Is the Grass Greener Where Cancer Danger is Greatest?

By Emily Green. Special to the Tribune. Emily Green is a staff writer for the Los Angeles Times, a Tribune newspaper.

The weapon of choice against the dandelion is the weed killer 2,4-D, most commonly mixed with fertilizer in "weed and feed" treatments. Each year, Americans apply an estimated 27 million pounds of it to home lawns, parks, cemeteries and anywhere else mown grass is found. It is thought to be the most widely used herbicide in the world. The appeal is that 2,4-D is selective: It kills broad-leaf plants such as dandelions but spares grass. It overwhelms the dandelion's hormone system, causing the weed to essentially grow itself to death. This "uncontrolled growth," says Thomas M. Cahill, an environmental chemist from Trent University in Ontario, Canada, is a kind of "cancer for plants."

The question among environmentalists and medical researchers is: Does cancer for plants also mean cancer for people?

EPA takes 2nd look

The Environmental Protection Agency, which ruled in 1997 that 2,4-D was not classifiable as a human carcinogen, is now reviewing the chemical's registration. Specialist committees are looking at the issue, says Joanne Miller, product manager for EPA's pesticide registration section. The EPA decision about registration is due in two years. Until then, "the bottom line is: We can't make a call," she says. "We can't rule out, and we can't say for sure."

That uncertainty is roiling the world of American lawn care, where the EPA estimates 20 percent of world production of 2,4-D is used. (That name, by the way, is the chemical signature for dichlorophenoxyacetic acid.)
Although 2,4-D has been used for decades, increasingly worried activists at the local level are demanding warning notices when it is used, blocking its use in city parks, and in some cases even getting it banned.

The manufacturers contend that hundreds of studies have shown no danger to humans.

"As long as label instructions are followed, it certainly poses no unreasonable risk," says Don Page, executive director of the industry's task force on 2,4-D research data. "The only verified examples of 2,4-D poisoning in humans is in suicides. If you drink enough of it, you can kill yourself."

By the 1980s, question marks loomed over the safety of 2,4-D, developed in 1944 in Britain. In 1986, a study published in the Journal of the American Medical Association suggested that Kansas crop workers who had applied 2,4-D had a heightened rate of non-Hodgkin's lymphoma, a cancer of the immune system. A later study also found higher than normal levels of the disease in lawn service applicators. In 1989, the National Academy of Sciences estimated that homeowners are likely to use 10 times more chemicals per acre on their lawns than farmers use on agricultural land.

Time for a review

Amid the furor sparked by the Kansas study, the EPA began its first review of 2,4-D since the chemical's introduction in the 1940s. In 1991, the National Cancer Institute said 2,4-D might cause a lymphatic cancer in dogs. It also calculated that diagnoses of non-Hodgkin's lymphoma among farm workers had been increasing 75 percent in the past 20 years. It attributed part of the rise to better diagnoses but also considered 2,4-D a possible contributor.

Page attacked the NCI's canvassing methods, then the interpretation of the results, and accused the institute of scaremongering to raise research funds.
His task force turned in the last of 270 toxicity studies in 1995. The results showed that the amount of 2,4-D it took to harm lab animals far exceeded anything expected to be encountered in the environment.

But in 1996, as the cancer risk argument rolled on, University of Minnesota pathologist Vincent Garry published a study in Environmental Health Perspectives showing that 2,4-D might also cause birth defects. Garry found almost twice the number of birth defects among children of pesticide applicators than in a control population. The children had been conceived in spraying season in a Minnesota farming region predominantly using 2,4-D.

In 1997, with the EPA review of 2,4-D still under way, the agency's Carcinogenicity Peer Review Committee stopped short of ranking the chemical as a probable cause of cancer. But three years later, one of its own statisticians and one of Garry's collaborators in the Minnesota study linked many cancers -- of the esophagus, stomach, rectum, throat, pancreas, larynx, prostate, kidney and brain -- to heavy wheat growing regions notable for 2,4-D use.

"We don't know what's causing it," says Dina Schreinemachers, the EPA statistician. "It's something associated with the wheat."

Buffalo takes 1st step

By 1991, homeowners were worried. Buffalo, N.Y., was the first city to require lawn care companies to post warning signs on chemically treated lawns. In New York, according to Audrey Thier of the Buffalo-based lobby Environmental Advocates, five counties have passed ordinances that require prior notice of spraying to neighbors, and eight municipalities have passed ordinances that phase out use of pesticides on government property.

At last reckoning by the General Accounting Office, 23 other states also had counties with some sort of notification requirements.

Pesticide bans are catching on

In 1991, the municipal council of Hudson, Quebec, banned the cosmetic use of pesticides for lawn care altogether. A coalition of lawn-care companies, including ChemLawn, sued to overturn the ban. Last June, the Supreme Court of Canada upheld the Hudson ban.

Since then, says Angela Rickman, deputy director of the Sierra Club of Canada, "more than 40 different communities are looking at pesticide restriction bylaws of one form or another" in her country. The Club declared May 11 "Dandelion Day" and is sponsoring "Getting Your Lawn Off Drugs" workshops this summer at Ottawa City Hall.

-- Emily Green