Environmental Contaminants in Breast Milk

Krista Nickerson, CNM, MSN


J Midwifery Womens Health. 2006;51(1):26-34. 

In This Article

Recommendations for Clinical Practice

There are huge gaps in the current knowledge about the effects of chemical contaminants in breast milk. Research regarding the type, extent, and distribution of contaminants is frequently limited by small samples, small geographic areas, and narrow chemical analyses. There are no standard protocols for toxin detection and measurement in breast milk, making comparability across studies next to impossible.[9] Moreover, there is little evidence for determining proper guidelines for health risk assessment. Current risk assessment methods do not consider breastfeeding exposure and are based on norms of adult body weight and food consumption data. The purpose of the US Food and Drug Administration's (FDA) food-monitoring program is to enforce compliance with the US Environmental Protection Agency (EPA) tolerance levels, not to determine dietary exposure to all environmental contaminants of concern.[44] As a result, there are no established "safe" levels for contaminants in breast milk currently.

Considering these limitations, how do clinicians incorporate knowledge of breast milk contaminants into clinical practice and relay it to our clients? Despite the well-established universal contamination of breast milk, the World Health Organization (WHO) makes this statement, "The advantages of breastfeeding far outweigh the potential risks from environmental pollutants. Taking into account breastfeeding's short- and long-term health benefits for infants and mothers, WHO recommends breastfeeding in all but extreme circumstances."[45] Therefore, our recommendations to clients should continue to reflect this message. However, clinicians should be aware of current EPA and FDA dietary guidelines concerning pregnant and breastfeeding women (refer to websites listed in Appendix A). Currently, there are only specific recommendations concerning methylmercury levels only in commercial fish. Midwives should be aware of contaminated water sources in their area and encourage women to avoid consumption of fish from these sources. To reduce dietary exposure to many POPs, preferably before conception occurs, women can reduce consumption of animal fats by choosing lean meats and low-fat dairy products.[46] Women should also be encouraged not to smoke. Counseling regarding this issue should be tailored to meet the learning needs of the individual client. An excellent patient education handout concerning breast milk contamination is available from the Physicians for Social Responsibility Web site (Appendix A).

Little is known about the response of mothers to being informed that their breast milk contains toxic chemicals. Hatcher[47] explored the psychological reactions of a group of nursing mothers in Michigan whose breast milk was inadvertently contaminated with PBB. Only 28% of the women achieved a reasonable understanding of the issues, and only one third of women who had their breast milk tested reported that the results had some bearing on the decision to breastfeed.

There may be specific subpopulations at risk for higher exposure to contaminants. Women who could have occupational or agricultural exposures to toxic chemicals should take steps to avoid or reduce potential exposures to herself and her fetus or newborn. Women and children of low socioeconomic status may constitute a sensitive population due to poor nutrition and residence in highly polluted neighborhoods.[43]


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