Environmental Engineering Reference
In-Depth Information
toxic waste containment sites, improper disposal and storage, and anthropogenic
discharges such as power plant emissions.
Group 3 represents nonmetallic inorganics such as arsenic (metalloid) and
asbestos, which are carcinogens.
Group 4 includes biological contaminants such as aflatoxins and pathogenic
microorganisms; animal and human drugs such as diethylstilbestrol (DES)
and other synthetic hormones; and food additives such as red dye No. 2.
An Associated Press report released March 9, 2008 (available at http://www.
metrowestdailynews.com/homepage/x1574803402), outlined the appearance of
antibiotics, hormonal preparations, personal care chemicals, antidepressants,
cholesterol control and cardiovascular medications, and pain relievers in
ultra-small concentrations (ppb and ppt) in drinking-water samples from 24 of
28 metropolitan areas of the United States. All of these chemical substances are
undetectable by the human senses.
Evaluation of the toxicity of existing and new chemicals on workers, users, and
the environment and their release for use represent a monumental task, as already
noted. Monitoring the total effect of a chemical pollutant on humans requires
environmental monitoring and medical surveillance to determine exposure and
the amount absorbed by the body. The sophisticated analytical equipment avail-
able can detect chemical contaminants in the parts-per-billion or parts-per-trillion
range. Mere detection does not mean that the chemical substance is automati-
cally toxic or hazardous. But detection does alert the observer to trends and
the possible need for preventive measures. Short-term testing of chemicals, such
as the microbial Ames test, is valuable to screen inexpensively for carcinogens
and mutagens. The Ames test determines the mutagenic potential of a chemical
based on the mutation rate of bacteria that are exposed to the chemical. However,
positive results suggest the need for further testing, and negative results do not
establish the safety of the agent. Other tests use mammalian cell cultures and cell
transformation to determine mutagenicity.
Prevention and Control
Prevention of the major causes of death, such as diseases of the heart, malignant
neoplasms, cerebrovascular disease, accidents, and other noninfectious chronic
and degenerative diseases, should now receive high priority. Prevention calls for
control of the source, mode of transmission, and/or susceptibles as appropriate
and as noted in Figure 1.1.
The prevention and control of environmental pollutants generally involves the
following three procedures:
1.
Eliminate or control of the pollutant at the source
. Minimize or prevent
production and sale; substitute nontoxic or less toxic chemical; materi-
als and process control and changes; recover and reuse; waste treatment,
separation, concentration, incineration, detoxification, and neutralization.
2.
Intercept the travel or transmission of the pollutant
. Control air and water
pollution and prevent leachate travel.
