Environmental Engineering Reference
In-Depth Information
TABLE 7.11
Data for Benzyl Acetate and Ethyl Acetate
CAS Registration
Number
Name
Chemical Formula
Carcinogenicity Rating
Benzyl acetate
140-11-4
C
6
H
5
CH
2
OCOOH
3
Not Available
Ethyl acetate
141-78-6
C
4
H
8
O
2
Not Available
Source:
United States Environmental Protection Agency, Integrated Risk Information
System (IRIS), http://www.epa.gov/ncea/iris/intro.htm (accessed October
21, 2009), 2009b.
hydrogen atom has been replaced by a different organic func-
tional group. Common uses of esters include the following
(ATSDR 2002b, 2002c, 2002d):
O
O
• Flame retardants
• Nail polish removers
• Glue
• Fragrances
• Clothing
FIGURE 7.15
Molecular structure of benzyl
acetate.
O
Polyester is the most common and most widely produced ester. They
also occur naturally, and are found in flowers, in fats as triesters
derived from glycerol and fatty acids, and in wine (ATSDR 2002b,c,d).
The structures of two ester compounds, benzyl acetate and ethyl ace-
tate are shown in Figures 7.15 and 7.16, respectively.
Table 7.11 presents the structural formula, CAS registration num-
ber, and carcinogenicity rating for benzyl acetate and ethyl acetate
(USEPA 2009b).
At high concentrations, ester compounds can irritate the skin and mucous membranes
and cause breathing difficulties (USEPA 2009b).
O
FIGURE 7.16
Molecular structure of
ethyl acetate.
7.7 Heavy Metals
Heavy metals naturally exist in the environment at amounts termed their background
levels. When human activities introduce additional heavy metals into the environmental
and the background levels are exceeded, they then become contaminants.
In terms of their characteristics, heavy metals are generally not soluble in water, except
for some varieties of arsenic and chromium VI at a neutral pH (Murray et al. 2004; SRC
2009). Heavy metals are not volatile but are often released into the atmosphere through the
combustion of coal, automobile exhaust, metal production, and other methods (Murray
et al. 2004).
The most common heavy metals occurring in urban areas include the following (Murray
et al. 2004):
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