Daily News Archive
July 25, 2006
Agricultural Pesticides Common In Rural House Dust
(Beyond Pesticides, July 25, 2006)
A new study finds that trace quantities of agricultural chemicals find
their way into rural homes—not only on the fruits and vegetables
that consumers buy, but also through dust that enters houses. The study,
to Crops and Residential Exposure to Agricultural Herbicides in Iowa,”
which was published in the June 2006 issue of the journal Environmental
Health Perspectives, shows that home exposure to agricultural herbicides
increases as the amount of nearby cropland increases.
The findings are disturbing considering the documented links between
pesticides and health effects, including non-Hodgkin's lymphoma. This
study was done as an offshoot of a larger non-Hodgkin's lymphoma study
financed by the National Cancer Institute, reports Science
In the new study, Mary H. Ward, PhD, of the National Cancer Institute,
and her colleagues collected dust vacuumed from the homes of 112 Iowa
lymphoma patients and healthy, randomly selected volunteers of the same
age. Using satellite-generated maps of agricultural fields in the state,
the team calculated the acreage of croplands near the home of each participant.
Both farm and in-town homes were included in the study. Because most
of Iowa’s cropland had been historically planted with corn and
soybeans, Dr. Ward's team probed homes for specific chemicals known
to be used on the local fields.
Analyses show that at least one of six primarily agricultural herbicides
is present in house dust from 28 percent of sampled homes. These chemicals
include acetochlor, alachlor,
fluazifop-p-butyl, and metolachlor. Atrazine and metolachlor are the
agents most commonly used to treat corn and soybeans. The next most-popular
herbicides used on the crops are trifluralin and dicamba. At least one
of these four herbicides show up in 43 percent of homes.
Although atrazine had been applied to nearly 70 percent of corn acreage,
it showed up in the house dust of only 8 percent of homes. Where detected,
however, its concentration in dust ranged from 60 to 4,700 parts per
billion (ppb). Metolachlor was found in about 20 percent of homes; its
concentration ranged from 27 to almost 3,200 ppb.
Most shocking is the amount of dust containing 2,4-D,
which was found to be present in 95 percent of homes, typically in concentrations
exceeding 1,000 ppb. In one house, 2,4-D's values reached an astounding
125,000 ppb. Used on crops, along roadsides, in forests, and on lawns,
2,4-D is the third most widely used herbicide in the United States and
Canada. According to Illinois EPA, 2,4-D is a probable endocrine disruptor
and a number of studies link 2,4-D to non-Hodgkin’s lymphoma.
The study also finds that farm workers' homes are generally the most
contaminated with weed killers. Some herbicide concentrations in their
dwellings more than tripled those present in the homes of people who
have never worked in agriculture.
Nearly 60 percent of the study's participants live within 550 yards
of cropland. The chance of finding agricultural weed killers in house
dust increases by six percent for every 10 acres of cropland found within
a roughly 800-yard perimeter of the house. The result was that herbicide-laced
dust showed up in three-quarters of homes having at least 300 acres
of cropland within that 800-yard perimeter.
Of nearly 120 studies that have investigated the risk of non-Hodgkin's
lymphoma associated with pesticide contact, most show an increased risk
for the disease—especially for herbicides—according to the
Lymphoma Foundation of America. Printed information from the foundation
states that the pesticides "more frequently associated with increased
lymphoma incidence and/or deaths" are the herbicides 2,4-D and
the triazines, which includes atrazine.
Cancer, however, is far from the only health or environmental risk associated
with agricultural pesticides. For instance, some herbicides used on
corn have been shown to disrupt normal reproductive development in frogs,
in studies so far (see Daily
News). Some biologists now suspect that such changes may explain
declining amphibian populations.
Agricultural pesticides may also affect human fertility. Four years
ago, epidemiologist Shanna H. Swan, PhD, of the University of Missouri
and her colleagues studied sperm in men from big cities and small towns.
In the study, sperm concentrations and quality in men from semi-rural
Missouri communities are below those of men from Minneapolis, Los Angeles,
and New York City (See Daily
News). This suggests, Dr. Swan told Science News Online
that "environmental exposure to current-use pesticides is associated
with poorer semen quality."
In an extension of that study, the Centers for Disease Control and Prevention
in Atlanta will soon measure agricultural pesticides in the urine of
men who had participated in the original study, notes Dr. Swan, now
at the University of Rochester.