Our limited understanding of how polyfluoroalkyl chemicals (PFCs) may impact on human health suggests the potential for a protective impact on brain health. This study was designed to explore the association between PFCs and cognitive ability in older adults.
We assessed the association between four PFCs, perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS), and self-reported limitation due to difficulty remembering or periods of confusion using data from participants aged 60-85 years from the 1999-2000 and 2003-2008 National Health and Nutrition Examination Surveys. We also considered whether diabetic status or diabetic medication use modifies this association in light of in vitro evidence that PFCs may act on the same receptors as some diabetic medications.
In multivariable adjusted models, point estimates suggest a protective association between PFCs and self-reported cognitive limitation (odds ratio, OR; 95% confidence interval, CI) for a doubling in PFC concentration: PFOS (OR, 0.90; 95% CI, 0.78, 1.03), PFOA (OR, 0.92; 95% CI, 0.78, 1.09), PFNA (OR, 0.91; 95% CI, 0.79, 1.04) and PFHxS (OR, 0.93; 95% CI, 0.82, 1.06). The protective association was concentrated in diabetics, with strong, significant protective associations in nonmedicated diabetics.
This cross-sectional study suggests that there may be a protective association between exposure to PFCs and cognition in older adults, particularly diabetics.
"Similar to the protective association we observed for PFOA, a cross-sectional study reported that PFAS exposures were associated with reduced prevalence of adult cognitive limitations (Power et al. 2013) and a prospective study of 320 children observed better cognitive abilities among children with higher prenatal PFOA exposure (Stein et al. 2013). In contrast, a cross-sectional study of US adolescents found that higher PFOA and PFOS concentrations were associated with parent-reported ADHD (Hoffman et al. 2010). "
[Show abstract][Hide abstract] ABSTRACT: Endocrine disrupting chemicals (EDCs) may be involved in the etiology of autism spectrum disorders, but identifying relevant chemicals within mixtures of EDCs is difficult.
To identify gestational EDC exposures associated with autistic behaviors.
We measured the concentrations of 8 phthalate metabolites, bisphenol A, 25 polychlorinated biphenyls (PCBs), 6 organochlorine pesticides, 8 brominated flame retardants, and 4 perfluoroalkyl substances in blood or urine samples from 175 pregnant women in the HOME Study (Cincinnati, OH). When children were 4 and 5 years old, mothers completed the Social Responsiveness Scale (SRS), a measure of autistic behaviors. We examined confounder adjusted associations between 52 EDCs and SRS scores using a two-stage hierarchical analysis to account for repeated measures and confounding by correlated EDCs.
Most of the EDCs were associated with negligible absolute differences in SRS scores (≤ 1.5). Each two standard deviation increase in serum concentrations of polybrominated diphenyl ether-28 (PBDE-28) (β = 2.5; 95% CI: -0.6, 5.6) or trans-nonachlor (β = 4.1; CI: 0.8-7.3) was associated with more autistic behaviors. In contrast, fewer autistic-behaviors were observed among children born to women with detectable vs. non-detectable concentrations of PCB-178 (β = -3.0; CI: -6.3, 0.2), β-hexachlorocyclohexane (β = -3.3; CI: -6.1, -0.5), or PBDE-85 (β = 3.2; CI: -5.9, -0.5). Increasing perfluorooctane concentrations were also associated with less autistic behaviors (β = -2.0; CI: -4.4, 0.4).
Some EDCs were associated with autistic behaviors in this cohort, but our modest sample size precludes us from dismissing chemicals with null associations. Perfluorooctane, β-hexachlorocyclohexane, PCB-178, PBDE-28, PBDE-85, and trans-nonachlor deserve additional scrutiny as factors that may be associated with childhood autistic behaviors.
Environmental Health Perspectives 03/2014; 122(5). DOI:10.1289/ehp.1307261 · 7.98 Impact Factor
"Another study of 571 children aged 12 to 15 years reported that higher serum levels of PFOA, PFOA, and PFHxS were all individually associated with significantly higher rates of ADHD . A cross-sectional study of 1,766 US adults aged 60 to 85 years reported that higher levels of PFOS, PFOA, PFNA and PFHxS were associated with modest yet nonsignificantly lower rates of cognitive limitation . "
[Show abstract][Hide abstract] ABSTRACT: Background. While perfluorinated compounds (PFCs) are a family of commonly used synthetic compounds with many applications, some PFCs remain persistent within the human body due, in part, to enterohepatic recirculation and renal tubular reabsorption. With increasing recognition of potential harm to human health associated with PFC bioaccumulation, interventions to facilitate elimination of these toxicants are welcome in order to potentially preclude or overcome illness. Minimal research has been undertaken thus far on methods to accelerate human clearance of PFCs. Methods. To test for possible oral treatments to hasten PFC elimination, a group of individuals with elevated PFC levels was treated with cholestyramine (CSM) and, after a break, was subsequently treated with Chlorella pyrenoidosa (CP). Stool samples were collected from all participants (i) prior to any treatment, (ii) during treatment with CSM, and (iii) during treatment with CP. Results. With CSM treatment, significant levels of three distinct PFCs were found in all stools, while levels were mostly undetectable prior to treatment. Following treatment with oral CP, undetectable or very low levels of all PFCs were noted in each sample tested. Conclusion. CSM appears to facilitate elimination of some common PFCs and may have some role in the clinical management of patients with accrued PFCs.
[Show abstract][Hide abstract] ABSTRACT: Background:
In animal studies, perfluorinated compounds affect fetal growth, development, viability, and postnatal growth. The limited epidemiologic findings on child neurobehavioral development are mixed.
We recruited and evaluated 320 children who participated in the C8 Health Project, a 2005-2006 survey in a Mid-Ohio Valley community highly exposed to perfluorooctanoate (PFOA) through contaminated drinking water. We examined associations among estimated in utero PFOA exposure, measured childhood PFOA serum concentration, and subsequent performance on neuropsychological tests 3-4 years later at ages 6-12 years. We assessed Intelligence Quotient (IQ) reading and math skills, language, memory and learning, visual-spatial processing, and attention. All multivariable linear regression models were adjusted for age, sex, home environment, test examiner, and maternal IQ. Models with measured childhood PFOA were additionally adjusted for child body mass index.
Children in the highest as compared with lowest quartile of estimated in utero PFOA had increases in Full Scale IQ (β 4.6, 95% confidence interval [CI] = 0.7-8.5) and decreases in characteristics of attention deficit/hyperactivity disorder as measured by the Clinical Confidence Index of Connors' Continuous Performance Test-II (β -8.5, 95% CI = -16.1 to -0.8). There were negligible associations between PFOA and reading or math skills or neuropsychological functioning.
These results do not suggest an adverse association between the levels of PFOA exposure experienced by children in this cohort and their performance on neuropsychological tests.
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