Environmental contaminants in breast milk

Are there dangerous chemicals in my breast milk?

We are all exposed to contaminants that can harm our health. We breathe them in, consume them in food and drink, and absorb them through our skin. Some of these are found in breast milk, but the levels of contaminants that babies get through breastfeeding are generally much lower than the levels obtained in other ways. Studies indicate that the benefits of breastfeeding outweigh the risk of exposure to the generally low levels of contaminants found in breast milk. Infant formula can also contain contaminants. Mothers at risk of higher levels of contaminants should have their levels tested. Mothers with very high levels of lead should temporarily stop breastfeeding until this is addressed. 

A) Describing environmental contaminants

People are regularly exposed to organic pollutants, toxins from fungus (mycotoxins), pesticides, heavy metals such as arsenic, lead, and mercury, and other contaminants that can pose a risk to health (Rappazzo 2017). 

If environmental contaminants are in a pregnant mother’s body, babies will be exposed before birth. Exposure is also possible through breast milk but amounts are generally low and not a reason for stopping breastfeeding. 

For more information about heavy metals and other environmental risks in your area, please contact your local health agencies. 

B) Low levels of contaminants in human milk

Some environmental contaminants are found in human milk (Mogensen 2015). Levels vary depending on the mother’s levels and the nature of the contaminant. Breasts sometimes filter out these chemicals and breast milk can have lower levels than those in the mother’s body (Salmani 2007). For example, lead levels in breast milk are less than 3% of the level in a mother’s blood (AAP 2005).

The current research shows that babies exposed to environmental contaminants through breast milk are not at risk of health consequences (Doréa 2019; LaKind 2018). The benefits of breastfeeding outweigh the risks of exposure to the generally low breast milk levels of these contaminants (Boersma 2000; Lapillonne 2020; Mead 2008; Sundkvist 2010). In addition, breastfeeding may protect the baby's brain and nervous system against their harmful effects.

Rarely, mothers may need to temporarily stop breastfeeding if they have been acutely poisoned or have very high levels of toxins in their body (DHHS 2009; Mead 2008).

C) Other sources of contaminants

The amount of contaminants a baby takes in through breastfeeding can be much lower than the amounts obtained in other ways (Kim 2007). Contaminants can be breathed in or taken in by mouth from:

Lead and other contaminants can be present in water making it unsafe for use when preparing infant formula.

Infant formula can also be a source of contaminants but there is even less research about environmental contaminants in infant formula than in breast milk (Gardener 2019; Lehmann 2018).

D) Lead

Lead has many documented harmful effects and is particularly so to children (WHO 2019).  

While most mothers have low lead levels, others are at risk of higher levels (Ettinger 2020). This includes mothers who:

  • Have lived or live in areas where lead contamination has been caused by:
    • Leaded gasoline.
    • Industry.
  • Work in certain manufacturing industries:
    • Battery.
    • Ammunition.
    • Plastics.
  • Renovate lead-contaminated houses.
  • Use or work with lead-glazed pottery.
  • Eat lead-contaminated items such as herbs, spices, or other foods.
  • Use lead-contaminated cosmetics such as eye-liner (kohl) (Shawahna 2018).
  • Drink lead-contaminated water.

Mothers who are at risk of high lead levels should have their blood lead levels measured. If the levels are above 40 micrograms per 100 millilitres, they should not breastfeed but rather express and throw out their milk until they are treated, the source of the lead is removed, and the blood lead levels are acceptable (ACOG 2012).


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