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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

When water is added to Sodium isobutyl xanthate it reacts with water to form the others substances: alcohol, sodium carbonate, trithiocarbonate and carbon disulphide because of its high water solubility.

Hydrolysis will be a significant factor in determining the environmental fate of Sodium isobutyl xanthate. In neutral or mildly alkaline solutions, Sodium isobutyl xanthate decomposes to the alcohol, carbon disulphide, sodium carbonate and sodium trithiocarbonate, the two salts arising from neutralisation of carbon disulphide with the sodium hydroxide liberated. In more strongly alkaline media, hydrogen sulphide is liberated. However, strongly alkaline conditions are unlikely to be encountered under the conditions of use in the mining industry. The half-life at pH 7 at 25°C is reportedly about 260 hours, increasing to over 500 hours in the pH range 8 to 11.

Sodium isobutyl xanthate is hydrolytically unstable when exposed to acidic conditions, reverting rapidly to isobutyl, carbon disulphide and caustic soda, and therefore will not persist in the acidic environment of tailings dams. If discharged to waterways, the chemical would be likely to persist for at least some days, hydrolysing only slowly in this more neutral environment. However, it is not expected to bioaccumulate in view of its ionic character

Sodium isobutyl xanthatedoes not fulfil the criteria for persistency, bioaccumulation and toxicity as laid down in the TGD (EC, 2003). Therefore, this substance is not consideredon PBT or vPvBsubstance.