Dataset Information

Perfluoroalkyl substances and thyroid function in older adults.

ABSTRACT: Current understanding of the thyroid disruptive properties of perfluoroalkyl substances (PFASs), particularly in aging populations, is limited. The objectives of this study were to (i) assess associations between thyroid function, as measured by serum thyrotropin (thyroid stimulating hormone, TSH), free thyroxine (fT4), total thyroxine (T4), and total triiodothyronine (T3), and serum perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in an aging population and (ii) determine if other persistent organic pollutants with thyroid disruptive properties including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) modify such associations. We conducted a cross-sectional study of 87 men and women 55 to 74years of age, without clinically-diagnosed thyroid disease, who resided in upper Hudson River communities in New York. Geometric means (standard deviations) of serum PFOS and PFOA were 31.6 (1.7) ng/mL and 9.17 (1.72) ng/mL, respectively. Multivariable linear regression analyses indicated that one interquartile range difference in PFOS corresponded to 4% and 9% increases in fT4 and T4 respectively. We detected statistical interactions between PFOA and age for effects on fT4 and T4; joint increases in PFOA and age were associated with increases in fT4 and T4, of 3% and 7%, respectively. We also detected statistical interactions between PFOS and total PCBs for the effect on T3 and between PFOA and total PBDEs for the effect on TSH. Our results suggest that PFASs are associated with subtle alterations in thyroid hormone levels in this population, and that these associations are likely to vary by age, and levels of PCBs and PBDEs.

SUBMITTER: Shrestha S

PROVIDER: S-EPMC4272864 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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Perfluoroalkyl substances and thyroid function in older adults.

Shrestha Srishti S Bloom Michael S MS Yucel Recai R Seegal Richard F RF Wu Qian Q Kannan Kurunthachalam K Rej Robert R Fitzgerald Edward F EF

Environment international 20141205

Current understanding of the thyroid disruptive properties of perfluoroalkyl substances (PFASs), particularly in aging populations, is limited. The objectives of this study were to (i) assess associations between thyroid function, as measured by serum thyrotropin (thyroid stimulating hormone, TSH), free thyroxine (fT4), total thyroxine (T4), and total triiodothyronine (T3), and serum perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in an aging population and (ii) determine if o ...[more]

PMID: 25483837

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Project description:BackgroundAlthough potential neurotoxicity of perfluoroalkyl and polyfluoroalkyl substances (PFAS) is suggested, previous epidemiologic studies have reported a 'protective' association between serum PFAS concentration and cognition function. Poor outcome assessment, residual confounding, non-monotonic dose-responses (NMDRs), and the role of reduced kidney function in PFAS excretion may be alternative explanations of these findings.ObjectivesWe examined the association of perfluoroalkyls with cognitive functions assessed using the Consortium to Establish a Registry for Alzheimer's Disease word learning and recall; the Animal Fluency; and the Digit Symbol Substitution tests.MethodsWe included 903 adults aged ≥60 years from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. We computed a composite z-score as an average of four individual cognitive z-scores and used it as the outcome. Linear and generalized additive models were used to evaluate linear and non-linear associations.ResultsWith the linearity assumption, perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) were significantly positively associated with composite z-score after adjustment for age, sex, race/ethnicity, education, smoking, poverty-income ratio, health insurance, food security, alcohol, and physical activity. Smoothing plots suggested NMDRs, especially for perfluorooctane sulfonate (PFOS) with a U-shape dose-response. When restricting to participants without chronic kidney disease (CKD) (n = 613), the positive associations for PFOA and PFNA observed in the whole population diminished, whereas PFOS was inversely and significantly associated with composite z-score. Also, negative confounding effects of fish/seafood consumption seem to be substantial. Effect estimates of composite z-score were -0.055 (95% CI: -0.097, -0.012, P = 0.01) for a doubling increase in PFOS.DiscussionThese findings suggest that the previous epidemiologic findings of a 'protective' association between PFAS and cognition may be explained by CKD, NMDRs and confounding by fish consumption. PFOS at the current population exposure level in the U.S. may be a risk factor for cognitive decline in older adults with normal kidney function.

Project description:BackgroundPer- and polyfluoroalkyl substances (PFAS) are widely applied in consumer and industrial products such as nonstick cookware, waterproof clothing, food packaging materials, and fire-fighting foams. These "forever chemicals" are hypothesized to impact neurobehavioral functions. Yet no previous study has explored the role of PFAS on audiometrically determined hearing impairment (HI).ObjectivesTo investigate the associations of serum concentrations of perfluoroalkyl substances with low-frequency HI (LFHI) and high-frequency HI (HFHI) in US adults.MethodsWe evaluated the cross-sectional associations in 2371 adults aged 20-69 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2003-2004, 2011-2012 and 2015-2016; and 449 adults aged ≥70 years from NHANES 2005-2006 and 2009-2010. Serum concentrations of perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), were measured using solid-phase extraction coupled to High Performance Liquid Chromatography-Turbo Ion Spray ionization-tandem Mass Spectrometry. LFHI was defined as a pure-tone average (PTA) of thresholds across 0.5-1-2 kHz >25 dB; HFHI defined as a PTA across 3-4-6 kHz >25 dB in the worse ear. Survey-weighted logistic regression models were used to compute odds ratios (ORs) and 95% confidence intervals (CIs) with adjustment for age, age-squared, sex, race/ethnicity, education, poverty-to-income ratio, body mass index, smoking status, exposures to occupational, recreational and firearm noises, and NHANES cycles.ResultsThere were no significant associations when perfluoroalkyl variables were fitted as a linear (log-transformed) term. However, statistically significant associations of HFHI with PFNA (OR = 1.70, 95% CI: 1.13-2.56) and PFDA (OR = 1.75, 95% CI: 1.00-3.05) were observed when comparing participants with serum concentrations ≥90th vs. <90th percentiles of PFNA (90th percentile = 1.8 ng/mL) and PFDA (90th percentile = 0.5 ng/mL), respectively, in adults aged 20-69 years. No significant associations were observed for other compounds in adults aged 20-69 years and for all compounds in adults ≥70 years.ConclusionsOur study does not provide strong evidence to support the ototoxicity of PFAS exposure. Non-linear threshold dose-response associations between serum concentrations of PFNA and PFDA and HFHI need further investigation.

Project description:BACKGROUND:Maternal thyroid hormones are essential for fetal brain development in early gestation. Perfluoroalkyl substances (PFASs)-widespread and persistent pollutants-have been suggested to interfere with maternal thyroid hormones in the second or third trimesters, but evidence for an association in the early pregnancy period is sparse. OBJECTIVES:Our goal was to evaluate the gestational-week specific associations of maternal thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels with plasma concentrations of six PFAS chemicals in the first and second pregnancy trimester. METHODS:A cross-sectional analysis was conducted using 1,366 maternal blood samples collected between gestational weeks (GWs) 5 and 19 (median, 8 gestational weeks) in the Danish National Birth Cohort (DNBC) during 1996-2002. We estimated the percentage changes of serum TSH and fT4 levels according to concentrations (in nanograms per milliliter) of six PFAS chemicals modeled as per interquartile range (IQR) increase or by exposure quartiles. Moreover, we contrasted the estimated week-specific TSH or fT4 levels by PFAS quartile and estimated ORs for binary high or low TSH and fT4 status based on the week-specific distribution according to IQR increase of PFAS. RESULTS:TSH levels followed a U-curve trend in early pregnancy with a nadir at GW10, whereas fT4 levels were less fluctuated in the samples. There were no apparent associations between any of the PFASs and changes of average TSH or fT4 levels in total samples. In gestational-week-specific analyses, we found that the estimated TSH values were higher among the highest perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), and perfluoroheptane sulfonate (PFHpS) quartiles compared with the lower quartiles from GW5 to GW10, but the difference became null or even reversed after GW10. For binary outcomes, perfluorodecanoic acid (PFDA) was associated with high fT4 status before GW10 [OR=1.46 (95% CI: 1.04, 2.05)]. CONCLUSIONS:We observed some gestational-week-specific associations between high exposure to several PFAS and TSH level in early gestations. Further research of the biology and the potential clinical impact regarding thyroid hormones disruptions in early pregnancy is needed. https://doi.org/10.1289/EHP5482.

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Perfluoroalkyl substances and thyroid function in older adults.

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Perfluoroalkyl substances and thyroid function in older adults.

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