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Environmental fate & pathways

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The calculated half life of monopropylene glycol in air is 0.83 days with an OH radical concentration of 1.5E06 OH/cm3 (Aopwin, 2000).

In accordance with column 2 of REACH Annex VIII, the hydrolysis test does not need to be conducted as the substance is readily biodegradable. Monopropylene glycol is expected to degrade rapidly in water from biological processes but is not expected to be significantly influenced by hydrolysis, oxidation, volatilization, bioconcentration, or adsorption to sediment (OECD SIDS, 2001).

The calculated half-life of monopropylene glycol in water is 2.3 years with an OH radical concentration of 10-17 mol/litre (Anbar, 1967). The indirect photolysis of monopropylene glycol by photochemically-produced hydroxy radicals is slow in water.

Under aerobic conditions, 106.8 % (O2 consumption), 81.7% (CO2 evolution) and 98.3% (DOC removal) biodegradation was found for 100 mg/l monopropylene glycol tested according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) (West et al., 2007) and in another OECD 301 F study 81 -97% biodegradation was found for 84 mg/l monopropylene glycol tested under aerobic conditions (The Dow Chemical Company, 1999). In further assessment monopropylene glycol is considered ready biodegradable. In an OECD306 test (seawater), after 64 days 95.8 % biodegradation was observed (DOC removal) and 90.6% biodegradation was observed (CO2evolution)(West et al., 2007)

Significant biodegradation was found in a simulation test with natural seawater after 64 days (The Dow Chemical Company, 2004). When released into a soil environment propylene is expected to biodegrade (98% after 105 days) (The Dow Chemical Company, 1986).

Simulation studies with sediment are not available.

 

Based on the result of the octanol/water partition coefficient (Log Kow = -1.07) monopropylene glycol is not expected to significantly accumulate in aquatic organisms.

Based on the result of the octanol/water partition coefficient (Log Kow of -1.07) monopropylene glycol is expected to have a low potential for adsorption/desorption.

 

The calculated Henry's law constant at environmental relevant temperature is 0.0566 Pa.m3/mol using EUSES calculation (The European Union System for the Evaluation of Substances, 2008).

Volatility is not expected to be a significant fate process due to its low vapor pressure and high water solubility.

Based on the EPIWIN Level III Fugacity Model monopropylene glycol is expected to partition primarily to soil (48.1%) and water (48.8%). (OECD SIDS, 2001).