In Vitro Solubility and In Vivo Toxicity of Indium Phosphide

Abstract

In Vitro Solubility and In Vivo Toxicity of Indium Phosphide: Isamu Kabe et al. Department of Preventive Medicine and Public Health, School of Medicine, Keio University—This study was designed to clarify the in vitro solubility and the in vivo basic toxicity of indium phosphide (InP). InP powder was clearly soluble in synthetic gastric fluid and quite insoluble in saline or synthetic lung fluid. Male ICR mice (SPF grade) were given InP at the doses of 0, 1,000, 3,000, and 5,000 mg/kg, intraperitoneally (i. p.) or orally (p. o.). During a 2‐week observation, no mice died. In i. p. treated mice, the serum indium concentration showed a dose‐dependent increase, and indium mainly accumulated in the lungs and liver. Dose‐dependent increases in lung and spleen weight were observed. Black granules of InP were deposited in the lymph nodes, spleen, lungs, and liver. Extramedullary granulopoiesis was observed. And eosinophilic exudates and mononuclear cells were seen in the pulmonary alveoli. Considering these findings, InP particles were presumably transferred to the spleen, liver, and lungs by way of lym‐ phokinetics, causing reticuloendothelial responses. Hematological examination showed increased proportions of stab cells and monocytes in 5000 mg/kg i.p. dosed mice. The p. o. administered mice showed no clear relationship between the dose and biological effects.

Two‐ and 13‐week Inhalation Toxicities of Indium‐tin Oxide and Indium Oxide in Rats

“…This finding can be interpreted as indicating that ITO particles are dissolved to greater extent in the deep lung than IO, resulting in higher blood contents of indium in the ITO-exposed rats. Kabe et al 22) demonstrated that indium phosphide powder is clearly soluble in synthetic gastric fluid indicative of acidic pH, while the powder is insoluble in saline or synthetic lung fluid (Gamble solution). Dittmar et al 23) reported that when indium phosphide particles are exposed to Gamble solution, a complex dynamic interaction with the particle surface results in high levels of dissolved indium.…”

Causal Relationship between Indium Compound Inhalation and Effects on the Lungs

“…It is well known that the inhalation of hardly soluble hazardous particles, such as crystalline silica, asbestos, and so on, induces pneumoconiosis. In animal experiments, intra-tracheal instillation of indium compounds induces pneumonitis, proliferation of fibrous tissues, pulmonary fibrosis, and other lung diseases [3][4][5][6] . The results of our study are consistent with these information.…”

“…Until the early 1990's, there was little information on the toxic effects of indium on humans or animals. In the mid 1990's, intra-tracheal instillation studies of particles of compound semiconductors such as indium phosphide, indium arsenide and indium trichloride revealed that metal compounds containing indium had a strong potential to induce severe lung damage [2][3][4][5][6] . In 2003, Homma et al 7) disclosed a case of interstitial pneumonia in a 27-yr-old male worker engaged in the wet surface polishing process of indium-tin oxide (ITO) target plates, high-density plates made of very hard ceramics composed of indium oxide and tin oxide, which are used to laminate transparent electroconductive thin-film on flat displays and solar cells.…”

Exposure to hardly soluble indium compounds in ITO production and recycling plants is a new risk for interstitial lung damage

“…Beginning in the mid-1990s, the authors’ institutions performed single or repeated intratracheal instillation experiments with fine particles of hardly soluble indium compounds such as indium phosphide (InP) and indium arsenide and found that these induce severe lung inflammation with fibrotic changes1 – 6 and have mild reproductive effects 7 8. The US National Toxicology Program (NTP) carried out an InP inhalation experiment for two years and concluded that there is clear evidence of carcinogenic activity of InP on the lungs in male and female rats and mice 9.…”