Page 301 - Materials Chemistry, Second Edition

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272 Waste Management Practices: Municipal, Hazardous, and Industrial
respectively. Recycling of batteries via specialized collection systems and prohibition on disposal are
practical approaches to reducing the amount of toxic metals in the waste stream. Such approaches are
more difficult to implement for plastics and pigment uses, however.

9.6.2 HEALTH EFFECTS OF METALS IN INCINERATOR ASH

Ash may be dispersed into the workplace or the local environment at all stages of ash management,
including during on-site handling and storage, transport, and handling at the disposal site. At each
step, there is potential for airborne and water-borne dispersal of ash. Most of the metals of concern
have the ability to be adsorbed by soils and sediments, and many can accumulate in living tissue;
therefore, heavy metals persist in the biosphere. Thus, long-term releases even at low levels can sub-
stantially increase metal levels in the environment. Figure 9.14 presents possible exposure routes to
air emissions from MSW incinerators and incinerator ash.
Many heavy metals of concern have well-defined health effects. Many are carcinogenic; how-
ever, they also exert neurological, hepatic, renal, hematopoietic, and other adverse effects, both in
humans and in other biota. As a very brief overview, arsenic, cadmium, beryllium, and lead are car-
cinogenic metals; arsenic, lead, vanadium, cadmium, and mercury are neurotoxins; zinc, copper,
and mercury are acutely toxic to aquatic life (Denison and Rustin, 1990). More detailed effects of
these and other metals are discussed in several excellent works (see Suggested Readings). Total

Deposition
Well Runoff on to soil
surface

Percolation to
ground water

Deposition
on food
and feed
Eating
vegetables
Drinking milk
Irrigation

Inhalation

Eating fish
Soil
Drinking water ingestion
Dermal absorption
Uptake by biota

FIGURE 9.14 Exposure pathways for emissions from a MSW incinerator (U.S. EPA, 1986).