a) Lead : Damages central and peripheral nervous system; affect brain development in children.
b) Chromium : Asthmatic bronchitis.
c) Cadmium : Accumulates in kidney and liver; neural damage.
d) Mercury : Chronic damage to brain and respiratory system.
e) Plastics including Polyvinyl Chloride (PVC) : Burning produces dioxin which can cause developmental and reproductive problems, damages the immune system.

The conventional wastewater treatment methods involve the following steps
Pre-screening : Wastewater generated from domestic and industrial activities is screened to remove soil and solid particulates.
Aeration : Screened wastewater is then pumped to an aeration tank. Here the microbial contaminants are removed by the biological degradation that occurs in the presence of air.
Sludge Management :
i) Sedimentation process : In this process, the solid particles in suspension form are allowed to settle. The particles that settle out from the suspension is known as sludge.
ii) Sludge removal : The sludge generated by the degradation process is transferred periodically from the tank for safe disposal.
Disinfection : Chlorination and ultraviolet (UV) radiation of treated water is required to remove any microorganism contamination.
Water recycling : The water will then be supplied for domestic or industrial purposes.

i) Use energy efficient appliances to save electricity like Compact Fluorescent Lamps (CFL), Light Emiting Diode (LED) bulbs and other electric equipments.
ii) Switch off the lights and fans, television and other electrical appliances when not in use.
iii) Switch of the mobile phone chargers when not in use.
iv) Maximise the use of solar radiation. Solar water heating system can be used instead of electric geysers.
v) Minimise the use of air conditioners.

i) It is available in abundance in our country and is free of cost.
ii) It is a renewable source of energy.
iii) It can be used for generating electricity or heat.
iv) It does not cause pollution.
v) Solar panels can be installed in remote and inaccessible areas (forests and hilly regions).

It is necessary to conserve or save coal and petroleum resources for the future use, which can be done by reducing their consumption
i) If electricity is saved, it will in turn reduce the use of coal.
ii) Using bicycle for covering short distances instead of using cars, scooters or motorcycles.
iii) Using pressure cooker can reduce the consumption of kerosene and LPG while cooking food. Solar cooker and solar heaters can be used wherever possible.
iv) Motor vehicles should be designed with fuel efficient engines to increase efficiency and also reduce air pollution