What a Hazardous Substance Is, and Why Every Statute Defines It Differently

In one line

There is no single Indian definition of a hazardous substance, and the one that applies decides whether a victim gets relief.

In the wording a student can write in an examination: a hazardous substance is defined in section 2(e) of the Environment (Protection) Act 1986 as any substance or preparation which, by reason of its chemical or physico-chemical properties or handling, is liable to cause harm to human beings, other living creatures, plants, micro-organism, property or the environment; the Public Liability Insurance Act 1991 defines it by reference to that definition together with such quantity as may be specified by notification and excludes radioactive material governed by the Atomic Energy Act 1962; the Manufacture, Storage and Import of Hazardous Chemical Rules 1989 apply to hazardous chemicals satisfying the criteria in their Schedule 1 or listed in it and to industrial activities above threshold quantities; and the Hazardous and Other Wastes (Management and Transboundary Movement) Rules 2016 define hazardous waste by reference to their own Schedules.

Why there are several definitions

Because each instrument is doing a different job.

Section 2(e) states a test. It is a general definition for a general Act, drawn widely so that nothing dangerous falls outside the Act's reach.

The rules of 1989 need a list. A rule that imposes detailed duties on an occupier must tell him whether he is caught, and a test cannot do that. Hence criteria and lists, and threshold quantities.

The waste rules need a different list. A hazardous waste is not the same thing as a hazardous chemical. A chemical is hazardous by its properties; a waste is hazardous by its origin and its constituents.

The Act of 1991 needs a quantity. Because compulsory insurance is imposed on an owner handling a hazardous substance, and it would be absurd to require a policy from a person keeping a litre of something.

So a student asked whether a substance is hazardous must ask: hazardous for what purpose.

The general definition, taken apart

Any substance or preparation. A mixture as well as a pure substance.

Which, by reason of its chemical or physico-chemical properties or handling. Two routes. Something may be hazardous because of what it is, or because of the way it is handled. The second limb is unusual and it matters: an ordinary material handled in a way that makes it dangerous is within the definition.

Is liable to cause harm. Liable, not certain. A propensity is enough.

To human beings, other living creatures, plants, micro-organism, property or the environment. Six objects, the last two of which take the definition beyond human health.

The lists, and how each is built

The rules of 1989. Schedule 1 contains criteria: toxic, highly toxic and extremely toxic categories defined by lethal dose and lethal concentration values, together with flammable, explosive and reactive categories; and lists of named chemicals. Schedule 2 and Schedule 3 set threshold quantities for isolated storage and for industrial activities. A chemical satisfying the criteria or listed, present above the threshold, brings the activity within the heavier duties.