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GE - PANUPS: Inadequate Pesticide Testing

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From: [] 
Sent: 27 March 1999 03:28 
Subject: PANUPS: Inadequate Pesticide Testing
P A N U P S 
Pesticide Action Network Updates Service 
New Study Points to Inadequate Testing of Pesticides 
March 26, 1999
A new study in the journal Toxicology and Industrial Health identifies 
significant shortcomings in toxicological testing protocols currently 
used to register pesticides in the United States. The five year study 
suggests that combinations of commonly used agricultural chemicals in 
concentrations that mirror levels found in groundwater can significantly 
influence immune and endocrine systems as well as neurological health. 
"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 Porter, 
lead author and University of Wisconsin professor of zoology and 
environmental toxicology. "Although they frequently co-occur, tests for 
these compounds in combination are very rare." 
The experiments performed by Porter's group suggest that children and 
the developing fetus are most at risk from 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 study focused on three commonly used farm chemicals: 
aldicarb, an insecticide; atrazine, an 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. 
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 also result in changes in the immune 
system and affect 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. 
Need for new testing methods 
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 in the U.S. are fundamentally flawed. The study 
listed six important deficiencies in current testing protocols: 
* Current tests do not require chemicals to be tested at low dose 
pulse exposure. Pulse doses of low levels of pesticides at critical 
times when developmental windows are open and body defenses are unable 
to respond may lead to permanent changes in a fetus. It is important to 
remember that the embryo has almost no defensive systems against 
chemicals and no feedback systems to modulate chemical concentrations 
early in its development. 
* Toxicological tests have typically focused on cancer and 
mutation endpoints and have not looked at other critical concerns such 
as endocrine and immune system effects that can occur. 
* Standard toxicological tests only evaluate one route of exposure 
at a time, rather than all possible routes (oral, cutaneous and 
* Most testing is done with pure forms of pesticidal active 
ingredients rather than with commercial formulations. There are three 
types of chemical additives that are missing from most testing: 
contaminants of manufacturing processes, toxic waste deliberately added 
from chemical reactor cleaning processes and "inert" ingredients. 
* Current testing requirements do not evaluate exposure effects 
from chemical mixtures. While it is impossible to examine all possible 
mixtures, common combinations generated in specific areas due to crop 
rotation and tillage practices could be examined. 
* Laboratory animals generally live in an environment where 
climate, nutrition and disease are carefully controlled. Researchers 
know that when additional stresses are present, toxic responses to 
registered chemicals occur that do not appear under current standard 
testing procedures.
Sources: Warren Porter, et al., "Endocrine, immune and behavioral 
effects of aldicarb (carbamate), atrazine (triazine) and nitrate 
(fertilizer) mixtures at groundwater concentrations," Toxicology and 
Industrial Health (1999) 15, 133-150. University of Wisconsin-Madison 
press release, March 15, 1999. 
Contact: PANNA.
Pesticide Action Network North America (PANNA) 
49 Powell St., Suite 500, San Francisco, CA 94102 USA 
Phone: (415) 981-1771 
Fax: (415) 981-1991 
Web: <>
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