For the purposes of this chapter, the following definitions shall apply
1° “Hazard” means the intrinsic property of a chemical agent which is likely to have a harmful effect;
2° “Risk” means the probability that the potential for harm will be achieved under the conditions of use and/or exposure;
3° “Health surveillance” means the assessment of a worker’s state of health in relation to his exposure to specific chemical agents in the workplace;
4° Biological limit value, the limit of concentration in the appropriate biological medium of the agent concerned, its metabolites or an indicator of effect;
5° Occupational exposure limit value, unless otherwise specified, the limit of the time-weighted average of the concentration of a hazardous chemical agent in the air in a worker’s breathing zone over a specified reference period.