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Environmental fate & pathways

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CAS# 297730-93-9 is of very low water solubility (21.3 µg/l) and is very volatile (vapor pressure, 847 Pa @ 20 °C). The measured Henry’s Law constant (HLC) is 464 atm m³/mol at 23 °C. It is not expected that CAS# 297730-93-9 will have a significant presence in the aquatic compartment.


CAS# 297730-93-9 is not expected to partition from the atmosphere to moist soils or surface waters. Upon direct release of CAS# 297730-93-9 to the aquatic compartment, the chemical is expected to volatilize rapidly, as indicated by the measured HLC (464 atm m³/mol at 23 °C). In direct testing of volatilization rate from water, the volatilization process followed first order kinetics. Rate constants for volatilization were 0.0798/hour for open vials, 0.108/hour for closed but unshaken vials, and 0.279/hour for closed and shaken vials, through an interfacial area in the range of 2.4 cm³ to 4.5 cm³. Also, a series of laboratory studies were conducted to evaluate the feasibility of completing a bioconcentration study on sediment dwelling Oligochaetes. The experiment began with spiking of CAS# 297730-93-9 to a well characterized loam soil. An artificial sediment was made by adding water to the soil to make a 50% suspension. When CAS# 297730-93-9 was added to the moist soil as per OECD 315 without additional water, recoveries were consistently maintained when sample containers were tightly capped but declined approximately 40% when the containers were left open to the atmosphere for two hours. When the artificial sediment (50% water) was tested, recovery of CAS# 297730-93-9 declined substantially below limit of quantitation after two hours’ exposure to open air. In an experiment designed to measure kinetics of dissipation from the artificial sediment, CAS# 297730-93-9 concentrations in the soil suspension declined with a half life of 13.7 minutes. When the artificial sediment was exposed to CAS# 297730-93-9 via the gas phase, subsamples of the water phase did not contain quantifiable amounts of the test substance. Therefore, this compound will not partition to water or sediment but will remain in the atmosphere when released from industrial applications.


Based on these results, CAS# 297730-93-9 will not partition to water, soil or sediment but will remain in the atmosphere when released from industrial applications. The BCF values for CAS# 297730-93-9 in laboratory studies with fish ranged from 287 to 8530. Based on this range, the chemical would be considered very bioaccumulative in aquatic organisms. However, substantial bioaccumulation of CAS#297730-93-9 in aquatic organisms is not expected due to lack of exposure in this compartment. Further, in a 28-day oral toxicity study in the rat, transient centrilobular hypertrophy was observed among necropsied animals at the highest dosage level (1000 mg/kg by gavage) at the end of the dosing period. The hypertrophy was not observed the end of the 14-day depuration period. Hypertrophy of this nature is seen as a result of induction of xenobiotic metabolizing enzyme or as an adaptive change to xenobiotic exposure. The reversibility of this hypertrophy provides evidence that CAS# 297730-93-9 depurates quickly when exposure ceases. Therefore, bioaccumulation in terrestrial organisms also not expected.