(Created 12/02)
UNL Environmental Health and Safety · (402) 472-4925 · http://ehs.unl.edu
that particular chemical. Health effects
can then occur in the organs, which are sensitive
to the toxicant.
•
Skin (or eye) absorption: Skin (dermal) contact can cause effects that are relatively
innocuous such as redness or mild dermatitis; more severe effects
include destruction of
skin tissue or other debilitating conditions. Many chemicals can also cross the skin barrier
and be absorbed into the blood system. Once absorbed, they may produce systemic
damage to internal organs. The eyes are particularly sensitive to chemicals. Even a short
exposure can cause severe effects to the eyes or the substance can be absorbed through
the eyes and be transported to other parts of the body causing harmful effects.
•
Ingestion: Chemicals that inadvertently get into the mouth and are swallowed do not
generally harm the gastrointestinal tract itself unless they are irritating or corrosive.
Chemicals that are insoluble in the fluids of the gastrointestinal tract (stomach, small, and
large intestines) are generally excreted. Others that are soluble are absorbed through the
lining of the gastrointestinal tract. They are then transported
by the blood to internal
organs where they can cause damage.
•
Injection: Substances may enter the body if the skin is penetrated or punctured by
contaminated objects. Effects can then occur as the substance is circulated in the blood
and deposited in the target organs.
Once the chemical is absorbed into the body, three other processes are possible: metabolism,
storage, and excretion. Many chemicals are metabolized or transformed
via chemical reactions in
the body. In some cases, chemicals are distributed and stored in specific organs. Storage may
reduce metabolism and therefore, increase the persistence of the chemicals in the body. The
various excretory mechanisms (exhaled breath, perspiration, urine, feces, or detoxification) rid
the body,
over a period of time, of the chemical. For some chemicals elimination may be a matter
of days or months; for others, the elimination rate is so low that they may persist in the body for
a lifetime and cause deleterious effects.
