Combined Effects of Prenatal Exposures to Environmental Chemicals on Birth Weight

Abstract

Prenatal chemical exposure has been frequently associated with reduced fetal growth by single pollutant regression models although inconsistent results have been obtained. Our study estimated the effects of exposure to single pollutants and mixtures on birth weight in 248 mother-child pairs. Arsenic, copper, lead, manganese and thallium were measured in cord blood, cadmium in maternal blood, methylmercury in maternal hair, and five organochlorines, two perfluorinated compounds and diethylhexyl phthalate metabolites in cord plasma. Daily exposure to particulate matter was modeled and averaged over the duration of gestation. In single pollutant models, arsenic was significantly associated with reduced birth weight. The effect estimate increased when including cadmium, and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) co-exposure. Combining exposures by principal component analysis generated an exposure factor loaded by cadmium and arsenic that was associated with reduced birth weight. MECPP induced gender specific effects. In girls, the effect estimate was doubled with co-exposure of thallium, PFOS, lead, cadmium, manganese, and mercury, while in boys, the mixture of MECPP with cadmium showed the strongest association with birth weight. In conclusion, birth weight was consistently inversely associated with exposure to pollutant mixtures. Chemicals not showing significant associations at single pollutant level contributed to stronger effects when analyzed as mixtures.

Gestational diabetes and offspring birth size at elevated environmental pollutant exposures

“…Larger studies with improved precision and accounting for multiple pollutants are needed to confirm this possibility and whether PFAS associations with birth outcomes indeed differ according to sex. In regard to mercury, findings from this and recent birth cohort studies, with reported lower mercury exposure levels compared to older birth cohorts, do not clearly support associations with birth size measures (Govarts et al 2016; Murcia et al 2016; Vrijheid et al 2016); however, associations of maternal low-level mercury exposure with adverse neurodevelopmental outcomes in the offspring in recent birth cohorts are well documented (Vrijheid et al 2016), adding to mounting evidence of mercury toxicity.…”

Characterizing Risk for Cumulative Risk Assessments

“…With the more direct exposure measures and combinations of stressors and confounding factors that are examined in epidemiological studies, it is more important for statistical modeling challenges to be considered (e.g., type II errors from insufficient statistical power to detect associations or statistical interactions, multicollinearity amongst mixtures) . Principal components regression and meta‐regression analyses may offer solutions to some of these challenges . As with risk characterization of chemical mixtures, another helpful strategy is to use information on individual stressors and pairwise interactions to quantify risk estimates for the different stressor combinations.…”

Cognitive performance among cohorts of children exposed to a waste disposal site containing heavy metals in Chile

“…In addition, people who live near these contaminated sites are generally low-income families with a higher level of vulnerability to the toxic effects of pollutants. Some evidence from geo-statistical studies reflect that the distribution of learning disorders and other health outcomes, coincides with the historical presence of significant sources of heavy metals and contextual factors such as low quality of housing, poverty, low educational attainment of the parents and other factors associated with the neighborhood (Govarts et al 2016, Margai and Henry 2003, Olivas-Calderon et al 2015, Rauh et al 2008, Tsuji et al 2015, Zeng et al 2016). This issue of environmental injustice has been documented throughout the world in many different countries (Claudio 2007, Cutter 2006).…”