Organic contaminants - Indoor Environmental Quality - page 104

tem cancer. These studies have not provided conclusive evidence of a causal
relationship. Formaldehyde exposures have been reported to be associated
with slight to moderate increases in risk for cancers of the buccal cavity,
nasopharynx, oropharynx, and lung. Studies of residents of mobile homes
have shown a significant increase in the risk of nasopharyngeal cancer in
individuals living in mobile homes (at exposure concentrations 0.10 ppmv)

for more than 10 years (compared to a randomly chosen population). Based
on available evidence, the USEPA, Occupational Safety and Health Admin-
istration (OSHA), and International Agency for Research on Cancer (IARC)
have listed formaldehyde as a Class 2A (suspected human) carcinogen.

≥

C. Acetaldehyde

Acetaldehyde is a two-carbon aliphatic aldehyde with a pungent, fruity
odor. Though it is used in a variety of industrial processes, its presence in
ambient and indoor air is almost always associated with the combustion
oxidation of fuels and products such as tobacco ( Table 4.6 ). It is a major
constituent of automobile exhaust gases and is the predominant aldehyde
found in tobacco smoke.
Exposures to acetaldehyde (in indoor environments) are likely to occur
from the infiltration of ambient air, ETS, combustion by-products from
unvented gas and kerosene appliances, flue gas spillage, leakage from wood-
burning appliances, and, in developing countries, unvented by-products of
wood, charcoal, and kerosene cooking fuels.
Exposures to acetaldehyde in indoor environments have not been char-
acterized. Compared to HCHO, it is a relatively mild irritant of the eye and
upper respiratory system. It is unlikely to cause irritant symptoms in most
indoor environment situations because of anticipated low exposure concen-
trations. The exception to this may be cooking fires in developing countries.
Acetaldehyde is a proven animal carcinogen and, as such, is a potential
carcinogen in humans.

D. Acrolein

Acrolein is a three-carbon aldehyde with one double bond. It is highly
volatile and has an unpleasant choking odor. It is used in the production of
a number of compounds and products. It is released into the environment
as a combustion oxidation product from oils and fats (containing glycerol),
wood, tobacco, and automobile/diesel fuels.
There are few published reports of acrolein in indoor air. In an apparently
unusual case, the author has observed significant acrolein levels (>0.1 ppm,
the OSHA PEL) in school administrative office spaces associated with the
application of a polyurethane insulation/rubberized roofing material.
Acrolein emissions and potential human exposures have been reported
for tobacco smoke ( Table 4.6 ) . They also occur in the ambient and indoor
environments with open windows, as a result of motor vehicle emissions