Pesticides decrease lung function in kids

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Taking a deep breath might be a bit harder for children exposed early in life to a widely used class of pesticides in agriculture, according to a new paper by University of California, Berkeley researchers. A new study has linked the levels of organophosphate pesticide metabolites in the urine of 279 children living in California’s Salinas Valley with decreased lung function. Each tenfold increase in concentrations of organophosphate metabolites was associated with a 159ml decrease in lung function, or about 8% less air, on average, when blowing out a candle. The magnitude of this decrease is similar to a child’s second-hand smoke exposure from his or her mother.

The findings are the first to link chronic, low-level exposures to organophosphate pesticides – chemicals that target the nervous system – to lung health for children.

“Researchers have described breathing problems in agricultural workers who are exposed to these pesticides, but these new findings are about children who live in an agricultural area where the organophosphates are being used,” said study senior author Dr Brenda Eskenazi, a professor of epidemiology and of maternal and child health. “This is the first evidence suggesting that children exposed to organophosphates have poorer lung function.”

The children were part of the Centre for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a longitudinal study in which the researchers follow children from the time they are in the womb up to adolescence. The researchers collected urine samples five times throughout the children’s lives, from age 6 months to 5 years, and measured the levels of organophosphate pesticide metabolites each time. When the children were 7 years old, they were given a spirometry test to measure the amount of air they could exhale. The study accounted for other factors that could affect the results, such as whether the mothers smoked, air pollution, presence of mold or pets in the home and proximity to highways.

“The kids in our study with higher pesticide exposure had lower breathing capacity,” said study lead author Dr Rachel Raanan, who conducted the research while she was a postdoctoral scholar in Eskenazi’s lab. “If the reduced lung function persists into adulthood, it could leave our participants at greater risk of developing respiratory problems like COPD (chronic obstructive pulmonary disease).”

The study did not examine the pathways for the children’s exposure to pesticides, but the researchers did recommend that farm workers remove their work clothes and shoes before entering their homes. They also suggested that when nearby fields are being sprayed with pesticides, children be kept away and, if indoors, windows should be closed. Pesticide exposure can also be reduced by washing fruits and vegetables thoroughly before eating.

“This study adds exposure to organophosphate pesticides to the growing list of environmental exposures – including air pollution, indoor cook stove smoke and environmental tobacco smoke – that could be harmful to the developing lungs of children,” said Raanan. “Given they are still used worldwide, we believe our findings deserve further attention.”

The authors noted that although organophosphate pesticides are still widely used, most residential uses of organophosphate pesticides in the US were phased out in the mid-2000s. In California, use of organophosphates in agriculture has also declined significantly from 6.4m pounds in 2000, when the study began, to 3.5m pounds in 2013, the year with the most recent pesticide use data. Just last month, the US Environmental Protection Agency proposed eliminating all agricultural uses of chlorpyrifos, one of the most heavily used organophosphates, and others are also under evaluation, steps that will continue the trend of declining use.

“Chronic obstructive pulmonary disease is an increasing cause of death around the world,” said study co-author and pulmonary specialist Dr John Balmes, a UC Berkeley professor of environmental health sciences with a joint appointment at the University of California, San Francisco School of Medicine. “Since we know that reduced lung function increases the risk for COPD, it is important to identify and reduce environmental exposures during childhood that impair breathing capacity.”

Abstract
Background: Organophosphate pesticides are heavily used in agriculture, and adverse associations with respiratory health in occupational settings have been reported. However, most of the evidence comes from studies where there were no biomarkers of exposure and no objective outcome measurement. Non-occupational chronic effects among residents living in agricultural communities are less well described.
Objective: To evaluate associations between early-life organophosphate exposure and lung function of children living in an agricultural community.
Methods: Participants were 279 children from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) longitudinal birth cohort. The area under the curve for organophosphate exposure was determined by urinary diethyl and dimethyl dialkylphosphate metabolites of organophosphate pesticides, which were measured five times during childhood (6–60 months). Spirometry was performed at age 7 years. Regression models controlled for maternal smoking during pregnancy, season of birth, particulate matter concentrations with aerodynamic diameter ≤2.5 μm (PM2.5), breast feeding duration, mould and pets at home, distance of home from a highway, food insecurity, maternal education, season of spirometry, sex, height and technician.
Results: Childhood diethyl, dimethyl and total dialkylphosphate concentrations were associated with significant decreases in lung function at age 7. Specifically, we found lower FEV1, (L/s) (ß=−0.16, 95% CI −0.30 to −0.02, p=0.03) and FVC (L) (ß=−0.17, 95% CI −0.34 to 0.01, p=0.06) per 10-fold increase of total dialkylphosphate levels.
Conclusions: Early-life organophosphate exposure as assessed by dialkylphosphate concentrations was adversely associated with 7-year-old children’s lung function.

University of California, Berkeley material
Thorax abstract


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