Diane Relf
Virginia Cooperative Extension
Many
people ask the question, "What risk do I assume if I use pesticides
around my home?" The risk of potential chemical injury is
determined by exposure and toxicity. Without both factors
there is no risk.
We handle
many chemicals (other than pesticides) in our everyday lives.
Gasoline is a good example. We know that it is toxic if ingested
or inhaled, but if we take care to limit our exposure to it
and handle it safely, we take little risk in using it. The
same is true with pesticides.
:
- There are three types of exposure: dermal, inhalation, and
ingestion. Dermal exposure is the most common type of exposure
for the applicator since the skin is easily exposed when
handling pesticides. Inhalation or breathing a pesticide
into the lungs is less common, but is still a potential
danger to the applicator. Ingestion occurs least frequently
with careful applicators, but exposures do occur when users
eat, smoke, or drink around pesticides or forget to wash
after use. Even though hands and forearms are most subject
to exposure, other parts of the body (eyes, abdomen, groin)
absorb pesticides more quickly. The eyes and skin can also
be badly damaged by the corrosive effects of many chemicals.
Exposure can be reduced significantly by following a few
good work practices. Always wear unlined rubber gloves
when handling and applying any pesticide. In addition,
if spray mist is a hazard, the use of waterproof clothing
may be necessary. At least, wear a long sleeved shirt
and long trousers, unlined rubber boots and splash-proof
goggles when handling any pesticide. The label may also
require you to wear other pieces of protective equipment
such as a chemical respirator. Remember, the greatest
risk to the applicator occurs when handling concentrated
chemicals (when mixing). Wearing a rubber apron in addition
to the above protection is advised when handling concentrates.
- To
quote Dr. Alice Ottoboni, author of the book, The Dose Makes
the Poison, "toxicity is the ability of a chemical to damage
an organ system, such as the liver or kidneys, or to disrupt
a biochemical process, such as the blood-forming mechanism,
or to disturb an enzyme system at some site in the body."
Simply stated, toxicity is the property of a chemical which
causes damage to the body of a living organism.
There are two types of toxicity, acute and chronic. Acute
toxicity refers to exposure to a single dose of a toxin
which produces symptoms within a short period of time
after the exposure. The pesticide label warns of the dangers
of acute toxicity through various precautionary statements
and signal words. Label signal words can be found prominently
displayed on the front panels of all pesticide labels.
They are based on a system which breaks pesticides into
categories and specific ratings of toxicity. These specific
ratings are described in terms of LD50, the lethal dosage
of a compound necessary to kill 50 percent of a population
of test organisms (rats, mice, etc.).
Every chemical you have in your home, whether it be in
food or designed as a tool for use in and around the home,
has some level of toxicity. Acute toxicity of various
pesticides and other chemicals commonly found around the
home can be compared by use of the LD50 ratings of each
when found in a concentrated form. These ratings change
when materials are diluted by manufacturers to be sold
as formulated products and are changed further when diluted
by the user during mixing. The higher the LD50 rating,
the lower the toxicity. In some cases, the acute oral
LD50 is so high that the chemical is said to be practically
non-toxic. Chemicals with very low LD50 ratings can be
highly toxic.
Acute toxicity from pesticides may be expressed as flu-like
symptoms or a nervous system disorder while symptoms of
chronic toxicity may be expressed in other forms. Chronic
toxicity is used to describe the potential long term effects
which could result from exposure to small amounts of a
toxin over time. Chronic toxicity may impact different
parts of the body than acute toxicity. Chemicals have
long been feared as potential causes of forms of cancer,
reproductive problems, and birth defects. There is little
research to prove that these possible effects occur. Many
critics point out that there is a definite correlation
between chemicals and chronic effects, while there are
just as many critics who argue the opposite.
- The
only way to resolve this argument at present is to recommend
that pesticides and other chemicals be used as a last resort
to other viable options. If you do choose to use a pesticide,
use it very carefully and reduce risk by limiting your exposure
to the chemical. Select the least toxic product that will
control the problem. Investigate alternative pest control
methods to use either in lieu of a pesticide or to integrate
with a chemical control.
Disclaimer
and Reproduction Information: Information in NASD does not represent
NIOSH policy. Information included in NASD appears by permission
of the author and/or copyright holder. More
NASD Review: 04/2002
(Originally
published as "Exposure, Toxicity, and Risk of Home Pesticide
Use," by M.J. Weaver, Assistant Professor, PPWS, and Extension
Coordinator, Chemical, Drug and Pesticide Unit, Virginia Tech,
in The Virginia Gardener Newsletter, Volume 7, Number 6.) August
1996
Diane
Relf, Extension Specialist, Environmental Horticulture
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