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This article is published with the
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SOLVENTS: ALL-PURPOSE POISONS
BIRTH DEFECTS
CONNECTIVE TISSUE DISEASE and rheumatoid
arthritis
CANCER
=======================Electronic Edition=======================. .
. RACHEL’S ENVIRONMENT & HEALTH WEEKLY #647 .
. ---April 22, 1999--- .
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. SOLVENTS: ALL-PURPOSE POISONS
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SOLVENTS: ALL-PURPOSE POISONS
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 [1.1 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.
(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;
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