Int. J. Environ. Res. Public Health 2009, 6 3129 Additionally, the toxicological assessment aim for this study is the assessment of the relationship between pathomorphological changes in kidney and the accumulation of toxic elements. 2. Results and Discussion 2.1. Incidence of Heavy Metals Regional variations in the occurrence of toxic elements in the kidneys of slaughtered pigs and the number of samples falling into specified concentration ranges are summarized in Table 1. Arsenic was detected in only one sample originating from the Vladimirci area (content 0.001 mg/kg), while Cd detection in the samples varied from 16.6% (Bogatić region) to 40% (Vladimirci region). Cadmium concentrations in the sampled kidneys from the regions under study ranged from 0.05 to 1.23 ng/g. The highest Cd concentration (1.23 ng/g, mean 0.185 ng/g) was found in Vladimirci region in contrast to Bogatić region where the lowest (0.05 ng/g, mean 0.027 ng/g) concentration was found. The occurrence of Hg varied from 23.3% (Vladimirci) to 43.3% (Senta region). The highest Hg level (0.055 ng/g, mean 0.0033 ng/g) was found in Vladimirci region, in comparasion to Senta region where lowest concentration (0.012 ng/g) of Hg was detected. However, the mean concentration (0.0034 ng/g) for Hg was slightly higher in the samples from the Senta region. A statistically significant difference (p < 0.001) was found among the Cd levels in the kidneys from the areas under study. Table 1. Percentage of samples contaminated with each toxic elements and their concentrations in kidneys from slaughtered pigs [ng/g]. Hg Toxic Region Vladimirci Senta Bogatić Total elements N 30 30 30 (ng/g) Cd n 12 7 6 25 % 40 23.3 16.6 27.7 X ±Sd 0.185 ±0.322a 0.022 ±0.043b 0.027 ±0.064c 0.078 ±0.20 Max. value 1.23 0.13 0.27 1.23 As n 1 nd nd 1 % 3.3 Nd Nd 3.3 X ±Sd 3.3 ×10-5 ±1.8 ×10-4 nd nd 3.3 ×10-5 ±1.8 ×10-4 Max. value 0.001 0.001 n 7 13 10 30 % 23.3 43.3 33.3 33.3 X ±Sd 0.0033 ±0.01 0.0034 ±0.0043 0.0025 ±0.004 0.0031 ±0,007 Max. value 0.055 0.012 0.014 0.055 N-total number of analyzed samples; n- number of contaminated samples; %- percentage of samples contaminated with each toxic elements; X - mean concentration level (ng/g); Sd- standard deviation; nd- not detected, a:b p < 0.001, a:c p < 0.001. 90 Results in Table 1 indicate a higher occurrence of Hg in the sampled kidneys (33.3%), when compared with the incidence of Cd (27.7%) in the samples. However, results showed that the