Overall, acreage treated probably provides the best basis for calculating probabilities because it accounts for differences in concentrations and usage rates among different classes of pesticides.
Among the crops that were significantly associated with childhood cancer in our analysis, sugar beets had the highest proportion of acreage treated with herbicides (98%%) [ 36].
The 1991 1998 average percentage of durum and other spring wheat acreage treated with any herbicides in Minnesota, Montana, North Dakota, and South Dakota was 91%, whereas the average percentages of winter wheat in Montana and South Dakota treated with any herbicide were 86%and67%7%, respectively.
Most of the spring and durum wheat produced in the United States is grown in Minnesota, Montana, North Dakota, and South Dakota, with more than 85% of the acreage treated with chlorophenoxy herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA).
The percentage of herbicide-treated acreage for spring and durum wheat is larger than for winter wheat, which is a better competitor with weeds (Lin et al. 1995).
Compare this to the early 1990s, when only an estimated 30-35 percent of all corn acreage were treated with insecticides at all.
Corn and soybeans are the major crops in Iowa; > 95% of corn and soybean acreage was treated with herbicides from the late 1970s through the 1990s (Iowa State University 1997).
In 1999, approximately 70%% of dry bean acreage was treated with ethyl dipropythiocarbamate (EPTC), 50 % with trifluralin, and 35 % with metolachlor [ 37].
Spring wheat, one of the major field crops in these four states, was treated for 85% or more of its acreage with chlorophenoxy herbicides.
