Norway rat, Rattus norvegicus in metropolitans, a bio-indicator for heavy metal pollution (Case study: Tehran, Iran)

The present research aims to assess the potential use of the Norway rat, Rattusnorvegicus as a bio-indicator for lead and cadmium accumulation in 10 urban zones in Tehran, the metropolitan city, Iran. During April to May 2014 we collected twenty adult Norway rats from the different predefined zones. By referring to the air pollution data collected over 15 years, the sampling areas were detected to collect rats. ANOVA test showed that the mean concentrations of cadmium and lead were significantly different for the areas studied as the highest value for both metals recorded in the central areas, exhibiting decreased trends towards the north. In the central parts of Tehran, the mean levels of lead and cadmium concentrations were found to be 73.06 and 5.20 μg.g-1 in the rats’ hepatic tissues, respectively. Meanwhile, the lead and cadmium concentrations were 1.85 and 0.07 μg.g-1, respectively in the northern parts of Tehran. In addition, we examined the concentration of lead and cadmium in the sludge obtained from the sampling points. The results also corresponded to the metal concentration in the rats liver samples. Therefore, the present study verified that the Norway rat could be used potentially as a bio-indicator for heavy metal contamination in polluted metropolitans, such as Tehran.