Introduction Terms Basic Principles is Occupational Hygiene 2010

35 3 FUNDAMENTALS OF TOXICOLOGY

3.1 Introduction

Toxicology is the study of the adverse effects of substances on living organisms. Industrial toxicology is concerned with the adverse effects on workers of substances handled in the workplace, although interest usually extends to adverse effects of products on consumers and of workplace effluents on the general public. Historically toxicology was the art and science of poisoning. It is today a discipline which makes use of information developed by a wide range of chemical, physical, biological and medical sciences in order to predict the likely adverse effects on man of an ever-increasing range of substances to which he is exposed.

3.2 Terms

Toxicity is the innate ability of substances to injure living things. Hazard assessment is the prediction of the toxic effects that will be evident under defined conditions of exposure. Risk assessment is the prediction of the probability that defined toxic effects will occur under defined conditions of exposure in a single person or a defined population. Substance covers a wide range of materials including single chemical compounds or mixtures of these, simple or complex naturally occurring or synthetically produced substances and micro-organisms. Substances may be chemically pure or contain additives or impurities and may be in the form of solids, liquids, gases, dusts, fibres, fumes or aerosols. Some e.g. fumes, dusts and aerosols may be difficult to identify. Substances to which man might be exposed in the workplace include materials used, packed, collected, stored, handled, disposed of or otherwise encountered. They may be final products, formulations, intermediates, components, off spec products, by-products, wastes and residues. 36 They may be materials used or which arise during maintenance or repair of plants or buildings or they may be formed or used during research, development or testing. NB. The above terms are used loosely by many people. For example the term toxicity is often used instead of toxic hazard, and toxic risk instead of toxic hazard. This is particularly so in relation to what people call risk assessment.

3.3 Basic Concepts