7 Carcinogenic Nature of Emerging Contaminants: Havoc for Present …
165
on health. These fibres when ingested are capable of causing an increase in the risk
of gastrointestinal cancer (Edelman 1988). The short asbestos fibres when ingested
penetrate into wall of intestine and may be removed through urine or get accumulated
on different organs and tissues. On long-term exposure to this substance, by the
workers, there may be maximum chances of colon cancer (Gerhardsson De Verdier
et al. 1992).
7.10.2 Arsenic
It is Class-A category of carcinogenic contaminant which occurs in nature as metalloid. Worldwide, the consumption of either arsenic-contaminated crops or water is
considered to be dangerous for life as it is capable of triggering many health risks
(Chan and Huff 1997). More than hundred millions of people all around, one hundred five countries are affected by the consumption of arsenic-contaminated drinking
water. Both inorganic and organic forms of arsenic prevail in contaminated water.
According to Smedley and Kinniburgh in the year 2002 and Basu and team in the year
2014, approximately ten milligram per kilogram amount of arsenic concentration is
found in soil (Smedley and Kinniburgh 2002; Basu et al. 2014). The concentration
of As in groundwater is in between 0.5 and 5000 Âμg per litre, reported by Ravenscroft and team in the year 2009 and Kippler and team in the year 2016 (Brammer and
Ravenscroft 2009; Pournara et al. 2016). Orpiment, arsenopyrite and realgar are some
of the major mineral sources for arsenic in groundwater (Islam et al. 2013). There
are four oxidation states in which arsenic occurs; they are arsine (trivalent arsenic),
elemental arsenic (zerovalent arsenic), arsenite (trivalent) and arsenate (pentavalent)
as reported by Sharma and team in the year 2014 (Sharma et al. 2014). The mobility
and solubility of arsenic are mainly dependent on redox reactions and pH. Arsenite
predominately exists in deep groundwater, i.e. reduced condition at high pH, and
pentavalent arsenic exists at low pH in oxidized surrounding, i.e. shallow groundwater, as reported by Abdallah and Gagnon in the year 2009, Bundschuch and team in
the year 2012 and Jackson and team in the year 2012 (Abdallah 2009; Bundschuh
et al. 2012; Jackson et al. 2012).
7.10.3 Radon
It is a radioactive gas which is naturally produced due to degradation of uranium
present in rocks and soil (Arnold 2006). Every year, in the USA, more than twenty
thousand people die due to lung carcinoma due to exposure to radon (Edling and Axelson 1983). This gas is responsible for more than fifty per cent of natural radioactivity
exposure, thereby causing health issue to general people as well as miners because
it is a universal contaminant of environment and water (Shuko 1986). From the
epidemiologic studies of the miners, the relation between lung cancer and radon is
165
on health. These fibres when ingested are capable of causing an increase in the risk
of gastrointestinal cancer (Edelman 1988). The short asbestos fibres when ingested
penetrate into wall of intestine and may be removed through urine or get accumulated
on different organs and tissues. On long-term exposure to this substance, by the
workers, there may be maximum chances of colon cancer (Gerhardsson De Verdier
et al. 1992).
7.10.2 Arsenic
It is Class-A category of carcinogenic contaminant which occurs in nature as metalloid. Worldwide, the consumption of either arsenic-contaminated crops or water is
considered to be dangerous for life as it is capable of triggering many health risks
(Chan and Huff 1997). More than hundred millions of people all around, one hundred five countries are affected by the consumption of arsenic-contaminated drinking
water. Both inorganic and organic forms of arsenic prevail in contaminated water.
According to Smedley and Kinniburgh in the year 2002 and Basu and team in the year
2014, approximately ten milligram per kilogram amount of arsenic concentration is
found in soil (Smedley and Kinniburgh 2002; Basu et al. 2014). The concentration
of As in groundwater is in between 0.5 and 5000 Âμg per litre, reported by Ravenscroft and team in the year 2009 and Kippler and team in the year 2016 (Brammer and
Ravenscroft 2009; Pournara et al. 2016). Orpiment, arsenopyrite and realgar are some
of the major mineral sources for arsenic in groundwater (Islam et al. 2013). There
are four oxidation states in which arsenic occurs; they are arsine (trivalent arsenic),
elemental arsenic (zerovalent arsenic), arsenite (trivalent) and arsenate (pentavalent)
as reported by Sharma and team in the year 2014 (Sharma et al. 2014). The mobility
and solubility of arsenic are mainly dependent on redox reactions and pH. Arsenite
predominately exists in deep groundwater, i.e. reduced condition at high pH, and
pentavalent arsenic exists at low pH in oxidized surrounding, i.e. shallow groundwater, as reported by Abdallah and Gagnon in the year 2009, Bundschuch and team in
the year 2012 and Jackson and team in the year 2012 (Abdallah 2009; Bundschuh
et al. 2012; Jackson et al. 2012).
7.10.3 Radon
It is a radioactive gas which is naturally produced due to degradation of uranium
present in rocks and soil (Arnold 2006). Every year, in the USA, more than twenty
thousand people die due to lung carcinoma due to exposure to radon (Edling and Axelson 1983). This gas is responsible for more than fifty per cent of natural radioactivity
exposure, thereby causing health issue to general people as well as miners because
it is a universal contaminant of environment and water (Shuko 1986). From the
epidemiologic studies of the miners, the relation between lung cancer and radon is