PRINCIPLES OF TOXICOLOGY

388 PROPERTIES AND EFFECTS OF ORGANIC SOLVENTS
Figure 16.12 Acrolein.
but its carcinogenic potential has not been investigated by extensive long-term tests. Acetaldehyde is
embryotoxic and teratogenic in animal tests and is the presumptive proximal toxicant, inducing these
effects when ethanol has been tested.
At concentrations in excess of 200 ppm in air, it is capable of eye irritation marked by conjunctivitis,
and even at 25–50 ppm, some individuals may experience its irritant effects. The odor threshold is less
than 0.1 ppm, thus affording a considerable margin of safety if used as a warning property, since the
OSHA PEL based on health effects is 200 ppm. While it is a minimal industrial health hazard, it may
represent an explosion hazard in some cases.
Acrolein (see Figure 16.12) is the unsaturated analog of propionaldehyde and the double bond
greatly enhances its toxicity in comparison. Acrolein is toxic by all routes of administration and
is capable of severe eye and pulmonary irritation. Since contact with the skin may produce
necrosis, its direct contact with the eyes must be carefully avoided. Even though it is a highly
reactive chemical, no carcinogenicity has been observed in tests thus far. The occupational
guideline for acrolein is 0.1 ppm, not much less than the level that is considered to be moderately
irritating (0.25 ppm).
16.9 TOXIC PROPERTIES OF REPRESENTATIVE KETONES
The paucity of reports in the literature regarding serious injury suggests that ketone compounds (see
Figure 16.13) do not present serious hazards to health under most circumstances, probably at least in
part because they have fairly effective warning properties (e.g., easily identifiable odor). Ketones are
recognized CNS depressants, but the vapors present at concentrations that are great enough to cause
sedation also are strongly irritating to the eyes and respiratory passages and, thus, typically are
avoidable. Lower concentrations, however, may be inhaled easily and may accumulate to levels that
impair judgment. Death, owing to overdose, typically results from respiratory failure. In general, the
toxic properties of the ketones increase with increasing molecular weight, and the unsaturated
compounds are more toxic than the saturated analogs.
Acetone (see Figure 16.14) is an extremely common industrial solvent and raw material in
industrial manufacturing processes. Several daily ingestions of acetone in doses as high as 15–20 g
produced limited adverse effects, including drowsiness. Skin irritation typically occurs only after
repeated prolonged contact. Persons unaccustomed to acetone may experience eye irritation at
500 ppm, while workers who are used to daily exposure can easily tolerate several thousand parts
per million in air. At 9000–10,000 ppm, unambiguous irritation of the throat and lungs occurs.
The odor threshold rises after initial contact in acclimated people. Studies of exposed
employees with average exposure to acetone concentrations of 2000 ppm typically reveal no
serious injury.