Inverse relationship between transfer efficiencies into reproductive system and exposure concentration for organic pollutants: Implications for hazard assessment

Organic pollutants impact fertility and reproductive outcomes. Assessing their risk required understanding the great variation of their parental transfer efficiency. To determine whether the proportion of organic pollutants transferred to the reproductive system varies with the level of parental contamination, we analyzed large-scale datasets on organic environmental contaminants found in parental blood, cord blood, and semen. Our results demonstrated that although chemical concentrations in seminal plasma and cord blood significantly increased with those in parental blood, the proportion of parental contaminants transferred to the reproductive system decreased as the chemical concentration in parental blood increased. Using a hierarchical model, a negative association between transfer efficiencies and parental contamination levels was revealed. It is estimated that 41.78% and 46.23% of the variance in transfer efficiencies can be explained by paternal and maternal blood concentrations, respectively. In comparison, chemical class accounted for 25.22% and 18.95% of the variance, while the remaining inconsistencies between studies contributed only 3.38% and 2.56% of the variance for paternal and maternal transfers, respectively. We observed no significant interaction between parental blood concentration and chemical properties. Thus, our findings implied that the transfer efficiency of organic pollutants is not just an intrinsic chemical property and the inverse association has significant implications for health risk assessments and benchmark dose estimations related to environmental pollutants.