(Beyond Pesticides, December 1, 2009) A new study published in the November 2009 issue of Occupational and Environmental Medicine, adds rhinitis, the inflammation of the mucous lining of the nose, to the long list of ailments linked to pesticide exposure. “Rhinitis associated with pesticide exposure among commercial pesticide applicators in the Agricultural Health Study,” examined data from 2,245 Iowa commercial pesticide applicators and evaluated the association between rhinitis and 34 pesticides used in the past year. Seventy-four percent of commercial pesticide applicators in the study reported at least one episode of rhinitis in the past year (current rhinitis), compared with about 20-30% of the general population.
Pesticide exposure and rhinitis were assessed at enrollment using two self-administered questionnaires. The first, completed at enrollment, obtained detailed information on use of pesticides on the market at the time of enrolment as well as smoking history, current agricultural activity and demographics. The second questionnaire, sent one month later, more detailed information on the pesticides, as well as medical history, including rhinitis, conjunctivitis, sinusitis and asthma.
Respondents reported using 16 herbicides, 11 insecticides, five fungicides and two fumigants in the past year. Five of the pesticides were significantly positively associated with current rhinitis: the herbicides 2,4-D, glyphosate and petroleum oil (inert), the insecticide diazinon and the fungicide benomyl. Diazinon and petroleum oil herbicide showed the most consistent association. The association for 2,4-D and glyphosate was limited to individuals who used both in the past year, suggesting a possible synergistic effect.
The authors hypothesize that exposure to pesticides may contribute to rhinitis by a number of mechanisms. First, organophosphates (OPs) inhibit the enzyme acetylcholinesterase, leading to an accumulation of acetylcholine, which stimulates nasal mucosa resulting in increased nasal secretion and congestion. Previous research has linked both petroleum and mineral oils to respiratory symptoms in metal workers and animal studies have shown respiratory impacts in the lungs, but not in the nose. Further research is needed to determine a mechanism or mechanisms, as well as to determine whether a synergistic effect occurs in the upper airway with use of glyphosate and 2,4-D.
Jane Hoppin, Sc.D. of the National Institute of Environmental Health Sciences in Research Triangle, NC, one of the researchers who contributed to this study, has conducted previous research that links AHS applicators with higher rates of wheeze. In this study, published in the June 2006 issue of the American Journal of Epidemiology, eight of 16 herbicides (strongest association with chlorimuron-ethyl) and the organophosphate insecticides terbufos, fonofos, chlorpyrifos and phorate, were significantly associated with wheeze.
The Agricultural Health Study is a prospective study of licensed pesticide applicators from North Carolina and Iowa recruited in 1993-1997 at the time of license renewal. The cohort includes 4,916 commercial applicators from Iowa and 52,395 private applicators, mostly farmers, from both states. More than 75% or 32,347 spouses of married private applicators also enrolled in the cohort. The study is a collaboration of the National Institute of Environmental Health Sciences (NIEHS), the National Cancer Institute (NCI), the Environmental Protection Agency (EPA) and the National Institute for Occupational Safety and Health (NIOSH).