(Beyond Pesticides, October 2, 2019) New data gleaned from the Kuakini Honolulu Heart Program — a longitudinal study of men of Japanese descent living on Oahu — demonstrate that occupational exposure to high levels of pesticides can increase risks for cardiovascular disease (CVD) in the forms of coronary heart disease (CHD) or stroke (CVA, or cerebrovascular accident). Further, researchers determined both that workers who experience high-level exposures may not experience such effects for years afterward, and that the maximum subsequent effects were seen within a decade of exposure. The study’s conclusion highlights the importance of pesticide applicator use of protective gear when handling toxic pesticides. These risks and harms could be eliminated through a transition to non-chemical means for pest control in agriculture, land management, and home and personal practices.

The Kuakini Honolulu Heart Program, after enrolling more than 8,000 Japanese-American men, 45–68 years old and living on Oahu, Hawaii between 1965 and 1968, has continued to examine and interview these subjects, and document morbidity and mortality among them. This study, which performed statistical analyses on 7,557 of the subjects, is the longest longitudinal study of cardiovascular disease and any association with chronic occupational pesticide exposure, taking into account epidemiologic risk factors for CVD. Data on rates of heart disease and stroke were available through December 1999, representing as many as 34 years of follow-up. Exposure to pesticides in subjects, who self-reported their occupations, was estimated via an OSHA (Occupational Safety and Health Administration) tool that assesses intensity and length of occupational exposure for each occupation.

As the study co-authors note in their research paper, published in the Journal of the American Heart Association in late September, previous research that has evaluated vocational chemical exposure and CVA, CHD, and CVD have looked only at CVD mortality. These researchers hypothesized that occupational exposure to pesticides would be a risk factor for CVD, CHD, and CVA, so they set out to examine where there is an association between such exposures and incidence of those three outcomes. They adjusted their analyses to accommodate for all relevant risk factors for CV (that were identified and measured as of 1999) and found, in the first 10 years of post-exposure follow-up, and compared to vocationally non-exposed men:

a roughly 45% higher risk of CHD or CVA in those with high-level pesticide exposure; the figure was 46% after adjusting for age, and 42% after adjusting for additional CHD risk factors beyond age

no significant relationship between low-to-moderate exposure to pesticides and the risk of CHD or CV

Occupations associated with pesticide exposures are typically agricultural or industrial, and include such workers as pesticide applicators, landscapers, forestry and agricultural workers, factory workers, pesticide manufacturing emplooyees, aircraft mechanics, and jet fuel refinery employees. Although the specific pesticides to which subjects had been exposed were not known, according to the Hawaii Department of Agriculture in 1969, common pesticides in Hawaii included several classes of organophosphates, organochlorines, insecticides, fumigants, and herbicides. (Many of these chemicals — such as DDT, heptachlor, chlordane, dieldrin, hexachlorobenzene, and toxaphene — have since then been banned because they are persistent organic pollutants.)

Cardiovascular health effects of exposures can manifest, as noted, years down the road, although the incidence dissipates after the first 10 years. This is because, in part, some pesticide compounds have very long half-lives and can persist for decades. Beatriz L. Rodriguez, MD, PhD, MPH, study co-author and professor of geriatric medicine at the University of Hawaii at Manoa, commented that, “After following the men for 34 years, the link between being exposed to pesticides at work and heart disease and stroke was no longer significant. This was probably because other factors tied to aging became more important, masking the possible relation of pesticides and cardiovascular disease later in life.”

The co-authors also identify some clinical healthcare implications of their findings:

• healthcare providers ought to be mindful of occupational exposure risks, particularly for those who work in agriculture

• both acute and chronic exposures to pesticides (or any other chemicals) need to be documented in people’s medical recordsagricultural workers need to employ personal protective measures, wear protective clothing and gear, and get monitored for development of cardiovascular disease

There are limitations of this research; one is that the cohort group within the study that had moderately intense exposure to pesticides constituted a small sample size, so researchers combined it with the low‐pesticide‐exposure group, which also contained a small number of subjects. Another limitation is that all subjects were male, as well as of Japanese descent. Thus, results may not be applicable to women or to people of different “racial” descent.

Zara Berg, PhD, study co-author and adjunct science professor at Fort Peck Community College in Poplar, Montana, noted that, “Previous studies have found that men and women may respond differently to pesticide exposure. One class of pesticides may give women heart attacks but not men and other pesticides may give men heart disease but not women. Hormones may also play a role in the impact of pesticide exposure and the development of cardiovascular disease.”

Beyond Pesticides regularly covers new research on the many health impacts of pesticide use, including those related to cardiac health, e.g.: 2011 coverage of a relationship between exposure to organochlorine pesticides and the development of atherosclerosis, and December 2018 reporting on associations between pesticide exposure and CVD among Hispanic and Latino workers in some U.S. cities. In addition, Beyond Pesticides has reported on evidence that endocrine disrupting chemicals, which some pesticides are, indirectly boost risk for cardiovascular (and other) anomalies, including this study that shows risks for children.

The Beyond Pesticides Pesticide-Induced Diseases Database is a useful source of information about disease development associated with exposures to pesticides. This report, Good Health Harmed by a Cascade of Complex Pesticide Effects, provides a broader look at health impacts. Such holistic context is important because human bodies comprise complicated systems that interact with one another, and whose functioning is mediated by chemical signals, whether as hormones, neurotransmittters, or others. Compromised function of any of those systems or of the body’s signaling capacity — whether because of pesticide exposures or any of a multitude of other factors — can affect multiple bodily systems.

To protect their cardiac and general health, individuals who may be at risk for high-level pesticide exposure through their job duties and sites must be extremely attentive to health and safety precautions because of their elevated risks. This is especially true for agricultural workers and pesticide applicators. The chemical assaults of pesticide exposure should be far more comprehensively evaluated by federal regulators, and those assessments should include adjuvant as well as active ingredients in pesticide products, as well as endocrine-disrupting, synergistic, low-dose, and epigenetic impacts.

All unattributed positions and opinions in this piece are those of Beyond Pesticides.

Source: https://www.ahajournals.org/doi/10.1161/JAHA.119.012569