Public health

Toxic residues in breast milk

Any animal product (meat, milk, eggs) on the plate of a breastfeeding mother could contain chemical residues that can be transmitted to the infant. “Farm animals are given anabolic steroids and antibiotics that can turn up later in breast milk, in trace quantities,” says Thierry Le Bricon, a graduate student in environmental health and occupational safety. He has studied the risks of contamination of breast milk by chemicals that come from fertilizers, industrial pollutants and antibiotics present in foods of animal origin.

Regulations designed to protect the health of Canadian consumers have been in place for a number of years. Health Canada requires an obligatory waiting period between administering medication to an animal and sending it to the abattoir, thereby limiting the presence of potentially toxic residues in foods. The Canadian Food Inspection Agency (CFIA) also monitors food periodically. Nothing that fails to meet the established standards will wind up in the grocery store.

Breast milk from vegetarian mothers appears to contain fewer chemical contaminants. “The concentration of chemicals in their breast milk is lower than it is in women who eat meat,” says Le Bricon. “In fact, fruit and vegetables (especially if they’re organic or have been washed) generally contain fewer chemical contaminants than animal products and by-products.”

The expert notes that it’s wise to avoid food that’s cooked on the barbecue, as burnt meat generates toxic substances like polycyclic aromatic hydrocarbons (PAHs), which can be found in breast milk. The beneficial effects of breastfeeding substantially outweigh any harmful effects, however, the French-born pharmacist is quick to point out. “Breastfeeding has so many advantages, both for the child, who is less likely to contract ear infections and diarrhea or develop allergies, and for the mother – bone remineralization, reduced risk of ovarian cancer. So there is no reason not to breastfeed.”

In Quebec, the Inuit of the far north and farming families get the highest exposure to toxic substances. The breast milk of Inuit women can contain various toxic products such as polychoric biphenyls (PCBs) or methyl mercury, which are present in the environment and in their traditional food chain. “Even in the populations that receive the most exposures, scientists are unanimous in recommending that mothers continue to breastfeed their infants,” says Le Bricon.

Children from rural families who are given reconstituted milk products mixed with well water are still at risk of nitrate intoxication. However, breastfed infants are protected, as nitrites (toxic products from nitrates) do not cross the natural protection barrier between mother and child. Babies who are bottle-fed with contaminated water could become sick.

The Quebec government, which recognizes the benefits of breastfeeding, has established various strategies to promote the practice, including Breastfeeding Week, held in October. The Quebec Ministry of Health and Social Services has set a goal for 2007 to have 85% of new mothers breastfeeding immediately after giving birth, 60% after four months, and 50% six months later.

To determine the degree of exposure to certain chemicals, experts use breast milk as an exposure marker, since it is both easy and inexpensive to obtain. However, the presence of a contaminant does not necessarily mean that it will eventually have repercussions in terms of health. “A substance may be hazardous, but that doesn’t mean that you or your child is at risk. What counts is the dosage of exposure,” says Le Bricon.