RESUMO
Tests have been carried out on 50 ex-workers of a hat-factory who had been exposed to mercury nitrate in order to investigate whether a symptomatological pattern attributable to professional exposure would be still present as a consequence of long term exposure and after a long latency period. Because of the small number of examined workers, the collected data have been compared with those of a control group in order to assess the significance of the results. The incidence of subjective and objective signs has been detected to be higher in female group. The symptoms and objective signs may only partially be included in the chronic hydrargiric pattern described by many Authors. These signs are not so marked as to be expected from heavy hydrargiric chronic poisoning and they include: changes in the oral cavity, psychic erethism and neurologycal signs of sensibility impairment.