Toxicology
- Toxicology is the science that deals with poisons and their effect
on living organisms.
Toxicity
- Toxicity is the inherent ability of a pesticide to cause harm to a
specific organism.
- Some pesticides are more toxic than others and present higher risks
to users, nontarget organisms, and the environment.
- The effect of the pesticide (the toxic reaction) is related to the
amount of pesticide (the dose) applied.
- Toxicity is often measured in LD-50, the Lethal Dose to kill 50% of
exposed individuals, or LC-50, the Lethal Concentration in water or air
to kill 50% of exposed individuals of a species.
- LD-50 does not provide information about long-term (or chronic) effects
such as cancer, sterility, and permanent nerve damage that can result
from repeated low level exposures.
- The Extension
Toxicology Network provides
more information on toxicity of specific pesticides.
Half-life
- The half-life is the length of time it takes for a pesticide
to lose half of its toxicity in a given environment.
- Pesticides that break down rapidly are less likely to cause harm.
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Indicator organisms
- An indicator organism is a test species that is used in experiments
to measure the toxicity of poisonous materials.
- Indicator organisms are exposed to various levels of toxic materials
over a period of time in order to determine their potential toxicity
to the organism and to evaluate their effects on survival and reproduction.
- Ceriodaphnia and Hyalella
are tiny aquatic invertebrates used as
indicator organisms to measure toxicity in water.
Click on image to enlarge
Illustration by Celeste Rusconi |
