The importance of measured intake in assessing exposure of breast-fed infants to organochlorines

OBJECTIVES: To estimate infants' intake of organochlorines (OCs) from their measured intake of breast milk; to compare these with the acceptable daily intakes (ADIs) set by the World Health Organization (WHO). DESIGN: Primiparous nursing mothers were recruited from either an industrial or rural area between January and November 1992. SETTING: Mothers volunteered in response to information displayed at their Infant Welfare Centre. All sampling was undertaken in the subject's home. SUBJECTS: The sole entry criterion was primiparity. Three breast milk samples were collected at one month intervals from each mother. OC levels were measured on a milk fat basis by gas chromatograph-mass spectrometer and individual milk intakes were used to determine the infant's daily OC intake. Of the 23 mothers who entered the study, 17 finished, resulting in 57 samples for intake determination. RESULTS: Some intakes of hexachlorobenzene (HCB), chlordane, dieldrin and heptachlor epoxide (HE) exceeded the ADI. High OC levels in breast milk did not necessarily result in a high intake for the infant. CONCLUSIONS: Assessment of the exposure of infants to OC contaminants in breast milk requires an accurate estimate of OC intake. Intakes estimated using inferred rather than measured values for milk fat and milk intake are not reliable indicators of actual intakes.