, and marginally respectively increased ratings. Moreover, faces presented within the threat context were rated as more unpleasant and marginally more arousing than faces presented in the safety context. Thus, olfactory stimuli can serve as context in fear conditioning, and a threatening olfactory context seems to enhance processing of stimuli perceived within this context.
Chemosensory problems challenge health through diminished ability to detect warning odors, consume a healthy diet, and maintain quality of life. We examined the prevalence and associated risk factors of self-reported chemosensory alterations in 3603 community-dwelling adults (aged 40+ years), from the nationally representative, US National Health and Nutrition Examination Survey (NHANES) 2011-2012. In this new NHANES component, technicians surveyed adults in the home about perceived smell and taste problems, distortions, and diminished abilities since age 25 (termed "alterations"), and chemosensory-related health risks and behaviors. The prevalence of self-reported smell alteration was 23%, including phantosmia at 6%; taste was 19%, including dysgeusia at 5%. Prevalence rates increased progressively with age, highest in those aged 80+ years (smell, 32%; taste, 27%). In multivariable logistic regression, controlling for sociodemographics, health behaviors, and chemosensory-related conditions, the strongest independent risk factor for smell alteration was sinonasal symptoms (odds ratio [OR] = 2.06; 95% confidence interval [CI]: 1.63-2.61), followed by heavy drinking, loss of consciousness from head injury, family income ≤110% poverty threshold, and xerostomia. For taste, the strongest risk factor was xerostomia (OR = 2.65; 95% CI: 1.97-3.56), followed by nose/facial injury, lower educational attainment, and fair/poor health. Self-reported chemosensory alterations are prevalent in US adults, supporting increased attention to decreasing their modifiable risks, managing safety/health consequences, and expanding chemosensory screening/testing and treatments.
Importance:
Myopia has reached epidemic levels in parts of East and Southeast Asia. However, there is no effective intervention to prevent the development of myopia.
Objective:
To assess the efficacy of increasing time spent outdoors at school in preventing incident myopia.
Design, setting, and participants:
Cluster randomized trial of children in grade 1 from 12 primary schools in Guangzhou, China, conducted between October 2010 and October 2013.
Interventions:
For 6 intervention schools (n = 952 students), 1 additional 40-minute class of outdoor activities was added to each school day, and parents were encouraged to engage their children in outdoor activities after school hours, especially during weekends and holidays. Children and parents in the 6 control schools (n = 951 students) continued their usual pattern of activity.
Main outcomes and measures:
The primary outcome measure was the 3-year cumulative incidence rate of myopia (defined using the Refractive Error Study in Children spherical equivalent refractive error standard of ≤-0.5 diopters [D]) among the students without established myopia at baseline. Secondary outcome measures were changes in spherical equivalent refraction and axial length among all students, analyzed using mixed linear models and intention-to-treat principles. Data from the right eyes were used for the analysis.
Results:
There were 952 children in the intervention group and 951 in the control group with a mean (SD) age of 6.6 (0.34) years. The cumulative incidence rate of myopia was 30.4% in the intervention group (259 incident cases among 853 eligible participants) and 39.5% (287 incident cases among 726 eligible participants) in the control group (difference of -9.1% [95% CI, -14.1% to -4.1%]; P < .001). There was also a significant difference in the 3-year change in spherical equivalent refraction for the intervention group (-1.42 D) compared with the control group (-1.59 D) (difference of 0.17 D [95% CI, 0.01 to 0.33 D]; P = .04). Elongation of axial length was not significantly different between the intervention group (0.95 mm) and the control group (0.98 mm) (difference of -0.03 mm [95% CI, -0.07 to 0.003 mm]; P = .07).
Conclusions and relevance:
Among 6-year-old children in Guangzhou, China, the addition of 40 minutes of outdoor activity at school compared with usual activity resulted in a reduced incidence rate of myopia over the next 3 years. Further studies are needed to assess long-term follow-up of these children and the generalizability of these findings.
Trial registration:
clinicaltrials.gov Identifier: NCT00848900.
Background:
Disparities in exposure to air pollution by race-ethnicity and by socioeconomic status have been documented in the United States, but the impacts of declining transportation-related air pollutant emissions on disparities in exposure have not been studied in detail.
Objective:
This study was designed to estimate changes over time (2000 to 2010) in disparities in exposure to outdoor concentrations of a transportation-related air pollutant, nitrogen dioxide (NO2), in the United States.
Methods:
We combined annual average NO2 concentration estimates from a temporal land use regression model with Census demographic data to estimate outdoor exposures by race-ethnicity, socioeconomic characteristics (income, age, education), and by location (region, state, county, urban area) for the contiguous United States in 2000 and 2010.
Results:
Estimated annual average NO2 concentrations decreased from 2000 to 2010 for all of the race-ethnicity and socioeconomic status groups, including a decrease from 17.6 ppb to 10.7 ppb (-6.9 ppb) in nonwhite [non-(white alone, non-Hispanic)] populations, and 12.6 ppb to 7.8 ppb (-4.7 ppb) in white (white alone, non-Hispanic) populations. In 2000 and 2010, disparities in NO2 concentrations were larger by race-ethnicity than by income. Although the national nonwhite-white mean NO2 concentration disparity decreased from a difference of 5.0 ppb in 2000 to 2.9 ppb in 2010, estimated mean NO2 concentrations remained 37% higher for nonwhites than whites in 2010 (40% higher in 2000), and nonwhites were 2.5 times more likely than whites to live in a block group with an average NO2 concentration above the WHO annual guideline in 2010 (3.0 times more likely in 2000).
Conclusions:
Findings suggest that absolute NO2 exposure disparities by race-ethnicity decreased from 2000 to 2010, but relative NO2 exposure disparities persisted, with higher NO2 concentrations for nonwhites than whites in 2010. https://doi.org/10.1289/EHP959.
The auditory system of nonhuman primates shows evidence of many similarities to humans, such as specializations for the processing of vocalizations overall, processing species-specific vocalizations in particular, and in some cases, the recognition of specific individuals based on call structure. Additionally, nonhuman primates are similar to humans in their excellent localization acuity. Nonhuman primates show differences from humans, though, and not only in the subtleties of the aforementioned abilities. With respect to overall auditory sensitivity, primates have traditionally been portrayed as unspecialized, although there is variation between species. Species in the semiorder Strepsirrhini are, on average, more adept at detecting higher frequencies, whereas the Haplorhini are, on average, more adept at detecting lower frequencies. In addition, a well-supported allometric model explains that smaller headed species with smaller interaural distances need to utilize high-frequency cues for sound localization. Overall auditory sensitivity, particularly to high frequencies, also has been related to increased sociality in some primates. The lack of identification of additional broad trends and relationships between audition and ecology may be partially attributed to the limited dataset, which lacks representation from several major taxonomic subgroups. Additionally, order-wide trends may be minimal given the many possible reasons why enhanced or reduced sensitivity to certain frequency regions may be beneficial for different species. These are just a few of the many facets of primate audition that need to be explored in more depth through additional data gathered via continually evaluated and refined methodologies.
The primate peripheral auditory organ closely resembles that of other terrestrial mammals. Acoustic communication has an important role in primate communities, and hearing characteristics are well-known for several species. In this chapter, morphological variation of the primate outer, middle, and inner ears is reviewed and is related to auditory data known from experimental work. Differences can be discerned among various primate groups, the greatest differences being between small, mainly nocturnal strepsirrhines and larger, mainly diurnal haplorhines. The evolutionary history of primate hearing is discussed in relation to different hypotheses of primate origins with the view that, as in the earliest mammals, the earliest primates were nocturnal and had good high-frequency hearing. Increased sensitivity to lower frequencies evolved later, although relatively early in the history of primates. This was made possible by an elongation of the cochlea and the disappearance of the secondary spiral lamina. The body size and ecology of primates is related to their ear size, and the role of hearing together with other sensory modalities, mainly vision and olfaction, is discussed.
This chapter outlines the evolution of auditory capacities during the course of human evolution and the implications for understanding when human language may have evolved. These findings are considered within the context of habitat acoustics, the mathematical theory of communication, and the frame/content theory of speech production. Compared to chimpanzees, the auditory pattern in the early hominin taxa Australopithecus and Paranthropus show a heightened sensitivity between 1.0 and 3.5 kHz but a similarly narrow bandwidth of maximum sensitivity. The early hominin auditory pattern may have facilitated short-range communication in open habitats, but their communication pattern apparently did not involve transmission of information beyond that of a chimpanzee. The early hominins likely were restricted to the frame stage of speech production, a phoneme-based, presyntactic form of communication with only limited word formation. In contrast, the Middle Pleistocene Atapuerca Sima de los Huesos (SH) hominins resemble H. sapiens in showing a broad region of heightened sensitivity between 1 and 5 kHz and a wider bandwidth of maximum sensitivity that is extended toward higher frequencies. The wider bandwidth in the Atapuerca (SH) hominins facilitated specialization in the use of complex, short-range vocal communication, including an emphasis on high-frequency consonant production and increased word formation. The Atapuerca (SH) hominins, then, may have been on the threshold of passing into the frame/content stage of speech production. The evolution of auditory capacities is consistent with the presence of some form of spoken language in the genus Homo prior to the appearance of H. sapiens.
Humans have a good sense of smell
In comparison to that of other animals, the human sense of smell is widely considered to be weak and underdeveloped. This is, however, an unproven hypothesis. In a Review, McGann traces the origins of this false belief back to comparative 19th-century neuroanatomical studies by Broca. A modern look at the human olfactory bulb shows that it is rather large compared with those of rats and mice, which are presumed to possess a superior sense of smell. In fact, the number of olfactory bulb neurons across 24 mammalian species is comparatively similar, with humans in the middle of the pack, and our sense of smell is similar to that of other mammals.
Science , this issue p. eaam7263
1 The olfactory system of vertebrates.- 1.1 Anatomy.- 1.2 Odorant characteristics.- 1.3 Function of the external nares and related structures.- 1.4 Evolutionary trends.- 1.5 Summary.- 2 Sources and chemistry of vertebrate scent.- 2.1 The sites of odour production.- 2.2 Chemical composition of odorants.- 2.3 Threshold levels of perception.- 3 Detection of food.- 3.1 Responses of young to food odours.- 3.2 The detection of plant food by odorous cues.- 3.3 The detection of animal food by odorous cues.- 3.4 Scavengers.- 3.5 Quasi-parasites.- 3.6 Summary.- 4 Reproductive processes.- 4.1 Sex attraction and recognition the advertisement of sexual status.- 4.2 Detection and induction of oestrus, ovulation and lordosis.- 4.3 Courtship, mating and related behaviours.- 4.4 Pregnancy.- 4.5 Parental behaviour imprinting.- 4.6 Growth physical and psychosexual development.- 4.7 Summary and conclusions.- 5 Odour discrimination and species isolation.- 5.1 Individual odour.- 5.2 Family, population and racial odours.- 5.3 Species odours and sexual isolation.- 5.4 Summary and conclusions.- 6 Dispersion and social integration.- 6.1 Intraspecific aggression.- 6.2 The social hierarchy.- 6.3 Territoriality.- 6.4 Correlation between aggression-motivated behaviour and scent deposition.- 6.5 Summary and conclusions.- 7 Alarm and defence.- 7.1 Detection of the predator.- 7.2 Transmission of alarm or warning signals.- 7.3 Active defence.- 7.4 Protection from intraspecific attack.- 7.5 Summary.- 8 Olfactory navigation and orientation.- 8.1 Olfactory navigation.- 8.2 Homing orientation.- 8.3 Summary.- 9 Applications of researches into olfactory biology.- 9.1 Pest repellents and attractants.- 9.2 Animal husbandry.- 9.3 Miscellaneous applications.- References.- Taxonomie index.
How does a person's smell affect others' impressions of them? Most body odor research asks perceivers to make social judgments based on armpit sweat without perfume or deodorant, presented on t-shirts. Yet, in real life, perceivers encounter fragranced body odor, on whole bodies. Our "raters" wore blindfolds and earplugs and repeatedly smelled same-sex "donors" in live interactions. In one condition, donors wore their normal deodorant and perfume ("diplomatic" odor) while in the other condition, donors were asked to avoid all outside fragrance influences ("natural" odor). We assessed the reliability of social judgments based on such live interactions, and the relationships between live judgments and traditional t-shirt based judgments, and between natural- and diplomatic odor-based judgments. Raters' repeated live social judgments (e.g., friendliness, likeability) were highly consistent for both diplomatic and natural odor, and converged with judgments based on t-shirts. However, social judgments based on natural odor did not consistently predict social judgments based on diplomatic odor, suggesting that natural and diplomatic body odor may convey different types of social information. Our results provide evidence that individuals can perceive reliable, meaningful social olfactory signals from whole bodies, at social distances, regardless of the presence or absence of perfume. Importantly, however, the social value of these signals is modified by the addition of exogenous fragrances. Further, our focus on judgments in same-sex dyads suggests that these olfactory cues hold social value in non-mating contexts. We suggest that future research employ more ecologically relevant methods.
Low birthweight is now known to be associated with increased rates of coronary heart disease and the related disorders stroke, hypertension and non-insulin dependent diabetes. These associations have been extensively replicated in studies in different countries and are not the result of confounding variables. They extend across the normal range of birthweight and depend on lower birthweights in relation to the duration of gestation rather than the effects of premature birth. The associations are thought to be consequences of developmental plasticity, the phenomenon by which one genotype can give rise to a range of different physiological or morphological states in response to different environmental conditions during development. Recent observations have shown that impaired growth in infancy and rapid childhood weight gain exacerbate the effects of impaired prenatal growth. A new vision of optimal early human development is emerging which takes account of both short and long-term outcomes.
Purpose:
To evaluate the global patterns in health burden of uncorrected refractive error (URE) by year, age and sex, region, and socioeconomic status, using disability-adjusted life years (DALYs).
Methods:
Global, regional, or national DALY numbers, crude DALY rates, and age-standardized DALY rates caused by URE, by year, or age and sex, were obtained from the Global Burden of Disease Study 2013. Human development index (HDI) in 2013 as a national socioeconomic indicator was obtained from the Human Development Report. Kruskal-Wallis test and linear regression were performed to explore the association between age-standardized DALY rates and HDI.
Results:
From 1990 to 2013, global DALY numbers caused by URE rose by 43.8%, crude rates remained relatively constant, and age-standardized rates fell by 8.8%. Global DALY rates increased with age, and older females had higher DALY numbers and rates than males of the same age. Age-standardized DALY rates in Eastern Mediterranean, South-East Asia, and Africa were higher than that at a global level. Multiple comparisons indicated higher age-standardized DALY rates in lower HDI countries. Age-standardized DALY rates were inversely related to HDI (standardized β = -0.616, P < 0.001).
Conclusions:
The global health of URE is improving but crude DALY rates are keeping constant, implying that health progress does not mean fewer demands of refractive services. Worldwide, older age, female sex, and lower socioeconomic status are associated with higher URE burden. The findings of this study may raise public awareness of the global URE burden and are important for health policy making.
Olfactory signals, often in synergy with visual signals, mediate the interactions between plants and animals. However, urbanization and agricultural practices are both sources of volatile organic compounds ( VOC s) and reactive oxygen species ( ROS ) that have the potential to interfere with plant–animal communication and to disrupt mutualistic interactions. In this review, we explore how anthropogenic airborne pollutants may disrupt chemical information transfer between flowering plants and flower visitors.
The emission of anthropogenic volatile pollutants ( AVP s) including VOC s and formation of ROS , for example from traffic or industries, and non‐natural biogenic VOC s, for example from introduced crops, may have a number of effects: (i) changes in plant signalling as a consequence of plants experiencing physiological stress; (ii) chemical interference (chemical degradation/transformation of infochemicals); (iii) increased levels of background noise impeding signal detection; and (iv) changes in pollinator signal perception and behaviour. All of the above in turn could have consequences for the biological fitness of plants and animals that rely on olfactory information as pivotal functional signals.
The study of anthropogenic airborne pollutants and their effects on plant signalling is just emerging and the impacts of this aspect of anthropogenic emissions are barely understood. Volatiles emitted from anthropogenically changed landscapes could, however, have far‐reaching consequences for ecosystem functioning in adjacent natural zones, particularly in fragmented landscapes. In response to the wide gap in our knowledge on the mechanisms that govern interference of anthropogenic VOC s with olfactory information, future research directions are proposed with the aim to inspire research to help elucidate the risks of anthropogenic VOC s for plant–pollinator communities and improve risk assessment strategies.
A lay summary is available for this article.
Aims
We investigated whether traffic-related air pollution and noise are associated with incident hypertension in European cohorts.
Methods and results
We included seven cohorts of the European study of cohorts for air pollution effects (ESCAPE). We modelled concentrations of particulate matter with aerodynamic diameter ≤2.5 µm (PM2.5), ≤10 µm (PM10), >2.5, and ≤10 µm (PMcoarse), soot (PM2.5 absorbance), and nitrogen oxides at the addresses of participants with land use regression. Residential exposure to traffic noise was modelled at the facade according to the EU Directive 2002/49/EC. We assessed hypertension as (i) self-reported and (ii) measured (systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg or intake of BP lowering medication (BPLM). We used Poisson regression with robust variance estimation to analyse associations of traffic-related exposures with incidence of hypertension, controlling for relevant confounders, and combined the results from individual studies with random-effects meta-analysis. Among 41 072 participants free of self-reported hypertension at baseline, 6207 (15.1%) incident cases occurred within 5–9 years of follow-up. Incidence of self-reported hypertension was positively associated with PM2.5 (relative risk (RR) 1.22 [95%-confidence interval (CI):1.08; 1.37] per 5 µg/m³) and PM2.5 absorbance (RR 1.13 [95% CI:1.02; 1.24] per 10 ⁻ ⁵m ⁻ ¹). These estimates decreased slightly upon adjustment for road traffic noise. Road traffic noise was weakly positively associated with the incidence of self-reported hypertension. Among 10 896 participants at risk, 3549 new cases of measured hypertension occurred. We found no clear associations with measured hypertension.
Conclusion
Long-term residential exposures to air pollution and noise are associated with increased incidence of self-reported hypertension.
Objectives:
The olfactory nerve is anatomically susceptible to injury from pollution in inspired air, but there are no large-scale epidemiologic studies investigating this relationship.
Methods:
Cross-sectional study using data from the National Social Life, Health, and Aging Project, a representative sample of home-dwelling US adults age 57-85 years. Olfactory function was tested using a validated 5-item odor identification test (Sniffin' Sticks). Exposure to fine particulate matter (PM2.5) at each respondent's home was estimated as 1-12 month moving averages prior to olfactory assessment using validated spatio-temporal models.
Results:
Olfactory dysfunction was significantly associated with PM2.5 exposures averaged over 3-12 months in urban-dwelling respondents. The strongest effect was for 6 month average exposure (per 1-IQR increase in PM2.5: OR 1.28, 95% CI 1.05, 1.55) adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and the season. Interestingly, the most deleterious effects were observed among the youngest respondents, 57-64 years old, and those living in the northeast and south.
Conclusions:
We show for the first time that air pollution exposure is associated with poor olfaction among urban-living, older US adults.
Anthropogenic (man-made) noise is rapidly becoming an universal environmental feature. While the impacts of such additional noise on avian sexual signals are well documented, our understanding of its effect in other terrestrial taxa, on other vocalisations, and on receivers is more limited. Little is known, for example, about the influence of anthropogenic noise on responses to vocalisations relating to predation risk, despite the potential fitness consequences. We use playback experiments to investigate the impact of traffic noise on the responses of foraging dwarf mongooses (Helogale parvula) to surveillance calls produced by sentinels, individuals scanning for danger from a raised position whose presence usually results in reduced vigilance by foragers. Foragers exposed to surveillance calls in traffic-noise compared to ambient-noise playback exhibited a lessened response (increased personal vigilance). A second playback experiment, using noise playbacks without surveillance calls, suggests that the increased vigilance could arise in part from the direct influence of additional noise (the ‘increased threat hypothesis’) as there was an increase in response to traffic-noise playback alone. Acoustic masking could also play a role. Foragers maintained the ability to distinguish between sentinels of different dominant class, increasing personal vigilance when presented with subordinate surveillance calls compared to calls of a dominant groupmate in both noise treatments, suggesting complete masking was not occurring. However, a signal transmission experiment showed that surveillance calls were likely inaudible during periods of peak traffic, but audible during approaching traffic noise, thus reducing perceived call rate; in dwarf mongooses, lower surveillance-call rates are associated with higher risk situations, necessitating greater vigilance. While recent work has demonstrated detrimental effects of anthropogenic noise on defensive responses to actual predatory attacks, which are relatively rare, our results provide evidence of a potentially more widespread influence since animals should constantly assess background risk to optimise the foraging–vigilance trade-off.
From 1690 to 1800 texts printed in England linked racial difference and foul odour through understandings of occupation, food, cosmetics and sweat. Even by the end of the eighteenth-century racial odour was represented as a labile, culturally and environmentally determined characteristic. This article traces how the social ‘use’ of olfactory stereotypes, particularly their links with cosmetics, food, and odorous spaces, determined the mobilization of explanations for and attitudes to racial scent. It argues that ideas of race should not be considered monolithic or described in terms of narratives that posit a divide between the body/culture, but that racial stereotypes should be understood as collections of traits, of which smell was one, with distinctive histories.
Background:
Olfactory dysfunction affects millions of people worldwide. This sensory impairment is associated with neurodegenerative disease and significantly decreased quality of life. Exposure to airborne pollutants has been implicated in olfactory decline, likely due to the anatomic susceptibility of the olfactory nerve to the environment. Historically, studies have focused on occupational exposures, but more recently studies have considered effects from exposure to ambient-air pollutants.
Objectives:
To examine all relevant human data evaluating a link between ambient pollution exposure and olfaction, and to review supporting animal data in order to examine potential mechanisms for pollution-associated olfactory loss.
Methods:
We identified and reviewed relevant articles from 1950 to 2015 by using PubMed and Web of Science, focusing on human epidemiologic and pathophysiologic studies. Animal studies were included only to support pertinent data on humans. We reviewed findings from these studies evaluating a relationship between environmental pollutant exposure and olfactory function.
Results:
We identified 17 articles, with additional 1 article added from a bibliography search, for a total of 18 human studies reviewed. There is evidence in human epidemiologic and pathologic studies that increased exposure to ambient air pollutants is associated with olfactory dysfunction. However, most studies have used proxies for pollution exposure in small samples of convenience. Human pathologic studies, with supporting animal work, have also shown that air pollution can contact the olfactory epithelium, translocate to the olfactory bulb, and migrate to the olfactory cortex. Pollutants can deposit at each location, causing direct damage and disruption of tissue morphology, or inducing local inflammation and cellular stress responses.
Conclusions:
Ambient air pollution may impact human olfactory function. Additional studies are needed that examine air pollution-related olfactory impacts on the general population by use of measured pollution exposures, and that link pollution exposure with olfactory dysfunction and related pathology.
Olfaction is an important medium of social communication in humans. However, it is not known whether olfactory function is associated with social network size. This study aimed to explore the underlying neural mechanism between olfactory function and social network. Thirty-one healthy individuals participated in this study. Social network size was estimated using the Social Network Index. Olfactory function was assessed with the Sniffin’ Stick Test. The results showed that there is a significant positive correlation between the size of an individual’s social network and their olfactory sensitivity. We also found that amygdala functional connectivity with the orbitofrontal cortex appeared to be related to olfactory sensitivity and social network size.
Summary Oxytocin promotes social interactions and recognition of conspecifics that rely on olfaction in most species. The circuit mechanisms through which oxytocin modifies olfactory processing are incompletely understood. Here, we observed that optogenetically induced oxytocin release enhanced olfactory exploration and same-sex recognition of adult rats. Consistent with oxytocin’s function in the anterior olfactory cortex, particularly in social cue processing, region-selective receptor deletion impaired social recognition but left odor discrimination and recognition intact outside a social context. Oxytocin transiently increased the drive of the anterior olfactory cortex projecting to olfactory bulb interneurons. Cortical top-down recruitment of interneurons dynamically enhanced the inhibitory input to olfactory bulb projection neurons and increased the signal-to-noise of their output. In summary, oxytocin generates states for optimized information extraction in an early cortical top-down network that is required for social interactions with potential implications for sensory processing deficits in autism spectrum disorders.
Air pollution (indoors and outdoors) is a major issue in public health as epidemiological studies have highlighted its numerous detrimental health consequences (notably, respiratory and cardiovascular pathological conditions). Over the past 15years, air pollution has also been considered a potent environmental risk factor for neurological diseases and neuropathology. This review examines the impact of air pollution on children's brain development and the clinical, cognitive, brain structural and metabolic consequences. Long-term potential consequences for adults' brains and the effects on multiple sclerosis (MS) are also discussed. One challenge is to assess the effects of lifetime exposures to outdoor and indoor environmental pollutants, including occupational exposures: how much, for how long and what type. Diffuse neuroinflammation, damage to the neurovascular unit, and the production of autoantibodies to neural and tight-junction proteins are worrisome findings in children chronically exposed to concentrations above the current standards for ozone and fine particulate matter (PM2.5), and may constitute significant risk factors for the development of Alzheimer's disease later in life. Finally, data supporting the role of air pollution as a risk factor for MS are reviewed, focusing on the effects of PM10 and nitrogen oxides.
In the first half the twentieth century, fish odors created heated conflicts along the Monterey coastline. Few scholars in environmental history, however, have analyzed the significance of olfactory perceptions of the physical environment. This article examines two disputes in which odors became connected to larger power struggles over nature and society. The first conflict involved Chinese fishermen, whose squid-drying fields emitted unpleasant smells that precipitated a campaign to eliminate them. The second conflict emerged when the sardine factories along Cannery Row also created foul odors, prompting real estate developers and tourism-oriented politicians to take legal action. The debates over odors pitted tourism against fisheries and ultimately revealed Montereyans' divergent ideas about the types of people and activities that should shape the Pacific shoreline. © 2004 by the Pacific Coast Branch, American Historical Association. All rights reserved.