Hexamethylene diisocyanate

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

A QPRM was elaborated for the verification of the BCF as calculated in the Epiwin software package.

Principles of method if other than guideline:

Calculated using BCF Program v2.17 of EPI-Suite software. The estimation methodology is based on the chemical structure of an organic compound and its log octanol-water partition coefficient (Kow). Depending on chemical structure, structural correction factors are applied.

GLP compliance:

no

Test organisms (species):

other: none, estimated by calculation

Type:

BCF

Value:

59.6

Basis:

other: calculation

Remarks on result:

other: QSAR

Any decomposition of the substance in water is not considered by the program.

Applicability domain (OECD principle 3)

i.       Molecular weights:

With a molecular weight of  168.2 g/mole the HDI is within the range of the training set (18.02 - 719.92 g/mole) as well as in the range of the validation set (27.03 - 991.15 g/mole).

ii.       LogKow:

With a logKow value of 3.20, the substasnce is within the range of training set (Non-Ionics: -1.37 – 11.26)

Structural fragment domain:

Regarding the structure HDI, the fragment descriptors found by the program are complete and listed in Appendix D (KOWWIN Fragment and Correction Factor descriptors).

Executive summary:

HDI (CAS-No. 822 -06 -0) is characterized by a BCF of 57.63 being calculated with BCFWIN v. 2.17 (Currenta, 2009).

Description of key information

Hexamethylenediisocyanate is characterized by a BCF of 58 being calculated with BCFWIN v. 2.17 (Currenta, 2009e). As HDI hydrolyses rapidly, the BCF of the hydrolysis product was calculated. The hydrolysis product hexamethylenediamine (HDA) is characterized by a BCF of 3 being calculated with BCFWIN v. 2.17 (Currenta, 2009d).

Additional information

The direct and indirect exposure of the aquatic compartment is unlikely because hexamethylene diisocyanate (HDI) hydrolysis completely in water within far less than 1 hour at environmental relevant concentrations. For this reason, an experimental study is not useful, andcalculated values can be used. Based on a log Kow of 3.2, a bioconcentration factors (BCF) of 58 was estimated for hexamethylene diisocyanate (HDI). For the hydrolysis product hexamethylene diamine (CAS 124-09-4), a BCF of 3 based on a log Kow of 0.02 was obtained. Neither the substance nor the hydrolysis product hexamethylene diamine do not have high bioaccumulation potential.