Environmental Health News

What's Working

  • Garden Mosaics projects promote science education while connecting young and old people as they work together in local gardens.
  • Hope Meadows is a planned inter-generational community containing foster and adoptive parents, children, and senior citizens
  • In August 2002, the Los Angeles Unified School District (LAUSD) Board voted to ban soft drinks from all of the district’s schools

#647 - Solvents: All-Purpose Poisons, 21-Apr-1999

In all industrialized societies, both men and women are often
exposed to organic solvents at work and in the home. Gasoline
contains a mixture of organic solvents, and solvents are major
components of lighter fluid, spot removers, many aerosol sprays,
paints, paint thinners, paint removers, fingernail polish and
remover, glues, and floor and tile cleaners.

In the past year or so, half a dozen studies have implicated
solvents in several serious health problems, including major
birth defects, immune system disorders (such as rheumatoid
arthritis, scleroderma, and lupus erythematosus), and several
kinds of cancer, including breast cancer.

Chemicals in the "organic solvent" class include aliphatic
hydrocarbons (mineral spirits, varnish, kerosene), aromatic
hydrocarbons (benzene, toluene, xylene), chlorinated
hydrocarbons (carbon tetrachloride, trichloroethylene,
tetrachloroethylene [also known as perchloroethylene, or perc]),
aliphatic alcohols (methanol), glycols (ethylene glycol), and
glycol ethers (methoxyethanol). There are hundreds of different
organic solvents on the market and it is rare to be exposed to
only one at a time; mixtures are common.

BIRTH DEFECTS

Several occupations dominated by women have potential exposure
to organic solvents: health care professions, work in the
clothing and textile industries, and the graphic arts, among
others.

In 1998, an analysis of five previous studies showed that women
exposed to organic solvents during pregnancy had a 64% increased
chance of giving birth to a baby with a major birth defect.[1] A
major birth defect was defined as "potentially life-threatening
or a major cosmetic effect." However, all five studies were
retrospective in design -- that is, women were asked after the
birth of their child whether they had been exposed to solvents
during pregnancy. All retrospective studies can suffer from
"recall bias." For example, people who give birth to defective
babies may have a heightened or otherwise distorted recollection
of what chemicals they were exposed to during pregnancy,
compared to women who gave birth to normal children.

Just last month, a "prospective" study of solvents and birth
defects was published in the JOURNAL OF THE AMERICAN MEDICAL
ASSOCIATION (JAMA).[2] The study was "prospective" because women
were asked about their solvent exposure during pregnancy before
they gave birth. Thus a "prospective" study avoids the problem
of "recall bias."

The JAMA study found that women occupationally exposed to
solvents during pregnancy have a 13-fold increased chance of
giving birth to a child with a major birth defect. A major birth
defect was defined as "any anomaly that has an adverse effect on
either the function or the social acceptability of the child."
Defects that occurred in babies born to women in the
solvent-exposed group included heart valve defects; soft
cartilage in the larynx; micropenis [abnormally small penis];
deafness; clubfoot; neural tube defect [opening to the spinal
cord at the base of the brain]; and hydronephrosis [a serious
kidney defect].

The JAMA study examined 125 women who were occupationally
exposed to organic solvents during pregnancy and an equal number
of pregnant controls matched for age, number of previous
pregnancies, smoking and drinking habits. In addition, the
control group had been exposed to chemicals known not to produce
birth defects.

All the exposed women worked with organic solvents for at least
the first 13 weeks of pregnancy. The most common occupations
were factory worker; laboratory technician; professional artist
or graphic designer; and printing industry worker. Other
solvent-exposed occupations included chemist; painter; office
worker; veterinary technician; funeral home worker; carpenter;
social worker; and car cleaner.

The two groups of pregnant women differed in several noteworthy
respects. Both groups had had an equal number of pregnancies,
but the solvent-exposed women had had significantly more
miscarriages (and thus fewer children born). Babies born to
solvent-exposed women weighed an average of 168 grams (5%) less
than babies born to the control group. Eight babies born to
solvent-exposed women fell in the category "low birth weight"
(defined as less than 2500 grams [5.5 pounds].) Among
non-exposed women, 3 babies had low birth weight. Among the
solvent-exposed group, 17 babies suffered "fetal distress" at
birth vs. 6 with fetal distress among the unexposed group. Fetal
distress was defined as fetal intestinal discharge during
delivery and/or abnormal fetal heart rate during delivery, or
the requirement of resuscitation or a neonatal intensive care
unit.

Among the 125 women occupationally exposed to solvents, 75
reported symptoms temporarily associated with their exposure, 43
had no symptoms of exposure, and for 7 such information was
missing. Twelve of the 13 major birth defects occurred among the
group reporting symptoms of exposure. The exposed women were
further divided into two groups -- those exposed for 7 months or
longer; and those exposed for 3 to 7 months. Sixteen women
exposed more than 7 months had labor with fetal distress vs.
only one among those with shorter exposure.

Organic solvents can readily pass from the mother to the fetus
in the womb, by passing through the placenta. The authors
conclude that pregnant women are endangered by occupational
exposure to solvents, and so are their babies, particularly if
the mother has symptoms of solvent exposure herself.

CONNECTIVE TISSUE DISEASE

Rheumatoid arthritis, lupus, and scleroderma are "rheumatoid"
disorders affecting the body's connective tissues. These are all
"autoimmune" diseases in which the body's immune system makes
too many antibodies, which are proteins usually directed against
invaders. In the case of autoimmune diseases, the antibodies are
mistakenly directed against the self.

If a person has several of the symptoms of these three
"rheumatoid" diseases but not enough of the symptoms of any one
disease to be diagnosed with that disease, they will be
diagnosed as having "undifferentiated connective tissue disease"
(UCTD). For reasons that are unknown, rheumatoid diseases strike
women somewhat more than men.

A recent case-control study of 205 women in Ohio and Michigan
with UCTD, and 2095 controls, revealed that the women with UCTD
were 3 times as likely as controls to have been exposed
occupationally to paint thinners and paint removers.[3] Paint
thinners include mineral spirits, white spirit, naphtha, VM & P
naphtha, Stoddard Solvent and Varsol, all of which are petroleum
distillates. Furthermore, women with undifferentiated connective
tissue disease were twice as likely as controls to have been
exposed on the job to mineral spirits.

Women in specific solvent-related occupations had a
greatly-increased chance of getting UCTD, compared to controls.
Women in the furniture refinishing industry had a 9-fold
increased chance of getting UCTD; women in perfume, cosmetic or
drug manufacturing had a 7-fold increased chance; women in
rubber product manufacturing had a nearly 5-fold increased
chance of getting UCTD.

The causes of rheumatoid diseases are not known, but something
triggers the immune system to attack the self instead of
restricting its attack to non-self invaders such as bacteria and
viruses. This carefully-done study indicates that
petroleum-based solvents may be one such trigger.

CANCER

Benzene, toluene, xylene and styrene are the cornerstones of the
petrochemical industry. They serve as the feedstock for the
manufacture of many other solvents, chemical intermediates,
dyes, explosives, and resins for the manufacture of plastics,
elastomers, and textiles. Many solvents contain benzene, toluene
and/or xylene in varying proportions.

Of these four large-volume chemicals, only benzene has been
clearly established as a human carcinogen. Benzene can cause
leukemia (cancer of the blood-forming cells) in exposed workers
and perhaps in others who have lesser exposures.

Based on studies of laboratory animals, styrene is a suspected
human carcinogen, but toluene and xylene fall in the "unknown"
category, chiefly because they have hardly been studied.

Last year a large case-control study in Canada examined the
experience of 3730 patients with 15 different kinds of cancer.
The authors of the study reported finding "limited evidence" of
an association between xylene and colon cancer; between benzene,
toluene and styrene and cancer of the rectum; and between
styrene and prostate cancer.

Most interestingly, a 1997 study examined the relationship
between breast cancer and solvents. There is evidence from
studies of laboratory animals that solvents can cause breast
cancer in some species. In humans, the evidence is spotty. Out
of 17 studies of occupational solvent exposure and cancer, 12
have shown no relationship while 5 have indicated that breast
cancer and solvents are related.[5] On the other hand, only one
of the 17 studies was specifically designed to look for breast
cancer, and women often make up a tiny proportion of an
occupational cohort so most studies do not have the necessary
power to reveal a relationship even if one exists.

Canadian researchers France P. Labreche and Mark S. Goldberg
have offered a formal hypothesis linking breast cancer to
solvents.[5] They point out that the breasts of women in
industrialized countries contain numerous solvents dissolved in
the fatty tissues. Breast milk contains acetaldehyde,
benzaldehyde, benzene, carbon disulfide, carbon tetrachloride,
chlorobenzene, chloroethane, ethyl chloride, chloromethane,
chloropentane, crotonaldehyde, cyclohexane, cyclopentane,
dichlorobenzene, 1,2-dichloroethane, dichloroethylene; ethyl
alcohol, ethylbenzene, and perhaps other solvents as well.[5]
(Despite the presence of these industrial poisons in breast
milk, breast feeding is still the best way to nourish an infant;
all alternatives are worse.) Often these solvents are present in
breasts at higher concentrations than in a woman's blood stream.

These solvents remain in breast tissue for long periods, in
contact with the very cells where cancers originate, Labreche
and Goldberg point out. Some of these solvents have estrogenic
properties, but Labreche and Goldberg are mainly concerned that
many solvents and their metabolic byproducts are, themselves,
capable of initiating, or promoting cancers. Labreche and
Goldberg, and perhaps others, have studies underway now to test
the solvents-cause-breast-cancer hypothesis.

--Peter Montague (National Writers Union, UAW Local 1981/AFL-CIO)

=====

[1] Kristin I. McMartin and others, "Pregnancy Outcome Following
Material Organic Solvent Exposure: A Meta-Analysis of
Epidemiologic Studies," AMERICAN JOURNAL OF INDUSTRIAL MEDICINE
Vol. 34 (1998), pgs. 288-292.

[2] Sohail Khattak and others, "Pregnancy Outcome Following
Gestational Exposure to Organic Solvents," JOURNAL OF THE
AMERICAN MEDICAL ASSOCIATION Vol. 281, No. 12 (March 24/31
1999), pgs. 1106-1109.

[3] James V. Lacey, Jr., and others, "Petroleum Distillate
Solvents as Risk Factors for Undifferentiated Connective Tissue
Disease (UCTD)," AMERICAN JOURNAL OF EPIDEMIOLOGY Vol. 149, No.
8 (1999), pgs. 761-770.

[4] Michel Gerin and others, "Associations Between Several Sites
of Cancer and Occupational Exposure to Benzene, Toluene, Xylene,
and Styrene: Results of a Case-Control Study in Montreal,"
AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 34 (1998), pgs.
144-156.

[5] France P. Labreche and Mark S. Goldberg, "Exposure to
Organic Solvents and Breast Cancer in Women: A Hypothesis,"
AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 32 (1997), pgs.
1-14.

Descriptor terms: women; solvents; birth defects; cancer;
connective tissue disease; uctd; scleroderma; rheumatoid
arthritis; immune system; lupus erythematosus; breast cancer;
colon cancer; cancer of the rectum;