I was also researching this when my kids were small, and I agree that this deserves more scrutiny. I was able to unearth at least a bit more. First: How much dirt do kids actually eat?
the median estimates of soil ingestion from the eight tracers ranged from a low of 9 mg/day (Y) to a high of 96 mg/day (V); … One child had soil ingestion values ranging from 5 to 8 g/day— How much soil do young children ingest: An epidemiologic study (Science Direct) scanned PDF found here
From personal experience, these numbers look pretty low. My kids definitely ate more than that—at least temporarily.
This is also the sentiment of this interesting and somewhat comprehensive article on the matter:
Eating Dirt (Gerald N. Callahan, US National Institutes of Health)
The risks of eating dirt focus on serious infections, which seem rare. So I looked at incidence rates of gastrointestinal infections and found
5% of the U.S. population has been infected with Toxocara. Globally, toxocariasis is found in many countries, and prevalence rates can reach as high as 40% or more in parts of the world —Toxocariasis (CDC)
Which are higher than I would have expected, but if you think about FGID as vaccination it makes more sense that many toddlers get it. Better earlier than later.
My summary is the same from this piece on eating dirt in the German magazine Spiegel:
CONCLUSION: Dirt does not clean the stomach, but the stomach cleans the dirt. So it doesn’t matter if children swallow some sand and their behavior is no reason to restrict their visits to the playground. On the contrary: if toddlers come into contact with many different microbes, their allergy risk is reduced. But they shouldn’t be encouraged to eat dirty food.
ADDED: Dirt from your own house and garden is most likely fine if
the house is not newly constructed, but nature had time to cultivate it for some years,
there are no sources of pesticides or pollutants in the vicinity (includes e.g., lead paint), and
no non-domesticated animals roam close to the house.
I was also researching this when my kids were small, and I agree that this deserves more scrutiny. I was able to unearth at least a bit more. First: How much dirt do kids actually eat?
From personal experience, these numbers look pretty low. My kids definitely ate more than that—at least temporarily.
This is also the sentiment of this interesting and somewhat comprehensive article on the matter:
Eating Dirt (Gerald N. Callahan, US National Institutes of Health)
The risks of eating dirt focus on serious infections, which seem rare. So I looked at incidence rates of gastrointestinal infections and found
and
Which are higher than I would have expected, but if you think about FGID as vaccination it makes more sense that many toddlers get it. Better earlier than later.
Interestingly, geophagy is common among primates.
My summary is the same from this piece on eating dirt in the German magazine Spiegel:
ADDED: Dirt from your own house and garden is most likely fine if
the house is not newly constructed, but nature had time to cultivate it for some years,
there are no sources of pesticides or pollutants in the vicinity (includes e.g., lead paint), and
no non-domesticated animals roam close to the house.
EDIT: Typos, clarity.