They are: any substance that has by law to be labelled as ‘very toxic’, ‘toxic’, ‘harmful’, ‘irritant’ or ‘corrosive’; substances for which a maximum exposure limit (MEL) has been set or an occupational standard has been set. They include harmful micro-organisms, substantial quantities of airborne dust or other substances that create comparable health hazards, including: dusts, fumes/gases, solvents, resins, pesticides, acids, alkalis, mineral oil and contaminants such as arsenic and phenols. See CONTROL OF SUBSTANCES HAZARDOUS TO HEALTH REGULATIONS.