Page 1018 - Basic _ Clinical Pharmacology ( PDFDrive )

1004 SECTION IX Toxicology

regulatory agencies in many countries have requirements for many sources except under certain extraordinary circumstances.
disclosure of hazardous materials and their health impacts, pro- In those cases, emergency alterations to standards may be made
prietary information exclusions often make it difficult for those and an emergency temporary standard may be promulgated after
who treat occupationally and environmentally poisoned patients appropriate regulatory procedures. The ACGIH TLV guidelines
to understand the nature and scope of the presenting illness. are useful as reference points in the evaluation of potential work-
Because many of these illnesses have long latency periods before place exposures. Compliance with these voluntary guidelines is
they become manifest, it is often a matter of detective work, when not a substitute for compliance with the OSHA requirements in
patients finally present with disease, to ascertain past exposure and the United States. TLVs do not have the force of law. Current TLV
relate it to present clinical effect. Monitoring of exposure concen- lists may be obtained from the ACGIH at http://www.acgih.org.
trations both in the workplace and in the general environment has
become more common, but it is far from widespread, and so it is Environmental Toxicology
often very difficult to establish the extent of exposure, its duration,
and its dose rate when this information is critical to the identifica- Environmental toxicology deals with the potentially deleterious
tion of the toxic disorder and its management. impact of chemicals, present as pollutants of the environment,
on living organisms. The term environment includes all the
Occupational Toxicology surroundings of an individual organism, but particularly the air,
soil, and water. Although humans are considered a target species of
Occupational toxicology deals with the chemicals found in the particular interest, other species are of considerable importance as
workplace. The major emphasis of occupational toxicology is potential biologic targets. Scientific study of signal occurrences in
to identify the agents of concern, identify the acute and chronic animals often provides early warning of impending human events
diseases that they cause, define the conditions under which they as a result of ecotoxic impacts.
may be used safely, and prevent absorption of harmful amounts of Air pollution is usually a product of industrialization, techno-
these chemicals. The occupational toxicologist will also be called logic development, and increased urbanization. On rare occasions,
upon to treat the diseases caused by these chemicals if he or she is natural phenomena such as volcanic eruptions may result in air
a physician. Occupational toxicologists may also define and carry pollution with gases, vapors, or particulates that are harmful to
out programs for the surveillance of exposed workers and the humans. Humans may also be exposed to chemicals used in the
environment in which they work. They frequently work hand in agricultural environment as pesticides or in food processing that
hand with occupational hygienists, certified safety professionals, may persist as residues or ingredients in food products. Air con-
and occupational health nurses in their activities. taminants are regulated in the United States by the Environmental
Regulatory limits and voluntary guidelines have been elabo- Protection Agency (EPA) based on both health and esthetic con-
rated to establish safe ambient air concentrations for many siderations. Tables of primary and secondary regulated air contam-
chemicals found in the workplace. Governmental and supragov- inants and other regulatory issues that relate to air contaminants
ernmental bodies throughout the world have generated workplace in the United States may be found at http://www.epa.gov. Many
health and safety rules, including short- and long-term exposure states within the USA also have individual air contaminant regu-
limits for workers. These permissible exposure limits (PELs) have lations that may be more rigorous than those of the EPA. Many
the power of law in the United States. Copies of the US Occupa- other nations and some supragovernmental organizations regulate
tional Safety and Health Administration (OSHA) standards may air contaminants. In the case of adjoining countries, transborder
be found on OSHA’s website at http://www.osha.gov. Copies of air and water pollution problems have been of concern in recent
the US Mine Safety and Health Administration (MSHA) stan- years. Particulates, radionuclides, acid rain, and similar problems
dards may be found at http://www.msha.gov. In addition to the have resulted in cross-contamination of air and water in differ-
PELs that appear in the OSHA publications and on the website, ent countries. Maritime contamination, too, has raised concern
OSHA promulgates standards for specific materials of particularly about oceanic pollution and has had an impact on the fisheries of
serious toxicity. These standards are developed following extensive some countries. This type of pollution is now the subject of much
scientific study, stakeholder input at hearings, public comment, research and of new international treaties.
and other steps such as publication in the Federal Register. Such The United Nations Food and Agriculture Organization and
standards have the force of law and employers who use these the World Health Organization (FAO/WHO) Joint Expert Com-
materials are obligated to comply with the standards. OSHA mission on Food Additives adopted the term acceptable daily
standards may be found in full on the OSHA website at http:// intake (ADI) to denote the daily intake of a chemical from food
www.osha.gov. that, during an entire lifetime, appears to be without appreciable
Voluntary organizations, such as the American Conference risk. These guidelines are reevaluated as new information becomes
of Governmental Industrial Hygienists (ACGIH), periodically available. In the United States, the Food and Drug Administra-
prepare lists of recommended threshold limit values (TLVs) tion (FDA) and the Department of Agriculture are responsible
for many chemicals. These guidelines are periodically updated. for the regulation of contaminants such as pesticides, drugs, and
Regulatory imperatives in the United States may also be updated chemicals in foods. Major international problems have occurred
from time to time when new information about toxicity becomes because of traffic among nations in contaminated or adulterated
available. However, this process is slow and requires input from foods from countries whose regulations and enforcement of pure