Death following exposure to fine particulate nickel from a metal arc process.

A man was taken ill suddenly while spraying nickel using a thermal arc process. He was relieved of his duties and sent home. His condition deteriorated and he was admitted to hospital with a diagnosis of pneumonia. Thirteen days after exposure he died. At post mortem examination the cause of death was determined to be shock lung or Adult Respiratory Distress Syndrome (ARDS). Reproduction of the conditions under which the man had operated the metal arc process produced nickel concentrations of 382.1 mg m-3 in the air next to the operator. Of this nickel, 64.6% was in the form of particles less than 1.4 microns in diameter; the majority being 50 nm in diameter. The total amount of nickel inhaled by the man, who operated the process for 90 min, was estimated to be nearly 1 g. The toxicity of the nickel is thought to be associated with the very fine particulate nature of the metal fume and the large amount inhaled. The importance of wearing adequate protective equipment while operating this metal arc process is stressed.

Activation of UICC crocidolite: the effect of conversion of some ferric ions to ferrous ions.

Asbestos fibers catalyze the generation of oxygen-centered radicals in the presence of oxygen or hydrogen peroxide. The amount of iron in asbestos fibers, its oxidation state, and its availability to specific chelating agents determine their ability to catalyze the aforementioned reactions. In the present study, the activation of UICC crocidolite was achieved by converting some of the ferric ions into ferrous ions. The activation process did not interfere with the size distribution, surface area, or crystal structure of these fibers. Although oxygen-centered radicals generated and lipid peroxidation produced by asbestos fibers are reported to play an important role in their toxicity, factors such as size, surface area, and durability are considered to be crucial determinants of fiber toxicity and carcinogenicity. The employment of the activated crocidolite in animal experiments to help further elucidate the importance of oxygen free radicals and lipid peroxidation in fiber-induced diseases is therefore proposed.

The prophylactic use of polyvinylpyridine-N-oxide (PVNO) in baboons exposed to quartz dust.

Twelve baboons were exposed to a quartz dust cloud. Four of these were also given polyvinylpyridine-N-oxide (PVNO) by aerosol and four received PVNO by aerosol and injection. A prophylactic effect was demonstrated during the course of treatment, but when treatment stopped the silicosis progressed to the same degree of severity as in the untreated animals.

Improvement in conditions at an amalgamation plant after an industrial hygiene survey.

After receipt of urine samples which showed higher than normal levels of mercury (Hg) from workers at a large goldmine, air samples were taken at the mine's amalgamation plant. These showed not only values higher than the threshold limit for Hg in air but also significant quantities of Hg on the worker's overalls. Recommendations were made for improvements and when these were completed samples were again taken at the plant. The mean Hg level in urine samples had dropped to one-third of its original value and concentrations in air were very much reduced.

A comparison of the effects of exposure of baboons to crocidolite and fibrous-glass dusts.

Epidemiological studies have not revealed any significant health hazards from exposure to fibrous glass and animal experiments have been inconclusive. Baboons exposed to a fibrous-glass dust cloud with size features similar to those of crocidolite asbestos developed focal peribronchiolar fibrosis with scant ferruginous body formation. The lesions were similar to those produced by crocidolite but were less extensive. No neoplasms occurred.

Submicroscopic fibres in industrial atmospheres.

Evidence obtained from a large number of samples of airborne dust from a number of different asbestos-using industries suggests that it would be possible to use gravimetric sampling to estimate the respirable fibre concentration of the atmosphere around specific operations. The precision of this method of estimating airborne fibre concentration is shown to be approximately the same as the variation between different counters using existing counting techniques. Tables are included showing the fibre content of industrial dusts in millions of fibres/mg of dust and the factors (with 95% confidence limits) by which light microscope counts should be multiplied to give the true counts of fibres longer than 5 micrometers.

Physical and chemical characteristics of UICC reference samples.

New data on the physical and chemical characteristics of the UICC standard reference samples are presented. Aspects such as fibre length and diameter distribution, composition and special electrical and magnetic properties are covered. The possibility of preparing samples with graded characteristics is raised. A new edition of the data sheets is proposed.

The effect of particle size on absorption of inhaled lead.

Baboons were exposed to dust clouds of Ph3O4 of different size distribution but of the same total gravimetric concentration. Blood samples were taken immediately after each exposure of 4 hours and the total blood lead was determined. The exposure to the lead-bearing dust was stopped after four weeks, but the blood sampling continued for another six weeks. Graphs are presented comparing the patterns of lead absorption obtained with different sized lead particles. The coarser lead particles resulted in a higher blood lead concentration than the finer.