Pollution & toxics
Heavy Metal Pollution
Environmental contamination by dense, toxic metals — notably cadmium, lead, and mercury — from industry, mining, and combustion, targeted by the 1998 Aarhus Protocol.
Definition
Heavy metal pollution is the release into air, water, and soil of metallic elements that are toxic at low concentrations, persist in the environment, and accumulate in organisms and food chains. The 1998 UNECE Protocol on Heavy Metals targets three particularly harmful metals — cadmium, lead, and mercury — requiring parties to cut emissions from industrial sources, combustion, and waste incineration.
References
regulatory framing and priority metals
Overview
What it means
Heavy metals do not degrade: lead from petrol and paint, mercury from coal and small-scale gold mining, and cadmium from fertilisers and batteries cycle through ecosystems for decades and concentrate in predators, including people. Effects are neurological, developmental, renal, and carcinogenic, and exposure is often highest in poor communities near polluting industry — an environmental-justice dimension.
How it is used
The term anchors emissions inventories, contaminated-land regulation, food-safety limits, and treaties such as the Minamata Convention on Mercury and the UNECE protocol.
Why it matters
Few pollutant classes combine persistence, toxicity, and inequality of exposure so starkly.
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