A cohort study of the association between secondary sex ratio and parental exposure to polybrominated biphenyl (PBB) and polychlorinated biphenyl (PCB)

Abstract

BackgroundPolybrominated biphenyl (PBB), a brominated flame retardant, was accidently mixed into animal feed in Michigan (1973–1974) resulting in human exposure through consumption of contaminated meat, milk and eggs. Beginning in 1976 individuals who consumed contaminated products were enrolled in the Michigan Long-Term PBB Study. This cohort presents a unique opportunity to study the association between parental exposures to PBB and offspring sex ratio.MethodsWe identified offspring of female PBB cohort participants (born 1975–1988) and obtained electronic birth records for those born in the state of Michigan. We linked this information to parental serum PBB and PCB concentrations collected at enrollment into the cohort. We modeled the odds of a male birth with generalized estimating equations accounting for the non-independence of siblings born to the same parents. We explored potential confounders: parental age and education at offspring's birth, parental body mass index at cohort enrollment, birth order, gestational age and year of offspring's birth.ResultsThe overall proportion of male offspring among 865 live births to cohort mothers was 0.542. This was higher than the national male proportion of 0.514 (binomial test: p = 0.10). When both parents were in the cohort (n = 300), we found increased odds of a male birth with combined parents' enrollment PBB exposure ≥ the median concentrations (3 μg/L for mothers; 6 μg/L for fathers) compared to combined parents' PBB exposure < the median concentrations (AOR = 1.43, 95% CI: 0.89–2.29), although this did not reach statistical significance. In addition, there was a suggestion of increased odds of a male birth for combined parents' enrollment PCB exposure ≥ the median concentrations (6 μg/L for mothers; 8 μg/L for fathers) compared to combined parents' enrollment PCB exposure < the median concentrations (AOR = 1.53, 95% CI: 0.93–2.52).ConclusionThis study adds to the body of literature on secondary sex ratio and exposure to environmental contaminants. In this population, combined parental exposure to PBBs or PCBs increased the odds of a male birth. Further research is needed to corroborate these findings and shed light on the biological mechanisms by which these types of chemicals may influence the secondary sex ratio.

Retardantes de chama bromados: uma revisão

“…Dessa forma, apresentam estrutura semelhante às bifenilas policloradas (PCBs) com uma nomeclatura análoga e um mesmo número de congêneres. 25 Sua produção comercial, entretanto, envolve um número restrito de compostos onde apenas 42 congêneres de PBBs foram sintetizados em laboratório. 26 Eles foram disponibilizados na forma de três misturas comerciais (NTP 2011): a) Hexabromobifenil (HxBB) -formado por 4,0% de pentabromobifenis, 62,6% de hexabromobifenis e 33,4% de heptabromobifenis.…”

“…20,31 Apesar da aplicação dos PBBs ter diminuído desde meados da década de 1970, resíduos dos mesmos continuam sendo reportados em amostras ambientais e em seres humanos de diferentes partes do globo, como China, Espanha e Estados Unidos. 25,[33][34][35][36][37] Os congêneres mais comumente encontrados são o PBB 153 e outros de baixa bromação como o PBB 29, 49, 52, 56, 77 e 80. 34,35,38,39 Resíduos de PBBs foram detectados em compartimentos ambientais como lodo de tratamento de efluentes domésticos na Austrália e em amostras de diversas espécies de peixes de valor comercial da Polônia e França, do Mar Báltico e do nordeste dos EUA, em cetáceos da costa sul e sudeste do Brasil e do Atlântico Norte, aves e ar do Ártico e em pandas na China.…”

“…15,33,34,[39][40][41][42] Muitos trabalhos referem-se especialmente ao acidente ocorrido em Michigan ou a região de descarga de efluentes da Michigan Chemical Corporation. 25,31,36,37,43 Entre eles, alguns reportaram valores elevados em amostras de sangue humano (933 a 1744 µg L -1 ) e em amostras de água (0,01 e 0,07 µg L -1 ) e sedimento (100 e 77000 ng g -1 ). 25,31 A absorção dos PBBs pelos organismos ocorre de forma rápida e inversamente proporcional ao número de bromos na molécula.…”

“…25,31,36,37,43 Entre eles, alguns reportaram valores elevados em amostras de sangue humano (933 a 1744 µg L -1 ) e em amostras de água (0,01 e 0,07 µg L -1 ) e sedimento (100 e 77000 ng g -1 ). 25,31 A absorção dos PBBs pelos organismos ocorre de forma rápida e inversamente proporcional ao número de bromos na molécula. 44 Devido a sua característica de lipofilicidade, as maiores concentrações são encontradas, principalmente, nos tecidos hepático e adiposo.…”

Impact of Brominated POPs on the Neurodevelopment and Thyroid Hormones of Young Children in an Indoor Environment—A Review

“…A large-scale American epidemiological study for infant-mother pairs with accidental exposure to PBBs from 1975PBBs from to 1997PBBs from (birth cohort in 1975PBBs from -1978PBBs from , first follow-up in 1978PBBs from -1993PBBs from , second follow-up in 1997 in Michigan indicates that increased BB-153 in maternal serum has no relation to period of gestation, but has a negative relation to low birth weight (Givens et al, 2007). In another epidemiological study from the same accident cohort (Terrell et al, 2009), the overall proportion of male offspring to the cohort mothers is 0.542, higher than the national male proportion of 0.514. If both parents fit into the PBBs birth cohort, there is an increase in the odds of a male birth with the parents in the high PBBs exposure group as compared to the low exposure group.…”