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Fish consumption in the Great Lakes

Fish consumption
    in the Great Lakes

Fish | Breast milk | Fish consumption advisories
Critical contaminants | Reducing exposure

Critical contaminants in breast milk
People in the Great Lakes basin get their food from a global market, this general market basket diet contributes to over 95 percent of their intake of Persistent Bioaccumulative Toxic (PBT) chemicals. Exposure assessments from all sources (air, water, food, and soil) were completed for the Canadian Great Lakes basin general population, for eleven PBT chemicals, including nine chemicals designated for zero discharge. The total estimated daily intake averaged over a lifetime was well below the Tolerable Daily Intake (TDI) established by Health Canada. Consequently, the approach by various agencies has been to examine groups at higher risk of exposure to persistent toxic substances from Great Lakes sources, such as high consumers of sport fish.

In Canadian populations, Craan and Haines (1998) reported a downward trend from 1967 to 1992 in the concentrations of organochlorine pesticides and PCBs in human breast milk. A similar decline could be expected of organochlorine concentrations in human breast milk in the Great Lakes basin.

Nonetheless, trace levels of PCBs and other PBT chemicals are found in breast milk of the general population. Very little is known about the effects of exposure of infants to moderately high levels of organochlorines during the breast-feeding period. Jacobson and others (1992) did not find an association between breast-feeding and developmental deficits in his Michigan fish consumers study (Van Oostdam et al, 1999). Rogan et al (1991) in reporting on the North Carolina Breast Milk and Formula Project, saw no evidence of adverse effects from exposure to PCBs or DDE (a metabolite of DDT) through breast milk, although they did report a subtle motor delay attributable to transplacental (in utero) exposure. Research is continuing into health risks of PBT chemical exposure from breast feeding and other exposure routes.

"There are many recognized advantages to breast-feeding to infants and to mothers, including improved nutrition, increased resistance to infection, protection against allergies, and better parent-child relationships. With full regard for the uncertainty over the toxic effects of organochlorines in human milk, the known benefits of breast-feeding are extensive and serve as a strong rationale for advising mothers to continue to breast-feed their newborns unless cautioned by their local health care worker to reduce or stop." (cited from Van Oostdam et al, 1999).

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