Factors associated with partitioning behavior of persistent organic pollutants in a feto-maternal system: A multiple linear regression approach

A Data-Driven Computational Framework for Assessing the Risk of Placental Exposure to Environmental Chemicals

A computational framework based on placental gene networks was proposed in this work to improve the accuracy of the placental exposure risk assessment of environmental compounds. The framework quantitatively characterizes the ability of compounds to cross the placental barrier by systematically considering the interaction and pathway-level information on multiple placental transporters. As a result, probability scores were generated for 307 compounds crossing the placental barrier based on this framework. These scores were then used to categorize the compounds into different levels of transplacental transport range, creating a gradient partition. These probability scores not only facilitated a more intuitive understanding of a compound's ability to cross the placental barrier but also provided valuable information for predicting potential placental disruptors. Compounds with probability scores greater than 90% were considered to have significant transplacental transport potential, whereas those with probability scores less than 80% were classified as unlikely to cross the placental barrier. Furthermore, external validation set results showed that the probability score could accurately predict the compounds known to cross the placental barrier. In conclusion, the computational framework proposed in this study enhances the intuitive understanding of the ability of compounds to cross the placental barrier and opens up new avenues for assessing the placental exposure risk of compounds.

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Prenatal exposure to 209 PCBs in mother-infant pairs from two cities in China: Levels, congener profiles, and transplacental transfer

Prenatal exposure to polychlorinated biphenyls (PCBs) has been well researched, but studies covering all 209 congeners are limited. Recent literature suggests a shift in the dominant congeners and increasing levels of unintentionally-produced PCBs (UP-PCBs) in environmental samples in China. To investigate the exposure levels and profiles of PCBs in pregnant women and newborns, as well as the characteristics of transplacental transfer, we measured 209 PCBs in 80 pairs of maternal serum (MS) and cord serum (CS) from Hangzhou and Mianyang, China. The levels of ∑PCBs of participants in this study were lower than those in developed countries and followed the order of (ng/g lw): Hangzhou-MS (148) > Hangzhou-CS (107) > Mianyang-MS (63.8) > Mianyang-CS (57.9). UP-PCBs (mainly PCB-11) contributed around 50% of ∑PCBs in serum, which is consistent with the environmental samples. Environmental burden and dietary intake may account for the differences in the exposure levels, while the historical production and release may have impacted the homologue profiles. Prenatal exposure to PCB-126 was associated with increased birth weight (n = 80, adjusted β = 0.270, p = 0.030). The body burden of dioxin-like PCBs of newborns in Hangzhou was 82.4 pg TEQ/kg bw, suggesting certain health risks under WHO tolerable daily intake of 1-4 pg TEQ/kg bw. Log₁₀ K_OW was negatively correlated with log₁₀-transformed transplacental transfer efficiency (R² = 0.36, p < 0.001), serving its importance for PCBs' transplacental transfer. This study is the first to investigate maternal and fetal exposure to PCBs in China based on their levels, congener and homologue profiles, and potential adverse effects. Our findings help to provide insights into the processes and factors influencing the transplacental transfer of PCBs.

Exposure levels of PCDD/Fs and PCBs in human blood and the transplacental transfer characteristics in cord blood of newborns near the industrialized area

Mono-to octa-chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in pooled blood from the general population living near a typical industrialized area were investigated. Less chlorinated PCDD/Fs (mean: 2602 pg L^-1) were 7.5 times those of highly chlorinated ones (mean: 349 pg L^-1). The average ΣPCBs and Σdl-PCBs concentrations in human (cord) blood were 2741 (117) and 18 (0.31) ng L^-1, respectively. Higher concentrations of highly chlorinated PCDD/Fs were found in females than in males across different ages. The mean concentrations (and toxic equivalents (TEQs)) of PCDD/Fs were 282 (27) pg L^-1 in males and 312 (32) pg L^-1 in females. The concentrations of the PCDD/Fs and PCBs increased with age for both males and females, which might be caused by the long half-lives of these compounds and decreases in metabolic rates with age as the metabolic of nutrients, food, and also PCDD/Fs and PCBs would trend to slow. The TEQ of total PCDD/Fs and PCBs was higher in blood from orthopedics patients (107 pg L^-1) than other patients. This result may be associated with the bone density and pollutant bioaccumulation. In addition, total concentration of PCDD/Fs and PCBs in blood of women at reproductive age were 6.6 and 37 times the cord blood of newborns, respectively. Positive correlation of PCDD/Fs and PCBs especially for the higher chlorinated compounds between female and cord blood were discovered, which might be caused by the transplacental transfer characteristics and blood barrier for macromolecules and reduce the chemical exposure risks for newborns.

Comparison of Dechlorane Plus Concentrations in Sequential Blood Samples of Pregnant Women in Taizhou, China

To develop an appropriate sampling strategy to assess the intrauterine exposure to dechlorane plus (DP), we investigated DP levels in sequential maternal blood samples collected in three trimesters of pregnancy, respectively, from women living in Taizhou. The median concentration of DPs (sum of syn-DP and anti-DP) in all samples was 30.5 pg g−1 wet-weight and 5.01 ng g−1 lipid-adjusted weight, respectively. The trimester-related DP concentrations were consistently strongly correlated (p < 0.01), indicating that a single measurement of DP levels could represent intrauterine exposure without sampling from the same female repeatedly; however, the wet-weight levels significantly increased across trimesters (p < 0.05), while the lipid-adjusted levels did not significantly vary. Notably, whether lipid-adjusted weight or wet-weight levels, the variation extent of DP across trimesters was found to be less than 41%, and those for other persistent organic pollutants (POPs) reported in the literature were also limited to 100%. The limitation in variation extents indicated that, regardless of the time of blood collection during pregnancy and how the levels were expressed, a single measurement could be extended to screen for exposure risk if necessary. Our study provides different strategies for sampling the maternal blood to serve the requirement for assessment of in utero exposure to DP.