PRINCIPLES OF TOXICOLOGY

402 PROPERTIES AND EFFECTS OF ORGANIC SOLVENTS
carcinogen and exhibits mutagenic potential in the bacterial tests. The USEPA has established a
carcinogenic potency factor (CPF) of 0.067 (mg/kg⋅day) –1 for inhalation exposure and 0.0067
(mg/kg⋅day) –1 for oral exposure. Although benzidine is one of the compounds regulated by OSHA as
a human carcinogen, no exposure standards or recommendations have been set by OSHA or ACGIH.
Other Nitrogen Compounds
Figure 16.29 Benzidine.
Figure 16.30 Hydrazine.
Because of its strong reducing capabilities, hydrazine (see Figure 16.30) is used in a wide range of
industrial chemical syntheses, photographic processes, and metallurgy. At sufficient concentration,
hydrazine is a strong skin and mucus membrane irritant, convulsant, hepatotoxin, and a moderate
hemolytic agent. It is readily absorbed through the lungs, the gastrointestinal tract, and through intact
skin, as evidenced by the fact that equivalent median lethal doses are observed in animal studies
following oral, intravenous, and intraperitoneal administration. The effects noted after absorption by
all routes include anorexia, weight loss, weakness, vomiting, excitement, and convulsions. Airborne
exposure may produce eye and respiratory tract irritation, lung congestion, bronchitis, and pulmonary
edema.
Hydrazine has been shown to be tumorigenic in mice, where lungs are the primary target organs.
A carcinogenic potency factor (CPF) or slope factor (SF) of 17.1 (mg/kg⋅day) for inhalation exposure,
and 3.0 (mg/kg⋅day) for oral exposure, has been established by USEPA. This compound has also shown
to be mutagenic in phage, bacteria, plants, Drosophila, and mammalian test systems. The ACGIH
TLV ® and the OSHA PEL for hydrazine have been set at 0.01 ppm and 1.0 mg/m 3 , based on observation
of damage to lung, liver, and kidney tissue at higher exposure levels.
16.15 TOXIC PROPERTIES OF REPRESENTATIVE ALIPHATIC AND AROMATIC
NITRO COMPOUNDS
These compounds have little industrial use and in general are oily liquids of low solubility and volatility.
Toxicologically, they can be classified as moderate irritants, because their anesthetic symptoms are
mild. Unsaturated compounds may be absorbed via the skin to a significant extent, while the saturated
chemicals are not. Halogenation produces definite skin irritation, some systemic absorption and,
therefore, toxicity. Aromatic nitro compounds are a class of chemicals, several members of which may
produce methemoglobin formation and/or sensitization to the compound.
Nitro derivatives of benzene and toluene also have prominent toxic effects other than sensitization,
CNS depression, or methemoglobinemia. The trinitrotoluene or dinitrobenzene compounds are well
absorbed by all routes of exposure. These compounds can uncouple oxidative phosphorylation, and
liver injury is often seen along with the toxicities previously mentioned. Other problems that have been