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PBT assessment

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PBT assessment: overall result

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

Conclusion on P / vP properties: vP (and P)

The test item is not readily biodegradable (11% degradation in 28 days) andis therefore considered to be very Persistant (vP) based upon the information available.

Conclusion on B / vB properties: not B/vB

The substanceis an unknown or variable composition, complex reaction products and biological materials (UVCB substance) containing molybdenum and is essentially insoluble in water.  QSAR calculations provide water solubility values below10-6mg/L.  The partition coefficient (Log Pow)of the substance was estimated to be18.94 using EPI SuiteTMsoftware.  The UVCB substance includes a fraction that does not contain molybdenum.  The water solubility and Log Powofthe fraction without molybdenumare5 x 10-5mg/mL at 20 °C and 5.84, respectively.  The typical molecular mass of the substance (C32H68Mo2P2O6S6) is 995.11 Daltons.  These data indicate that the substance is relatively large (> 500 Daltons), has very low water solubility (< 0.1 mg/L), and is a highly lipophilic (Log Pow > 5.6) molecule, and thus the substance is not bioavailable via the oral route in accordance with Lipinski's rule of five, and thus is not expected to be absorbed by fish. In addition, acute oral toxicity study in rats did not show any systemic effects up to 2000 mg/kg, the highest doses tested.   Although the substance was not tolerated at 10 and 21.5 ml/kg in acute oral toxicity study in rats with oral LD50of 6.81 ml/kg body weight, equivalent to 7709 mg/kg (relative density of 1.132), the observations were largely local gastrointestinal effects due to overload of highly hydrophobic substance in gastrointestinal tract, diarrhea with the test substance in stools, and corresponding poor clinical conditions. Lower thymus weight and higher liver weight were noted at 1000 mg/kg/day, the highest dose tested, in a 6-day repeated dose oral range-finding toxicity study in rats. Systemic effects were also notedin the combined repeated dose oral toxicity study with the reproductive/developmental toxicity screening test in rats, which are hepatocellular hypertrophy, thyroid follicular cell hypertrophy and mucosal hyperplasia with erosion or ulceration in the nonglandular stomach.  The thyroid follicular cell hypertrophy was likely secondary to the liver effect and the mucosal hyperplasia may be secondary to direct irritation of the mucosa.  However, no information is currently available on possible degradation products produced in the gastrointestinal tract.

Conclusion on T properties: not T

No evidence of toxicity has been reported in any study on the test item.

Likely routes of exposure:

The primary route of test item release release will be to wastewater.

It may be released to air through use processes, however, the vapour pressure is 0.0045 Pa at 25°C

and therefore air exposure is expected to be negligible.

 

Release to soil may occur from spreading of STP sludge’s, however this is advised against.

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