Cadmium levels in kidneys from Swedish pigs in relation to environmental factors--temporal and spatial trends.

The kidney cadmium level in pigs slaughtered at the age of 5-7 months was analysed with respect to geographical and temporal trends. During the period 1984-1992, a total of 1051 samples of porcine kidney from 31 abattoirs were analysed for cadmium at the National Food Administration within the control programme for livestock production. The mean kidney cadmium level was 0.11 +/- 0.07 mg/kg wet wt. (mean +/- S.D.). Regression analysis showed that the cadmium concentration in pig kidney has increased by 2% per year. By using Geographic Information System (GIS), geographical trends in cadmium concentration of porcine kidney were analysed and correlated to cadmium levels in moss and pH in the mor layer of podsolized soil. These two parameters explained 60% of the random variation in cadmium levels in porcine kidney. There were significant differences between individual abattoirs, but no significant longitudinal or latitudinal trend was found. Variation in kidney cadmium levels within breeding stocks was investigated. Kidneys from eight stocks, with five pigs from each, were analysed for cadmium concentration. In spite of the homogeneous treatment of the pig within the same stock, kidney cadmium levels varied on average by a factor of two between individuals. There was a significant correlation between cadmium in feed and cadmium levels in porcine kidney (P = 0.002). The temporal increase in cadmium levels in porcine kidney should be further investigated. An increase in cadmium body burden in pig may be an indicator of an increase in human cadmium exposure.