The sperm count of our
species is in serious decline!
extract from ToxCat
Volume 2-2, Spring, 1996
published by TC Publications
Scientists studying the impact of man-made chemicals on human health
claim human males will be infertile by the middle of the next century if
present industrial trends are maintained.
The culprits - chemicals which have the ability to mimic hormones, particularly
the female sex hormone estrogen - are widespread in society and include
pesticides (such as DDT), industrial chemicals (such as PCBs) and environmental
pollutants such as dioxin. Most, though not all, of the estrogen-mimicking
chemicals involve chlorine.
If you live in a large industrialised city take a look around you. What
do you see beyond the bustle of modern commerce, people moving, working,
surviving? All around you are cars, buses, lorries and trains. Look into
the sky, chances are youll see an aeroplane taking people on holiday or
perhaps a business trip. All these forms of transport are powered by a combustion
process and built with industrial chemicals. What else do you see? Buildings,
construction sites, machinery, glass, steel, concrete and wood. Look closer;-
metals, plastics, electrical wires, pipes, paints, solvents, detergents.
Go into shops you find clothes made from synthetic fibres, electronic appliances
made with strong durable plastics, cosmetics made from chemicals, food grown
with the aid of pesticides, tin cans whose lining leaches chemicals into
the fish, meat, vegetables and sauces they contain. Visit the countryside
where the vegetables and cereals and pulses are actually grown, where cattle
and sheep graze on intensively farmed land, where the farmers have planted
chemically treated disease resistant seeds and used herbicides, pesticides
and fertilisers to increase the production of their crops All around us
are the products of the chemical and oil industries.
Most western countries have had these products for more than half a century
but all of us, wherever we live, have been exposed over the past 25 years
to the effects of modern industrial chemicals, in the food we eat, the water
we drink and the air we breath. While we have been exposed to these chemicals,
occupationally, environmentally and through food, some scientists have tried
to determine the impact on our health. There has been a frequent, persistent
argument, significantly from industry, that there is a safe level for all
chemicals and as long as we take no more than "the threshold level"
into our bodies we will not come to any harm. Many scientists who have gone
against this line of thought have been ridiculed in the past! But not any
more!
In 1979 a group of mothers in Taiwan unwittingly consumed PCB- contaminated
rice oil over a period of ten months. It has now been found that boys born
to these women have matured with reduced penises - thus providing the first
direct evidence that polychlorinated biphenyls (PCBs) are teratogenic (birth-defect
producing) in humans.
The scientists who studied the 115 "yucheng" (oil-disease)
children believe they were exposed to the chemical before and after birth
via their mothers blood through the placenta while they were still in the
womb and as young babies via their mothers milk. [1]
The evidence that pesticides such as 2,4,5-T, Lindane and DDT, along with
other industrial chemicals like PCBs, dioxin and many of the chemicals used
in everyday household items, have the ability to affect the endocrine systems
of animals - including humans, is becoming harder to ignore.
The simple easy-to-understand fact that 115 Taiwanese teenage boys have
smaller penises than normal was the first confirmation that humans, as well
as wildlife, are being similarly affected by exposure to "endocrine
disrupting chemicals" such as DDT, PCBs, dioxin, and many more man-
made chemicals.
The evidence is now accumulating that dozens of pesticides and other
chemicals can mimic hormones, particularly the female sex hormone estrogen,
and disrupt the endocrine system.
As with wildlife, it seems that the reproductive system of humans, predominantly
the male, is more prone to damage from these chemicals. As well as reduced
penis size, the Taiwanese teenagers had a variety of physical defects at
birth ranging from; dark coloured heads, faces and genitals, to abnormal
nails that were often dark and ridged, split or folded.
The effects of these hormone mimicking chemicals doesnt stop at reducing
the size of the penis. Research at the Medical Research Councils Reproductive
Biology Unit at Edinburgh and at Brunel University, Middlesex, is among
the latest to find new evidence of a link between declining male fertility
and synthetic "hormone mimicking chemicals." [2]
"The balance of the debate is shifting in support of the theory
that this group of chemicals which is being pumped into the environment
is having an effect on our reproductive system. "I think we should
follow the lead of Sweden and Denmark and start to phase out these chemicals.
The issue will certainly not go away," said Dr Charles Tyler, fertility
researcher at Brunels University.
This issue - as to whether chemicals are affecting fertility - is not
quite as new as most people believe. As long ago as 1978 scientists working
for the Thames Water Authority discovered that 40% of the male roach fish
in the River Lee, Hertforshire were hermaphroditic (that is having both
male and female sex organs) and were sterile. It was believed that chemicals,
notably estrogen - probably contained in contraceptive pills, in the effluent
from the Mill Green sewage works which treats industrial and domestic waste
was to blame.
Strangely this research was deliberately kept under wrap with the findings
not made available for other scientists to study. [3]
Defending this secrecy John Sexton, Director of Environment and Science
at Thames Water Utilities Ltd, said the "first findings were of very
little consequence and the whole works should be completed by government
departments." [3]
This view was not shared by scientist Paul Johnson of Exeter University
who said, "science and the pursuit of science are all about evaluating
problems and expanding the knowledge base. If the results of works are not
published its impossible to make progress" [3]
In 1982 scientists at Liverpool University, on a commission from Thames
Water Authority, fed sewage effluent to rats in order to monitor its effects.
Initial results suggested major hormonal effects, including disruption of
the reproductive cycle. Later tests however did not confirm this. [3]
In 1987 the Department of the Environment and the Fisheries Ministry
(MAFF) commissioned a survey of rainbow trout in 31 rivers in England &
Wales. The fish were situated in cages near sewage effluent outlets. There
was something estrogenic at all the outlets. [3]
John Sexton maintained the amount of hormone found in the drinking water
supplied by the Thames Water Authority posed no danger to health because
"the body produces the same hormones, so adjusts itself." [3]
"Man made hormones [as produced by hormone mimicking chemicals]
are different from natural hormones," said Dr Vyvyan Howard of the
Department of Fetal and Infant Pathology at the University of Liverpool.
"They are persistent. Natural hormones will be destroyed within the
body in half an hour. Man-made hormones stay in the body for years and years
switching on enzyme systems." Hormones are incredibly potent at amounts
as low as fractions of a millionth of a gram. "If it affects those
fish, then its affecting us," he added. "We have had a very long
time to adjust to natural estrogen", said Prof Carlos Sonnenschein.
[16]
Thames Water Authority admitted they were concerned about "the implications
the findings might have for the people downstream (i.e.: north London) who
rely on the river Lee for the source of their drinking water". This
has not stopped the British government successfully putting pressure on
the European Union to throw away the strict directives on drinking water,
replacing them with new regulations that are less restrictive on some substances,
specifically pesticides - which have been implicated by a host of scientists
as environmental estrogens.
Once again the British government is showing an appalling lack of commitment
to the "precautionary principle" enshrined in international protocols
and exhibiting an alarming indifference to the health of the British public.
It is thought by many that pressure to relax the standards of chemical
contamination in drinking water by the government is a result of pressure
from outside the water industry. To meet the proposed stricter regulations
would have required major expenditure by the companies concerned and this
would have made a big dent in their profits and reduced the price of their
shares.
"Our job is to ensure that if a standard like that is imposed then
it is necessary. If it is necessary then we would fully subscribed to it
and support it", said John Sexton, "but all the recent evidence
is suggesting that the standard at the moment is too strict and the money
being spent by us putting in additional treatment in could be better spent
in other areas."
"Even though some of the pesticides and herbicides have been shown
to have estrogenic activity?" he was asked.
"Oh yes, having estrogenic activity per se isnt a problem, the question
we have to look at is what substance, at what levels?" [3]
That certain chemicals are capable of mimicking sex hormones appears to
have been accepted by a large body of the scientific community as the evidence
continues to mount up. Man-made chemicals such as organochlorine pesticides
(DDT, for example, which was used in large quantities until the 1960s when
it was banned or restricted in the western world) head the list of environmental
estrogens. The Danish Environmental Protection Agency, focusing on the work
of several scientists studying this problem, identified 27 classes of pesticide
in common use as environmental estrogens. PCBs (used as industrial chemicals
in capacitators and transformers) are among five classes of industrial chemicals
now known as environmental estrogens.
Alkylphenol polyethoxlates (nonionic surfactants used in detergents,
emulsifiers, wetting agents and dispersing agents in household products
and in agricultural and industrial products such as herbicides and paints;
also used as spermicides in contraceptive foams, jellies and creams) and
phthalate esters (used in most commercially available plastics, including
polyvinyl chloride [PVC]) are other chemicals responsible for xenoestrogenic
behaviour. Environmental pollutants such as dioxins and furans (unwanted
by-products from the combustion of chlorinated hydrocarbons) have also been
implicated. [14]
Chemicals found in food wrapping, tin cans and even some face creams
and dental fillings have also come under the microscope. [2]
This source of exposure to estrogenic chemicals via food was discovered
when Spanish scientists found that bisphenol-A leaches from the inner lining
of food cans into many vegetables. Also worrying is the fact that this chemical
also leaches out of plastic babies bottles. [15]
Dr. Richard Sharpe of the Medical Councils Reproductive Biology unit
in Edinburgh announced in July 1995 that he had experimental evidence that
prolonged exposure to low levels of phthalates, comparable to those found
in human diets, could cause a reduction in testis size in developing rats.
Any reduction in testis size would be expected to reduce sperm production.
[4]
Two recent studies have found that sperm count in men has declined precipitously
over the past 20 years. [5] A report in the
British Medical Journal in August 1994 comparing men of similar ages, sperm
count in 3729 Scottish men had declined 41% among those born in 1969 compared
to those born in 1941. The New England Journal of Medicine reported in February
1995 that sperm count has declined 33% during the past 20 years among a
study-population of 1,351 healthy, fertile men in Paris, France.
Researchers at the North London Royal Free Hospital, measuring the pregnancy
rate between 1977 and 1989, found, despite improved techniques, it had fallen.
Jean Ginsburgh, Consultant Endocrinologist at the hospital, said: "When
checking sperm count we found that the men were producing 96 million [sperm
per cubic centimetre] which is a decent sperm count, but we found we had
a higher proportion of poor or no motiIity and the quantity and quality
had declined." She is convinced the cause is environmental, "something
very general that every body takes, water, food, bread, milk. [3]
Alan Bennett, a male infertility specialist in Albany, New York State,
where men are suffering major reproductive problems said: "Its rare
in my practice to find a man with a sperm count of 100 million cc. I see
a lot of men who are normal with a sperm count of 30 to 40 million. In the
US we now have a normal count of 20 million, whereas when I was training
it was 60 million, so in the twenty five years Ive been practising its gone
from 60 million to 20 million, that says something." [3]
In 1992 a historical analysis of 62 separate sperm-count studies by Elisabeth
Carlsen concluded that sperm count among men throughout the industrialised
world has declined by about 50% in the last 50 years.[6]
Two years later these findings were challenged by researchers who said it
might have been caused by Carlsens erroneous choice of statistical methods,
and not by an actual decline in sperm count. [6]
The chemical industry is attempting to undermine the scientific evidence
and its scientists will no doubt be quick will be quick to point out that
no one knows for sure what is causing the apparent decline in sperm count
among men. But the report from MRC Reproductive Unit goes a long way to
laying the blame at this industrys doorstep.
It is still remotely possible that the decline is not real. For example,
these 62 studies may have examined men who are not typical of the general
population and various factors that influence sperm count may not have been
fully accounted for. [7]
As Carlsen and her co-workers said in 1994, defending their 1992 conclusion:
"The most cautious conclusion that can be drawn from the existing
data is that semen quality has declined significantly between 1940 and 1990."
Various hypothesis have been suggested as to the cause of the decline
but the one getting the most attention is that hormone mimicking chemicals
in the mothers blood is affecting the male child before it is born. This
hypothesis suggests that the male child is being born with fewer Sertoli
cells. These are the cells that cause the production of sperm after puberty.
Reduced numbers of Sertoli cells (and reduced sperm count) have been observed
in the male offspring of estrogen- exposed pregnant rats. [8]
Researchers studied a group of 1,351 healthy men in Paris who had donated
sperm to a sperm bank maintained by a hospital, starting in 1973. Each of
the men had fathered at least one child. One percent of the men were farmers
and 16% were manual labourers; 40% were classified as "technicians"
and 38 % as "executives." From 1973 to 1992 their average (mean)
sperm count declined at the rate of 2.1% each year from 89 million per cubic
centimetre (cc) to 60 million per cc. During the same period the proportion
of motile sperm (that is sperm able to swim) declined at a rate of 0.6%
per year, and the proportion of "normal" sperm (compared to misshapen
sperm) declined at the rate of 0.5%. In sum, the quantity and quality of
sperm declined simultaneously.
This study answers some of the concerns of some of the critics of Carlsens
1992 study. Those critics charged that abstinence from sex causes an increase
in sperm numbers and a decrease in sperm with good motility and Carlsen
could not control for that. The study in Paris took into account the length
of abstinence before samples were taken. It also controlled for age and
for the year of birth. The decline in sperm quantity and quality, linked
to year of birth, was still observable after controlling for length of abstinence
and age.
Among the Paris group, a subgroup of 382 men in a narrow age range (28
to 37 years) was chosen for special analysis; they had all reported a similar
period of abstinence (3 to 4 days). Among this group, there was a clear
decline in sperm count from 1973 to 1992; from 101 million per cc to 50
million per cc, a reduction by half. The average 30-year-old born in 1945
would have a count of 102 million per cc; the average 30-year-old born in
1962 would have a count of 51 million. "We conclude," the French
researchers said, "that there has been a true decline in the quality
of semen during the past 20 years, since the characteristics of semen from
a fertile man of a given age in 1992 were significantly poorer than those
of a fertile man of the same age in 1973."
The Scottish researchers completed their study in response to criticism
of Carlsens 1992 analysis of 62 sperm-count studies showing a 50% reduction
in 50 years. They had records for 3,729 semen donors born between 1940 and
1969. They examined these by statistical techniques chosen to avoid the
(controversial) criticisms that had been levelled at Carlsens work. They
found an apparent decline in sperm count from 128 million per cc (in men
born in the 1940s) to 75 million in men born in the late 1960s, a 41% loss
in a single generation.
"Thus we do not accept that the evidence for a fall in sperm concentrations
is unconvincing," they concluded. Stewart Irvine, a gynaecologist at
the Medical Research Councils Reproductive Biology Unit in Edinburgh, Scotland,
who studied sperm production of Scottish males told Lawrence Wright, writing
for the New Yorker: "I had a colleague visiting from Australia, and
he had with him a laptop computer with lots of data from infertile couples.
He said, Im sure these sperm count drops are rubbish. Im sure there are
other explanations for it. And I said, Well, just take your data and plot
it by year of birth and see what you get. He got the same result."
[12, pg 46]
Several researchers have noted that the decline in sperm quality (count,
motility and normal shape) coincides with an increasing incidence of abnormalities
of the male genital tract, including testicular cancer and cryptorchidism
(undescended testicles) in various countries. [9]
Such abnormalities have doubled in frequency during the past 30 years in
many parts of the world. [10]
In Scotland, for example, testicular cancer has doubled since 1960 and
is striking a younger population (ages 15 to 44) every year. The cause of
these increasing abnormalities remains a mystery.
One clue that may tie all the threads of evidence together is the record
of what happened to the sons of women who were given a synthetic hormone,
diethylstilbestrol (DES), during the fifties and sixties. About a million
women were given DES as a "morning after" pill to reduce the likelihood
of pregnancy. Their sons have shown an increase in genital tract abnormalities
AND reduced sperm count.
Data from animal experiments has confirmed that chemicals effect sexual
development. Pregnant rats given a single, very low, dose of dioxin on the
15th day of gestation, produce male offspring that have genital tract abnormalities
(particularly undescended testicles) and a low sperm count after they mature.
[11]
The New England Medical Journal stated in February 1995 that the significant
decline in the concentration of sperm during the past 20 years in the Paris
area,may be related to an interaction of the age of the [sperm] donors and
the chronologic period [in which they are living] that in turn could implicate
factors affecting all the inhabitants of an area, such as the water supply
or environmental pollution.
Danish pediatric endocrinologist (hormone specialist) Niels E. Skakkebaek
said that in the late 1980s he and his colleagues had been wondering why
it was so difficult for sperm banks to establish a core of donors. "In
some areas of Denmark, they were having to recruit ten potential donors
to find one with good semen quality." In 1990 Skakkebaek studied sperm
quality in Danish men starting with men working in what is classed as "non-hazardous"
jobs such as office workers and labourers who did not work directly with
industrial chemicals or pesticides. These were men thought to be quite healthy.
For decades it had been believed that the average man produced about
a hundred million sperm per millilitre of semen, of which about 20% was
expected to be immobile. Skakkebaek reported that 84% of the Danish men
he studied had sperm quality below the standards set by the World Health
Organisation (WHO). The men themselves seemed normal in every other respect.
[12, pg43]
On the basis of the worlds medical literature, Skakkebaek calculates
that in 1940 the average sperm count was 113 million per millilitre, and
that 50 years later it had fallen to 66 million. [12,
pg44] Still more serious is a three-fold increase in men whose sperm count
was below 20 million - the point at which their fertility would be jeopardised.
Skakkebaek has gained a wide reputation for his studies on testicular
cancer which in the past 50 years has become a particularly common disease
in Denmark with nearly one in 100 men affected. In his paediatric practice
Skakkebaek was seeing many boys with malformed genitals. A study in 1984
of 2,000 Danish school boys found that 7% of them had one or both testicles
lodged inside their bodies - a condition that may lead to sterility and
a higher risk of testicular cancer. Skakkebaek sees the decline in sperm
count as only one part of a much larger assault on the male reproductive
organs, high rates of testicular cancer, undescended testicles, hypospadias
(a condition in which the urethral opening in on the underside of the penis
not on the tip) are all increasing.
Pierre Jouannet, director of the Centre dEtude et de Conservation des
Oeufs et du Sperme in Paris, simply did not believe Skakkebaeks conclusions.
Jouannet had data on 1,350 Parisian men, all of whom had fathered at least
one child and therefore were of proven fertility, so he analysed them, expecting
to refute Skakkebaeks studies. To his astonishment he found that sperm counts
in his group had dropped steadily at 2% per year for the past 20 years;
in 1973 the average count was 89 million per millilitre and in 1992 it was
60 million. [12, pg45] The expected sperm count
for a Parisian man born in 1945 was 102 million, whereas the count of those
born in 1962 was exactly half that number. [12,
pg45]
Jouannet had been convinced. And when he projects the decline into the
future he sees serious trouble for the human species. At the present rate
of decline, he reported gravely, "it will take 70 or 80 years before
it [sperm count] goes to zero". [12, pg45]
Difficulty conceiving occurs at 20 million or less; sterility occurs at
five million or less.
In the United States the number of donors with good-quality sperm has
become distressingly low. Back in 1981 researchers at the Washington Fertility
Study Centre reported that the sperm count of their donors, who were largely
medical students, had suffered a steady decline over the previous eight
years. The researchers worried that, if the decline continued at the same
rate, within the decade there would be no potential donors who could meet
the approved or recommended standards.
The fact is that the number of morphologically normal sperm [meaning
sperm with a normal shape] produced by the average man has dropped below
the level of those of a hamster, which has testicles a fraction the size
of a mans. [12, pg44]
In the United States, where infertility is defined as failure to produce
a child after a year of normal sex, according to the National Centre for
Health Statistics, the percentage of infertile couples has risen from 14.4
in 1965 to 18.5 in 1995. [12, pg44]
There has been little published research comparing racial and ethnic
sperm counts, particularly in Africa and many Third World countries. But
the studies that we do have show low counts nearly everywhere: the latest
count in Nigeria is 64 million per millilitre; in Pakistan, 79.5 million;
in Germany, 78 million; in Hong Kong, 62 million. [12,
ppg44-45]
"Infertility is definitely going up," said Dr. Marc Goldstein,
director of the Centre for Male Reproductive Medicine at New York Hospital.
"I see it in my practice. There is a decline in fertility in men and
an increase in infertility in older couples. Studies show an increase in
infertility from 11% to 16 % in all married couples." He believes part
of it may be life style: marijuana, cocaine, alcohol, and sexually transmitted
diseases can all reduce sperm counts. [13, pg80]
But wildlife do not smoke marijuana or drink alcohol and there are numerous
reports of reproductive problems caused by chlorinated chemicals in wildlife.
It is something more fundamental than life style, Skakkebaek observed. Whatever
is happening to men, he noted, some part of it must take place during the
early stages of human development - in the womb or else shortly after birth
- because damage to the male urogenital system is evident in certain very
young patients. [12, pg47]
Sharpe concurred the decline in sperm is linked to some event that affects
the endocrine system which governs the bodys hormones. This must happen,
he said, either in the womb or shortly after birth. "I have absolutely
no doubt this is the most important time in your life, certainly if youre
a male," he said. "This is when your sperm- producing capacity
as an adult is settled once and for all." [12,
pg48]
Changes in life style wont help men whose sperm producing capacity has
been crippled at birth.
In a series of experiments, Sharpe exposed pregnant rats to "minute
quantities" of DES and to other synthetic estrogens; he showed a 5%
to 15% decline in sperm count in male offspring when they matured. Philippe
Grandjean, a professor of environmental medicine at Odense University in
Denmark summarised the situation in an interview with Lawrence Wright: "We
thought in the past that these toxic substances would act on a target -
an enzyme or DNA or the cell membrane, or something like that. But what
these endocrinologists have suggested to us is that industrial chemicals
can actually mimic hormones. It looks as if the receptors arent very good
at recognising whats a hormone and whats not a hormone - perhaps because
they were never previously challenged. These receptors have been kept almost
unchanged in the mammalian world, because they worked. They functioned very
well. But in this century we have generated all these new chemicals and
injected them into the environment, suddenly the body is exposed to new
substances that in some cases can interact with that receptor. The human
species is totally unprepared for this, because it has never happened before.
I think the perspective is both very exciting and very, very frightening."
[12, pg51]
Most, though not all, of the estrogen-mimicking chemicals involve chlorine.
Day 56 is the day sexual differentiation sets in the human but what happens
during gestation from that period on is in many ways just as critical as
what happened before those first 56 days. The secondary sex organs of a
young man are developing right through until he reaches puberty.
If, as Theo Colborn of the World Wide Fund. has theorised, the number
of chemicals that can harm reproduction add up to hundreds, if not thousands,
the only way to regulate them all will be to "reverse the onus"
that now falls on individuals to prove they have been harmed by a toxic
substance. We now have between 300 and 500 chemicals in our bodies in measurable
amounts that werent there 40 years ago" she said.
"The responsibility should not be on the people exposed to chemicals
to prove they have been hurt," said David LaRoche, the secretary of
the International Joint Commission (IJC). "The responsibility should
be on industry to prove that chemicals cause no harm." [13,
pg84]
Professor Carlos Sonnenschein (Tufts University School of Medicine, Boston
) believes most chemical manufactures have alternative inexpensive chemicals
they could use. "When we discover a product contains estrogen disruptors
we should stop and look to alternatives." [16]
"I have heard that the Chlorine Chemistry Councils budget is around
$100 million," Gordon Durnil former chairman of the IJC.told Esquire
reporter Daniel Pinchbeck. Durnil "Its a lot of money. You could use
it to buy some research. Why dont they do some research to say what they
are doing is safe?" Durnil asked. [13,
pg84]
Unfortunately, the truth about the sperm count is that it is under attack
from many different sources. Earl Gray, a senior research biologist with
U.S. Environmental Protection Agency (EPA), testified before Congress in
1993 that; "Our studies [in rats] show that a single dose of dioxin
administered during pregnancy permanently reduces sperm counts in the males
by about 60 per cent." [12, pg53]
"With sperm counts, Ive been more impressed by the dioxins and the
PCBs than by the estrogens and anti-androgens," Gray said. "We
get surprising effects at relatively low doses." [13,
pg53]
"Probably half the jobs in the world are associated in some way
with chlorine," said Durnil. "As a society, we are going to have
to confront our dependence on this chemical." [13,
pg82]
Thus, although it remains a hypothesis that estrogen-mimicking chemicals
are causing the observed tract, in sperm reduction it is a hypothesis that
is being taken very seriously by a large number of scientists world wide.
They are working aggressively to confirm its truth or falsehood. It is after
all, an important matter for the future of the human species.
"When we discover a product contains estrogen disruptors we should
stop and look to alternatives."
Full details.
Endnotes
[1] Marguerite Holloway, "Dioxin
Indictment," Scientific American Vol. 270 (January 1994), pg 25.
[2] The Observer 25 February
1996.
[3] Dispatches "Down for
the Count.
[4] ENDS Report 246 July 1995
pg3.
[5] Jacques Auger and others,
Decline in Semen Quality Among fertile Men in Paris during the past 20 years,"
NEW ENGLAND JOURNAL OF MEDICINE Vol. 332, No. 5 (February 2, 1995), pgs.281-285.
And: D. Stewart Irvine, "Falling sperm quality," BRITISH MEDICAL
JOURNAL Vol. 309 (August 13, 1994), pg. 476.
[6] Elisabeth Carlsen and others,
"Evidence for decreasing quality of semen during past 50 years,"
BRITISH MEDICAL JOURNAL Vol. 305 (1992), pgs. 609-613.
[7] Richard J. Sherins, "Are
Semen Quality and Male Fertility Changing?" NEW ENGLAND JOURNAL Vol.
332 No 5 (Feb.2, 1995), pg. 327, says that studies conducted so far have
not properly controlled for differences in age, abstinence before semen
analysis, ejaculatory frequency, and the number of samples analysed per
person, all of which can effect sperm count. Another author who has registered
scepticism of the 1992 findings is Stephen Farrow, "Falling sperm quality:
fact or fiction?" BRITISH MEDICAL JOURNAL Vol. 309, No. 6946 (July
2, 1994), pgs. 1-2.
[8] A. Giwercman and N.E. Skakkebaek,
"The human testisan organ at risk?" INTERNATIONAL JOURNAL OF ANDROLOGY
Vol. 15 (1992), pgs. 373-375. And: Richard M. Sharpe and Niels E. Skakkebaek,
"Are oestrogen involved in falling sperm counts and disorders of the
male reproductive tract?" THE LANCET Vol. 341 (May 29, 1993), pgs.
1392-1395. And: R. M. Sharpe, " Declining sperm counts in men - is
there an endocrine cause?" JOURNAL OF ENDOCRINOLOGY, Vol. 136 (1993),
pgs. 357-360.
[9] A. Giwercman, cited above
in note 8; and see Peter Boyle and others, "Changes in Testicular Cancer
in Scotland," EUROPEAN JOURNAL OF CANCER AND CLINICAL ONCOLOGY Vol.
23 (1987), pgs. 827-830. And: A. Giwercman and others, "Evidence for
increasing evidence of abnormalities of the human testis: a review,"
ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 101, Supplement 2 (1993), pgs. 65-71.
[10] See Sharpe and Skakkebaek,
cited above.in note 8.
[11] Thomas A. Mably and others,
"IN UTERO and Lactational Exposure of Male Rats to 2,3,7,8-Tetrachlorodibenzo-P-dioxin.
3. Effects on Spermatogenesis and Reproductive Capability." TOXICOLOGY
AND APPLIED PHARMACOLOGY Vol. 114 (May, 1992), pgs. 118-126.
[12] Lawrence Wright, "Silent
Sperm," NEW YORKER (January 15, 1996), pgs. 42-48, 50-53, 55.
[13] Daniel Pinchbeck, "Downward
Motility," ESQUIRE (January 1996), pgs. 79-84.
[14] Danish Environmental Protection
Agency, Male Reproductive Health and environmental chemicals with estrogenic
effects. April 1995. Miljo- Kopenhawn, Denmark.
[15] Prof Anna Soto, Lecture,
Liverpool University 7 May 1996.
[16] Lecture, Liverpool University
7 May 1996
Much of this feature was adapted from RACHELS Environment
& Health Weekly #372 #432 & #477 from the Environmental Research
Foundation (see below). The ERF provides a electronic version of RACHELS
ENVIRONMENT & HEALTH WEEKLY free of charge even though it them costs
considerable time and money to produce it.. You can help by making a contribution
(anything you can afford, whether 5 or 500) to: Environmental Research Foundation,
P.O. Box 5036, Annapolis, MD 21403-7036 Tel: (410) 263-1584; Fax: (410)
263-8944. Internet: erf@igc.apc.org.
For more information on declining sperm contact Communities
Against Toxics Article taken from ToxCat ISSN 1355 5707 Volume 2 - 2 Spring
96. Copyright © 1996-97 Ralph Ryder TC Publishing. All Rights Reserved. |
