PCBs (PCBs)

Polychlorinated Biphenyls (PCBs) are a family of organochlorine compounds — biphenyl molecules with 1-10 chlorine atoms substituted on the aromatic rings, giving 209 possible congeners. PCBs were manufactured globally from 1929 (commercialised as Aroclor by Monsanto in the US, Clophen in Germany, Kanechlor in Japan) until production was banned in 1977-1985 in most jurisdictions. They were prized for thermal stability, electrical insulation, non-flammability and chemical inertness — making them the dominant dielectric fluid in transformers and capacitors from 1940 through the 1970s, and also used in hydraulic fluids, heat-transfer fluids, plasticisers and carbonless copy paper.

The toxicity profile is severe. PCBs are persistent organic pollutants (POPs) — Stockholm Convention Annex A listing in 2004 mandated elimination — with soil half-lives of 10-40 years and bioaccumulation factors of 10⁴-10⁷ in aquatic food chains. They are endocrine disruptors, neurotoxins (cognitive impairment in children exposed via maternal contamination), liver toxins, and IARC Group 1 human carcinogens. The 1968 Yusho rice oil disaster in Japan (PCB-contaminated rice bran oil sickened over 14,000 people) and the 1979 Yu-cheng equivalent disaster in Taiwan are the canonical mass-exposure events. PCB congeners with non-ortho substitution (PCB-77, 126, 169) are particularly toxic and act through the same aryl hydrocarbon receptor pathway as dioxins.

India's regulatory framework treats PCBs under the Hazardous and Other Wastes (Management and Transboundary Movement) Rules 2016, Schedule I category 12.1 (PCB-containing or contaminated equipment) and category 12.2 (PCB-contaminated waste oils, soils, materials). PCB-containing transformers and capacitors must be identified, labelled, taken out of service per CPCB guidelines (2007, updated 2018), stored in leak-proof containment, and destroyed in CPCB-authorised facilities. The Stockholm Convention obligation requires India to phase out PCB use in equipment by 2025 and disposal by 2028 — a deadline India is unlikely to fully meet given the legacy installed base of pre-1985 transformers in state electricity utilities.

For Indian e-waste recyclers, the operational reality is that any pre-1985 transformer or capacitor encountered in scrap is presumed to contain PCBs until tested. Field testing uses a clor-N-oil test kit (chemical colour change in the presence of chloride) for initial screening; quantitative confirmation requires GC-ECD at NABL labs. PCB-contaminated transformer oil at concentrations above 50 mg/kg (under Indian rules) must go to high-temperature incineration (above 1,200°C, 2-second residence time, rapid quench) — only a handful of CPCB-authorised facilities operate at this specification. Disposal cost runs Rs 80-200 per kg of contaminated oil, plus the cost of decontaminating the transformer steel and copper for material recovery. Mixing PCB transformer oil into general waste oil pyrolysis or fuel-substitution is a Section 31A violation and a public health liability — the operational discipline is mandatory pre-acceptance testing of every pre-1985 transformer.