Part 4 emphasizes the impact of human activity on natural ecosystems. As human populations grow, and technology changes, the magnitude of human actions becomes more apparent. The natural ecosystems on land and water are modified to meet human needs. The heavy use of pesticides in agriculture is discussed in this section. Part 5 deals with the major types of pollution.
Pollution affects the health and welfare of humans and other organisms.
Air pollution, solid waste, and hazardous and toxic substances are discussed in this section. The cost of pollution cannot always be measured in financial terms, but may be reflected in the mental and physical health of the populace. Government often uses risk assessment and analysis to help set policy regarding pollution and other environmental issues. Separate chapters deal with the ways in which government sets policy and evaluates risk. New to This Edition 1.