MANAGING PLASTIC WASTE - Plastics and Environmental Sustainability - page 406

energy as well. The plastics fraction in MSW is readily incinerated and
would contribute at least 10-12% of this energy. In the United States, MSW
contains about½%ofchlorine, abouthalfofitderived fromPVCwaste.The
possibility of chlorine-containing waste being converted into toxic dioxins
or dioxin-like chemicals has been discussed in the research literature
(Shibamoto et al., 2007).
In late 1980s, the health hazards of dioxins and furans potentially emitted
from burning mixed waste were recognized (Huang and Buekens, 1995).
Polychlorinateddibenzo- p -dioxins(PCDDs),polychlorinateddibenzofurans
(PCDFs), and polychlorinated biphenyls (PCBs) are classes of compounds
potentially formed in during burning of wastes containing chlorine.
Incinerating waste with organic or inorganic chlorides along with lignin
(newsprint or wood) or plastics, especially those with aromatic structure,
can yield these compounds (Yasuhara et al., 2002). About 90% of human
exposure to these chemicals is via ingestion with food, especially in meats
and dairy products. They are highly toxic 6 even at low levels, have very low
solubilityinwater,bioaccumulative, andarepersistent organic pollutantsin
the environment. While some human epidemiological studies are available,
the weight of evidence on their toxicity is based on animal studies. TCDD,
one of the congeners (see Fig. 9.9 ), is one of the most toxic substances
known with a median lethal dose (LD 50 ) of 1 µg/kg body weight in guinea
pigs. In general, dermal toxicity, hepatotoxicity, immunotoxicity,
reproductive toxicity, teratogenicity, endocrine disruption, and
carcinogenicity effects have been associated with dioxins.