[Timber Loftis]

Pesticides
Study Says Infant Respiratory Problems
May Be Caused by Herbicide Use on Wheat


HELENA, Mont.--Babies born over a three-year period in high wheat-producing areas suffered twice as many circulatory and respiratory birth defects as children born in similar rural areas where little wheat was grown, a new federal study has found.
The study, published in the July issue of Environmental Health Perspectives, suggests that greater exposure to herbicides used on wheat crops may be responsible for the increase in birth defects.

Dina Schreinemachers, a statistician with the Environmental Protection Agency in North Carolina, examined more than 43,000 births between 1995 and 1997 in 147 rural counties in Minnesota, Montana, North Dakota, and South Dakota. She used statistics from the Department of Agriculture to categorize the study areas as either high- or low- wheat-producing counties and then compared the counties' rates of birth defects as provided by the National Center for Health Statistics.


'Pointing the Finger.'

Schreinemachers told BNA July 14 that while her "hazard identification study" makes no direct links between herbicide use and birth defects, it is "pointing the finger in that direction."
In the study, Schreinemachers writes, "In rural, agricultural counties where wheat acreage occupies a larger percentage of the land and where use of chlorophenoxy herbicides is higher, anomalies ... significantly increased." For both boys and girls, those increases were more than twofold for circulatory and respiratory malformations. Musculoskeletal malformations increased by 50 percent.

Schreinemachers also found a significant increase in infant deaths from congenital anomalies among boys.

"Boys conceived during April-June (the time most herbicides are used) and born in high-wheat counties were almost five times more likely to be diagnosed with a birth anomaly than the boys in low-wheat counties conceived during other months of the year," she wrote.

Schreinemachers said that while the results indicate that male fetuses may be more vulnerable to herbicide exposure than female fetuses, she has no explanation for the reason for that difference.

She stressed that the study was an ecological, or population, study and that individual connections between herbicides and birth defects were not made nor was that its intention.

"I was looking at groups of people, not individuals," she said. And, she added, "Groups may not always accurately represent the individuals in that group."


Agribusiness Group Says Study Is Flawed

Ray McAllister, vice president for science and regulatory affairs for the agribusiness group CropLife America, was critical of the study.
"We are all concerned about finding the causes of birth defects," McAllister said. "But a wild goose is being chased here."

McAllister said that among the flaws of the study is that Schreinemachers used wheat farming as a surrogate for herbicide exposure.

"That may not be valid," he said. And, he added, Schreinemachers established no direct link between any individual birth defect and a specific exposure to a herbicide.

He added that all herbicides must go through a "wide battery of toxicology tests" before being marketed and that there is "a tremendous body of data that supports registration" of chlorophenoxy herbicides.

Among the most commonly used chlorophenoxy herbicides is 2,4-D and MCPA, or 4-chloro-2methylphenoxyacetic acid. The herbicides have been sold in the United States for nearly 60 years and are commonly used in residential and urban settings as well as for agricultural uses, McAllister said. They are safe when used as directed, he said.


Consistent With Earlier Studies

Schreinemachers agreed with McAllister that her study has limitations and is not conclusive. But, she added, according to information from the Department of Agriculture, 85 percent of the wheat-producing land in the sampled states was treated with a chlorophenoxy herbicide, and it was reasonable to use wheat production as a surrogate for herbicide use.
Her results also are consistent with earlier studies pointing to a connection between herbicide exposure and birth defects, she said.

"In conclusion, although results from the present study should be viewed with caution, the consistency of these results with other studies points to a potentially hazardous scenario in terms of specific excess birth defects," she wrote.

Schreinemachers advised that there should be additional studies focusing on developmental effects from, and toxicology of, chlorophenoxy herbicides.

The EPA has said it will consider Schreinemachers' findings as part of the body of knowledge it uses to register or review herbicides.

By Grant Sasek

Copyright © 2003 by The Bureau of National Affairs, Inc., Washington D.C.