Neurotoxicity of polychlorinated biphenyls and related organohalogens.

Halogenated organic compounds are pervasive in natural and built environments. Despite restrictions on the production of many of these compounds in most parts of the world through the Stockholm Convention on Persistent Organic Pollutants (POPs), many "legacy" compounds, including polychlorinated biphenyls (PCBs), are routinely detected in human tissues where they continue to pose significant health risks to highly exposed and susceptible populations. A major concern is developmental neurotoxicity, although impacts on neurodegenerative outcomes have also been noted.

Perfluoroalkyl substances, thyroid hormones, and neuropsychological status in older adults.

Minimal data exist regarding the neurotoxicity of perfluoroalkyl substances (PFASs) in aging populations and the possible mediating effects of thyroid hormones (THs). Hence, the aims of this study were to: (i) assess associations between PFASs and neuropsychological function, and (ii) determine if such associations are mediated by changes in circulating THs in an aging population. We measured perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), total thyroxine (T4) and free thyroxine (fT4) in serum and performed neuropsychological tests in 126 men and women aged 55-74 years and living in upper Hudson River communities.

Thyroid function and neuropsychological status in older adults.

Overt thyroid dysfunction is recognized as a risk factor for neuropsychological deficits in aging populations, yet evidence for how changes in levels of circulatory thyroid hormones impact specific neuropsychological domains is limited. Here we report cross-sectional associations between serum thyroid hormone concentrations and several neuropsychological function domains among men and women aged 55-74years. We administered neuropsychological tests to assess memory, learning, executive function, measures of attention, visuospatial function, affective state, and motor function.

Perfluoroalkyl substances and thyroid function in older adults.

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.

Tibial bone lead, but not serum polychlorinated biphenyl, concentrations are associated with neurocognitive deficits in former capacitor workers.

Objective: To determine the relationships between tibial bone lead and serum polychlorinated biphenyl (PCB) concentrations and neurocognitive function.

Methods: The study population consisted of men and women former capacitor workers had been employed by the General Electric Corporation between 1946 and 1977. Regression analyses evaluated the association between neurocognitive function and lipid-adjusted serum PCB and tibia lead concentrations.