Moldy whiff kills brain cells.

Watch out, Hurricane Katrina and Rita cleanup crews. A common black mold that blooms on moist cellulose-based materials--from wallboard and ceiling tiles to cardboard--creates a toxin that can kill certain brain cells. In an experiment with mice, the chemical, satratoxin, targeted neurons running from the inside of the nose to the brain's smell center.

"This is the first demonstration that a neuron can be killed by satratoxin," notes Jack R. Harkema of Michigan State University in East Lansing.

The fungal toxin's "specificity is what's really unique," notes Harkema's Michigan State colleague James J. Pestka. Among the exposed nasal cells, the toxin proved lethal only to those that sense odors.

The black mold Stachybotrys chartarum, commonly found in water-damaged buildings, had already been linked to people's respiratory irritation and asthma. To identify nasal effects, Harkema, Pestka, and Zahidul Islam, also of Michigan State, made mice inhale a single dose of satratoxin and then monitored tissue changes over the next month.

Within a day of exposure, 75 to 80 percent of the olfactory neurons in the animals' noses had died, Harkema notes. Although these cells can regenerate, he says, even after a month, many had still not been replaced.

As little as 25 micrograms of toxin per kilogram of mouse-body weight elicited this neural toxicity. The scientists now plan to evaluate whether prolonged exposure to even lower doses--as could be assaulting hurricane-cleanup crews--might trigger similar changes.

A full report of the findings will appear in an upcoming Environmental Health Perspectives.--J.R.