Ingestion of wild and potentially toxic mushrooms is more common in the United States than most people realize. The National Poison Data System (NPDS) reported that over the last 18 years 133,700 cases of mushroom exposure, mostly by ingestion, have been reported in the United States. That averages to 7,428 per year. There was minor or no harm in 86% of the adult cases and minor or no harm in 62% of the cases involving children less than six years of age. Of the 133,700 reported cases, 704 (an average of 39 per year) resulted in major harm. Fifty-two (almost three per year) fatalities were reported. All deaths occurred in adults. Misidentification of mushroom species appears to be the most common cause. The term “appears” is used because in 75% to 95% of the cases the exact species involved in the exposure was never identified.
This training module does not address molds, mildews, or yeasts which, including mushrooms, are all categorized as fungi. An article in the American Journal of Botany published in 2011 stated there could be one to greater than five million different species. However, a more recent article in Microbiology Spectrum published in 2017 argued that that number was a vast overestimation and suggested that more a realistic number is between 2.2 and 3.8 million species. Figures vary by articles somewhat, but overall it is estimated there are somewhere around 70,000 species or fewer than 10% of fungi that have been described by mycologists to date. Of this number, greater than 90% have been classified within the phyla of which we are concerned: Basidiomycota and Ascomycota. Only about 100 mushroom species in those two phyla have been confirmed as poisonous.
