1. Environmental Causes of Infertility
Afolabi, Michael O.S.
Chemical Pathology Department, University
College Hospital, Ibadan, Oyo State.
cur i ousm kl @yahoo.com
ai

2. Introduction & Background
Infertility is an increasingly
common reproductive dysfunction
that affects over 10% of couples
worldwide (Kumar, 2007) which
translates into roughly 80 million
couples (Inhorn et al, 2008).
2

3. Increased industrialization as well as
the rise in the incidence of infertility
has stimulated the scientific
community to begin exploring
possible nexus between infertility
and environmental factors.
3

4. Background to Vaccination in Nigeria
Such a view may be justified on the
ground that contemporary life
involves unavoidable interface with
the biologically active products of
industrial and agricultural processes
that continuously alter the physical,
chemical and thermal environment.
4

5. B A C K GROU ND TO VACCINATION IN NIG ERIA
On the other hand, biological
man lives in and interacts
with a socio-cultural
environment which
prescribes and proscribes
conventions and practices
that may have attendant
health sequelae.
5

6. Against this conceptual template, this paper
explores the cause and effect relationships
between some “non-self” environmental
factors on the aetiology of infertility.
Specifically, it examines the effects of heavy
metals such as lead (Pb), arsenic
(As), cadmium (Cd); chemicals such as
bisphenol A and socio-cultural practices
such as female circumcision and
contraception vis-a-vis infertility.

7. Methods
h
This paper adopts an analytic and
conceptual approach to its subject
matter.
It employs the archival method of
academic research. Relevant extant
literature in the fields of endocrinology,
clinical and reproductive toxicology
were consulted.
7

8. Conceptual Clarifications
Causality
In the natural sciences, the notion of
causality implies being the triggering factor
for the occurrence of a phenomenon.
Importantly, the phenomenon and its cause
exist in a one to one relationship such that
the presence of the cause guarantees the
happening of the phenomenon.
8

9. Aim
However, causal claims are not
always explicit in the biological and
medical sciences due to the
influence of the mantra ‘correlation
does not imply causation’ (Russo
and Williamson, 2011);
9

10. a
The Environment
The environment connotes the
surrounding(s) of an organism and
constitutes what is external as opposed to
the internal milieu. To borrow the
phraseology of Burnet (1969), the
environment may be seen as the non-
self, external agents and forces to which all
forms of life including man are exposed.
10

11. s
Today, mankind unavoidably comes in
contact with several non-self environmental
factors such as heavy metals and several
chemicals many of which can modulate
biological systems to influence physiology
and promote disease states
(Skinner, Manikkam and Guerrero-
Bosagna, 2011).
11

12. a
Infertility
Literarily, this means absence of
reproductive capacity. In more scientific
terms, however, infertility is commonly
defined as the failure of conception after at
least 12 months of unprotected coital
intercourse between a couple (Irvine, 1998).
Infertility may also entail the inability to
carry a pregnancy term(Sule, Erigbali and
Eruom, 2008).
12

13. Non-self Environmental Realities & Infertility
Ali-Saleh et al (2008) argued that exposure to
environmental factors exert varying effects on
fertility. As noted earlier, mankind faces a
number of unavoidable non-self environmental
factors which include:
Heavy Metals
Chemicals
Heat
Socio-cultural factors
13

14. A
Heavy Metals
Several heavy metals are present in
the environment in amounts
alarmingly unsafe for human health
(Ali and Ali, 2010). These metals
such as cadmium, lead, arsenic, and
mercury are primarily nonessential
xenobiotics (Meeker et al, 2010) that
have accumulatory potential (Hanf
et al, 1996) .
14

15. Cadmium
Cd is used in industry principally in galvanizing and
electroplating, batteries and electrical conductors.
Its toxicity lies in the fact that it modulates gene
expression and signal transduction. Akinloye et al
(2006) opine that Cd interferes with testicular
steroidogenesis whereas Siu et al (2009) have
averred that the deleterious action involves the
disruption of the blood–testis barrier .
15

16. Arsenic
As exposure occurs via food and water. It is
alarming to note that in Asia rice and products
such as rice bran and rice crackers have elevated
levels of As (Stone, 2008). Arsenic exerts
deleterious effect on the Y chromosome (Ali and
Ali, 2010). However, chromosomal abnormalities
such as this are associated with infertility as well as
habitual abortion (Massolini, Menaton and
Castagna, 2000; Musacchio, 2010). As also has
oestrogenic effects
16

17. Lead
Epidemiologic studies have found reduced
fertility rates among the families of exposed men
(Markku, Marja-Lissa and Markku, 2000). Pb
causes oligospermia, poor sperm motility
(Hammond and Gronowski, 2006) as well as
decrease in testicular function via the
hypothalamic-pituitary axis (Sokol, Madding
and Swerdloff, 1985).
17

18. Chemicals
Anetor, Adeniyi and Anetor (2009) note
that there has been a three-fold increase in
the use of chemicals in the last fifty years.
Many of these chemicals are present in daily
life and household products and exert their
effects even at very low concentrations
(Giudice, 2006). Being on top of the food
chain means that humans accumulate
several of these toxicants.
18

19. Bisphenol A
BPA is an ingredient used in manufacturing
polycarbonate plastic and epoxy resins
(Kuehn, 2007). It is contained in consumer
products including baby bottles, plastic
containers and dental sealants (Kaiser, 2007;
Li et al, 2010). It is a genotoxic chemical with
clastogenic properties (Tiwari et al, 2012).
Studies have shown that BPA affects
androgen receptors, male reproductive
organs including, seminal vesicles, testes
and epididymis, (Richter et al, 2007;
Bouskine et al, 2009). 19

20. Dichlorodiphenyltrichloroethane
DDT is an organochlorine compound
which is used as a pesticide in
agriculture and public health programs
in developing countries. Jaga (2000)
notes that it has estrogenic activity.
Because ERs are normally found in such
sites as Leydig cells, ovary, uterus and
cervix, exposure to DDT constitutes a
chemical agent of infertility in male and
female humans.
20

21. Drugs
Drugs are compounds of chemical elements
that interacts with the body’s chemistry
causing a chain reaction of events (Kamienski
and Keogh, 2006) and are one of man’s
greatest arsenals against diseases. Some drugs
have however been linked with infertility
21

22. Csoka and Szyf (2009) note that antidepressants
exert epigenetic effects that may give rise to
infertility. Anti-cancer drugs such as 5-aza-20-
deoxycystidine decrease global DNA methylation
which leads to altered sperm
morphology, decreased sperm motility, decreased
fertilization capacity, and decreased embryo
survival (Rajender, Avery and Agarwal, 2011). In
the same vein, Hammond and Gronowski (2006)
observe that use of chlorambucil may give rise to
azoospermia while cyclophosphamide depresses
spermatogenesis. 22

23. Heat
Global warming and certain industrialization-
associated occupations expose humans to higher
temperatures. However, heat stress exerts deleterious
effects on testicular functioning and impairs
spermatogenesis (Ahmad et al, 2012) and may
likewise give rise to oligozoospermia,
asthenozoospermia, and teratozoospermia. The
heat/infertility connection is further exacerbated by
the fact that increased atmospheric temperatures
enhance the release of heavy metals from the soil
into the environment (Egli et al, 2010).
23

24. Socio-cultural Factors
Female Circumcision
FC is practiced in more than 30 African
countries, mainly in a belt reaching from east to west
Africa north of the equator (Almroth et al, 2005), and
about 2 million procedures are done every year
(WHO, 1998). Almroth et al (2005) reported a positive
association between the anatomical extent of FC and
primary infertility. Infections arising from Fc and
subsequent development of tubal-factor infertility.
Des has also been reported. Dessel (2006) reported a
higher prevalence of genital mutilation involving the
labia majora in women with primary infertility.
24

25. Contraception
Today, contraception is seen as a fundamental human
right of persons wishing to prevent unwanted
pregnancies (Hatcher et al, 1997). Some contraceptive
approaches however appear to play a role in infertility.
Huhtamemi (1994) reported the adverse effects of
hormone-based contraceptives on sperm counts and
fertility. Ethinyl oestradiol has also been linked with
female infertility (Joffe, 2003) and diethylstilbestrol
has been linked with testicular dysgenesis, (Yiee and
Baskin, 2010). There have also been reports of delayed
conception of up to 42 months following use of pills
(Speroff, Glass and Kase, 2000).
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26. Concluding Remarks
A commonsensical approach to avoiding
the effect of these environmental non-
self factors involves limiting contact
which will however not work in all
contexts. Nutrigenomics has been
suggested as a more promising panacea
as it offers a strong defence against the
adverse effects of these toxicants on the
genome (Anetor, 2010).
26

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29
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