Establishing Exposure Guidelines. Toxicity data from both animal experimentation and
epidemiological studies is used to establish exposure guidelines. The method for deriving a
guideline is dependent upon the type of chemical as well as duration and frequency of exposure.
It is also important to make the distinction between an experimental dose (mg/kg) and an
environmental concentration (mg/m
3
or ppm). In order to make safety decisions, exposure
guidelines are presented as concentrations so that these values can be compared to concentrations
measured by air monitoring instrumentation.
TABLE 3 Toxicity Rating Toxicity Rating or Class Oral Acute LD 50 for Rats Extremely toxic
1 mg/kg or less (dioxin, botulinum toxin)
Highly toxic
1 to 50 mg/kg (strychnine)
Moderately toxic
50 to 500 mg/kg (DDT)
Slightly toxic
0.5 to 5 g/kg (morphine)
Practically nontoxic
5 to 15 g/kg (ethyl alcohol)
TABLE 4 LD 50 Values for Rats for a Group of Well-Known Chemicals Chemical LD 50 (mg/kg) Sucrose (table sugar)
29,700
Ethyl alcohol
14,000
Sodium chloride (common salt)
3,000
Vitamin A
2,000
Vanillin
1,580
Aspirin
1,000
Chloroform
800
