In a recently published five-year follow-up study, breast cancer risk was not associated with:
   - Number of acres of corn planted
   - Atrazine sales
   - Atrazine levels in the water supplies.

But, this begs the question, what is the best way to estimate exposure to atrazine? For instance, what is sold in one county may be applied in another county. This study did not use more accurate, direct measures of exposure to atrazine, such as skin exposures, estimates of drift, or actual levels of atrazine in the air or dust of farm homes. Unfortunately, ecological studies can only give us very limited information.