The following story can be found at:
http://www.news.wisc.edu/thisweek/Research/Bio/Y99/pesticide.html
Thought it would interest some of you.
peace
misha
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Pesticide, fertilizer mixes linked to range of health problems
(posted 3/15/99)
The natural mix of chemical pesticides and fertilizers, such as
occurs when agricultural chemicals seep into groundwater, may have a
broad range of effects on human and animal health, a new study shows.
The study, published in the current issue of the journal Toxicology
and Industrial Health, suggests that combinations of commonly used
agricultural chemicals, in concentrations that mirror levels found in
groundwater, can significantly influence the immune and endocrine
systems as well as neurological health.
Conducted over five years, the study of mice suggests that current
methods used by the Environmental Protection Agency (EPA) and others
for studying the toxic effects of low-levels of pesticides may be
flawed.
"The single most important finding of the study is that common
mixtures, not the standard one-chemical-at-a-time experiments, can show
biological effects at current concentrations in groundwater," said
Warren P. Porter, the lead author of the study and a UW-Madison
professor of zoology and environmental toxicology. Although used
worldwide, "tests for these compounds in combination are very rare,
although they frequently co-occur."
The experiments performed by Porter's group suggest that children and
the developing fetus are most at risk from the pesticide-fertilizer
mixtures. Their influence on developing neurological, endocrine and
immune systems, said Porter, portend change in ability to learn and
in patterns of aggression.
The privately funded Wisconsin study focused on three commonly used
farm chemicals: aldicarb, an insecticide; atrazine, a herbicide; and
nitrate, a chemical fertilizer. All three are in wide use worldwide
and are the most ubiquitous contaminants of groundwater in the United
States.
In the series of experiments, when mice were given drinking water
laced with combinations of pesticides and nitrate, they exhibited
altered immune, endocrine and nervous system functions. Those changes,
according to Porter, occurred at concentrations currently found in
groundwater.
Effects were most noticeable when a single pesticide was combined
with nitrate fertilizer. This was true for herbicide as well as
insecticide, said Porter, and chips away at the notion that
herbicides have no significant influence on animals.
"Herbicides can have neurological impacts and hormonal impacts and
immune impacts," he said. "They are not the harmless chemicals they
are sometimes portrayed to be. They can be every bit as biologically
active as insecticides or fungicides."
The apparent influence of pesticide and fertilizer mixtures on the
endocrine system -- the system of glands such as the thyroid that
secrete hormones into the bloodstream -- may have a cascade effect,
spilling over to the immune system and affecting fetal brain
development.
"Thyroid disruption in humans has multiple consequences," Porter
said. Some of these include effects on brain development, level of
irritability, sensitivity to stimuli, ability or motivation to learn,
and altered immune function.
A curious finding of the study is that animals may be more vulnerable
to the influence of such chemicals depending on the time of year:
"Our current working hypothesis is that animals are seasonally
vulnerable because of subtle modulation of natural seasonal variation
in hormone levels," according to Porter. "For example, thyroid
hormone level varies seasonally and we have now shown that two
different chemical mixtures will modulate thyroid hormone levels."
The new study, Porter contends, adds to a growing body of evidence
that current testing methods required for the registration and use of
chemical pesticides are fundamentally flawed. In addition to a lack of
testing of combinations of chemical compounds, Porter said there is a
narrow focus on looking principally for carcinogenic effects or
obvious cell mutations.
Neurological, immune and endocrine tests for pesticides have been
mandated by federal law for almost three years, but there has been no
enforcement of these laws, Porter said.
"Toxicological testing so far has been extremely limited in scope and
focused on mechanisms that require extensive mutations or cell damage
to show any effects. They do not adequately assess the potential for
biological effects under real world exposure scenarios."
Co-authors of the paper include James W. Jaeger of the UW-Madison
Department of Zoology, and Ian H. Carlson of the Endocrinology
Laboratory, University of Wisconsin Hospital.
C 1999 Board of Regents of the University of Wisconsin System
Source: UW-Madison Office of News and Public Affairs
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Michele Gale-Sinex, communications manager
Center for Integrated Ag Systems
UW-Madison College of Ag and Life Sciences
Voice: (608) 262-8018 FAX: (608) 265-3020
http://www.wisc.edu/cias/
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If you knew what life was worth, you
would look for yours on earth. --Bob Marley
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