Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability:

Hydrolysis:

Key study

In an EU Method C.7 study conducted under GLP conditions Molyvan 855 hydrolyses in water at a neutral pH (~ 6-7) with a half life of 10.3 days at 15 deg C. Molyvan 855 hydrolyses following pseudo first order kinetics to form molybdenum and coco diethanolamide which was analytically confirmed in this study.

Biodegradation:

Biodegradation in water: screening

Key study:

In a biodegradation study conducted according to Japanese Guideline study on microbial degradation of chemical substances (MHLW/PFSB Notification No. 1121002 Nov 21, 2003, METI/MIB Notification No. 2 Nov 13 2003, and MOE/EPB Notification No. 031121002 last revised Nov 20, 2006) under GLP conditions, degradation of Molyvan 855 averaged 57% (based on BOD) and elimination was 98% (based on residual test substance) after 28 days in sludge. The parent substance is fully eliminated with molybdenum turning to molybdic acid. Structurally modified, water soluble substances also were produced. (Mitsubishi Chemical Medience Corporation, 2009).

Supporting study:

In a study conducted according to Japanese Guideline,Degree of Decomposition of Chemical Substances by Microorganisms, etc. in Test Methods for New Chemicals based on Kanhogyo No. 5, Yakuhatsu No. 615 and kikyoku No. 392 (1984), similar degradation rates were observed. Decomposition averaged 61% (based on BOD) after 28 days in sludge, although overall decomposition of two primary substance constituents averaged 92% (based on TOC) and 97% (based on HPLC). (Kagakuhin Kensa Kyokai Foundation, 1987).

Biodegradation in in water and sediment

According to 9.2.1.2 Column 2 of Annex IX of the European Union (EU) Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) 1907/2006 regulation, the simulation testing on ultimate degradation in surface water study need not be conducted if the substances is highly insoluble in water, or the substance is readily biodegradable. Experimental evaluation of the water solubility resulted only in a limit value (actual value <1.25 mg/L, slightly soluble) due to the necessity to employ a visual method. Subsequent computer modeling of individual components, performed to provide definitive solubility data, resulted in a majority of the estimated values being within the “insoluble” classification range (actual values were 0.005 to 0.21 mg/L). Although Molyvan 855 does not meet the criteria for "readily biodegradable", degradation of the substance averaged 57% and 61% (based on BOD) and elimination was 98% and 97% (based on residual test substance) after 28 days in sludge in two biodegradation studies. This endpoint is, therefore, being waived.

Biodegradation in soil

According to 9.2.1.3 Column 2 of Annex IX of the European Union (EU) Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) 1907/2006 regulation, soil simulation testing (for substances with a high potential for adsorption to soil) study need not be conducted if the substance is readily biodegradable, or if direct and indirect exposure of soil is unlikely. Although Molyvan 855 does not meet the criteria for "readily biodegradable", degradation of the substance averaged 57% and 61% (based on BOD) and elimination was 98% and 97% (based on residual test substance) after 28 days in sludge in two biodegradation studies. Additionally, Molyvan 855 is considered immobile in soils based on the estimated adsorption coefficient (log10 Koc) values in the range of 3.52 to at least 5.43 for the dominant lauric acid and myristic acid reaction products. The less abundant fatty acid constituents resulted in estimated adsorption coefficient (log10 Koc) values in the range of 2.44 to at least 6.47. The upper value of each range was reported as a limit value due to possible additional reaction of the organic subunits, resulting in higher molecular weight species containing multiple coconut oil alkyl residue groups. It is acknowledged that such products would present even higher adsorption coefficients. This endpoint, therefore, is being waived.

Bioaccumulation:

Key study

In an OECD 305 study conducted under GLP conditions, Molyvan 855 does not exhibit a bioconcentration potential, as all measured components of the complex reaction mixture have bioconcentration factors (BCF) of less than or equal to 617, for both the low and high exposure levels. Five main components (identified as A, B, C, D and E) were analysed and evaluated for bioconcentration potential, all of which had BCF values below 100. Component C was detected in some fish at the high exposure level on Days 28 through 60, but was not detected in fish from the low exposure level throughout the exposure period. Since results for all but one main component were below the limit of detection, the variation in bioconcentration factors could not be assessed, and the steady state attainment could not be determined. Four additional components (identified as F, G, H and I) were analytically monitored and resulted in BCFs ranging from 9 to 617. (Mitsubishi Chemical Medience Corporation, 2011)

Transport and distribution:

Adsorption/desorption:

Key study

Based on solubility data available for the test item, the batch equilibrium method for quantification of adsorption properties would not be feasible employing the procedure detailed within OECD Method 106. This was because of the limited water solubility of the test item.

The HPLC estimation method procedure detailed in OECD Method 121 also was considered not to be valid for this test item, due to potential non-partitioning interaction of the molybdenum containing functional group with the HPLC column stationary phase. In the absence of chemically related reference substances of known adsorption coefficient values with which to construct the calibration curve, it was considered that a valid adsorption coefficient based on HPLC retention time could not be determined for this test item.

As the experimental procedures detailed within the above referenced guidelines were concluded to be either unfeasible or invalid, due to the nature of this test item, alternative validated estimation methods have been employed.

Estimation of adsorption coefficient was performed using both a Quantitative Structure Activity Relationship (QSAR) method and a molecular connectivity index (MCI) method. Estimations were performed on an individual component basis, with no specific molybdenum correction factor employed, and the results were presented as a range of adsorption coefficient values. The estimated adsorption coefficient (log10 Koc) values were in the range of 3.52 to at least 5.43 for the dominant lauric acid and myristic acid reaction products. The remaining, less abundant fatty acids resulted in estimated adsorption coefficient (log10 Koc) values in the range of 2.44 to at least 6.47. The upper value of each range was reported as a limit value due to possible additional reaction of the organic subunits, resulting in higher molecular weight species containing multiple coconut oil alkyl residue groups. It is acknowledged that such products would present even higher adsorption coefficients. The calculation procedure undertaken was limited to the initial reaction products containing only a single coconut oil alkyl residue group as this was sufficient to demonstrate the theoretical immobility of this substance in soils.

Other distribution data:

Key study

Important differences are found between the behaviour of the substance in purified water compared with aqueous media containing biotic matter. The primary difference is that presence of biotic matters seems to eliminate organic molybdenum species in favour of molybdic acid and structurally modified organic species, and this leads to a compartmental distribution which predominates in the aqueous phase with negligible matter in the organic phase.

Proposed compartmental distributions:

Molyvan 855J: Water 100%, sludge 0%

Molybdic acid: Water 100%, sludge 0%

Structurally modified organic substances: Water 100%, sludge 0%