Human Breast Milk Contamination in the United States and Canada by Chlorinated Hydrocarbon Insecticides and Industrial Pollutants: Current Status

Abstract

Widespread contamination of human breast milk with chlorinated hydrocarbon insecticides has been repeatedly documented in population surveys in the United States and Canada over the past two decades. Unfortunately, it was not until the most recently published assessments that a strong effort has been made to apply proper biostatistical sampling methodologies to such surveys. This deficiency, along with frequent omission of information on variables known to affect the levels of such contaminants in breast milk, makes precise historical comparisons difficult. Given these uncertainties, it appears that organochlorine insecticide residues in human breast milk have not noticeably changed over the past two decades in the United States despite the regulatory restriction placed on several of these substances, such as DDT, since 1970. The surveys have revealed that total DDT levels continue to approach and exceed the Acceptable Daily Intake (ADI) level recommended by WHO. Perhaps of greatest concern is the ubiquitous contamination by polychlorinated biphenyls (PCBs) of breast milk, with levels of the upper 30% of the population being within a factor of 10 of those levels producing adverse health effects in humans and monkeys. The carcinogenic risk assessment for consumption of PCB-contaminated breast milk is also discussed.