Agrochemical Impacts On Human And Environmental Health: Mechanisms And Mitigation

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Research collecting pigeons to test homing instincts

There exist several sources of environmental contaminations which can impact wildlife species. Agrochemicals are routinely used to control weeds and insects on crops and gardens throughout the U.S. and Nevada. During the application process and subsequent to it, non-target organisms can come into contact with these agrochemicals either through direct spraying, or ingestion of the chemicals through food and or water. Another important source of environmental contamination is from anthropogenic origins such as mining.

Acute toxicities resulting in death of the animals are easily identifiable and highly regulated. Sub-lethal exposures, however, are more difficult to identify and although these exposures may not cause immediate death to the organisms, they could cause long term effects which might impact the organism’s ability to survive.

Birds, and in particular migratory birds, may be exposed to these environmental contaminants repeatedly. Migratory birds are protected during migration by an international treaty, The Migratory Bird Treaty Act. As Nevada is part of an important flyway for several migratory bird species, this is a particularly important issue for Nevada particularly in light of the current and historic gold and silver mining conducted in the state.

 We have developed a model which we believe is useful in testing whether low-dose exposure to environmental and agrochemical contaminants has an adverse effect on migratory birds. We use the homing pigeon (Columba livia) as our avian model to determine the impact of various environmental and agrochemical exposures to migratory birds.

Previous studies have tested cyanide and arsenic compounds as well as neurotoxic agrochemicals widely used in California on various crops. In most cases, a dose-dependent increase in the time required to return to the “homing” roost occurred. These results show that low-dose exposure to these compounds results in a decreased ability to fly back to the roost which would imply a decreased ability for migration. Many of these compounds have also shown effects on these birds ability to successfully reproduce.

For the purposes of this study we want to test this model with other neurotoxic compounds which are persistent in the environment such as mercury and lead compounds. We wish to test whether these compounds will have the same effect as the carbamate and organophosphate compounds had that we tested.

We also wish to expand upon our understanding of the longer term effect of these exposures by testing the offspring of these birds for both learning (to home) and reproductive abilities. These studies will allow us to assess potential short and long term population level effects due to these exposures, 

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