• asbestos
• cumulative exposure
• pleura
• risk

Sir,

The criticisms by Boffetta1 give us the opportunity to provide more details on the methods and results of our study.2

First, the proportion of proxy respondents among controls was 7.2% (table 1) and not 93% as erroneously indicated by Boffetta. As expected, the exposure–response trend was steeper for direct interviews that provided more detailed information (see online supplementary table S3).

Casale Monferrato inhabitants are aware of asbestos-related cancer risks. However, this applies to the entire community, not only to cases, therefore it is an unproven assumption that local awareness explains our study results because of participation and recall biases. On the contrary, if exposed controls selectively entered the study because of their motivation, our findings would be biased towards the null. After study publication, we investigated demographic and social characteristics of respondents and non-respondents, observing no differences (paper in preparation). Our findings are neither isolated nor unexpected, but consistent with our previous studies on mesothelioma risk in the area, making biases an even less likely explanation.3 ,4

Exposure assessment methods were described in detail2 and were a development of largely used methods.5–7 Cornerstones were the detailed reconstruction of occupational, residential and familial life, and the blind …