Health and safety—the downward trend in lead levels

Lead has been known and used by man for thousands of years and its toxic properties have been known for almost as long. In consequence, a wide body of legislation has built up and is designed to protect individuals in both the occupational and the general environments. At the occupational level, two types of controls are widely employed, namely, lead-in-air and lead-in-blood. Limits placed on the amount of lead-in-air are designed to ensure that individuals are not exposed to unsafe levels of lead via inhalation. Currently, the most common standard is 0.15 mg m−3 but there is a clear downward trend and levels as low as 0.05 mg m−3 are mandatory in some countries. Controls on the amount of lead-in-blood give a more direct indication of the exposure experienced by individuals. The most common level presently employed is 70 μg m−3 but, as knowledge of the health effects of lead improves, lower levels are being introduced and 50 μg m−3 is now fairly common. While women are no more sensitive to lead than men, some countries do employ lower blood-lead limits for women in the workplace in order to protect any developing foetus. This paper examines the levels currently in force in various countries and describes developments which are now taking place in the legislation that is being enacted in several parts of the world. As far as the general public is concerned, only a relatively small number of countries employ controls. Where controls do exist, however, they are set at much lower levels than for the occupational environment in order to protect the most sensitive members of the population. Several countries employ limits on lead in ambient air. Traditionally, these have been set at either 1.5 or 2.0 μg m−3, but several countries are currently considering sharp downward revisions to levels of the order of 0.5 μg m−3. A few countries offer guidance on acceptable blood levels for the general population, most commonly for children. Again downward revisions are taking place but where data are available, there is a very encouraging downward trend also in average blood-lead levels found amongst members of the population. These must be due to a combination of factors which have reduced exposures to lead. The net result is that, at least in the more industrialized countries, average blood-lead levels have fallen to extremely low levels and very few individuals can be found with blood lead levels above currently accepted levels of concern.