Effects of mixtures of polychlorinated biphenyls (PCBs) and three organochlorine pesticides on cognitive function differ between older Mohawks at Akwesasne and older adults in NHANES

Nozomi Sasaki; Gayle Morse; Laura Jones; David O Carpenter; Akwesasne Task Force on the Environment

doi:10.1016/j.envres.2023.116861

Effects of mixtures of polychlorinated biphenyls (PCBs) and three organochlorine pesticides on cognitive function differ between older Mohawks at Akwesasne and older adults in NHANES

Environ Res. 2023 Nov 1;236(Pt 2):116861. doi: 10.1016/j.envres.2023.116861. Epub 2023 Aug 9.

Authors

Nozomi Sasaki¹, Gayle Morse², Laura Jones³, David O Carpenter⁴; Akwesasne Task Force on the Environment⁵

Affiliations

¹ Institute for Health and the Environment, University at Albany, Rensselaer, NY, 12144, USA. Electronic address: nsasaki@albany.edu.
² Institute for Health and the Environment, University at Albany, Rensselaer, NY, 12144, USA; Department of Psychology, School of Health Sciences, Russell Sage College, Troy, NY, 12180, USA.
³ Center for Biostatistics, Bassett Research Institute, Bassett Health, Cooperstown, NY, 13326, USA; Epidemiology and Biostatistics, SUNY Albany School of Public Health, Rensselaer, NY 12144, USA.
⁴ Institute for Health and the Environment, University at Albany, Rensselaer, NY, 12144, USA.
⁵ Mohawk Nation at Akwesasne, Hogansburg, NY, USA.

PMID: 37562737
DOI: 10.1016/j.envres.2023.116861

Abstract

Background: Akwesasne Mohawks has been exposed to high concentrations of polychlorinated biphenyls (PCBs) and background levels of organochlorine pesticides, hexachlorobenzene (HCB), dichlorodiphenyl dichloroethylene (DDE), and mirex. We have previously reported relative contributions to the mixture of low- and high-chlorinated PCBs, HCB, and DDE on cognitive decrements in Mohawks of various ages.

Objective: This study examines differences in the mixture effects of PCB congener groups, HCB, DDE, and mirex on cognitive function in older Mohawks and less PCB-exposed older adults from the National Health and Nutrition Examination Survey (NHANES) 1999-2002 cycles.

Methods: We used Bayesian kernel machine regression (BKMR) to evaluate the mixture effects of different PCB congener groups, HCB, DDE, and mirex on cognitive function in both populations. Models were adjusted for age, sex, education levels, and race/ethnicity focusing on individuals 60 years and older.

Results: Older Mohawks had 3-fold higher mean total PCB concentrations and 1.8-fold higher mirex, but slightly lower mean DDE and HCB levels than NHANES older adults. Higher mixture concentrations were significantly associated with greater cognitive decline. In older Mohawks, low- and high-chlorinated PCBs, HCB, and DDE contributed to the cognitive score decline. In contrast, score decline in older NHANES adults were primarily from high-chlorinated PCBs and DDE with a threshold dose of approximately 2.08-2.27 ng/g and 2.02-2.40 ng/g, respectively.

Conclusion: Mixtures of PCBs and organochlorine pesticides increase the risk of cognitive decline in both older Mohawks and NHANES older adults. However, contributions to these mixture effects show significant differences. In older Mohawks, high- and low-chlorinated PCBs, DDE, and HCB are the primary contributors, while high-chlorinated PCBs and DDE are important contributors in NHANES older adults. Due to chronic heavy exposures to PCBs, older Mohawks had a significantly increased risk of cognitive decline compared to general older adults from NHANES.

Keywords: BKMR; Cognitive impairment; DDE; HCB; Mixture effects; PCBs.