Body burdens of mercury, lead, selenium and copper among Baltimore newborns

Umbilical cord blood or serum concentrations of mercury, lead, selenium and copper were measured with inductively coupled plasma mass spectrometry in a population of 300 infants born in Baltimore, Maryland. Geometric mean values were 1.37 μg/L (95% confidence interval: 1.27, 1.48) for mercury; 0.66 μg/dL (95% CI: 0.61, 0.71) for lead; and 38.62 μg/dL (95% CI: 36.73, 40.61) for copper. Mean selenium was 70.10 μg/L (95% CI: 68.69, 70.52). Mercury, selenium and copper levels were within exposure ranges reported among similar populations, whereas the distribution of lead levels was lower than prior reports; only one infant had a cord blood lead above 10 μg/dL. Levels of selenium were significantly correlated with concentrations of lead (Spearman's ρ=0.20) and copper (Spearman's ρ=0.51). Multivariable analyses identified a number of factors associated with one of more of these exposures. These included: increase in maternal age (increased lead); Asian mothers (increased mercury and lead, decreased selenium and copper); higher umbilical cord serum n−3 fatty acids (increased mercury, selenium and copper), mothers using Medicaid (increased lead); increasing gestational age (increased copper); increasing birthweight (increased selenium); older neighborhood housing stock (increased lead and selenium); and maternal smoking (increased lead). This work provides additional information about contemporary prenatal element exposures and can help identify groups at risk of atypical exposures.

Research Highlights
► Babies with higher umbilical cord lead levels were more likely to be of lower SES, have Asian mothers, have older mothers, live in neighborhoods with older housing stock and have mothers who smoked during pregnancy.
► Umbilical cord mercury levels were higher among babies of Asian mothers.
► Umbilical cord blood selenium increased with birthweight and copper levels increased with gestational age; selenium and copper levels were significantly correlated.
► Newborn umbilical cord blood selenium levels were higher among babies who had higher blood levels of lead and also among those with mothers living in neighborhoods with older housing stock.
► Babies with higher umbilical cord n−3 fatty acids had higher umbilical cord blood levels of mercury, selenium and copper, suggesting fish and seafood as a common source of these metals.