INTRODUCTION AND LITERATURE REVIEW
In today’s industrialized world,
exposure to pollutants in which heavy metals like arsenic, lead,
manganese are an example is of high risk. These metals are present even
in drinking water. Arsenic is mostly present in underground water. These
metals are highly distributed in our environment and are thus consumed
in quantities greater than what by the body requires (Ferrer, 2003).
Increased levels of arsenic in the
environment, is an attribute to industrial product and waste,
agricultural pesticides and herbicides. Although manganese is an
essential element, toxicity can be gotten from drinking water, food,
occupation and so on. Exposure to these heavy metals can cause poison
and damage to models (the human body. Effects of arsenic have been
reported in both human and experimental ATSDR a, 2012; Kannan et al.,
2001). Mn exposure can also cause neurotoxicity (ATSDR b, 2007).
Manganism, a consequence of exposure to high Mn levels, is a known
neurological syndrome with many symptomatic analogies to Parkinson’s
disease (Santamaria, 2008). Manganese and arsenic also target the same
organ in the body, namely the brain (ATSDR, 2007a,b,c).
Given their co-existence in soil and atmosphere, exposure to toxicity does not occur in isolation (Kordaset al.,
2010). Indeed, in the real world, exposures to complex mixtures are
the rule, rather than exception (Scherer, 2005). Over the last several
decades, the incidence of neurological diseases has increased (WHO,
2006).Mn poisoning results in an irreversible condition known as
“manganism,’’ a neurodegenerative disorder that resembles Parkinson
disease in both symptomatology and the underlying cellular mechanisms
(Ellingsen et al., 2008; Martinez-Finley et al., 2012).
Neurological disorders induced by
chronic metal exposure can be progressive and manifest clinically
decades after the initial exposure (Gil and Pla, 2001). The onset of
neurotoxic effects is largely subtle, insidiously manifested and
unidentifiable as a clearly defined disease (Shy, 1993).
Exposure to arsenic- and
lead-contaminated drinking water has been associated with an increased
occurrence of congenital heart defects (CHDs). Groundwater is a vital
hidden natural resource
(Tularam and Krishna 2009; Lashkaripour
and Ghafoori 2011). Groundwater can be found in most environments and
generally requires no prior treatment and can be found close to the
points of demand often at low cost (MacDonald and Calow 2009). Arsenic
poisoning or arsenicosis is a condition caused by the
ingestion, absorption or inhalation of dangerous levels of arsenic,
higher than the normal 10ppb which the body can tolerate.
The male reproductive system consists of two major parts: the testes, where sperm are produced, and the penis, according to Merck Manuals.
The penis and urethra belong to both the urinary and reproductive
systems in males. The testes are carried in an external pouch known as
the scrotum, where they normally remain slightly cooler than body
temperature to facilitate sperm production.Metals may cause a wide
spectrum of reproductive and developmental adverse effects such as
reduced fertility, abortions, retarded growth at the intrauterine
cavity, skeletal deformities, malformations and retarded development
especially of the nervous system.
Arsenic and manganese tend to decrease motility of sperm in the male reproductive system even though the sperm are active.
The important mechanisms of action of arsenic are placental transfer, oxidative stress, direct binding with thiol group etc.
The toxicity of arsenic in male and
female reproductive organs is also explained. It also throws some light
on the therapeutic strategies for metal toxicity.Manganese is a
suspected reproductive toxicant and exposure to it has the potential to
negatively affect the human reproductive system. The severity and nature
of the adverse effect is variable and can be influenced by factors such
as level of exposure and individual sensitivity to the chemical.
Effects on the male reproductive system can include such things as
altered sexual behavior, altered fertility and problems with sperm shape
Manganese also have some positive
effects on the reproductive system, they include It helps to produce sex
hormones and sperm. Manganese acts as a catalyst for breaking down
fatty acids and cholesterol. Manganese has a positive effect on the male
reproductive system,It also enhances the brain's aptitude for receiving
and sending messages,Sex hormones are produced in the pituitary gland,
where a considerable amount of manganese exists. Because of this,
manganese is believed to assist in sexual health.
Studies have been carried out on the
individual effect of manganese and arsenic on the male reproductive
system, this research however concentrates on both their individual
effect and also their combined effect on the reproductive system.
Earlier studies have shown that both accumulate in the brain and affect
production of hormones.
Apart from affecting the reproductive
system of man, arsenic and manganese cause other side effect including
cancer. Arsenic and manganese have been shown to induce oxidative damage
in the membrane leading to production of free radicals that may induce
cancer and apoptosis. On the other hand some studies have suggested that
arsenic can aid cancer treatment as it assists blood thinning.
These studies however have not been confirmed. The effects of arsenic
and manganese can be assessed in male induced rats using assays like
H202, Lipid Peroxidation, GSH, GST, SOD etc.
Pollution of the environment by these
heavy metals is indeed a cause for alarm and have caused adverse effect
to the human body as stated by WHO, unsuspected sources like underground
water have shown lack of awareness by individuals.
1.2 LITERATURE REVIEW
Any foreign substance that enters the body is called xenobiotics. These substances can undergo any of the following pathways;
- Excretion from the body unchanged
- Undergo spontaneous reaction of its own
- Undergo metabolism.
Most xenobiotics undergo the third
pathway, however if the body is over exposed to a compound it will
induce its own reaction and might likely undergo the above second
pathway. Arsenic and managanese are foreign compounds which enter the
body through various means.
Arsenic is a chemical element with symbol Asandatomic number 33. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. Arsenic is a metalloid. It can exist in various allotropes, although only the gray form has important use in industry.A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, goats, chickens, and presumably many other species, including humans. However, arsenic poisoning occurs in multicellular life if quantities are larger than needed.
Arsenic contamination of groundwater is a problem that affects millions of people across the world (Mameli et al., 2001).
Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides.
However, these applications are declining. Arsenic can be found
naturally on earth in small concentrations. It occurs in soil and
minerals and it may enter air, water and land through wind-blown dust
and water run-off (Martinez-Finley et al., 2012).
Despite its notoriety as a deadly
poison, arsenic is an essential trace element for some animals, and
maybe even for humans, although the necessary intake may be as low as
0.01 mg/day. Most arsenic is found in conjuction with sulfur in minerals
such as arsenopyrite (AsFeS), realgar, orpiment and enargite. None is
mined as such because it is produced as a by-product of refining the
ores of other metals, such as copper and lead.
A very high exposure to inorganic arsenic can cause infertility and
miscarriages with women, and it can cause skin disturbances, declined
resistance to infections, heart disruptions and brain damage with both
men and women (Dhatrak and Nandi, 2009; Mej?´a et al., 1997).
Finally, inorganic arsenic can damage
DNA. A lethal dose of arsenic oxide is generally regarded as 100mg.
Organic arsenic can cause neither cancer, nor DNA damage. But exposure
to high doses may cause certain effects to human health, such as nerve
injury and stomachaches.