Bug sprays seem to really like toys.

Pesticide foggers used for treating an entire room usually carry labels instructing occupants to vacate the premises for 1 to 3 hours. The intent is to limit inhalation of the potentially toxic vapors or contact with wet residues. A new study now finds that for young children, dry residues can provide a greater source of exposure -- and can continue to do so for a week or more.

Scientists in New Jersey hired a licensed professional to spray two Rutgers University apartments with a pesticide, following instructions on the label. The researchers then placed hard plastic toys and stuffed animals in rooms an hour after they had been fogged. Throughout the next 2 weeks, they swabbed the furniture for residues and removed toys for testing. Their findings, reported in the January Environmental Health Perspectives, show that the toys -- far more than the furniture -- accumulated pesticide residues for at least 1 week.

"I didn't expect this. It was a big surprise," notes study leader Paul J. Lioy of Rutgers and the University of Medicine and Dentistry of New Jersey in Piscataway. Indeed, the data suggest that the pesticide leaped "like a grasshopper" from one surface to another for 2 weeks, with certain plastics and foam effectively sopping it up "like a sponge," Lioy says. The fact that the toys acquired far higher residues than the furniture or linoleum floor, he says, traces to their particular chemical affinity for holding onto the pesticide. Though his team had used chlorpyrifos, a popular termite and roach killer, Lioy said any semivolatile pesticide should leap similarly.

The team estimates possible toddler exposures, beginning 1 week after fogging, at more than 200 micrograms per kilogram of body weight daily -- 20 times the recommended allowable daily intake. Some 39 percent of the exposure would come through the skin, with virtually all of the rest from children putting residue-laden fingers or toys in their mouth.

The findings "should be a big boon to the toy box industry," Lioy told Science News, because the easiest way to cut exposures would be to put toys away whenever they're not in use -- at least for the first 2 weeks after any fogging.