Environmental Engineering Reference
In-Depth Information
of concentrations with a median value of 0.09 ppmv in a study of mobile
homes and homes with particle board underlayment. Studies in Canada and
California indicate significant dose-dependent symptoms associated with
HCHO exposure concentrations of <0.10 ppmv.
Asthmatic reactions to HCHO and asthmatic/pulmo-
nary-type symptoms have been reported in field investigations of occupa-
tional and residential HCHO exposures. These studies suggest that HCHO
may be a pulmonary irritant and may be capable of inducing asthmatic
attacks by specific sensitization reactions. Controlled bronchial challenge
studies (which are the standard for confirming the induction of asthmatic
symptoms on exposure to a substance) of asthmatic patients in the U.S. and
Canada have been unable to identify any changes in pulmonary function at
exposure concentrations of 2 to 3 ppmv. Less well-controlled bronchoprovo-
cation tests in Europe indicate that formaldehyde-induced pulmonary func-
tion changes in exposed workers occur but that such responses are rare.
Significantly increased prevalence rates of asthma and chronic bronchitis
among children in homes with HCHO levels in the range of 0.06 to 0.12
ppmv (especially in homes with ETS) compared to those less exposed were
observed in an epidemiological study of HCHO concentrations, respiratory
symptoms, and pulmonary function conducted in Arizona. A linear decrease
in peak expiratory flow rates with HCHO levels was observed with an
estimated decrement of 22% at 0.06 ppmv. This study is significant since it
apparently shows a strong dose-response relationship between pulmonary
symptoms and HCHO concentrations in the range of
b.
Asthma.
0.06 to 0.12 ppmv;
levels which are still likely to occur in U.S. mobile homes. Also notable is
that pulmonary function decrements were observed in both asthmatic and
nonasthmatic children
The induction of asthma or asthmatic symptoms may occur as a conse-
quence of a specific hypersensitivity reaction or a response to a nonspecific
irritant. The former suggests that an immunological mechanism is respon-
sible. Though specific IgE antibodies for HCHO have not been demonstrated,
several investigators have shown that some formaldehyde-exposed individ-
uals develop antibodies against formaldehyde-human serum albumin con-
jugates. The clinical significance of these findings has not been established.
≥
Formaldehyde has been shown to cause a variety of geno-
toxic effects in cell culture and
c.
Cancer.
assays. These include DNA-protein
cross-links, sister chromatid exchange, mutations, single-strand breaks, and
aberrations in chromosomes. These results indicate that HCHO is both geno-
toxic and mutagenic and is therefore likely to be carcinogenic. Several high-
concentration, chronic animal exposure studies have demonstrated that
HCHO can cause squamous cell carcinomas in the nasal passages of rats
and mice.
A number of epidemiological studies have attempted to evaluate the
potential relationship between HCHO exposure and upper respiratory sys-
in vitro
