Cyanide Intoxication

To the Editor.—  We read with great interest the recent article by Blanc et al¹ regarding toxic reactions to cyanide in silver reclamation workers. We feel that several of their conclusions are misleading and not justified by the findings of their study. The study design itself is flawed (as the authors recognize) in that it is a retrospective study using self-reported symptoms. We do not know how many asymptomatic workers were excluded from the study, nor if workers had an interest in reporting positive symptoms. These difficulties are further compounded by the fact that there are no direct measurements of either tissue cyanide or environmental cyanide during plant operation. In addition, no measurements were made of other possible environmental toxins, especially carbon monoxide and organic solvents.It is essential to know how the diagnosis of cyanide poisoning was made in the index case. Limited information is presented with regard