oo

° Formaldehyde is found in the resin glues used in the plywood industry.

Workers should be aware of risks
due to formaldehyde exposure

ormaldehyde (HCHO) is one of the most im-
portant products of the chemical industry. It
is used in the manufacture of resins, particle
board, plywood, leather goods, paper, phar-
maceuticals and other products. As such,
occupational and residential exposures to this
chemical have become quite common.

‘The primary route of exposure to formaldehyde
is by inhalation. Formaldehyde is a gas at room
temperature. Low concentrations of formaldehyde
are found in the air primarily as a result of burning
organic fuel such as wood, coal, gas, oil, gasoline
or diesel fuel.

Occupational exposures can be found wherever
formaldehyde or formaldehyde-based resins are
used. Table 1 lists some of the occupations where
exposure to formaldehyde can occur. Residential
exposures can occur from the presence of
formaldehyde-based furnishings and panelling as

well as from the use of urea formaldehyde foam
insulation. Cigarette smoke is also a source of in-
door formaldehyde. Sidestream tobacco smoke
may contain up to 40 ppm of formaldehyde. Table
2 summarizes occupational and environmental ex-
posures to formaldehyde.
ABSORPTION, METABOLISM, AND DISTRIBUTION

Formaldehyde is readily absorbed through the
lungs and gastrointestinal tract and, to a much
lower extent, through the skin. Formaldehyde is
very water soluble and is usually absorbed in the
upper airways and nose. It routinely does not pen-
etrate deep into the lungs.

Formaldehyde is also produced in the body and
is normally found in the blood. It has been estimat-
ed that the body produces 50 grams (1% ounces) of
formaldehyde per day. The fact that the body me-
tabolizes such large amounts of formaldehyde sug-
gests that formaldehyde is not a poison to the
internal organs.

Health effects associated with formaldehyde ex-
posure are most likely to occur at body sites with
direct contact with this chemical: the eyes, nose
and throat.

TOXICITY OF FORMALDEHYDE

Odour detection is, for some individuals, the
most sensitive reaction to formaldehyde. An odour
threshold range of between 0.05 and 1.0 ppm has
been reported for formaldehyde.

A large number of studies, some of which are
summarized in Table 3, have investigated the
health effects of formaldehyde. The range of expo-
Sures reported to cause sensory irritation is quite
broad, and some individuals become symptomatic
at lower levels of exposure. The level of discom-
fort reported is also subjective. Some people may
report mild discomfort while others report moder-
ate or no discomfort at similar exposures, Individ-
uals have reported eye irritation, throat irritation,
fatigue, headache, and nausea in environmental air
concentrations between 0.1 and 1 ppm.

- The United States National Research Council
has concluded formaldehyde can produce a sensa-

tion of eye irritation in some individuals at 0.05
ppm.

- The World Health Organization Working
Group on Assessment and Monitoring of Exposure
to Indoor Air Pollutants has concluded that indoor
formaldehyde concentrations of less than 0.06
ppm were of limited or no concern while “concen-
tration of concern” was
above 0.12 ppm.

‘TABLE 2 a
Some reported levels

mental exposure to formaldehyde

SITE LEVEL (ppm)

Environmental Outdoor Exposure

Rural pastures

Los Angeles Basin

Outdoor Air in Industrial Cities

Smog

Environmental Indoor Exposures
Conventional Homes:

Homes with Urea formaldehyde foam insulation
Mobile Homes

Schools

Offices

Clothing Stores

Sidestream cigarette smoke
Occupational Exposures

Plywood manufacturing

Particle board manufacturing

Urea formaldehyde foam manufacturing
Urea forinaldehyde form installation

ported, but the likelihood that formaldehyde caus-
es other allergic disorders is not great, if at all.
CARCINOGENESIS

High levels of formaldehyde inhalation, approxi-
mately 15 ppm, have been associated with the ap-
pearance of cancer of the nose in rats and mice. A
large number of occupational epidemiologic stud-
ies have been performed to assess whether formal-
dehyde is a human carcinogen. Although some
studies have suggested that there may be an in-
creased risk of cancer, particularly in the nose,
others have not confirmed this finding. The pos @®
tive studies have suggested an association with
cancer only in groups with long term high expo-
sure.

The U.S. National Cancer Institute and the
Formaldehyde Institute supported a large study of
formaldehyde workers which found that at higher
levels of exposure, formaldehyde was associated
with lung cancer. At the same time, however, oth-
er occupational exposures which could influence
these findings occurred. Formaldehyde exposures
without other occupational exposures were not
associated with an increased risk of lung cancer.

Both the U.S. Environmental Protection Agency
(EPA) and the U.S. Occupational Safety and
Health Administration (OSHA) regard formalde-
hyde as a possible human carcinogen and regulate
it as such. The U.S. National Institute for Occupa-
tional Safety and Health (NIOSH) considers

formaldehyde to be a hu-

- Although workers
exposed to levels of
formaldehyde between
0.12 and 1.6 ppm report-
ed an increased frequen-
cy of irritant symptoms
to the eyes, nose and
throat, they exhibited no
change in lung function.

- Asthmatic and non-

Workers should be exposed

to as low a level as possible
Uf formaldehyde can not
be eliminated

man carcinogen. The
American Conference of
Government Industrial
Hygienists (ACGIH)
gives formaldehyde an
A2 designation, one that
is reserved for suspect
human carcinogens. It
recommends that work-
er exposure by all routes
should be carefully con-

asthmatic subjects have
reported similar re-
sponses to the irritant ef-
fects of formaldehyde exposures between 0.05 and
0.125 ppm where symptoms have been reported.
Other studies investigating long-term occupational
exposure to formaldehyde have not shown any ad-
verse effects on lung function at low levels of ex-
posure.

~ Asthmatic and non-asthmatic.subjects have re-
ported similar responses to the irritant effects of
formaldehyde. An investigation of asthmatics did

TABLE 1
Some occupations with exposure to formaldehyde

Anatomists Bakers
Biologists Bookbinders
Botanists Deodorant makers
Dress-goods shop personnel Dressmakers
Drug Makers Electrical insulation makers
Embalmers Fertilizer makers
Formaldehyde resin makers Fumigators
Fur processors Glue and adhesive makers
Histology technicians Ink makers
Medical personnel Oil well workers
Paper makers Particle board workers
Rubber makers Soil sterilizers and greenhouse workers
Taxidermists ‘Textile waterproofers
Varnish workers Wood preservatives

not demonstrate evidence of airway hyperractivity
in one hour controlled exposures to 3 ppm of
formaldehyde.

In summary, odour detection can begin as low
as 0.05 ppm and some individuals may also experi-
ence eye irritation at this level. As the level of ex-
posure increases, more individuals may
experience eye irritation and upper airway and
nasal symptoms can occur. Levels up to 3 ppm
have not led to tightening of the airways in asth-
matics, but these individuals will complain of
more symptoms.

ALLERGIC RESPONSES
Skin sensitivity to formaldehyde has been re-

trolled to levels as low

as reasonably achiev-

able.
EXPOSURE GUIDELINES

The current ACGIH Threshold Limit Value
(TLV) for formaldehyde is 0.3 ppm ceiling concen-
tration, meaning that exposures should not exceed
this level at anytime. This number is used as a
guideline for monitoring occupational exposures
in Manitoba. The ACGIH recognizes that this expo-
sure level “may not eliminate all workers com-
plaints of sensory irritation associated with
exposure to formaldehyde”. Health and Welfare
Canada’s exposure guideline for formaldehyde in
residential air is 0.10 ppm as a five minute average.
A target level of 0.05 ppm is recommended.
PROTECTION
Workers should be exposed to as low a level of

formaldehyde as possible. If the formaldehyde
cannot be replaced by a less toxic compound,
workplaces with elevated levels of formaldehyde
exposure should institute engineering controls.
Where elevated exposure cannot be prevented,
workers should wear appropriate respiratory pro-
tective devices.

TABLE 3
Human adverse health effects associated with inhala-

tion of various concentrations of formaldehyde, select-
CONCENTRATION (ppm) .

ed studies
REPORTED HEALTH EFFECTS FORMALDEHYDE

None reported !

Odor Threshold

‘Upper airway irritatior/increased nasal airway

resistance 1

This article is reprinted from “Focus” with the permission of tho Manitoba Federa-
tion of Labour Health and Safety Centre.

10/LUMBERWORKER/JUNE, 1995