=======================Electronic Edition========================
RACHEL’S HAZARDOUS WASTE NEWS #323
—February 3, 1993—
News and resources for environmental justice.
——
Environmental Research Foundation
P.O. Box 5036, Annapolis, MD 21403
Fax (410) 263-8944; Internet: erf@igc.apc.org
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NEW PERSPECTIVES ON TOXICS–PART 2: MALE REPRODUCTIVE SYSTEM
IS HARMED BY TOXIC EXPOSURES, CAUSING BIRTH DEFECTS, STERILITY
The ancient Greeks observed that men heavily exposed to lead
became sterile. But this knowledge was not passed to the Romans,
who stored their drinking water and their wine in lead-lined
containers. Romans also added lead to some of their drinks as a
sweetener. Based on examination of lead in Roman bones, some
historians conclude that the Roman upper classes probably
couldn’t reproduce themselves, contributing to the fall of
Rome.[1]
Until very recently, scientists paid little attention to the
effects of environmental agents on human reproduction. The modern
period began in 1941 when blindness, deafness and death were
reported among the offspring of pregnant women exposed to rubella
(German measles). The thalidomide catastrophe in 1954-1961
brought home the potential dangers of chemicals, in this case a
prescription drug. (See RHWN #322.) The birth of nearly 20,000
defective children following a Rubella epidemic in the early
1960s confirmed the association of environmental factors and
birth defects.[2]
As recently as the early 1970s, few state governments were
maintaining records of birth defects. In 1974 the federal
government established the first national register of birth
defects, monitoring hospital records that account for about 15%
of all births.[3] Even today this program monitors only birth
defects observed in newborns, which probably represent only about
a sixth of the total defects that actually occur because many
defects do not become apparent for several years.[2]
As of 1980, approximately 200,000 birth defects were estimated to
have occurred in the U.S., accounting for about 7 percent of all
live births. In addition, more than 560,000 infant deaths,
spontaneous abortions, stillbirths and miscarriages were recorded
due to defective fetal development.[2]
In 1990, the federal Centers for Disease Control (CDC) reported
trends in birth defects between 1979 and 1987 in the U.S. They
looked at 38 specific defects and found that 29 of the 38 had
increased, two had decreased and 7 had remained stable.[3] The
largest increases (29 percent and 20.2 percent) occurred in
defects of the heart; no doubt some of this increase is due to
better detection methods. However, there was also a 9.6 percent
increase in eye defects and a 2.7 percent increase in cleft lip,
so it seems likely that real increases are occurring.
As we reported last week, the traditional view of birth defects
highlights the role of women and disregards the role of men, even
when there is good evidence showing men exposed to toxic
chemicals father defective children. The traditional reason for
ignoring such research is that, until recently, there has been no
satisfactory theory to explain how male exposures could affect
offspring, so a cause-and-effect relationship could not be
established. The argument was that women are born with all the
eggs they will ever have, so each egg can be exposed to toxins
over a long period. Men on the other hand, produce new sperm
constantly, so any individual sperm has only a brief opportunity
to be exposed to toxins.
Another reason for ignoring the effect of toxins on male
reproduction was the “macho sperm” theory, which said that only
the fittest sperm were hardy enough to go the distance necessary
to fertilize an egg.[4] According to this theory, defective sperm
could never reach an egg to fertilize it, so men couldn’t be
responsible for producing defective children. Now research has
shown that the female reproductive tract has ways of moving
sperms along whether they are healthy or defective.
Researchers used to believe that there was an effective barrier
between blood vessels and the tissues where sperm originates in
the testes. It is now known that the barrier is not effective
against many chemicals.
Then of course there’s a cultural bias, reaching back to the
Salem witch trials, to blame women for trouble. “You don’t have
to be Sigmund Freud to figure out that there are cultural factors
to say why we have paid so much attention to the female and so
little to the male,” says Dr. Devra Lee Davis, an epidemiologist
with the National Research Council.
Research during the past decade has shown that there are two
basic ways that chemicals can affect male reproduction.[5,6]
Chemicals can directly affect the testes, where sperm originates.
The numbers of sperm can be diminished, or some sperm can be
damaged, or sperm may even carry toxins directly into the egg.
Alternatively, toxins can attack the male nervous system, or
endocrine system, affecting the flow of hormones that act as
messengers regulating the complex chemical processes that must
all work well for conception to occur.
No matter what the mechanism of damage may be, there is a growing
body of evidence showing that male exposure to toxins can produce
defective children. Here is a sampling:
** A nationwide study of 99,186 pregnancies in Finland showed an
increased likelihood of spontaneous abortion if the father was
occupationally exposed to rubber chemicals, solvents used in the
manufacture of rubber products, solvents used in oil refineries,
or ethylene oxide.[7]
** A study of 22,192 children born with birth defects in British
Columbia showed that paternal occupation as a fire fighter was
related to the occurrence of heart defects. Fire fighters are
often heavily exposed to carbon monoxide and to polycyclic
aromatic hydrocarbons (PAHs)–the nasty chemicals in smoke and
soot.[8]
** A study of paternal occupation among 149 patients with Wilm’s
tumor (a childhood cancer of the kidney) showed that a
significantly greater number of the fathers were exposed to lead
on the job, compared to fathers of a control group of children
without the disease.[9]
** A study of 6000 men in Finland showed that paternal exposure
to organic solvents nearly tripled the likelihood of spontaneous
abortion as a pregnancy outcome, compared to controls not exposed
to organic solvents. Painters, wood workers (for example,
carpenters in the construction, furniture industry and the boat
industry) were found to be at risk. The solvent toluene stood out
as a particularly bad actor in his study. [10]
** A study of anesthetists in the West Midlands region of England
(half men, half women) showed that, during a 20-year period, 9.3%
of their children were born with defects, and 31% of the
anesthetists reported having trouble begetting children.
Furthermore nearly all the children were born underweight. The
gender of the anesthetists did not affect the likelihood of
problems in their children, but female children seems to suffer
greater birth defects. [11]
** A recent review of several studies of paternal occupational
exposures in relation to childhood cancer in the offspring showed
consistently that work in hydrocarbon-related occupations (the
petroleum and chemical industries), especially exposure to paint,
is associated with brain cancer. Male exposure to paint is also
linked to leukemias in offspring. [12]
What does all this evidence mean? It means neither men NOR women
can be safely exposed to toxic chemicals. Instead of banning
women from the workplace, the workplace should be cleaned up.
–Peter Montague, Ph.D.
===============
[1] S.C. Gilfillan, “Lead Poisoning and the Fall of Rome,”
JOURNAL OF OCCUPATIONAL MEDICINE Vol. 7 (Feb. 1965), pgs.
53-[60.]60.
[131] (1990), pgs. 312-321.
Descriptor terms: reproductive hazards; health; birth defects;
lead; rubella; endocrine disruptors; solvents; pahs; occupational
safety and health; men; males; fathers; children; spontaneous
abortion; petroleum industry;