November 29, 2005

Job exposure to pesticide may raise cancer risk

NEW YORK (Reuters Health) - Daily on-the-job exposure to
the pesticide diazinon appears to increase the risk of lung
cancer and possibly other cancers, according to new findings
from the US government-sponsored Agricultural Health Study, a
project begun in 1993 to investigate the health effects of
pesticides on farm families in Iowa and North Carolina.

By December 2002, 301 of 4,961 men with occupational
exposure to diazinon had developed lung cancer compared with
968 of 18,145 with no occupational exposure to diazinon.

"We found evidence of an association of lung cancer and
leukemia risk with increasing lifetime exposure days to
diazinon," Dr. Michael C. R. Alavanja from the National Cancer
Institute in Rockville, Maryland and colleagues report in the
American Journal of Epidemiology.

The results were unchanged after adjusting for cigarette
smoking, "suggesting that confounding due to smoking probably
does not explain the elevated risks of lung cancer," the
authors write.

They also point out an association between diazinon use and
lung cancer was reported in an earlier analysis of the
Agricultural Health Study, with fewer years of follow-up.

Diazinon is an organophosphate -- a chemical derived from
nerve gas agents developed during World War II. Studies linking
organophosphates to neurological disorders and other largely
noncancer health risks prompted the US Environmental Protection
Agency in 2000 to start phasing out residential use of diazinon
in home, garden and lawn products. By 2004, the phase out was

The EPA has also proposed new restrictions on agricultural
use of diazinon. Nonetheless, in 2004, approximately 4 million
pounds of the pesticide were applied in agricultural settings
in the US.

In a 1997 review of the cancer-causing potential of
diazinon, the EPA classified the chemical as "not likely a
human carcinogen" based on studies in rodents. However, some
laboratory and epidemiologic data, including the latest
findings from the Agricultural Health Study, paint a different

Alavanja and colleagues add that as more cancer cases
accrue in the study, they will be in a better position to
"clarify whether diazinon is associated with cancer risk in

SOURCE: American Journal of Epidemiology, December 1, 2005.