Blood Cd-concentration in dairy cattle living in different area of Cd-pollution

Cadmium (Cd) is an important environmental pollutant in in- dustrialised countries and it is becoming an even more widely used metal in industry for its technologically advanced properties (Elinder et al, 1981). Retention of Cd in small quantities has been demonstrated in all animal tissues, but about 50 to 75 percent of the body burden of cadmium is stored in the liver and kidneys (Lind et al., 1997). Its half-life in the body is not known exactly and it may be as long as 30 years (Lind et al. 1997; Venugal and Luckey, 1979) and there is progressive accumulation in the soft tissues, particularly in kidneys. The slow excretion and prolonged retention in tissues suggest that no homeostatic mechanism exists for cadmium (Venugal and Luckey, 1979). The aim of this study is to evaluate blood Cd-concentration in healthy dairy cattle (established by clinical examen and haematolog- ical and biochemical analysis) who live in different Cd-polluted area and to verify the possibility of using these animals as bioindicators of Cd-pollution. Materials and methods: Blood samples were obtained from 37 dairy cattle (aged between 5 and 12 years) living in three different areas of Leghorn province (Italy). These areas have been choosen in relation with the degree of cadmium-pollution and have been divided in low (group 1: 6), medium (group 2: 18) and high (group 3: 13) degree cadmium-polluted area (Scerbo et al., 1999) Blood samples for Cd evaluation have been collected from the caudal vein in lithium-heparinized vacuum tubes (Vacutainer® ) and stored at -20°C. Blood cadmium concentrations have been evaluated by elec- trothermal atomic absorption spectrometry after a high pressure microwave assisted oxidating digestion of the organic matrix of the samples (atomic absorption spectrometer 4100ZL with inte- grated platform pyrolitic graphite electrothermal furnace and A-70 autosampler - Perkin Elmer, USA). The background compensation was made with a longitudinal Zeeman effect corrector (Tsalev et al., 1995, 1996a-b; Slaveykova et al., 1997). Statistical analysis: Mean and standard error (SE) have been calculated for each group; t Student test for unpaired data has also been calculated. Different between groups has been considered statistical significative for p<0.05 and high significative for p<0.01. Results: Blood Cd concentrations ranged respectively: from 0.3 to 1.7 ppb (μg/Kg) (mean: 0.82; SE: 0.23) in low degree Cd-polluted area; from 0.1 to 2.3 ppb (mean; 0.83; SE: 0.12) in medium Cd- polluted area; from 6.00 to 568.00 ppb (mean: 131.54; SE: 43.03) in high Cd-polluted area. There is no differences in blood Cd-concentration between group 1 and 2 (p<0.95); there is an high significative difference between group 2 and 3 (p<0.01) and between 1 and 3 (p<0.01). Discussion and conclusions: Our results confirm that the relation between environmental exposure to Cd and blood concentration is evident especially in high risk areas for environmental Cd-pollution (group 3). The metal presence, then, could be an early indication of a real risk of buildup in animals living in highly industrialized surroundings. As an outcome, it could be also hypothesized the possibility of a cadmium buildup and carry from productive subjects to man, by way of the food chain (meat and milk). Furthermore it could be an opportunity to use subjects in animal husbandry as biomonitors for cadmium exposition alert in zones at environmental risk.