Household insecticide use linked to all-cause and CVD mortality: JAMA

USA: Long-term exposure to pyrethroid insecticides is associated with an increased risk of cardiovascular death and early death, suggests a recent study published in JAMA Internal Medicine.

Pyrethroid insecticides are a special chemical class of active ingredients that are found in many modern insecticides and widely used in households. Pyrethrin and its synthetic derivatives are used in garden insecticides, pet sprays, mosquito repellents, and lice shampoos. They are extremely effective and cause no acute reactions in humans, but they are absorbed by the body and then metabolized and excreted in the urine.

Widespread exposure to pyrethroid insecticides has been reported among the general population in the US and worldwide. However, little is known about the association of pyrethroid exposure with long-term health outcomes in adults. Wei Bao, Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, and colleagues examined the association of pyrethroid exposure with all-cause and cause-specific mortality among adults in the United States.

For the study, the researchers tested pyrethroid levels in urine samples from 2,116 adults selected from a large national health survey. The group was then followed for an average of 14 years.

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Key findings of the study include:

• During a median of 14.4 years of observation, 246 deaths occurred, including 41 associated with cardiovascular disease and 52 associated with cancer.


• Participants with higher urinary 3-phenoxybenzoic acid levels were at a higher risk of death during the follow-up period, with death occurring in 8.5% (unweighted, 75 of 709), 10.2% (unweighted, 81 of 701), and 11.9% (unweighted, 90 of 706) of participants across increasing tertiles of urinary 3-phenoxybenzoic acid levels.


• After adjustment for age, sex, race/ethnicity, socioeconomic status, dietary and lifestyle factors, body mass index, and urinary creatinine levels, the hazard ratios for all-cause mortality, cardiovascular disease mortality, and cancer mortality among participants with the highest tertile compared with those with the lowest tertile of urinary 3-phenoxybenzoic acid levels were 1.56, 3.00, and 0.91, respectively.

"Our findings demonstrate that environmental exposure to pyrethroid insecticides was associated with an increased risk of all-cause and cardiovascular disease mortality. Further studies are needed to replicate the findings and determine the underlying mechanisms," concluded the authors.

The study, "Association Between Exposure to Pyrethroid Insecticides and Risk of All-Cause and Cause-Specific Mortality in the General US Adult Population," is published in JAMA Internal Medicine.

DOI: https://doi.org/10.1001/jamainternmed.2019.6019