Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability

Phototransformation in air

For 2-isopropylnaphthalene (2-IPN) [CAS No. 2027 -17 -0], a constituent of the substance isopropylnaphthalene (MIPN) [CAS No. 29253-36-9] at approx. 65 %, the half-time of decomposition (DT50%) was 20 to 30 h, when the test material had been coated onto the glass wall of the test tube or adsorbed onto filter paper under artificial UV-test conditions (simulated sunlight).

Hydrolysis

Due to its chemical structure, isopropylnaphthalene (MIPN) cannot be hydrolysed. The structure of the molecule does not contain any hydrolysable groups.

Phototransformation in water

Using a high-pressure mercury lamp as irradiation source (simulated sunlight), the photolytic half-life of 2-isopropylnaphthalene (2-IPN), was approx. 22 h in distilled water (elimination constant 0.031/h), while it was only approx. 1 h in the presence of salt (0.5 M NaCl).

Phototransformation in soil

No data available (not required for REACH)

Biodegradation

Biodegradation in water: screening tests

In a valid follow-up study applying the OECD method 310 (Ready Biodegradability - CO2 in Sealed Vessels, Headspace Test), biodegradation of 60 % was reached after 23 d within a 12-days window, hence just failing the 10-days window (Fiebig/NOACK 2013). GC-analysis demonstrated >99% elimination of the original substance after 16 days. In a MITI II test (OECD 302 B, 28 d) using a concentration of 30 mg/L of MIPN, only poor biodegradation was observed with a low BOD of about 12 %. However, GC-analysis suggested significant primary degradation under test conditions (removal of the pristine test substance of about 93 %). This study has been disregarded, because a negative selective stress usually imposed on the inoculum in these Japanese investigations favour the loss of indigenous potent microorganisms carrying special properties of decomposition.

Biodegradation in water and sediment: simulation tests

No data available

Biodegradation in soil

No data available

Mode of degradation in actual use

No data available (not required for REACH)

Bioaccumulation

Bioaccumulation: aquatic / sediment

In a valid guideline test (OECD 305) [NITE Japan 2011, report date 1982], using flow-through conditions, mean BCF values at steady-state (time 4 to 8 wks) reached 870 and 640 at 50 and 5 µg/L, respectively. Tentative DT50 depuration times can be estimated to be about 1.5 to 2 days. There was no evidence of a high bioaccumulating potential under the standard test conditions applied.

Bioaccumulation: terrestrial

No data available (not required for REACH)

Transport and distribution

Adsorption/Desorption

Koc for isopropylnaphthalene was estimated to be 7455 using the calculation tool US EPA EPI Suite). Accumulation of MIPN in soil and/or sediment is to be expected.

Henry’s Law constant

Using measured values for vapour pressure and water solubility, Henry's Law constant was determined to be 147 Pa*m³/mol indicating quite rapid volatilisation of MIPN from water into air.

Distribution Modelling

Results of distribution modelling with a Fugacity level III model give evidence that MIPN is distributed mostly into soil (ca. 86%) and to a much lesser degree into water (ca. 9%) and sediment (ca. 4%). Percentage in air is minimal (ca. 0.4%).