CONTACT: DAVE PEDERSEN
Iowa City IA 52242
(319) 335-8032; fax(319) 335-8034
Release: Oct. 6, 2000
EDITORS: This study in the American Journal of Industrial Medicine is available
online at http://www3.interscience.wiley.com/cgi-bin/jtoc?ID=34471
UI study finds link between livestock insecticide application and lung
IOWA CITY, Iowa -- Farmers who apply insecticides to their livestock are
nearly four times more likely to have symptoms of lung disease than farmers
who don't apply insecticides to their farm animals, according to a study by
researchers at the University of Iowa College of Public Health.
This new finding, in a study published in the October issue of the American
Journal of Industrial Medicine, is consistent with results of other studies
involving pesticide usage, said Nancy L. Sprince, M.D., UI professor of occupational
and environmental health and lead author of the study.
"Other studies have shown that exposure to heavy grain dust in grain
elevators or exposures to organic dusts in animal confinement facilities can
lead to asthma-like symptoms such as wheezing in the chest," Sprince
said. "Ours is the first study to show that this specific type of insecticide
application to livestock causes any health effects."
The results were based on responses from 385 Iowa farmers enrolled in the
Iowa Farm Family Health and Hazard Surveillance Project, a population-based
study that assessed diseases and injuries in relation to farm exposures. This
part of the Farm Family Study examined the association between airway disease
symptoms and farm exposures, including those from pesticides, grain dust,
animal confinements and silos. The data were collected in 1994 from farm families
in 18 Iowa counties, two counties from each of the state's nine crop and livestock
reporting regions. A cooperative agreement with the National Institute for
Occupational Safety and Health funded the study.
After adjusting for factors such as age and smoking, UI researchers found
that the likelihood of asthma-like symptoms for farmers who personally apply
insecticides to their livestock nearly quadrupled. In addition, these farmers
were nearly three times as likely to experience flu-like symptoms called organic
dust toxic syndrome (ODTS). The procedure itself involves pouring or
spraying insecticide directly over the animal, creating the potential for
skin and inhalation exposure for the farmer.
Stephen Reynolds, Ph.D., UI professor of occupational and environmental
health and a
co-investigator on the study, noted that since the survey was done in 1994,
more farmers have switched to "ear-tagging" their livestock -- attaching
a clip containing insecticide to the animal's ear. The chemical is spread
among the livestock as the animals come into contact with each other. The
procedure requires less direct human handling of insecticides and is less
toxic than pouring or spraying.
"A number of farmers still do the hand-pouring," Reynolds said.
"We think this is an area that needs further study."
Sprince, Reynolds and their colleagues are planning to develop a grant proposal
for a follow-up study to gauge firsthand the exposures farmers face when applying
insecticides to their livestock.
"The information we had for this study was self-reported from questionnaires,"
she said. "We need to measure farmers' symptoms and lung function, and
measure dust and pesticide concentrations in the air, to get a better idea
of what's going on in the body and in the environment where these farmers
do this type of work."
The UI researchers also reported other findings from the study:
- Farmers who had conventional vertical silos (storage units for hay and
silage used for animal feed) were almost three times more likely to have
asthma-related symptoms and 2.4 times more likely to have the flu-like symptoms
of ODTS than farmers without vertical silos. Sprince said that this finding
confirmed previous studies done in this area.
- Farmers with animal confinement buildings were three times as likely
to report having a cough, four times as likely to have chest tightness while
at work and twice as likely to have the
flu-like symptoms of ODTS.
- Unlike results of most studies of grain elevator workers, the UI study
results in Iowa farmers did not show an association between respiratory
symptoms and grain production. This suggested that exposures of Iowa grain
farmers may be different from those of grain elevator workers, Sprince said.
Around 13 percent of the farmers included in the study identified themselves
as smokers, which is about half the national average, Sprince said. She added
that newer data from 1999 suggest that smoking rates among Iowa farmers have
fallen even further.
"We're seeing some healthy behaviors among farmers, in terms of not
smoking," Sprince said. "It's the occupational exposures and the
related health symptoms that we need to examine more closely."
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