Breast-Feeding Exposure of Infants To Cadmium, Lead, and Mercury: a Public Health Viewpoint

Abstract

The purpose of this report is to provide an overview of the public health implications of exposure via breast milk to cadmium, lead, and mercury for nursing infants and to provide health-based guidance. Daily intakes were calculated and compared with guidance values used for public health assessments at hazardous waste sites. Cadmium, lead, and mercury under normal conditions are found in breast milk at concentration ranges of < 1 microgram/L, 2-5 micrograms/L, and 1.4-1.7 micrograms/L, respectively. Women exposed environmentally or occupationally can have higher levels in their breast milk. Concentrations of about 5 micrograms/L (cadmium), 20 micrograms/L (lead), and 3.5 micrograms/L (mercury) appear to be adequate screening levels. Many factors affect both the distribution of cadmium, lead, and mercury in breast milk and the health consequences to an infant. It is not clear what additional impact low-level exposure via breast milk may have on an infant born with a body burden to one of these metals. There is sufficient evidence to make the case that contaminated breast milk is a source of potential risk to infants in certain populations. Prevention strategies that include behavior modification and proper nutrition should be communicated to women at risk. Identification and elimination of exposure pathways and a critical analysis of the benefits of breast feeding versus heavy metal exposure are needed on a site-specific or individual basis. Research is required to better understand the impact of low-level exposure to heavy metals via breast milk. Breastfeeding should be encouraged under most circumstances.

Smoking, cereal consumption, and supplementation affect cadmium content in breast milk

“…Under normal conditions (non-occupational exposure), Cd levels in breast milk have been reported to be less than 1 mg/l (Abadin et al, 1997). In agreement with these data, we registered a maximum level of 0.73 mg/l.…”

“…Cadmium levels in breast milk have markedly decreased in Austria over the last decades and are now among the lowest in Europe (Table 4). The screening level (minimal risk level; MRL) for Cd in breast milk is 5 mg/l (Abadin et al, 1997). By definition, MRLs are estimates of daily human exposure to a chemical that are likely to pose no appreciable risk of adverse health effects over a specified duration and route of exposure.…”

Levels of lead in breast milk and their relation to maternal blood and bone lead levels at one month postpartum.

“…Despite the many well-recognized benefits of breast-feeding for both mothers and infants, detectable levels of lead in breast milk have been documented in population studies of women with no current environmental or occupational exposures (Abadin et al 1997). Because lead accumulates in bone, women who were chronically exposed to environmental lead during infancy and adolescence may have a significant bone lead burden when they reach reproductive age.…”

Environmental contaminants in human milk

“…These gaps can be filled through human epidemiologic study. Consideration of the high milligrams per kilogram per day dose delivered to the nursing infant and the persistence of the delivered dose for nearly a lifetime may require modifications in regulatory risk assessment models for persistent, biocumulative chemicals and for chemicals that can cross the placenta ( Pohl and Hibbs, 1996;Abadin et al, 1997) .…”