A trace metal survey of non-occupationally exposed Gauteng residents

Specific reference values for background levels of body burden of trace metals are not available for South Africa. Currently, laboratories measuring trace metal levels in workers use internationaly established values for comparison. A preliminary cross-sectional survey of 107 non-occupationally exposed volunteers of both genders and all races provided blood and urine samples. The samples were collected with consideration for possible routes of contamination. Seven metals were measured in blood and ten in urine. Reference ranges for a Gauteng population were then calculated using the central 95% of data to provide lower and upper limits, which were then compared to international limits. The trace metal levels described had both lower and higher reference ranges in blood and urine compared to international studies. This reflects the differences in the environments. Statistically significant differences in metal levels were observed by gender. The differences in detected trace metal levels in our sample as compared to other published data demonstrate the need for the establishment of local reference values for laboratories. The establishment of local 95% reference ranges would also allow South Africa to determine its exposure levels compared to those internationally. This would assist with establishing pollution control priorities.