Toxics (Pb, Cd) and trace elements (Zn, Cu, Mn) in women during pregnancy and at delivery, South Benin, 2014–2015

Highlights: • Lack of data on maternal exposure to toxic and trace elements in Africa. • Longitudinal blood measurements of Pb, Cd, Zn, Cu and Mn during pregnancy in Benin. • Evidence of maternal exposure to Pb and Cd. • Identification of potential sources for Pb exposure during pregnancy. During pregnancy, fetal development can be hindered by maternal exposure to toxic elements and abnormal concentrations of trace elements. Few data are available in African countries. Our goal was to assess the body burden of lead (Pb), cadmium (Cd), manganese (Mn), zinc (Zn) and copper (Cu) in pregnant women in Benin. The study was carried out in Sô-Ava district, from November 2015 to April 2016. Sixty women were recruited from the RECIPAL pre-conceptional cohort study. In all women, blood samples were collected during the first trimester of pregnancy. Thirty-two women had additional maternal and cord blood samples collected at delivery. Blood samples were analyzed by inductively coupled plasma mass spectrometry. At delivery, Cd median (IQR) concentration in maternal blood was 0.34 µg/L (0.24–0.46) in this non-smoking population. Pb median (IQR) concentration in maternal blood at delivery was 37.4 µg/L (30.5–52.0), with 31.3% of blood Pb levels above the 50 μg/L threshold. These pregnant women lived in semi-rural lakeside villages. Potential sources of Pb exposure identified during pregnancy were having water supply by drill pump and activities such as smoking fish by the woman and fishing by the household head. At delivery, Zn, Cu, and Mn median (IQR) concentrations in maternal blood were, respectively, 5415 μg/L (4894–5822), 1609 μg/L (1295–1771) and 16.0 μg/L (12.5–20.8). Pb, Cd, Mn and Cu blood concentrations were significantly higher at delivery than during the first trimester of pregnancy. Pb, Cd, Zn and Cu concentrations were significantly lower in cord blood than in maternal blood, contrary to Mn concentration, which was significantly higher in cord blood than in maternal blood at delivery. This exploratory study is the first one performed in Benin, and warns us about exposition of women from Sô-Ava district to Pb and Cd during pregnancy.