224
12.3.1 Heavy Metal Toxicity
Manufacturing of electronic devices widely uses heavy metals like Cd and Pb in
circuit boards and computer batteries, Cu in electrical wiring, etc. (Achillas et al.
2013; Stevels et al. 2013; Zeng et al. 2014). A study done by Morf et al. (2007)
found that the average fraction of plastic in E-waste has Pb, Ni, Sn, Zn and Sb at a
concentration > 1000 mg kg
−1
and > 100 mg kg
−1
for Cd. Primitive processes and
techniques are extremely popular in developing nations like India and China.
Therefore, it became a new cause of environmental pollution these decades (Chi
et al. 2011; Song and Li 2014). The unregulated processing by using primitive
techniques like a chemical process, acid baths and burning to procure valuable
metals cause severe heavy metal pollution in the terrestrial and aquatic ecosystem
(Deng et al. 2007; Wei and Liu 2012).
Additionally, incineration done prior to landfilling increases the mobility of
heavy metals, especially Pb (Gullett et al. 2007). In a study by Luo et al. (2011),
which collected samples of soils and vegetables from prior incineration sites for
heavy metal analysis, the results demonstrated high doses of Zn, Pb, Cu and Cd with
values of 3690, 4500, 11,140 and 17.1 mg kg
−1
, respectively. Also, soils of paddy
fields and nearby gardens had a comparatively high level of Cu and Cd. Similarly,
the high level of Cd and Pb was observed in inedible parts of vegetables, which goes
beyond the maximum permissible limit in China. High doses of Cd, Pb and
polybrominated biphenyls were found higher in rice and other crops cultivated near
E-waste recycling units. This is because heavy metals are discharged during
recovery of precious metals that enter the soils where crops and vegetables are
grown by polluting irrigation water or through foliar uptake of heavy metals by air
(Bi et al. 2009). Oral intake of contaminated food is an important pathway for
translocation of heavy metals from the environment to the human population.
Developing nations like China and India are a hub for recovery of precious metals from E-waste by informal reprocessing of printed circuit boards, batteries and
cables. The complete step of the process is accomplished by people involved irrespective of gender and age who work without using proper protection in a harmful
environment. In a study by Ha et al. (2009) observed high doses of heavy metal in
soil at a recycling slum in Bangalore that contained up to 4.6 mg kg
−1
In, 180 mg kg
−1
Sb, 2850 mg kg
−1
Pb, 39 mg kg
−1
Cd, 49 mg kg
−1
Hg, 957 mg kg
−1
Sn and 2.7 mg kg
−1
Bi. The concentrations recorded were 100 times more than control site. A similar
study by Pradhan and Kumar (2014) analysed heavy metals in soil, water and plant
samples collected from recycling sites in Mandoli Industrial Area, Delhi. Results
revealed that a high level of heavy metals concentration was found in soil samples
like Cu (115.50 mg kg
−1
), As (17.08 mg kg
−1
), Pb (2645.31 mg kg
−1
), Cd
(1.29 mg kg
−1
), Se (12.67 mg kg
−1
), Zn (776.84 mg kg
−1
), native plant samples
(Cynodon dactylon) and water samples.
B. Vaish et al.
12.3.1 Heavy Metal Toxicity
Manufacturing of electronic devices widely uses heavy metals like Cd and Pb in
circuit boards and computer batteries, Cu in electrical wiring, etc. (Achillas et al.
2013; Stevels et al. 2013; Zeng et al. 2014). A study done by Morf et al. (2007)
found that the average fraction of plastic in E-waste has Pb, Ni, Sn, Zn and Sb at a
concentration > 1000 mg kg
−1
and > 100 mg kg
−1
for Cd. Primitive processes and
techniques are extremely popular in developing nations like India and China.
Therefore, it became a new cause of environmental pollution these decades (Chi
et al. 2011; Song and Li 2014). The unregulated processing by using primitive
techniques like a chemical process, acid baths and burning to procure valuable
metals cause severe heavy metal pollution in the terrestrial and aquatic ecosystem
(Deng et al. 2007; Wei and Liu 2012).
Additionally, incineration done prior to landfilling increases the mobility of
heavy metals, especially Pb (Gullett et al. 2007). In a study by Luo et al. (2011),
which collected samples of soils and vegetables from prior incineration sites for
heavy metal analysis, the results demonstrated high doses of Zn, Pb, Cu and Cd with
values of 3690, 4500, 11,140 and 17.1 mg kg
−1
, respectively. Also, soils of paddy
fields and nearby gardens had a comparatively high level of Cu and Cd. Similarly,
the high level of Cd and Pb was observed in inedible parts of vegetables, which goes
beyond the maximum permissible limit in China. High doses of Cd, Pb and
polybrominated biphenyls were found higher in rice and other crops cultivated near
E-waste recycling units. This is because heavy metals are discharged during
recovery of precious metals that enter the soils where crops and vegetables are
grown by polluting irrigation water or through foliar uptake of heavy metals by air
(Bi et al. 2009). Oral intake of contaminated food is an important pathway for
translocation of heavy metals from the environment to the human population.
Developing nations like China and India are a hub for recovery of precious metals from E-waste by informal reprocessing of printed circuit boards, batteries and
cables. The complete step of the process is accomplished by people involved irrespective of gender and age who work without using proper protection in a harmful
environment. In a study by Ha et al. (2009) observed high doses of heavy metal in
soil at a recycling slum in Bangalore that contained up to 4.6 mg kg
−1
In, 180 mg kg
−1
Sb, 2850 mg kg
−1
Pb, 39 mg kg
−1
Cd, 49 mg kg
−1
Hg, 957 mg kg
−1
Sn and 2.7 mg kg
−1
Bi. The concentrations recorded were 100 times more than control site. A similar
study by Pradhan and Kumar (2014) analysed heavy metals in soil, water and plant
samples collected from recycling sites in Mandoli Industrial Area, Delhi. Results
revealed that a high level of heavy metals concentration was found in soil samples
like Cu (115.50 mg kg
−1
), As (17.08 mg kg
−1
), Pb (2645.31 mg kg
−1
), Cd
(1.29 mg kg
−1
), Se (12.67 mg kg
−1
), Zn (776.84 mg kg
−1
), native plant samples
(Cynodon dactylon) and water samples.
B. Vaish et al.