Study

Mushroom poisoning epidemiology in the United States

Brandenburg, William E.; Ward, Kimberlie J.

Mycologia, 2018

Peer-reviewedlongitudinal studynot applicable

What they did

National poison-centre records of mushroom exposures over eighteen years were analysed for outcome severity, age distribution and, where recorded, the identity of the fungus involved.

Studied in: Agaricomycetes
Sample size: 133700 mushroom exposure cases reported to US poison centres, 1999–2016

The overwhelming majority of reported exposures produced no or minor effects, and a very small fraction produced major harm or death. Deaths were concentrated in cases where the species was identified as amatoxin-containing, and identification was recorded in only a small minority of cases overall.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

Mushroom exposures reported to poison centres are common and mostly benign, while the small number of severe cases are dominated by a few genera.

How NatureHQ reads it

Two things worth taking from this, pulling in opposite directions. The absolute risk from a random mushroom exposure is low, which is why most people who have eaten something unidentified are fine — and that is exactly why the folklore survives, because it appears to work. And the severe cases cluster in a handful of genera whose members are not visually distinctive, so the low base rate provides no protection at all in the case that matters.

Limitations

Poison-centre data capture only exposures somebody reported, so the denominator is unknown.
The fungus was identified in a minority of cases, so species-level conclusions rest on a selected subset.
One country over one period; the species present, and therefore the risk profile, differ elsewhere.