Monday March 15 2:38 PM ET

Herbicides may raise lymphoma risks

NEW YORK, Mar 15 (Reuters Health) -- Exposure to certain herbicides and fungicides may increase the risk of developing non-Hodgkin lymphoma, according to Swedish researchers.

One of these suspected carcinogens -- 4-chloro-2-methyl phenoxyacetic acid (MCPA) -- ``is still used widely in agriculture as a weed killer,'' according to study authors Dr. Lennart Hardell of Orebro Medical Center in Orebro, and Dr. Mikael Eriksson of University Hospital in Lund, Sweden. Their findings are published in the March 15th issue of the journal Cancer.

Non-Hodgkin lymphoma leads to nearly 24,000 deaths in the US each year.

In their study, the researchers questioned 404 Swedish men diagnosed with non-Hodgkin lymphoma about exposure to various types of herbicides and fungicides throughout their lives Those reports were then compared with the exposures of over 700 healthy ``control'' subjects.

The authors conclude that ``exposure to both herbicides and fungicides resulted in significantly increased risks for non-Hodgkin lymphoma.'' Exposure to herbicides in general was associated with a 60% increase in risk compared with those who were not exposed, while contact with MCPA nearly tripled cancer risk.

``Only exposure during the most recent decades before diagnosis of non-Hodgkin lymphoma was associated with an increased risk,'' according to Hardell and Eriksson.

Exposure to fungicides was also associated with a nearly fourfold increase in cancer risk, according to the researchers, with risks rising as the duration of exposure to these types of chemicals increased.

Hardell and Eriksson point out that herbicides and fungicides are known to suppress the immune system. Previous research suggests that non-Hodgkin lymphoma may be caused by a viral attack upon a weakened immune system.

Certain carcinogenic herbicides, most notably the dioxins found in Agent Orange, have been banned in most countries for decades. However, the investigators point out that chemicals like MCPA are ``still much in use in agriculture as a weed killer.'' They believe that more research is needed into the potential health hazards of these types of compounds.

SOURCE: Cancer 1999;85:1353-1360.