Categories of danger describe the nature of hazard posed by a substance or preparation. Under Directive 67/548/EEC there are 15 categories of danger. Substances and preparations may be: (a) explosive: (b) oxidizing (c) extremely flammable (d) highly flammable (e) flammable (f) very toxic (g) toxic (h) harmful (i) corrosive (j) irritant (k) sensitizing (l) carcinogenic (m) mutagenic (n) toxic for reproduction, (o) dangerous for the environment. Under GHS these categories will be replaced by hazard classes.