Robert A Canales

Robert A Canales
George Washington University | GW

MS MS PhD

About

62
Publications
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737
Citations
Introduction
• Ideas for research collaborations are welcome. • I am a team scientist, engineer, and data scientist conducting creative quantitative research in environmental health, environmental engineering, and public health. • I use applied mathematics and statistics in systems science, exposure reconstruction, and risk analysis.

Publications

Publications (62)
Article
Quantitative data on human-environment interactions are needed to fully understand infectious disease transmission processes and conduct accurate risk assessments. Interaction events occur during an individual's movement through, and contact with, the environment, and can be quantified using diverse methodologies. Methods that utilize videography,...
Article
Full-text available
Expanding agribusiness in Northern Mexico has increased demand for workers from Southern Mexico, with hundreds of thousands migrating for work annually. Extreme temperatures, physical labor, and low fluid consumption place workers at risk for heat strain and dehydration, commonly underreported hazards in the agricultural industry. The objectives of...
Article
Monitoring of environmental contaminants is a critical part of exposure sciences research and public health practice. Missing data are often encountered when performing short-term monitoring (<24 h) of air pollutants with real-time monitors, especially in resource-limited areas. Approaches for handling consecutive periods of missing and incomplete...
Article
Full-text available
Imidacloprid is a neonicotinoid insecticide commonly injected through agricultural drip irrigation systems to reduce the population of vine mealybugs (P. ficus) in grape farms. There is a growing concern of potential human health effects of imidacloprid, however, there is limited information on the exposure to imidacloprid in farm workers. Imidaclo...
Article
Demographic and clinical indicators have been described to support identification of coccidioidomycosis; however, the interplay of these conditions has not been explored in a clinical setting. In 2019, we enrolled 392 participants in a cross-sectional study for suspected coccidioidomycosis in emergency departments and inpatient units in Coccidioide...
Preprint
Objectives Studies suggest that body composition can be independently improved through physical activity (PA). We performed a Mendelian randomization (MR) study to test the incremental benefits of sedentary behavior and various physical activity (PA) exposures on body composition outcomes as assessed by anthropometric indices, lean body mass (LBM)...
Article
Full-text available
Background: Neighborhood-scale air pollution sampling methods have been used in a range of settings but not in low air pollution airsheds with extreme weather events such as volatile precipitation patterns and extreme summer heat and aridity-all of which will become increasingly common with climate change. The desert U.S. metropolis of Tucson, AZ,...
Article
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Background: There are growing health concerns about exposure to toxicants released from recycled tire rubber, which is commonly used in synthetic turf and playground mats. To better estimate children's exposure and risk from recycled tire rubber used in synthetic turf and playground mats, there is a need to collect detailed accurate information on...
Preprint
Demographic and clinical indicators have been described to support identification of coccidioidomycosis (CM); however, the interplay of these conditions has not been explored in a clinical setting. In 2019, we enrolled 392 participants in a cross-sectional study for suspected CM in emergency room and inpatient units within Coccidioides endemic regi...
Article
Full-text available
On August 5th, 2015, 3 million gallons of acid mine drainage was accidentally discharged from the Gold King Mine near Silverton, Colorado into Cement Creek which is a tributary to the Animas and San Juan Rivers. The government-initiated risk assessment only assessed a recreational scenario (i.e. hiker drinking from the river), failing to recognize...
Article
Indoor and outdoor concentrations of PM2.5 were measured for 24 h during heating and non‐heating seasons in a rural solid fuel burning Native American community. Household building characteristics were collected during the initial home sampling visit using technician walkthrough questionnaires, and behavioral factors were collected through question...
Article
Full-text available
Chronic kidney disease of unknown etiology (CKDu) is an epidemic that affects young agricultural workers in several warm regions of the world. However, there is a lack of monitoring of kidney issues in regions with extremely warm environments such as the Northwest of Mexico, a semi-arid region with a growing agricultural industry, where migrant and...
Article
Irrigation water regulations use Escherichia coli as an indicator of fecal contamination. However, it is well documented that bacterial indicators may not be ideal for predicting viral pathogen presence. Viral pathogens survive relatively long periods in water, are resistant to treatment processes, and cause a large number of illnesses annually. Th...
Article
Full-text available
Current microbial exposure models assume that microbial exchange follows a concentration gradient during hand-to-surface contacts. Our objectives were to evaluate this assumption using transfer efficiency experiments and to evaluate a model's ability to explain concentration changes using approximate Bayesian computation (ABC) on these experimental...
Article
Viral infections are an occupational health concern for office workers and employers. The objectives of this study were to estimate rotavirus, rhinovirus, and influenza A virus infection risks in an office setting and quantify infection risk reductions for two hygiene interventions. In the first intervention, research staff used an ethanol-based sp...
Article
Chronic kidney disease of undetermined cause (CKDu) is an epidemic that is disproportionately affecting young workers in warm regions throughout the world. Even though the risk factors of CKDu are not fully understood, several factors, such as pesticides and heat exposure, have been proposed to explain the pattern of this disease. However, little i...
Article
Background: Quantitative tools are needed to relate infection control interventions to infection risk reductions. Methods: A model for predicting virus concentrations on hands was used to predict rotavirus, rhinovirus, and influenza A virus doses. Variability in behaviors, transfer efficiencies for various contact types, and surface areas of con...
Article
Objectives To develop an exposure and risk assessment model to estimate listeriosis infection risks for Peruvian women. Methods A simulation model was developed utilizing Listeria monocytogenes concentrations on kitchen and latrine surfaces in Peruvian homes, hand trace data from Peruvian women, and behavioral data from literature. Scenarios invol...
Article
Understanding healthcare viral disease transmission and the effect of infection control interventions will inform current and future infection control protocols. In this study, a model was developed to predict virus concentration on nurses’ hands using data from a bacteriophage tracer study conducted in Tucson, Arizona, in an urgent care facility....
Article
Norovirus accounts for a large portion of the gastroenteritis disease burden, and outbreaks have occurred in a wide variety of environments. Understanding the role of fomites in norovirus transmission will inform behavioral interventions, such as hand washing and surface disinfection. The purpose of this study was to estimate the contribution of fo...
Article
Background: Evidence suggests that doffing and possibly disposal of used personal protective equipment (PPE) can lead to environmental contamination. Aim: To ascertain the potential for site and floor contamination when medical gloves are inappropriately disposed. Methods: Fifteen healthcare workers (HCWs) disposed of gloves inoculated with bacteri...
Article
Abstract Introduction: Household reliance on biomass and solid fuels has resulted in an estimated 4.3 million pre-mature annual deaths globally. Despite the prevalent use in developing nations, recent studies suggest that low income rural populations of the United States, and other affluent countries, may experience similar exposures to HAPs due to...
Article
Full-text available
Data below detection limits, left-censored data, are common in environmental microbiology, and decisions in handling censored data may have implications for quantitative microbial risk assessment (QMRA). In this paper, we utilize simulated data sets informed by real-world enterovirus water data to evaluate methods for handling left-censored data. D...
Article
Full-text available
It is known that the use of EPA-registered surface disinfectant sprays can reduce infection risk if used according to the manufacturer's instructions. However, there are currently no standards for health care environments related to contamination levels on surfaces. The significance of this research is in quantifying needed reductions to meet vario...
Article
Infectious disease transmission is frequently mediated by the environment, where people's movements through and interactions with the environment dictate risks of infection and/or illness. Capturing these interactions, and quantifying their importance, offers important insights into effective interventions. In this study, we capture high time-resol...
Article
Background: Infection risk estimates from swimming in treated recreational water venues are lacking and needed to prioritize public health interventions in swimming pools. Quantitative infection risk estimates among different age groups are needed to identify vulnerable populations. High risk populations can be targeted during public health interv...
Article
Full-text available
Arsenic exposure has been associated with decreased club cell secretory protein (CC16) levels in adults. Further, both arsenic exposure and decreased levels of CC16 in childhood have been associated with decreased adult lung function. Our objective was to determine if urinary CC16 levels in children are associated with arsenic concentrations in env...
Technical Report
From 1962 to 1971, US military sprayed herbicides over Vietnam. Congress passed the Agent Orange Act of 1991 to address whether exposure to these herbicides contributed to long term health effects in Vietnam veterans. The legislation directed the Secretary of Veterans Affairs to request the IOM to perform a comprehensive evaluation of scientific an...
Technical Report
The VA asked the Institute of Medicine (IOM) to evaluate whether service in ORH C-123s could have exposed AF Reservists to herbicide residues at levels harmful to their health. In Post-Vietnam Dioxin Exposure in Agent Orange–Contaminated C-123 Aircraft, an expert IOM committee performs a qualitative assessment based on the science and evidence avai...
Conference Paper
Agricultural pesticides can contaminate farmworkers' homes by track-in on shoes, clothes, and skin, as well as through air-infiltration from pesticide spray drift or wind-resuspension of contaminated soil particles from nearby fields. The objective of this exploratory study was to gain a better understanding of which housing characteristics are mos...
Article
Full-text available
The Child-Specific Aggregate Cumulative Human Exposure and Dose (CACHED) framework integrates micro-level activity time series with mechanistic exposure equations, environmental concentration distributions, and physiologically-based pharmacokinetic components to estimate exposure for multiple routes and chemicals. CACHED was utilized to quantify cu...
Article
During meal events, a child's food can be contaminated through contacts with objects and surfaces, and/or unwashed hands that have chemical residues, increasing ingestion exposure of contaminants for the child. This is not surprising, given that very young children eat more with the hands than adults, are active, and play with toys and objects whil...
Article
Estimation of aggregate exposure and risk requires detailed information regarding dermal contact and mouthing activity. We analyzed micro-level activity time series (MLATS) of children aged 7-12 years to quantify these contact behaviors and evaluate differences by age and gender. In all, 18 children, aged 7-12 years, were videotaped while playing o...
Article
Full-text available
Farmworkers' children may have increased pesticide exposure through dermal absorption and non-dietary ingestion, routes that are difficult to measure and model. The Cumulative Aggregate Simulation of Exposure (CASE) model, integrates the complexity of human behavior and variability of exposure processes by combining micro-level activity time series...
Article
Existing microbial risk assessment models rarely incorporate detailed descriptions of human interaction with fomites. We develop a stochastic-mechanistic model of exposure to rotavirus from nondietary ingestion iterated by simulated intermittent fomes-mouth, hand-mouth, and hand-fomes contacts typical of a child under six years of age. This exposur...
Article
Information on the fraction of total hand surface area touching a contaminated object is necessary in accurately estimating contaminant (e.g., pesticides, pathogens) loadings onto the hands during hand-to-object contacts. While several existing physical–stochastic human exposure models require such surface area data to estimate dermal and non-dieta...
Article
Full-text available
Many units in public housing or other low-income urban dwellings may have elevated pesticide residues, given recurring infestation, but it would be logistically and economically infeasible to sample a large number of units to identify highly exposed households to design interventions. Within this study, our aim was to devise a low-cost approach to...
Article
Many units in public housing or other low-income urban dwellings may have elevated pesticide residues, given recurring infestation, but it would be logistically and economically infeasible to sample a large number of units to identify highly exposed households to design interventions. Within this study, our aim was to devise a low-cost approach to...
Article
This study was conducted to describe exposure prone behaviors of infants and toddlers in the farmworker community. Analysis of hand and mouth contact frequencies and durations aids understanding of how children interact with their environment and are exposed via contact with surfaces. All 23 participating children (8 female infants, 5 male infants,...
Article
Full-text available
Many dermal exposure models use stochastic techniques to sample parameter distributions derived from experimental data to more accurately represent variability and uncertainty. Transfer efficiencies represent the fraction of a surface contaminant transferred from the surface to the skin during a contact event. Although an important parameter for as...
Article
The Cumulative and Aggregate Simulation of Exposure (CASE) framework is an innovative simulation tool for exploring non-dietary exposures to environmental contaminants. Built upon the Dermal Exposure Reduction Model (DERM) and established methods for collecting detailed human activity patterns, the CASE framework improves upon its predecessor. Alth...
Article
Full-text available
Microlevel activity time series (MLATS) data were gathered on hand contact activities of 38 children (1–6 years old) by videotaping in primarily outdoor residential environments. The videotape recordings were then translated into text files using a specialized software called VirtualTimingDevice™. Contact frequency (contacts/h), duration per contac...
Article
Submitted to the Department of Civil and Environmental Engineering. Copyright by the author. Thesis (Ph. D.)--Stanford University, 2004.
Article
Full-text available
In 1994, Stanford University's Exposure Research Group (ERG) conducted its first pilot study to collect micro-level activity time series (MLATS) data for young children. The pilot study involved videotaping four children of farm workers in the Salinas Valley of California and converting their videotaped activities to valuable text files of contact...
Article
Detailed information on children's mouthing activities helps researchers assess children's exposure to toxicants via the non-dietary ingestion route (i.e., exposure resulting from contacts between the mouth and non-dietary objects such as fingers, toys, and dirt). For the analyses presented in this article, 38 children (20 female and 18 male) aged...
Article
The objectives of this work are to demonstrate methods for the collection and incorporation of contact-specific surface area measurements in dermal exposure assessments and illustrate the potential difference in resulting dermal and non-dietary ingestion estimates using this type of surface area data. Continuing the work of Stanford's Exposure Rese...
Article
Detailed information on children's mouthing activities helps researchers assess children's exposure to toxicants via the non-dietary ingestion route (i.e., exposure resulting from contacts between the mouth and non-dietary objects such as fingers, toys, and dirt). For the analyses presented in this article, 38 children (20 female and 18 male) aged...

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Projects

Projects (3)
Project
Collection and methodologies related to capturing behavior and activity data for computational exposure science and simulation
Project
Assessment, risk analysis, and health effects of chemical, physical, and microbial agents in agricultural settings
Project
Quantative assessment, methodologies, and simulation related to infection risk and healthcare environments