Niveaux du plomb sanguin, du plomb urinaire, de l’acide δ-aminolévulinique et des porphyrines urinaires chez les personnes vivant à Kinshasa, R.D. Congo : une étude pilote de biosurveillance

Objectives: Existing naturally in the earth’s crust, Lead is a widely used heavy metal. It is an environment toxicant that may deleteriously affect nervous, hematopoietic, skeletal, renal, endocrine and reproductive systems. Lead is classified in its inorganic form as possible human carcinogen (group 2A) by IARC. Exposure to lead in the environment continues to be a serious public health problem for all ages. Children are particularly susceptible to lead poisoning. They absorb more lead from their environment and their developing central nervous systems are vulnerable to the toxicant. During the last twenty years, important measures of public health were undertaken in several countries to decrease lead exposure. In the best of our knowledge, this is not the case in D.R. Congo. A study indicated a relatively important lead impregnation of the Kinshasa population (mean 120 μg/L). However, there have been no reported studies in the evaluation of the relationship between urinary lead, urinary δ-aminolevulinic acid (δ-AlaU) and urinary porphyrins and lead blood level in Congolese people. This is the aim of this study targeting at first people living in Kinshasa.
Methods: Blood lead and urinary lead levels were measured using inductively coupled plasma mass spectrometry. The Bio-Rad ALA/PBG by Column Test and spectrophotometer method were used to quantify the concentration of δ-Ala in urine. The separation of porphyrins was carried out by HPLC coupled with fluorescence detector.
Results: 37% of studied population presented blood lead levels above the 100 μg/L threshold (geometric mean: 133.29 μg/L) with a higher concentration in women than in men (140.30 μg/L vs 130.78 μg/L). 50% of children (0-17 years) presented blood lead levels above the 100 μg/L threshold and 43% of the same population presented blood lead levels above 50 μg/L as accepted nowadays in US. In the adult population, some targeted occupations were found to be associated with high blood lead. A small correlation was observed between urinary lead and blood lead, but no correlation was noticed between δ-AlaU and Porphyrins with lead blood levels.
Conclusion: This study confirmed a relatively important Pb impregnation of the Kinshasa population and the existence of a major public health issue requiring corrective actions and the implementation of an appropriate regulation. Also, urinary lead, urinary δ-Ala and urinary porphyrins seems to not to be sensitive markers for monitoring exposure to lead.