What to take into account when assessing health risks

A health risk assessment should consider:

• How toxic the chemical is (toxicity). The more toxic the chemical, the more likely it is to cause health problems, even in small amounts.
• How it gets into the body (route of exposure). The route affects the risk. Some chemicals are very toxic however they enter, through the skin, by breathing or by swallowing. For asbestos, the principal occupational health risk is inhaling airborne fibres. Material in good condition and unlikely to be disturbed may be managed in place, but competent assessment must consider damage, deterioration and foreseeable work. Do not infer no risk merely because nobody is currently cutting it.
• How much you are exposed to (dose). For some chemicals, the higher the amount, the greater the damage. Acetone, for example, is an industrial solvent that is also found in nail varnish remover. It is more dangerous to a worker who uses large amounts than to a person who uses a little remover.
• How long you are exposed (duration). The longer the exposure, the greater the danger. One person may work with a chemical for half an hour a day and another for eight hours a day. One may be exposed for a month and another for twenty years.
• Reaction and interaction with other chemicals. Some chemicals in combination form a different chemical that is more hazardous than the originals (a reaction). Ammonia and bleach used together, for example, can produce a highly toxic gas. Some combinations increase the likelihood of harm. Workers exposed to asbestos, for example, increase their chance of lung cancer if they smoke.
• Individual differences. Heredity, body size, age, smoking, drinking, allergies, sensitivities and previous exposure to other toxic chemicals all matter. Chemicals can be more harmful to some people than to others. Lead is much more harmful to small children than to adults because it affects the developing brain and nervous system. If two people work with asbestos and one of them smokes, the smoker is more likely to develop asbestos-related lung cancer.

Sources of information

There are two main ways of communicating chemical hazards to employees: the label on the chemical container and the safety data sheet (SDS).

Product labels

In most countries, chemical manufacturers and suppliers must label their products with information that follows the Globally Harmonized System (GHS) for hazard classification and labelling. A GHS label must show the following for each chemical product.

• Product identifier: the brand name, chemical name, common name, generic name or trade name of the hazardous product.
• Initial supplier identifier: the name, address and telephone number of the manufacturer or importer.
• Pictogram or pictograms: a hazard symbol inside a red square set on one of its points.
• Signal word: a word that alerts the reader to a potential hazard and shows how severe it is.
• Hazard statements: standard phrases that describe the nature of the hazard of the product.
• Precautionary statements: standard phrases that describe the measures to take to minimise or prevent harm from exposure or from improper handling or storage.
• Supplemental label information: some is required depending on the classification of the product. For example, the label of a mixture containing ingredients of unknown toxicity at 1% or more must state the percentage of those ingredients. Labels may also give extra information about precautions, hazards not yet covered by the GHS, physical state or route of exposure, as long as it does not contradict or detract from the standard information.

Safety data sheets

Safety data sheets (SDSs), previously called material safety data sheets (MSDSs), contain information about the health and safety properties of workplace chemical products. The supplier or manufacturer writes them and gives them to purchasers. An SDS is divided into sections, and each must contain certain required information.

Summary notes for Element 7 · Cheat sheet · Glossary. A study aid, not published or endorsed by NEBOSH.