Arsenic (III, V), indium (III), and gallium (III) toxicity to zebrafish embryos using a high-throughput multi-endpoint in vivo developmental and behavioral assay

Abstract

Gallium arsenide (GaAs), indium gallium arsenide (InGaAs) and other III/V materials are finding increasing application in microelectronic components. The rising demand for III/V-based products is leading to increasing generation of effluents containing ionic species of gallium, indium, and arsenic. The ecotoxicological hazard potential of these streams is unknown. While the toxicology of arsenic is comprehensive, much less is known about the effects of In(III) and Ga(III). The embryonic zebrafish was evaluated for mortality, developmental abnormalities, and photomotor response (PMR) behavior changes associated with exposure to As(III), As(V), Ga(III), and In(III). The As(III) lowest observable effect level (LOEL) for mortality was 500 μM at 24 and 120 h post fertilization (hpf). As(V) exposure was associated with significant mortality at 63 μM. The Ga(III)-citrate LOEL was 113 μM at 24 and 120 hpf. There was no association of significant mortality over the tested range of In(III)-citrate (56-900 μM) or sodium citrate (213-3400 μM) exposures. Only As(V) resulted in significant developmental abnormalities with LOEL of 500 μM. Removal of the chorion prior to As(III) and As(V) exposure was associated with increased incidence of mortality and developmental abnormality suggesting that the chorion may normally attenuate mass uptake of these metals by the embryo. Finally, As(III), As(V), and In(III) caused PMR hypoactivity (49-69% of control PMR) at 900-1000 μM. Overall, our results represent the first characterization of multidimensional toxicity effects of III/V ions in zebrafish embryos helping to fill a significant knowledge gap, particularly in Ga(III) and In(III) toxicology.

Keywords: Arsenic; Ecotoxicity; Gallium; III/V materials; Indium; Zebrafish.

Fig. 1

Mortality incidence in zebrafish embryos (out of 32 replicates) after 24 and 120 hpf. Rows: As(III) (A), As(V) (B), Ga(III)-citrate (C), In(III)-citrate (D). White bars indicate hits above the statistically significant threshold (p ≤ 0.05).

Fig. 2

Comparison of active endpoints for 500 μM As(III) (Panel A) and As(V) (Panel B) exposure to zebrafish embryos with chorions (white bars) and without chorions (black bars). The dashed line is the statistical significance threshold (p ≤ 0.05) for endpoints with total hits above the threshold.

Fig. 3

Activity of developmental endpoints in zebrafish embryo assay for As(V). White bars indicate hits above the statistically significant threshold (p ≤ 0.05). In all treatments and controls, the total number of embryos assayed was 32.

Fig. 4

Photomotor response (PMR) behavioral assay. Panel A – Average movement in 24 hpf embryos exposed to In(III)-citrate. Red line indicates a light pulse. Panel B - Normalized peak movement index upon initial light pulse for As(III) (●), As(V) (○), In(III)-citrate (■), and Ga(III)-citrate (▲).