Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

PIAX is a non-volatile solid. If released to water it will decompose releasing volatile degradation products (mainly 3-methyl-1-butanol, 1-pentanol and CS2) to atmosphere. From the known degradation products the most volatile and the most hazardous substance is carbon disulphide (repeated dose toxic and reproduction toxic). Carbon disulphide (CS2) released during the hydrolysis is expected to volatilize to atmosphere based on a Henry’s law constant of 1748 Pa m3/mol at 25 °C and a vapour pressure of 47 kPa at 25 °C. If released to atmosphere, the half life of CS2through reaction with hydroxyl radicals is estimated at 5.5-15 days, and through photolysis the atmospheric half life is estimated to be about 11 d (WHO 2003). The loss of CS2from 10 to 25 % water solutions at 20°C has been reported to be 0.02 % (Aero Xanthate Handbook 1972). Overall, the emissions of CS2from mining processes to air are considered insignificant. The measured CS2emissions in the process area have been undetectable or up to 7.8 mg/m3(maximum 16 mg/m3). Available air monitoring data for sites where solid xanthates are used indicate that atmospheric levels of CS2are generally below 31 mg/m3(10 ppm).

If PIAX is released to soil, it has low potential to adsorb to soil (log Kow-0.76, estimated Koc 5.183 based on this log Kowvalue) and is not persistent. The substance is hydrolytically unstable, and laboratory studies on biodegradation also present the substance to be inherently biodegradable. Also the decomposition products have a low potential to adsorb to soil. When the substance comes in contact with water or moisture, hydrolysis will take place, alcohols (3 -methylbutan-1 -ol and pentan-1-ol) and CS2being the most critical decomposition products. The relevant alcohols are readily biodegradable having also low log Kow values (< 4). If the alcohols are released to soil, they are expected to have very high mobility based upon an estimated Koc< 4. Volatilization from moist soil surfaces is expected based upon a Henry's Law constant of 1.41 Pa m3/mol and the vapor pressure (ca. 0.3 kPa at 25 °C) and low adsorption to soil. CS2has a low adsorption potential (log Koc= 1.8), and is expected to evaporate rapidly based upon a Henry's Law constant of 1748 Pa m3/mol at 25 °C and vapor pressure 47 kPa at 25 °C.