Sperm Count Decreasing in Males
Over the past 50 years, there has been a noticeable drop in the sperm
count of the male demographic. There appears to be numerous factors that are
contributing to this potentially disastrous phenomenon, and the possible extinction of the human race due to the decrease in
fertility of our male species. Because these changes are recent and appear to
have occurred internationally, though more drastically in the Western world, it has been presumed that they are caused by
the effects of environmental or lifestyle factors on the male rather genetic
changes – which has been deemed impossible given such the short space of time.
If the decrease in sperm counts were to continue at the rate that it is then in
a few years it is a realisation that we will witness widespread male
infertility.
As many as one in five healthy young men between the ages of 18 and 25
produce abnormal sperm counts, even the sperm t produced however is usually
poor quality. Only between 5 and 15 per cent of their sperm is good enough to
be classed as "normal" under strict World Health Organisation rules –
and the study taken was on healthy participants. The reasons for poor sperm
counts are vague to say the least, however, compiled below is a list of the
most likely causes.
Food sources: Today, a higher proportion of
farm animals are being fed hormones such as growth hormone, oestrogen and
testosterone to increase their size and reproductive competence as increased
protein to fat ratios result in increased yields, for example cattle and
battery hens. These hormones may be
transferred across species barriers directly when we eat them and so there is a
potential risk that we may be ingesting food that carries oestrogen in it. The
consumption of fats (especially animal fats), proteins, and refined
carbohydrates can substantially affect oestrogen excretion and metabolism, so
the overall effect of eating a modern western diet, high in fat and low in
fibre, is increasing our exposure to endogenous substances are those that
originate from within an organism, tissue, or cell) oestrogens. A study, published in the journal Human Reproduction, found 41 million
fewer sperm per millilitre of semen after just one portion of soya every two
days, the authors stated that plant oestrogens in foods such as tofu, soy mince
or milk may interfere with hormonal signals. Milk particularly is of an
increasing concern, with oestrogen like chemicals being added when it is
pasteurised and there already being oestrogen similar compounds present in the
milk due to the cows being fed a diet rich in such additives.
Plastics: Plastics are often treated with substances that are similar to oestrogen such as Bisphenol A (BPA). Bisphenol A is an additive
to plastics found in many household products. A 2008 study in the journal
Fertility and Sterility showed that men with high concentrations of BPA in
their urine also had low sperm counts. Food packaging is a major source of BPA,
which can leach into the
food contents, especially vegetables and fatty foods . A man called Boockfor
et al carried out experiments injecting rats with a chemical called octylphenol, another plastic used in detergents, plastics and paints. a
decrease of FSH secretion in the foetus which consequently decreased Sertoli
cell number and thus spermatozoa number was observed. It is still uncertain as to the extent to which the human
body is actually exposed to chemicals such as octylphenol, and as yet there is
no direct proof that there is any link between chemical exposure and changes in
sperm counts in man, however . Likewise, for
years dentists have widely used these sorts of agent in fillings. In these
patients oestrogen like compounds have been found at high concentration in
their saliva.
Sexually
transmitted infections: Sexually
transmitted infections can have a great impact on the
testicles, which in turn affects sperm production. One example of this would be gonorrhoea, an infection that has become
particularly rife in recent years; the reason sperm become damaged is because when
bacteria become present in
the ejaculate, the body produces chemicals that can hinder sperm function.
Stress:
Stress can decrease sexual function and interfere with the hormones needed to
produce sperm. Research led by the Population Council in 1997 found that stress hormones overpower
the enzymes responsible for ensuring that cells in the testes produce
testosterone, which is necessary for sperm formation.
Obesity:
Animal studies have shown that embryo implantation and fetal development
decreased when sperm came from obese fathers. And a study in France found that
obese men were 42 percent more likely to have low sperm counts than non-obese
men, and an 80 percent chance of having
ejaculate with no sperm in it at all. However,
it is suggested that it is not the excess fat itself that disrupts healthy
sperm production but rather the toxins and chemicals found in fat-based foods
which come from the processes used in their production.
Pesticides: Modern pesticides tend to contain many agents that have oestrogen
mimicking properties; the most potent being
Vinclozolin, a fungicide used on many types of fruits and vegetables, is
thought to be blocking the effects of the male sex hormones and causing a
decrease in sperm count. Furthermore the runoff of pesticides
and insecticides flows into rivers, which often lead into our water supply,
potentially disrupting hormonal
processes. A recent study showed that the excess of
oestrogen like chemicals in rivers are causing fish to not only become
infertile, but in some cases change sex, although it is not clear whether this
has an effect on males as yet.
Use of drugs, alcohol or tobacco: The use of
tobacco and drugs could dramatically decrease the sperm count however there are
no yet proven studies as with most of the other theories. The effect is
probably worse in the case of the mother however who is bearing the child
rather than the child using drugs etc him/herself.
Testicular Cancer: There have been a rise in the number of
testicular cancer cases in the past 50 years and it could be that the cancer is
disrupting the Sertoli cells in the testes or harming sperm production in some
other way. However, it is perhaps the treatment of the cancer that could be the
greater danger. Since sperm cells divide quickly, they are an easy target for
damage by chemotherapy. The higher the dose of chemo, the longer it takes for
sperm production to get back to normal, and the more likely it is to stop.
Permanent infertility results if all the stem cells in the testicles are
damaged to the point that they can no longer produce maturing sperm cells. The
damage is most severe when men are treated with both chemo and radiation
therapy to the abdomen or pelvis.
 |
| Rates of Testicular Cancer |
 |
| Decrease in Sperm Counts of Adults |
As is clear from the two graphs shown above, there could potentially be a strong link between a rise in cases of testicular cancer and a decrease in sperm count over the past 35 years. However as written multiple times this cannot be officially recognised it could be caused due to a number of other potential contributing factors.
Radiation: With increasing ozone layer
depletion due to the use of aerosols in the past and still in some countries,
more radiation is reaching man. Exposure to radiation has further increased
with the invention of televisions, microwaves, x-rays, nuclear weapons and the
construction of power stations. It has been proven that radiation reduces sperm
production in adult males, though to not such a great difference. The effects
of radiation on sperm production is more pronounced in children and the effects
are seen at lower doses than those seen in adults.
Although these elements could all potentially increase the risk of a poor sperm count, scientists believe that the most crucial influence on fertility is the development of the foetus in the womb. Sertoli cells, which in the adult act as guardians for the development of sperm cells, are the very first cells to form from a "genital ridge" of the human male foetus. The number of sperm that can be produced in an adult man is critically dependent on the number of Sertoli cells that develop in his foetus, so anything that interferes with the formation of Sertoli cells in a mother's womb will affect sperm production many years later. "Maternal-lifestyle factors in pregnancy can have quite substantial effects on sperm counts in sons in adulthood, and the most logical mechanism by which this could occur is via reducing the number of Sertoli cells,", in essence this means that it is the mother who essentially determines the condition of the sperm, and that the foetus can greatly affected by any of the above causes.
In summary, the causes for the decrease in sperm count are unknown and are just being theorised; the major triggers being speculated as an increasingly poor health of the mother which can directly affect the health of sperm of the offspring, and also environmental oestrogen mimickers. The reason for this ambiguity is that there are simply too many possible contributing factors. Other suggestions include taking hot baths and placing laptop computers on the lap or keeping the groin too warm just from clothing can negatively impact sperm count; even the radiation from mobile phones has been questioned. However perhaps the most certifying outcome of the research into sperm counts is that if we don't do anything to change exposure to possible influences then it is almost certain that not too far into the future, we, homo sapiens could become extinct because of something so fundamental as a poor quality of male, human gametes.
NB: The effect of ‘false’ oestrogens, is that they latch
on to hormone receptor sites in the body, in turn possibly blocking the action of
the naturally occurring hormone. Another explanation is that the chemicals may
mimic its action, switching on or turning off biochemical pathways, and remaining in the body far longer than natural oestrogen. The result is that false oestrogens have 'potentially devastating effects on oestrogen-sensitive tissues in both sexes,
particularly in the developing foetus.’
References:
References:
http://www.telegraph.co.uk/health/healthnews/9722963/Male-fertility-under-threat-as-average-sperm-counts-drop.html
http://www.independent.co.uk/news/science/out-for-the-count-why-levels-of-sperm-in-men-are-falling-1954149.html
http://en.wikipedia.org/wiki/Endocrine_disruptor#Types_of_endocrine_disruptors
http://www.independent.co.uk/environment/male-fertility-fears-over-pollution-in-water-supply-654356.html
http://archive.ispub.com/journal/the-internet-journal-of-urology/volume-2-number-1/the-sperm-count-has-been-decreasing-steadily-for-many-years-in-western-industrialised-countries-is-there-an-endocrine-basis-for-this-decrease.html#sthash.uJaqEtVM.dpbs
