Family Clustering of PBB Exposure Open Access

Wang, Xiao (2015)

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Background: PBB contamination of food served as a major exposure source following an industrial accident in Michigan in the 1970s. People living in the same household at the time of the accident were expected to have similar serum PBB levels. Thus, husbands and wives may have similar PBB levels even 40 years later. PBB can also pass from mother to children, by means of breastfeeding or in utero. In addition, there may exist genetic factors that influence PBB absorption, distribution, metabolism and excretion which lead to correlated levels between parents and children.

Methods: Current PBB levels were collected and analyzed during 2012 and 2014. Paired t-tests, correlation statistics and the linear regression analyses were performed on the log-transformed current PBB levels in mother and child, father and child, as well as spouse pairs. Scatter plots presented logarithmically on un-transformed PBB levels and on log-transformed PBB levels, for the three types of family pairs were also generated. All of the analyses use α = 0.05 as the significant level.

Results: There were 134 family groups in the study, including 63 spouse pairs, 84 mother and child pairs, 44 father and child pairs. Significant Pearson correlations coefficients using the log-transformed current PBB levels were found within each of the three types of family pairs. The spouse pairs have the strongest Pearson correlation, with a coefficient of 0.635 and a p-value of <0.001. The results of the paired t-tests show there were significant mean differences between husbands and wives, mothers and children, fathers and children's current PBB levels.

Conclusion: Females' current PBB levels are significantly lower than males in spouse pairs. Because PBB can be transported from mothers to children through breast milk and in utero, we would expect for the mothers' PBB levels to have more impact on children's PBB levels, compared to fathers' PBB levels. However, the coefficients between mother and child pairs, and father and child pairs are almost identical (0.388 versus 0.399). Although the correlation between fathers and children's current PBB levels is significant, further investigation is needed to address the mothers' PBB levels as a confounder.

Table of Contents

Introduction. 1

Methods. 4

Data and Statistical Analyses. 7

Results. 9

Discussion. 23

References. 25

Appendix. 27

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