Question
My four-year-old son came in from the garden the other day covered in dirt, including his mouth. I know it’s not ideal for him to eat dirt, but should I be on the lookout for any serious health consequences?
Answer
This is pretty common behaviour for children under three and is fueled by curiosity. In fact, in Canada and the U.S. it is estimated that 20 percent of kids eat up to a teaspoon of soil on many occasions.
There is a rare eating disorder where dirt is consumed, but for the average child in their backyard, it is surprising that more harm does not come from eating dirt. In fact our hygiene hypothesis suggests that early exposure to bacteria will reduce allergies and other immune diseases as well as improve resistance to disease.
For the most part, soil in backyards and playgrounds is not unhealthy, but some soil can be contaminated with lead and arsenic. There can also be other chemical contamination, harmful bacteria from sewage or manure, parasites and roundworm from pets. If you live near a gas station or a factory that uses pesticides or makes paint or batteries, you might want to get your soil tested. If you use manure or sewage sludge to fertilize your lawn then keep children away from this soil.
Lead is a toxin that can damage young children. Lead levels are lower in Canada than in the U.S., likely due to differences in the paint industry. A diet high in zinc, iron and calcium helps reduce the amount of lead absorbed from soil or ingested in paint.
Roundworm, if ingested, survives in a child’s stomach and hatches in the intestine. Toxocara worms live in dogs and cats and can also be ingested from soil. Make sure that pets are dewormed and animal feces are always removed.
Dr. Marla Shapiro is a medical doctor, author, broadcaster, lecturer and parent.
Originally published in ParentsCanada magazine, April 2014.
