Long-term study tracks health impact of pesticide use
By Randy Buhler
Colorado State University Cooperative Extension
Logan County Agent, Agronomy
A recent news release from Larry Schulze, Pesticide Education Specialist, with the University of Nebraska--Lincoln Extension describes results from the Agricultural Health Study. The Agricultural Health Study is a quarter century long study that measures health status of participants versus the general population. The project has collected data for more than 14 years.
The AHS has almost 90,000 participants. Participants are certified private pesticide applicators and their spouses active in farm work and an additional 5,000 commercial pesticide applicators. North Carolina has 31,000 participants and Iowa has 59,000 plus the 5,000 commercial applicators.
The study made three general comparisons. Applicators and spouses were compared to the general population to find differences in cancer rates. Applicators and spouses who have cancer were compared to those without cancer or other diseases to see if pesticide exposure or other factors contributed to the diseases. The third comparison placed those using a particular pesticide versus those not using it to see if any differences in cancer rate or other health problems were evident.
Applicators were healthier than the general population. For 18 of 20 specific cancers the rates were lower for applicators and their spouses. Prostate cancer is 14 percent higher in male applicators than in the general population. Skin melanomas are 50 percent higher among farm wives than the general population.
Separating known risk factors for prostate cancer showed a strong association with exposure to methyl bromide (fumigant). For men over 50, association with prostate cancer existed for those who were exposed to aldrin, chlordane, DDT, dieldrin, endrin, hexachlor, and toxaphene. Those men with a family history of prostate cancer had increased risk from exposure to Sutan herbicide; the organophosphate insecticides chlorpyrifos, coumaphos, fonophos, and the pyrethroid insecticide permethrin for animal uses.
The scientists found an association between exposure to metolachlor and pendimethalin herbicides and chlorpyriphos and diazinon insecticides with lung cancer. There was no evidence of spouses' exposure to the 50 pesticides evaluated and breast cancer. A higher breast cancer risk was evident when their applicator spouses had used 2,4,5-TP herbicide; dieldrin insecticide; and captan fungicide. Only those women with a family history of breast cancer had a higher risk when their husbands used diazinon. The herbicide 2,4-D was not related to increased breast cancer risk in spouses of applicators.
Alachlor herbicide application was associated with multiple myeloma and leukemia in pesticide users versus non-users.
Paraquat, EPTC(eptam), parathion, malathion, chlorpyrifos, atrazine and alachlor were associated with wheeze. Wheeze is a respiratory condition symptom common with asthma, allergies, smoking, operating diesel tractors, frequent solvent use; and animal, egg and dairy production activities. It is the sound produced by narrowed passages deep in the lungs.
The study showed a consistent association with applicators reporting retinal degeneration and the use of fungicides. More lifetime-days of exposure strengthened the association. Products associated with retinal degeneration include benomyl, captan, chlorothalonil, copper ammonia carbonate, ferbam, maneb, metalaxyl, PCNB, and sulfur. Spouses of applicators were nearly twice as likely to have retinal degeneration. The fungicides maneb, mancozeb, and ziram were strongly associated with this effect.
When the scientists focused on reproductive health of women aged 21 to 40 years old, they learned those women who used pesticides of any type were more likely to have longer menstrual cycles and missed periods. The pesticides most associated with this were lindane, atrazine, and mancozeb or maneb.
The AHS most recently reported that women who mixed or applied pesticides during the first trimester of pregnancy had more than twice the risk of developing gestational diabetes. No increased risk was found for women whose exposure was to residential pesticides or indirect exposure during the first trimester.
This information should encourage all who use pesticides to observe the warnings and personal protective equipment requirements for using those pesticides. Expect more information during the continuing 10 years of this landmark study.