Environmental Engineering Reference
In-Depth Information
as catalysts in vinyl chloride manufactured by hydrochlorination of
acetylene, an obsolete process used rarely in modern times. Mercury
can be accidentally or otherwise released into the environment (as in
the case of pollution in Minamata Bay, Japan, leading to widespread
regional neurotoxic effects).
b. Soft PVC products use phthalate plasticizers at high weight fractions
(sometimes as high as 50-60% by weight). Over 6 MMT of phthalates
(in 2011) is used annually in PVC products. Phthalates are released into
the environment during production use and disposal of plasticized PVC
products. Phthalates are endocrine disrupters and a health hazard as
extensively discussed in
Chapter 7
.
c. Lead and cadmium compounds are often used as thermal stabilizers in
PVC. The presence of these metal residues complicates disposal of PVC
waste. The industry is moving to phase out the use of lead. About a third
of the production uses a process that uses and releases mercury into the
environment.
d. There is no infrastructure to effectively recycle PVC waste. Even by
2020, its mechanical recycling will only reach a maximum of 18%
(Leadbitter, 2002) under the best conditions. It cannot be easily
incinerated as HCl is formed during the combustion and has to be
sequestered in lime. Also, there is the possibility of dioxin formation
during incineration.
In a recent study (Technical Science Advisory Committee of the U.S. Green
Building Council, Altshuler et al., 2007), PVC was compared to competing
materials in windows (aluminum and wood), pipe (cast iron and ABS),
siding (aluminum and fiber cement), and resilient floor (sheet vinyl,
linoleum, and cork). Impacts assessed for each product category were as
follows: carcinogenicity, total health hazard, and adverse environmental
impacts (acidification, eutrophication, smog, ozone depletion, global
climate change, fossil fuel depletion, and ecotoxicity). The PVC products
either ranked the worst or tied with the worst choice, in human health
assessments even when the comparison was based on low-end estimates.
It ranked higher than cast iron pipes, aluminum siding, and aluminum
windows on overall environmental impact but not significantly different
from ABS pipes, wooden windows, wood, or fiber cement siding.
