Modification of the Smith and Naylor technique for the identification of ferruginous bodies

Smith and Naylor's technique has been successfully used by many authors around the world to recover inorganic particles from the lungs. In this short report we compare the results of counting inorganic particles recovered from human lung tissue by two different methods: Smith and Naylor's technique and a modification to it. We used ferruginous bodies (FB) as markers for inorganic particles and we compared the results of the FB counts in both methods. In the traditional technique the interface formed in the 1:1 ethanol-chloroform mixture is discharged and FB are counted only in the formed pellet. Our modification also quantified FB in the interface fraction. Post-mortem samples from each of the lung lobes were taken from 22 individuals, totalling 198 samples. Each sample was digested in liquid commercial bleach and processed by both techniques. Our results showed that the modified technique was more sensitive in the detection of FB than the traditional method, with 16 out of 22 individuals showing positive identification against 14 out of 22, respectively. Furthermore, the modified technique proved not only to be more sensitive, but also almost twice as accurate: 49 FB/g vs. 26.7 FB/g of dry tissue.