TOXICOLOGY 1161
For a chemical to be classified as a known human carcinogen
there must be sufficient evidence to support a causal relation-
ship between its exposure and the occurrence of human cancer.
For substances to be listed as an anticipated human carcinogen
there must exist sufficient evidence that it is a carcinogen, but
alternative explanations exist or there is insufficient evidence
supporting classification, experimentally and epidemiologi-
cally, as a carcinogen.
Regardless of the classification used, evidence of car-
cinogenicity for a substance requires epidemiological and
experimental evidence. Epidemiological information is con-
sidered to be the strongest in establishing a substance as a
carcinogen.REGULATORY TOXICOLOGYRegulatory toxicology is the area that interrelates toxicol-
ogy with regulatory standards. The purpose of this area is to
establish standards to provide protection against a specific
chemical or group of chemicals. In many cases, standards are
established before the full knowledge of a chemical is com-
plete. Some identify this type of decision making to be part
of risk assessment. In the United States, regulations related to
toxicology can be generally divided into the major agencies
that promulgate criteria for chemicals. These are the Food and
Drug Administration (FDA), the Environmental Protection
Agency (EPA), OSHA, MSHA, and the Consumer Product
Safety Commission (CPSC). There are other agencies (e.g.,
the Department of Transportation), but for the purposes of
this section they are considered minor. The agencies that are
important for environmental engineers are the EPA and OSHA.
However, those with the mining industry will also consider
MSHA of great importance. The EPA, in general, establishes
standards for environmental protection, and OSHA for protec-
tion related to those in the occupational environment. For con-
sumer substances and products, the CPSC regulates toxicity.
OSHA came into existence with the passage of the
Occupational Safety and Health Act on December 29, 1970
(effective April 28, 1971). OSHA as well as MSHA are partof the U.S. Department of Labor. OSHA has five major parts,
with each regulating different industrial groups (Table 9).
The OSHA act sets out two primary duties for employers,
which are for them to maintain a workplace free of recognized
hazards and to comply with OSHA regulations. The act also
requires that employees comply with the act, although clari-
fication of this requirement is often lacking. Requirements of
the employer are called the General Duty Clause. States can
have their own OSHA plan and enforce OSHA as a state pro-
vision if they meet certain requirements. Currently, there are
23 state plans.
Commonly, environmental engineers will be required
to interact with OSHA inspectors. OSHA often conducts
inspections as a random process, or more frequently does
so as a result of complaint. When an inspection occurs, the
inspector will present identification to the management of
the facility. If a labor union exists, the inspector must also
notify the labor-union representative. Usually there is then
an examination of the OSHA records, usually materials
safety data sheets (MSDS) and the OSHA 200 form. Lack
of MSDS, which is part of the Hazard Communication
Plan, is one of the most frequently cited violations. A
walkthrough is then conducted, which may include the
collection of samples. At the end of this process there is
a closing conference. At this time alleged violations are
discussed. If citations are issued they can consist of one of
three types: imminent danger, serious violations, and will-
ful violations.
Employers can contest citations. This is usually initiated
through an informal hearing. If the employer then decides
to contest the citation, there is a specific process that must
be undertaken. OSHA has an independent review commis-
sion as part of the Department of Labor to hear contested
citations. To contest the citation, the employer must file
notice within 15 working days by certified mail. There isTABLE 8
IARC classification groups for carcinogenic substancesGroup 1: Carcinogenic to humans (common called “known”) carcinogen
(examples: asbestos, arsenic) (evidence supports the chemical or
substance as a human carcinogen)
Group 2A: Probably carcinogenic to humans (examples: diethyl sulfate,
vinyl bromide) (limited evidence in humans and sufficient evidence in
experimental animals)
Group 2B: Possibly carcinogenic to humans (examples: bracken fern,
chlordane) (limited evidence in humans and less than sufficient
evidence in experimental animals)
Group 3: Unclassified or not classified as carcinogenic to humans
(examples: aldrin, aniline) (inadequate evidence in humans and
inadequate or limited evidence in animals)
Group 4: Probably not carcinogenic to humans (example: caprolactam)
(evidence suggesting lack of carcinogenicity in humans and animals)TABLE 9
Sections of the CFR related to OSHA standards29 CFR 1910—General industry
29 CFR 1915—Shipyards
29 CFR 1917—Marine terminals
29 CFR 1918—Longshoring
29 CFR 126—ConstructionTABLE 10
Some environmental acts of importanceClear Air Act
Clean Water Act
Toxic Substance Control Act
Resource Conservation and Recovery Act
National Environmental Policy Act
Comprehensive Environmental Response, Compensation, and Liability
Act Emergency Planning and Right to Know ActC020_003_r03.indd 1161C020_003_r03.indd 1161 11/18/2005 11:09:31 AM11/18/2005 11:09:31 AM