Environmental Engineering Reference
In-Depth Information
of a chemical such as polychlorinated byphenyl (PCB). The U.S. Environ-
mental Protection Agency (EPA) “zero-discharge”
goal
is a step in this
direction.
2. Select the cleanest available source of drinking water, as free as possible
from microbiological and toxic organic and inorganic chemicals.
3. Make available water with optimum mineral content, such as through flu-
oridation and water hardness control.
4. Prohibit taking of fish and shellfish from contaminated (e.g., pathogen,
methylmercury, PCB) waters.
5. Regulate food production, processing, and service to ensure freedom from
toxic substances and pathogens and to assure food of good nutritional
content.
6. Provide decent housing in a suitable living environment.
7. Provide a safe and healthful work and recreational environment.
8. Promote recycling, reuse, and zero discharge of hazardous wastes.
9. Eliminate disease vectors (arthropods and other animals, including rodents)
at the source. Practice integrated pest management.
10. Isolate infected persons and animals from others during their period
of communicability and provide medical treatment to eliminate disease
reservoir.
11. Educate polluters, legislators, and the public to the need for regulation and
funding where indicated.
12. Adopt and enforce sound standards.
13. Support comprehensive environmental health, engineering, and sanitation
planning, surveillance, and regulation programs at the state and local levels.
See also “Control of Susceptibles (Host Factors)” in this chapter.
Control of Mode of Transmission
Several types of factors may be brought into any discussion of disease expression
and transmission. An environmental factor, in the context of disease transmis-
sion, would be any external physical, biological, or chemical condition, other
than the agent, that contributes to the disease process.
4
As an example, sev-
eral environmental factors, including high humidity, high temperature, neutral
to slightly alkaline soils, presence of organic matter, variety of animal reser-
voirs, and infected cattle herds, appear to contribute to the high endemic rate
of leptospirosis in certain tropical countries.
5
Several species of
Leptospira
are
pathogenic. The causative agent of Weil's disease is the pathogenic spirochete,
Leptospira interrogans
serovar Icterohemmoragiae. The disease is one of the
leading zoonoses worldwide and, while the incidence is infrequently encoun-
tered in the temperate climates (0.1 to 1 case per 100,000 individuals per year),
it is more prevalent in tropical areas of high rainfall (10 to 100 cases per 100,000
