Lowering time trend of blood lead levels in Belgium since 1978.

Since 1978, the biological screening of the Belgian population was regularly monitored by measuring blood lead levels. Over 11 years, 6070 samples were analyzed in urban, rural, and industrial areas. The median values of blood lead concentration dropped from 170 to 78 micrograms/liter of blood, i.e., a lowering of about 55%. The trend persists when taking into account some individual characteristics which influence blood lead levels such as gender, age, tobacco, and areas. These influences and the possible environmental causes of the observed trend are discussed.