Comparative study on the tumorigenicity in mice of gallium arsenide, gallium phosphide and gallium oxide following subcutaneous and intraperitoneal injections

Chronic toxicity, including tumorigenicity, of gallium arsenide (GaAs), gallium phosphide (GaP) and gallium oxide (Ga₂O₃) was studied in male ICR mice which received either a subcutaneous or an intraperitoneal injection of each material once only. The doses received either subcutaneously or intraperitoneally were 48 mg Kg⁻¹ as Ga or 480 mg Kg⁻¹ as Ga of each material suspended in 0.2 cm³ of olive oil. The control groups received the vehicle only, either subcutaneously or intraperitoneally. In the study using subcutaneous injections, no tumors were observed in the subcutis at the site of injection, and there was no significant difference concerning the survival periods of each group compared with the control group at the termination of the observation period. In the study using intraperitoneal injections, the total tumor incidence in all the experimental groups, except for the GaAs (480 mg Ga Kg⁻¹) groups, was significantly different compared with the control group. However, all these tumors appeared to be spontaneous, rather than induced by the materials themselves. Moreover, in the GaAs (480 mg Ga Kg⁻¹) and Ga₂O₃ (48 mg Ga Kg⁻¹) groups, the number of survival days was significantly lower compared with the control group. From this study, it seems that neither GaAs, GaP nor Ga₂O₃ were tumorigenic to mice when injected subcutaneously. Although it remains unclear whether the increased production of total tumors in each group following intraperitoneal injections was directly due to the tumorigenic action of GaAs, GaP or Ga₂O₃ or not, it appears that these substances produce a potential systemic toxicity in mice following intraperitoneal injections.