Blood heavy metals and brain-derived neurotrophic factor in the first trimester of pregnancy among migrant workers

Lead, mercury, cadmium and arsenic are the priority heavy metals of major public health concern in industrialized countries. Exposure to them can cause cognitive impairment and depressive disorders through an effect on Brain-derived neurotrophic factor (BDNF) which is an important biomarker of pregnancy. Despite a number of prior studies on heavy metals pollution, there is few of studies on the effect of heavy metals on BDNF during early pregnancy. This study aims to examine the association between maternal blood heavy metals concentrations and BDNF during the first trimester pregnancy among Myanmar migrants in Thailand.

This cross sectional study, a part of ongoing birth cohort was conducted at the antenatal care clinic from June to October 2018. A total of 108 with Myanmar migrant pregnancy with a single viable fetus of 0 to 14 gestation weeks who stayed within the industrial plant at least 3 months before were recruited. Socio-demographic characteristics and health behaviors were accessed using a self-report questionnaire. Maternal blood heavy metals (lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As)) were measured using an inductively coupled plasma mass spectrometer and plasma BDNF was measured using an enzyme-linked immunosorbent assay. Multivariate binary logistic regression were modeled to access the association.

Median (interquartile rank: IQR) concentrations were: BDNF (6.49 (1.79) μg/ml), Pb (2.77 (1.46) μg/dL), Hg (0.62 (0.54) μg/dL), Cd (0.93(0.86) μg/L) and As (0.40 (0.11) μg/dL) respectively. We categorized BDNF concentrations into high (> median) (n = 54) and low (≤ median) (n = 54) groups. After adjusting for potential confounders, high blood total arsenic concentration had 2.6-fold increased odds (aOR = 2.603, 95% CI: 1.178, 5.751) of low plasma BDNF level as compared with low blood total arsenic group. However, there was no significant association between BDNF and Pb, Hg and Cd.

The present findings demonstrate higher blood total arsenic level were more likely to have lower BDNF in early pregnancy. Our study suggested that heavy metal could be worsen BDNF level which plays its important role on biological effect of maternal depressive disorder and newborn neurodevelopment.