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Unformatted text preview: essive exposure
to a teratogen during pregnancy or cancer from excessive exposure to a carcinogen).
Some important details about toxic effects:
● Acute poisoning is characterized by rapid assimilation of the substance.4 Often, but
not always, the effect is sudden and can be painful or severe and even fatal.
Normally, a single exposure is involved. Examples: carbon monoxide or cyanide
● Chronic poisoning is characterized by repeated exposures with a duration measured
in months, or years.4 Symptoms may not be immediately apparent. Examples: lead
or mercury poisoning, pesticide exposures.
● Substances in combination may result in the synergistic effect. When two or more
hazardous materials are present, the resulting effect can be greater than the effect
predicted for the individual substances. Example: exposure to alcohol and chlorinated solvents. The opposite is also possible; two poisonous substances can lessen
each other’s effects, called the antagonistic effect. Example: cyanide and amyl
● Allergens are agents that produce an immunologic reaction, and you may
encounter them in the laboratory. Asthma-like symptoms or dermatitis are typical
allergic reactions. Not everyone is susceptible to allergens. A susceptible individual
will not suffer an allergenic reaction unless he or she has been sensitized by at least
one previous exposure. For some allergens, an individual must be exposed several
times before suffering an allergenic response. Tell your instructor if you know or suspect that you are allergic to a chemical in your laboratory.
Except for allergenic exposures, the toxic effects from exposure to a chemical
depend on the severity of the exposures. Generally, the larger or more frequent the
exposure, the more severe the result. Consequently, you can reduce or even avoid
harm by keeping exposures to a minimum. The following section explains how. Exposure Limits
Toxic chemicals can cause harm if they are ingested. Therefore, do not eat or drink
anything in the...
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This document was uploaded on 02/27/2014 for the course PHYS 1B at UCSD.
- Spring '07