India may have issued directives to ban the use and manufacture of polychlorinated biphenyls (PCBs) to reduce pollution, but decades of using these toxic industrial chemicals in electrical and electronic equipments have contaminated the country’s soil, air, and possibly water as well.
Analysis of soil samples from seven cities, including New Delhi and Mumbai, by SRM University, Chennai, and UK and Chinese institutes discovered that the average concentration of PCBs in Indian soil was almost twice the amount found in global background soil — at 12 ng/g (nanogram per gram) dry weight as against 6ng/g — but as much as that recorded in Pakistan and urban areas of China.
These persistent organic pollutants (POP) stay in the environment for longer periods, get dispersed over long distances, and accumulate in the fatty tissue of humans, land and marine animals.
On Tuesday, evidence proving the presence of PCB came to the fore even after more than four decades of banning its manufacture in the US. Results of a study lead by the UK-based University of New Castle revealed high concentrations of PCBs and polybrominated diphenyl ethers (PBDEs) in the fatty tissue of amphipods (a type of crustacean) from deep below the Pacific Ocean surface.
Studies have also shown that long term exposure on humans can cause certain cancers, birth defects, damage the central nervous system, immune and reproductive systems, and can affect the food chain.
Researchers said informal recycling of e-waste, open burning of dumped solid waste, combustion of coal and industrial waste, ship breaking activities acts as a sink for heavy chlorine compounds.
“Though the problem of PCBs is fading in developed world, developing economies such as Ghana, China and India are finding it as more of a recent problem mostly associated with crude e-waste recycling processes and open burning of municipal waste,” said Paromita Chakraborty, lead investigator, SRM University.
Chakraborty added, “The existing PCB database in India is restricted to stockpiles present with power companies of both government and private enterprises. PCB emissions from ship breaking, informal e-waste recycling and open burning of solid waste needs to be thoroughly accounted.”
India is a signatory to the Stockholm Convention, a global treaty, and has banned the import and manufacture of PCBs – it is among the ‘dirty dozen’ list of banned pollutants – and ordered an end on its use in any form by the end of 2025.
“It is for policymakers to note that despite India never having manufactured PCBs, the loads are still high. It leads to taking measures for identifying contaminated sites and remedying them to a level where they do not emit PCBs into the air,” said Ravi Agarwal, director, Toxics Link, a Delhi-based environment non-government organisation.
In their study, 84 samples of surface soil up to 20 cms and air samples were collected from different sites in New Delhi, Mumbai, Chennai, Bengaluru, Kolkata, Goa, and Agra along urban-suburban-rural transects. Large quantities of the heavier PCB compounds were prevalent in urban areas.
The study found Chennai to be most contaminated in terms PCB concentration in soil, with an informal e-waste shredding site recording maximum concentration. Located at close proximity from the port, Chennai imports e-waste in addition to its domestic generation of nearly 47,000 tonnes of e-waste annually. A village in Bengaluru came next due to a former open solid waste dumping ground. Apart from direct emission of PCBs in such hotspots, reemission from soil is acting as secondary source of PCBs in Indian atmosphere.
Though lesser soil PCB concentration was found in New Delhi and Mumbai, but these cities showed high levels in the air largely due to emission during the crude process of informal e-waste recycling. The study stated that high PCB concentration in Mumbai is likely to be due to the combined effects of ship-breaking and informal e-waste recycling, uncontrolled burning of municipal solid waste where e-waste and biomedical waste find its way in the pile.
“Policies should be devised to regularise the ship breaking and e-waste recycling sectors by partnership ventures. Sustainable growth of e-waste recycling sectors can not only solve the problem of releasing hazardous toxicants but also can be an important source to make money,” said Dr. Chakraborty.
Added Agarwal, “The linkage to e-waste is important since India is one of the fastest growing e-waste generators in the world, especially in densely populated urban landscapes. Unfortunately we do not have an adequate regulatory response to PCBs in the erroneous belief that these are mostly legacy issues, while such research shows otherwise.”
Eastern part of New Delhi houses several informal electronic waste recycling units. New Delhi alone generates 15,000 tonnes/year in addition to the electronic waste (e-waste) imported for recycling purpose. High levels of tetra and penta PCB congeners were observed in soil samples from eastern New Delhi.
Mumbai: Highest level of penta chlorinated biphenyl, contributing about 69% of total PCB concentration was observed at Kurla. The ratio of PCB-118 to PCB-77 in soil for this site reflects secondary metal smelting process. Informal e-waste shredding takes place at few locations close to this site. Hence elevated dioxin like PCB concentration in Mumbai was suspected to be impacted by both ship breaking activity and informal e-waste recycling leading to. Re-emission of lighter congeners was observed only in the hotspots within the city limit of Mumbai.