7 Carcinogenic Nature of Emerging Contaminants: Havoc for Present …
167
team in the year 2005 (Gutiérrez-Dabán et al. 2005; Li and Chen 2002). These PAHs
get washed in the water bodies through agricultural run-off, industrial effluents,
atmospheric deposition sewage, etc. According to Matsui and team in the year 2000
and Flotron and team in the year 2003, it was reported that many of the PAHs up
to some extent get reduced by the existing wastewater treatment plants but fail to
minimize the level below the permissible limit for aquatic organism (Matsui et al.
2000; Flotron et al. 2003). According to Madras and team in the year 1998, Ko and
team in team in the year 2000 and Zheng and team in the year 2007, it was reported
that techniques which can be promising in effectively reducing the PAHs and its
removal in wastewater treatment plant are adsorption by activated carbon, reverse
osmosis, membrane filtration, UV radiation and ozonation, etc. (Zheng et al. 2007;
Madras et al. 1994; Ko et al. 2000). But, establishing these techniques will enhance
the cost in the treatment plants. Hence, it is necessary to find pathways which will be
equally efficient, selective as well as economical for removal of polycyclic aromatic
hydrocarbon from the wastewater.
7.10.6 Microbiologic Agents
The principal microbes existing in drinking water which can be ingested are protozoa, bacteria and viruses (Gerba and Smith 2005). Depending on various raw water
sources, the concentration of these microbes varies. Schistosoma haematobium is a
microorganism originating in water and capable of causing risk of bladder cancer
in many subtropical and tropical regions where the native disease is schistosomiasis
(Gerba and Pepper 2019). The infection caused due to Helicobacter pylori leads to
chances of gastric lymphoma, stomach cancer and many other (Kim 2011). Moreover, the reason behind growth of infections due to Helicobacter pylori in drinking
water is lack of hygiene, overpopulation, etc. (Kakelar 2019).
7.10.7 Nitrate
Over the last decades, the degree of deposition of nitrogen has been doubled on the
surface of the land mainly due to a wide range of utilization of nitrogen-containing
fertilizers, burning of fossil fuels and opting nitrogen fixation crops over natural
vegetation (Jenkinson 2001). This heavy amount of nitrogen-based compounds on
surface of land gets converted into nitrate, and a major part of it gets washed into the
groundwater. From the data reported from Geological Survey of USA of private wells,
it was observed that 9% of studied sample crossed the maximum contaminant level
which is 10 mg/L. In order to prevent methemoglobinemia, susceptible to infants,
the permissible amount of nitrate in drinking water is set to be ten milligram per litre
by US Environmental Protection Agency (Kumar 2013).
167
team in the year 2005 (Gutiérrez-Dabán et al. 2005; Li and Chen 2002). These PAHs
get washed in the water bodies through agricultural run-off, industrial effluents,
atmospheric deposition sewage, etc. According to Matsui and team in the year 2000
and Flotron and team in the year 2003, it was reported that many of the PAHs up
to some extent get reduced by the existing wastewater treatment plants but fail to
minimize the level below the permissible limit for aquatic organism (Matsui et al.
2000; Flotron et al. 2003). According to Madras and team in the year 1998, Ko and
team in team in the year 2000 and Zheng and team in the year 2007, it was reported
that techniques which can be promising in effectively reducing the PAHs and its
removal in wastewater treatment plant are adsorption by activated carbon, reverse
osmosis, membrane filtration, UV radiation and ozonation, etc. (Zheng et al. 2007;
Madras et al. 1994; Ko et al. 2000). But, establishing these techniques will enhance
the cost in the treatment plants. Hence, it is necessary to find pathways which will be
equally efficient, selective as well as economical for removal of polycyclic aromatic
hydrocarbon from the wastewater.
7.10.6 Microbiologic Agents
The principal microbes existing in drinking water which can be ingested are protozoa, bacteria and viruses (Gerba and Smith 2005). Depending on various raw water
sources, the concentration of these microbes varies. Schistosoma haematobium is a
microorganism originating in water and capable of causing risk of bladder cancer
in many subtropical and tropical regions where the native disease is schistosomiasis
(Gerba and Pepper 2019). The infection caused due to Helicobacter pylori leads to
chances of gastric lymphoma, stomach cancer and many other (Kim 2011). Moreover, the reason behind growth of infections due to Helicobacter pylori in drinking
water is lack of hygiene, overpopulation, etc. (Kakelar 2019).
7.10.7 Nitrate
Over the last decades, the degree of deposition of nitrogen has been doubled on the
surface of the land mainly due to a wide range of utilization of nitrogen-containing
fertilizers, burning of fossil fuels and opting nitrogen fixation crops over natural
vegetation (Jenkinson 2001). This heavy amount of nitrogen-based compounds on
surface of land gets converted into nitrate, and a major part of it gets washed into the
groundwater. From the data reported from Geological Survey of USA of private wells,
it was observed that 9% of studied sample crossed the maximum contaminant level
which is 10 mg/L. In order to prevent methemoglobinemia, susceptible to infants,
the permissible amount of nitrate in drinking water is set to be ten milligram per litre
by US Environmental Protection Agency (Kumar 2013).