The wild rat as sentinel animal in the environmental risk assessment of asbestos pollution: A pilot study

- A workflow of activities from capture of wild rats up to the final analyses (PCR, Histology, SEM-EDS) was set up.
- Health status of captured wild rats was monitored on carcasses and organs to avoid risk for people.
- Data from wild rats were compared with those from laboratory rats, used as positive and negative controls.
- Measurement feasibility of the lung asbestos fibre burden, was proved by SEM-EDS both quantitatively and qualitatively.
- A good rationale for using wild rats as sentinels of the soil contamination level was provided.

Asbestos has been banned in many countries, including Italy. However, sources of exposure may still exist, due to asbestos in-situ or past disposal of asbestos-containing waste. In an urban area with past high environmental exposure, like Casale Monferrato, the lung fiber burden in sentinel animals may be useful to identify such sources. A pilot study was conducted to assess the feasibility of its determination in wild rats, a suitable sentinel species never used before for environmental lung asbestos fiber burden studies.Within the framework of pest control campaigns, 11 adult animals from 3 sites in the urban area of Casale Monferrato and 3 control rats from a different, unexposed town were captured. Further, 3 positive and 3 negative control lung samples were obtained from laboratories involved in breeding programs and conducting experimental studies on rats. Tissue fiber concentration was measured by scanning electron microscopy with energy dispersive spectrometry.Asbestos (chrysotile and crocidolite) was identified in the lungs from rats from Casale Monferrato, but not in control rats and in negative control lung samples. Asbestos grunerite at high concentration was found in positive control lung samples.Measurement of the lung fiber burden in wild rats has proved feasible: it was possible not only to detect, but also to characterize asbestos fibers both qualitatively and quantitatively. The pilot study provides the rationale for using wild rats as sentinels of the soil contamination level in Casale Monferrato, to identify areas with the possible presence of previously unrecognized asbestos sources.