MUSHROOM PRODUCTION IN RESPECT OF MERCURY CONTENT

Abstract

The actionable level of total mercury in mushrooms (Agaricus bisporus (Lange) Sing.) is set at 0.05 ppm and when it was discovered that a small percentage of Ontario grown commercial mushrooms exceeded this level (0.06–0.33 ppm), a survey was undertaken to determine the source. Compost was found to be the most likely source. Mushrooms with the highest residues of total mercury were grown on compost that contained from 0.42 to 0.61 ppm mercury. Mushrooms with low residues were grown on compost with only 0.08–0.23 ppm mercury. The ingredient of compost that had contributed the highest mercury content was horse manure. This ingredient contained residues that ranged from 0.23–0.42 ppm in the elevated compost and 0.05–0.25 ppm in the others. The mercury in compost, manure and mushrooms was not methyl mercury and was deemed inorganic.