Page 45 - ACCB 2020

Nanotechnology for Combating Microbial Contamination. do Nascimento et al

Bay of South Korea and adjacent inland areas for the 2.2. Inorganic contaminants
presence of various organic pollutants, such as polycy- Heavy metals pose serious health threats even at very
clic aromatic hydrocarbons (PAHs), nonylphenol (NP), low concentrations. Some are cumulative poisons, ca-
octylphenol (OP), bisphenol A (BPA), organochlorine pable of assimilation, storage, and concentration by
(OC), various pesticides, and polychlorinated biphenyls organisms exposed long periods to low concentrations.
(PCBs). The results showed that the presence of all the Eventual metal built-up in tissues can cause harmful
above-mentioned pollutants in varying concentrations. physiological effects. The heavy metals appear to be the
The concentration reported for PAHs was about 17 to main pollutants in this century (20). Discharged heavy
3,100 ng/g on a dry weight basis (DW). Whereas, the metals are responsible for a serious threat to human,
concentrations of NP, OP, and BPA in sediments were animal, and plant health and natural water. According
found to be 1040, 120, and 54 ng/g (DW), respectively. to Järup (21), various heavy metals like lead, cadmium,
Besides, some other important pesticides include orga- mercury, arsenic, and many others have been extensi-
nophosphorus, organochlorine, carbamate, triazine, and vely used by humans for thousands of years. Different
chlorophenoxy acid compounds which were reported in studies carried out all over the world including WHO,
the samples. Therefore, in nutshell, it can be said that if United States Environment Protection Agency (US-
such contaminated water is used either for drinking or EPA) demonstrated the presence of heavy metals such
daily household purpose then it is hazardous for human as arsenic, cadmium, chromium, copper, iron, lead,
health. Moreover, if such water is released into any kind manganese, nickel, zinc, etc. in water resources which
of water bodies then it will cause harmful effects to the are found to be toxic (10,22,23).
fl ora and fauna thereby affecting the complete ecosys-
tem. Many studies reported that diverse functions of wet-
lands and other water resources are being adversely
Another compound, dibromochloropropane, a soil fu- affected by human activities. For example, Harike wet-
migant used to control nematodes has been commonly land, Punjab, India is one of the important wetlands as
reported in water resources (17). These chemicals usua- it provides a signifi cant site for diverse fl ora and fauna.
lly possess the potential for bio-magnifi cation and bio- Brraich and Jangu studied the intensity of heavy metal
accumulation. In both cases, such chemicals can have a pollution particularly toxic metals in Harike wetland
tremendously hazardous effect on humans and the en- that occurred due to discharge from various industries
vironment. Lindane, or γ-HCH (hexachlorocyclohexa- (24). The report suggested that this wetland is highly
ne), an organochlorine pesticide (gamma isomer of polluted due to the rapid industrialization, urbanization,
1,2,3,4,5,6-HCH), is used all over the world for con- and dumping of solid wastes. Further analysis showed
trolling various agricultural pests. However, this com- the presence of lead, chromium, iron, copper, nickel,
pound is known to be bioaccumulated, causing cancer zinc, and cadmium which have drastically deteriorated
and disturbing the homeostasis of the endocrinal sys- the quality of water. Among these, the concentration of
tem (18). However, Maes et al proposed solutions like many metals was found to be higher than the interna-
metal-organic frameworks (MOFs) for the extraction of tional standards. As mentioned earlier, such a quality
phenol and p-cresol from contaminated water based on of water is not safe for various aquatic life and is even
the isotherm for phenol uptake from the liquid phase unfi t for human drinking and irrigation purposes. Mo-
mechanism to minimize the adverse effects caused due reover, many other recent studies carried out worldwide
to such organic contaminants (19). Chemical pesticides reported the contamination of water resources by heavy
used for agricultural purposes are always threat to the metals (25–29).
ecosystem. Generally, it is observed that they either get
wash away with the rainwater so that they will reach 2.3. Microbial contamination
the rivers and large water bodies thereby making it non- Microbial contamination of water continues to be a ge-
habitable for the aquatic animals and plants. Secondly, neral problem across countries and is one of the main
such pesticides can also get percolated and contamina- causes of illness and deaths with 37,7 million affected
te the groundwater. Such contamination will make the by waterborne diseases yearly. Ashbolt reviewed that
groundwater non-potable / non-drinkable. Overall, the poor quality drinking water, sanitation and hygiene are
overuse of pesticides for agricultural purposes can re- collectively responsible for about 1,7 million deaths per
sult in the contamination of all water bodies. year worldwide mainly due to the infectious diarrhoea
(31,32). Most important is, 90% of deaths are in chil-

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Rev. Asoc. Col. Cienc.(Col.), 2020; 32: 42-62.