Page 780 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Appendix G

Comments on Health

Most polymers are nontoxic under the normal and intended use. (Some biopolymers, such as snake
venom, should not be dealt with except under very controlled conditions.) Most of the additives
employed are also relatively nontoxic. Even so, care should be exercised when dealing with many
of the monomers of synthetic polymers and when dealing with polymeric materials under extreme
conditions such as in commercial and domestic fi res.

G.1 FIRE
Fire hazards involve not only burning (most deaths occur from the ingestion of volatiles pro-

duced by the fire). Carbon monoxide, the major cause of death, causes unconsciousness in less
than 3 minutes due to its preferential attack on hemoglobin.
Interestingly, one important observation concerning burning in general is where colored smoke is
produced. Some materials burn producing lots of dark-colored smoke. Some of this colored smoke
may be due to the production of aromatic substances containing fused-ring systems that may con-
tain harmful chemicals, including respiratory toxins and cancer-causing agents.

G.2 MEASURES OF TOXICITY
Toxicity involves the affect of various materials on living objects, including bacteria, plants, mice,

fish, and humans. Tests to determine the toxicity of materials are typically done in a number of
ways, including inhalation, simple skin contact, and injection under the skin.
While mainly concerned with the affects of various agents on humans, most standard tests are
carried out on animals, often a suitable test animal that is believed to be a good model for transfer-
ring results from the animal tests to humans. Table G.1 contains some of the toxicity values found
in today’s literature.
While commercially available, synthetic polymers are relatively nontoxic, the monomers vary
greatly in toxicity. This points out the need for monomers and other potentially toxic chemicals to
be removed from the polymers. Table G.2 contains the time–weight average (TWA) for some mono-
mers as cited by the U.S. Occupational Standards. For comparison, entries for some well-known
toxic materials have been added.

G.3 CUMULATIVE EFFECTS
While exposure of the general public to toxins is to be avoided, exposure of people that deal with
commercial chemicals on a daily basis is even more important. Such people must take special care
to avoid exposure since the toxicities of many of these chemicals are accumulative in our bodies
slowly building to levels that may be unhealthy.
Most of the toxic, environmentally unwanted chemicals of a decade ago have been eliminated
from the common workplace. This includes halogenated hydrocarbons such as carbon tetrachloride
and aromatic hydrocarbons such as benzene and toluene. Further, chemicals that are known to be
potentially toxic, such as some monomers, are being eliminated from the polymeric materials to
within the limits of detection.

743

9/14/2010 3:44:47 PM
K10478.indb 743
K10478.indb 743 9/14/2010 3:44:47 PM