N-hexane neuropathy in offset printers.

In an offset printing factory with 56 workers, 20 (36%) developed symptomatic peripheral neuropathy due to exposure to n-hexane. Another 26 workers (46%) were found to have subclinical neuropathy. The initial change in the nerve conduction study was reduced amplitude of the sensory action potentials, followed by reduced amplitude of the motor action potentials, reduction in motor conduction velocities and increase in distal latencies. These changes indicate primary axonal degeneration with secondary demyelination. Sural nerve biopsy in a severe case showed giant axonal swellings due to accumulation of 10nm neurofilaments, myelin sheath attenuation and widening of nodal gaps. The development of neuropathy bore no direct relationship to the duration of exposure, hence factors such as individual susceptibility may be important. Optic neuropathy and CNS involvement were uncommon and autonomic neuropathy was not encountered.

A survey of the respiratory health of silica-exposed gemstone workers in Hong Kong.

Respiratory symptoms and radiographic and lung function alterations were studied in a cross-sectional survey of gemstone workers in Hong Kong. The study population included a group of grinders, polishers, and buffers who were heavily exposed to dust (principally free silica) and a less exposed group of cutters and carvers. Among all 218 male workers who answered the respiratory questionnaire, heavily exposed workers reported significantly higher prevalence of respiratory symptoms suggestive of mucus hypersecretion. Radiological pneumoconiosis defined as opacities with profusion of 1/0 and above was found in 27% of 157 workers who accepted radiographic and lung function examination. Radiological opacities were significantly related to increasing years of employment in both groups of workers after taking into account age and smoking habits. Decline in forced vital capacity (FVC) was significantly related to increasing years of employment in both groups after allowing for the effects of age, height, and smoking. A modest decline in forced expiratory volume in one second (FEV1) was related to dust exposure which was of borderline statistical significance in polishers and buffers who smoked. Radiological pneumoconiosis did not have an independent effect on lung function when allowance was made for dust exposure.

Silicosis in jade workers.

The recent finding of cases of silicosis among jade workers in Hong Kong points to this disease being an occupational hazard. The source was found to be the silica flour that was added in a polishing process. Five cases are described together with the results of environmental investigation in a workplace. In three cases the disease was of early onset, rapidly progressive, and presented the features of galloping silicosis noted in other occupational exposures to silica flour. One patient had massive fibrosis and severe glomerulonephropathy, an association that has also been previously noted. One case showed evidence of active tubercular infection in addition to silicosis and two had healed lesions. Silica concentrations in the workplace during the suepect process were well above accepted threshold limit values.

An outbreak of illness after occupational exposure to ozone and acid chlorides.

New labelling processes installed without adequate ventilation control in an electric motor factory exposed production line workers to toxic gases. Symptoms of eye and respiratory tract irritation together with complaints of headache, fever, chills, dizziness, malaise, general weakness, nausea, and vomiting were widespread. Chest signs, radiographic abnormalities, reduction in ventilatory function, and blood gas abnormalities were found in some cases. Epidemiological analysis of the spatial and temporal distribution of cases supported an exposure effect relationship. Investigations suggested ozone and possibly phosgene and associated trichloroacetyl chlorides as the toxic agents that were generated by an ultraviolet print curing arrangement and perchloroethylene used as a cleaning solvent.