Page 348 - Industrial Ventilation Design Guidebook

304 CHAPTER 5 PHYSIOLOGICAL AND TOXICOLOGICAL CONSIDERATIONS

Many metals are potent kidney toxins. These metals cause similar signs and
symptoms. At low doses, the symptoms include leakage of sugars and amino acids
into the urine due to glomerular damage and polyuria due to lack of concentrating
capability of the kidney. Large doses cause cellular necrosis, anuria, increased con-
centrations of blood-urea-nitrogen, and subsequently the total breakdown of kidney
function and ultimately death. In addition to direct cell injury, some metals induce
vasoconstriction in the kidney. Metals such as nickel and cadmium strongly induce
the synthesis of metal binding proteins in the liver, notably metallothionein. 152
Halogenated hydrocarbons may cause kidney damage in addition to liver dam-
age. A nephrotoxic dose of carbon tetrachloride increases the relative weight of the
kidneys, induces swelling of tubular epithelium in the kidneys, and causes lipid de-
generation, tubular casts, and necrosis of the epithelium of the proximal tubulus.
Several other halogenated hydrocarbons, e.g., tri-and tetrachloroethylene, also in-
duce this kind of kidney damage. 153
Reproductive Tox/c/ty
The reproductive system is a very complex, hormonally-controlled entity.
The female endocrine system is more complex than that of the male, and toxic
effects that are directed toward the female reproductive system are, therefore,
more difficult to assess than those targeted at the male system. In addition, the
effects of toxic compounds on the reproductive system clearly differ between
females who are pregnant and those who are not, because pregnancy changes,
female physiology and because the target of the toxic effects may also be the
fetus. The effects of chemicals on the fetus will be discussed in the section on
teratogenesis (see Section 5.3.4.5). The assessment of reproductive toxicity is
further complicated by the fact that the timing of essential events, e.g., the
process of organogenesis, is different in different species, and therefore extrap-
olating results obtained in animal experiments to predict the toxic effects of
chemicals on human reproduction is problematic.
It needs to be noted that a toxic effect on the reproductive system may be
mediated through alterations in normal functions of the central nervous sys-
tem, gonads (ovaries, testicles), or on the pharmacokinetics of reproductive
98 154 155
hormones. ' '
Compounds Affecting Reproduction Compounds that can affect reproduc-
tive function include several drugs and occupationally important chemicals such as
solvents and pesticides as well as a number of environmentally relevant com-
pounds. A group of chemical compounds that has received much attention recently
is endocrine disrupters, many of which are halogenated hydrocarbons, e.g., PCBs.
98 156 157
These are known to induce feminization in fish and other animal species. ' '
There is intense debate about the significance of these compounds to human health.
Tobacco smoke and ethyl alcohol also have major effects on human reproduction,
the effects of alcohol being especially important. Table 5.17 lists compounds that
may disturb the functions of female and male reproductive functions.
Toxicity to Blood and Blood-Forming Tissues
Blood-forming tissues consist of bone marrow, spleen, lymph nodes and the
reticuloendothelial system. These produce the elements of blood and are impor-
tant for the immunological defense systems.