Glutaral

Toxicity to soil microorganisms

Description of key information

 The carbon transformation test with glutaraldehyde resulted in an EC10 after 28 days of 10.45 mg a.i./kg dry matter soil or 9.2 mg a.i./kg wet matter soil (converted to an organic matter content of 3.4 %);  The nitrate transformation test resulted in an EC10 after 28 days of 17.5 mg a.i./kg dry matter soil and an EC50 after 28 days of 546 mg a.i./kg dry matter soil (converted to OM content of 3.4 %).

Additional information

The adverse effects of glutaraldehyde 50% on aerobic soil microorganisms were investigated by means of the carbon transformation test, which measures the carbon transformation by the glucose induced soil respiration; the test followed OECD Guideline 217 (BASF AG 38G0674/053272). Soil was collected from Mechtersheim (Germany). The soil was defined as silty sand according to German DIN. Following nominal concentrations of glutaraldehyde 50% in soil were tested: 10, 26, 68, 176, 456 and 1186 mg/kg dry matter soil. The test mixtures were incubated up to 28 days in the dar at 20.4 °C. Sampling time points were at day 0, 7 and 28; at each time point, 3 samples per test concentration were taken and were supplemented with glucose. Glucose induced respiration rates were measured for 12 consecutive hours in respiration measurement units OxiTop by measuring the negative pressure resulting from absorbed CO2 produced by glucose. The calculated respiration rate was expressed as mg O2 released / kg dry mater soil/h. The EC10 after 28 days was 10.45 mg a.i./kg dry matter soil; the EC50 after 28 days was 1045 mg a.i./kg dry matter soil.

In a further approach, the adverse effects of glutaraldehyde 50% on aerobic soil microorganisms were investigated by means of the nitrate production test according to OECD Guideline 216; meal was used as source of nitrogen (BASF AG 37G0674/053271). Soil was collected from Mechtersheim in, Rheinland-Pfalz, Germany; the weather conditions were sunshine and 15 °C. The soil was defined as silty sand according to German DIN. Following concentrations of test substance in soil were tested: 10, 26, 69, 175, 457 and 1186 mg/kg dry matter soil; the test mixtures were incubated up to 28 days in the dark, in test pots closed with a perforated aluminum cap, at a mean temperature of 20.6 °C. Sampling time points were day 0, day 7 and day 28; at each time point, 3 samples per test concentration were considered. The content of nitrate in aqueous soil extracts was determined by means of ion chromatography using an IC system Dionex DX 120 apparatus. The percentage of inhibition of the nitrate production in the treated soil samples versus untreated controls was calculated. The microbial nitrogen transformation process in soil was not affected by glutaraldehyde when applied at a concentration of 10 mg/kg dry matter of soil. The prolonged application of glutaraldehyde at test concentrations above 10 mg/kg dry matter of soil resulted in dose-dependent increased inhibition of nitrate production by soil microorganisms, which resulted in an EC50 after 28 days of 360 mg a.i./kg dry matter of soil; the EC10 after 28 days was 11.5 mg a.i./kg dry matter of soil.

In conclusion, the carbon transformation test with glutaraldehyde resulted in an EC10 after 28 days of 9.2 mg a.i./kg dry matter soil; the EC50 after 28 days was 1045 mg a.i./kg dry matter soil. The nitrate transformation test resulted in an EC10 after 28 days of 17.5 mg a.i./kg dry matter soil and an EC50 after 28 days of 516 mg a.i./kg dry matter soil.