Shoe makers' polyneuropathy in Italy: the aetiological problem

Abstract

Since 1957, when the first cases of toxic polyneuropathy in shoemakers were reported, nearly 400 cases have been described in the Italian literature. The substance considered responsible for the disease was triorthocresylphosphate (TOCP) contained in glues, artificial leathers, and some types of paints However in numerous chemical analyses of glues and leathers taken from factories where cases of the disease had occurred, little or no TOCP could be found. In addition the disease manifests itself more frequently during winter and spring, which is not consistent with the absorption of the causative agent through the skin and/or gastrointestinal tract. In order to clarify the etiology of the disease, 122 workers in the shoe industry affected by toxic polyneuropathy were studied during the period 1971-1974. Working places were visited and samples of glues and solvents were subjected to chemical analysis. The polyneuropathy chiefly affects workers engaged in the glueing and cleaning process, but it also affects subjects who do not have direct contact with glues or solvents. The disease is more common in women (68%) than in men (32%) and, in its more severe form, begins with overwhelming prevalence during winter and early spring regardless of the kind of work performed in the shoe industry. No direct relation was found between the severity of the disease and the number of years of work in the shoe industry or of the specific exposure. The polyneuropathy is found almost exclusively among workers of the artisan type in small shoe factories, where standards of hygiene are low. Chemical analysis of glues and cleaning fluids collected from 5 different factories, with 20 cases of polyneuropathy, showed the presence of paraffin hydrocarbons with a low boiling point (pentane, 2 methyl pentane, 3 methyl pentane, n-hexane, etc) in concentrations of more than 80% by weight. That these are the causative agents is supported by the following evidence. They are able to cause an experimental polyneuropathy. In the 5 different factories with 20 workers affected, these compounds were found in more than 80% of the total solvents in glues and cleaning fluids. They were also present in similar concentrations in a glue considered responsible for 40 cases of polyneuropathy which occurred in Naples in 1973. An investigation in shoe factories in the Marche region from where most of the patients examined came, showed that in 75% of the work places examined the concentration of these substances was much higher than the threshold limit value proposed by the American Conference of Governmental Industrial Hygienists. The present findings and those of Japanese authors who reported cases of polyneuropathy attributed to n-hexane show similarities which include the type of work, the clinical picture, the epidemiologic data, the poor hygienic conditions of work places, and the composition of the solvents used. Shoe markers' polyneuropathy is due to the use of glues and/or solvents containing paraffin hydrocarbons with a low boiling point, to poor environmental hygiene (small work places without any system for removing toxic vapors), and to bad personal hygiene.