Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

The test substance, phenol, isopropylated, phosphate (3:1), is a liquid under all environmental conditions and only sparingly soluble in water. It has a low volatility (based on a vapour pressure result of 0.45 kPa at 20 °C). As such, any environmental release will result in virtually all of the substance compartmentalising into soil and water compartments, with little release directly to atmosphere.

 Any potential exposure to the environment would result in rapid redistribution from soil and water due to its volatility.  The high adsorption to soil (based on the soil adsorption study, discussed below) indicates that the majority of the substance will partition to soil and sediment rather than water should it be released to the environment. This is supported by a Level III fugacity model in the US EPA EPISUITE (Mackay,) which assumes steady-state but not equilibrium conditions. The Level III model in EPI Suite predicts partitioning between air, soil, sediment and water using a combination of default parameters and various input parameters. This model has been used to calculate the theoretical distribution of phenol, isopropylated, phosphate (3:1) (as one specific isomer as an indication) between four environmental compartments (air, water, soil, sediment) at steady state in a unit world. Partitioning is detailed to be:

-        Air 0.157 %

-        Water 9.31 %

-        Soil 76.2 %

-        Sediment 14.3 %

It should be noted that as the majority of the substance distributes to the soil compartment; and the low solubility in water, this indicates that the substance is likely to persist in this compartment rather than distribute to the soil pore water.

Phenol, isopropylated, phosphate (3:1) displays a low ready biodegradability in that it achieved 17.9% biodegradation in a 28-day closed bottle test, indicating that it is unlikely to achieve a half life of less than 40 or 60 days within fresh water attributed to ready biodegradation alone.

However it is expected to hydrolyse slowly under normal environmental conditions.  Experimental studies on hydrolytic effects demonstrated that the substance does undergo hydrolysis at environmentally relevant pH’s, with a half life of 18.5 days at pH 7. As such, some degradation is anticipated via this route. Studies on direct phototransformation in water are not available but it is assumed on the basis of chemical structure that the substance is not degraded by direct photolysis. It is concluded, therefore, that abiotic processes would contribute significantly to the depletion of the substance within the environment.

 Phenol, isopropylated, phosphate (3:1) has a measured log Pow of 4.92 to 5.17. This value indicates that possible bioaccumulation in the food chain could reasonably be anticipated. However, on the basis of a weight of evidence approach, there is sufficient information available to state that the substance is not bioaccumulative in aquatic species. The highest value attained in an OECD 305 study on the substance was 776L/kg ww. This is below the threshold value quoted in the Regulation of 2000 or 5000 which indicates the potential to bioaccumulate.  The substance is not considered to be “bioaccumulative” or “very bioaccumulative” on the basis of the available data.

 A screening organic carbon-water partitioning coefficient (Koc) is available for the substance, using a HPLC Estimation method. This resulted on a log Koc value of 3.43-3.93 at 25 °C with Koc of 2704 to 8569. As such, adsorption to soil is deemed to be medium, based on this study assessment. Such a medium potential indicates that the substance would bind to soils and sediments and thus, reduce overall exposure potential to aqueous organisms. However, exposure related effects to sediment and soil dwelling organisms is considered to be minimal. This is on the basis of the existing classification and labelling as “hazardous” to the environment. Risk Management Measures ensure that there should be no release to the environment. Hence exposure is considered to be mitigated.

Based on its limited water solubility high partition coefficient and low biodegradability, it can be concluded that phenol, isopropylated, phosphate (3:1) could potentially be persistent within the environment. However, abiotic effects within the environment will result in eventual removal from the environment. The substance is also not considered to be bioaccumulative on the basis of the data available. Hence significant contact with the organisms in the food chain can considered to be minimised.

Finally, phenol, isopropylated, phosphate (3:1) demonstrates low acute toxicity in mammalian studies, but some extended effects, particularly in subacute studies indicate some reproductive potential effects. Therefore effects due to initial exposure are not anticipated, although prolonged exposure may result in effects on environmental organisms.