On-the-job exposure to high levels of pesticides might raise the risk of developing heart disease or having a stroke, according to a long-term study in Hawaii.
Farm and agricultural workers need to wear personal protective equipment and, even after they retire should continue to have their health monitored for cardiovascular complications, the authors conclude in the Journal of the American Heart Association.
“Pesticides have a long half-life and exist in the body for a long time, so side effects may appear even 10-20 years later,” said lead author Zara Berg of Fort Peck Community College in Peck, Montana.
“Many workers may not think that exposure during their younger or middle years is crucial, but it actually is,” said Berg, who worked on the study as part of her doctoral research at the University of Hawaii at Manoa in Honolulu.
For the analysis, Berg’s team used data from the Kuakini Honolulu Heart Program, established in 1965 to study heart disease in middle-aged Japanese-American men living on the island of Oahu.
Participants were born between 1900 and 1919 in Japan or Hawaii and were between ages 45 and 68 at the beginning of the study. Data was updated through 1999, which allowed for up to 34 years of follow-up with surviving participants.
Berg and colleagues focused on 7,557 men who had provided information on their work history and had no heart disease at the beginning of the study period.
To gauge pesticide exposures, the research team used the Occupational Safety Health Administration exposure scale, which estimates typical pesticide amounts encountered during an 8-hour workday and 40-hour workweek based on a participant’s job, age and years worked in that industry, particularly for industrial, factory and agricultural workers.
Berg’s team then looked at medical records to assess who developed cardiovascular disease, which they defined as coronary heart disease or a cerebrovascular incident such as a stroke.
Overall, just 451 men had high exposure to pesticides and 410 men had low-moderate exposure, while the rest had none.
After adjusting for other cardiovascular risk factors like age, weight, physical activity, alcohol and smoking, researchers found that the men with high pesticide exposure were 42 percent more likely than those with none to develop cardiovascular disease during the first 10 years of follow-up.
“High exposure during middle age led to cardiovascular disease sooner,” Berg noted. “Pesticides can also affect cholesterol and the concentration of heavy metals in the body.”
Heart disease wasn’t associated with low or moderate levels of exposure to pesticides, and the link to high exposure was not seen in the longer term up to 34 years.
One limitation of the study is that only a small proportion of men had high or low-moderate pesticide exposure, the authors note. The fact that the men were all from a single ethnic group is a strength of the analysis because it removes some potential confounding differences, they add, but also means the results might not be generalizable to other populations.
“Most importantly, workers should save their medical records and document potential exposure, especially if their employers don’t,” Berg said. “Wear proper protective equipment and clothing, and request some if it’s not provided.”
Research studies are still trying to unpack how pesticides contribute to heart disease and death, whether through inflammation or oxidative stress, as well as how often or how much exposure is most harmful.
“Research on human exposure to environmental pollutants is highly complex and difficult,” said Juan Pedro Arrebola of the University of Granada in Spain, who wasn’t involved in the study.
“In my opinion, the main advice should be to use the ‘precautionary principle,’ or in plain words, ‘better safe than sorry,’” he told Reuters Health by email.
“It’s not a matter of going into panic because we’re surrounded by chemicals, and many of them have considerably helped us, but to avoid as much exposure as possible.”