Dear XXXXXXXXX:
Fungi and People. You just never know.
A brief look at Scopulariopsis brevicaulis Species.
One of the most striking features of
Scopulariopsis brevicaulis is its association with human deaths by producing arsine gas from arsenate dyes found in wallpapers.
Arsenic is a minor constituent of soil. Volatilization and methylation of dimethylarsinic acid and methylation of arsenate and arsenite naturally occur in soil. These bicohemical reactions end up with production of trimethylarsine and dimethylarsine. Arsenic is found in pesticides as well; the currently used ones are methylarsonic acid and dimethylarsinic (cacodylic) acid pesticides.
Arsine is the most toxic form of arsenic. At concentrations above 0.5 ppm, it has a garlic-like odor. However, it is toxic at concentrations much lower than this.
The whole story started when arsenate dyes were formulated to be used in wallpapers. The most famous of these dyes was
Schweinfurter green, one of several green copper-arsenic dyes that were manufactured and incorporated into wallpapers in 1810s. Following the widespread use of these green wallpapers in Germany, France, and other countries, two things drew attention: A garlic odor in some rooms with these wallpapers and the death of people who slept in these rooms. These people got sick and died secondary to tubular necrosis and renal failure. In 1897, the Italian chemist B. Gosio showed that the deaths were due to the production of a gas which could not then be identified. This gas was thus called
Gosio gas.
This gas was produced by
Penicillium brevicaulum, the mould fungus today known as
Scopulariopsis brevicaulis. The whole story was clarified by Frederick Challenger in 1945 when he identified the gas as trimethylarsine. We today know the whole mechanism of the production of this gas.
Scopulariopsis brevicaulis consumes the starch found in the wallpaper paste. Meanwhile, the fungus converts the arsenate found in the paper to trimethylarsine oxide. Finally, the oxide is reduced to trimethylarsine and the gas, which is toxic and causes human deaths is released. Although the phenomenon was initially related only to
Scopulariopsis brevicaulis, other moulds found in the environment may also theoretically be able to liberate volatile arsenic compounds by using the same mechanism.
Hats off to B. Gosio & Frederick Challenger!
John Rex, Mike McGinnis &
the entire doctorfungus team
