1,5-naphthylene diisocyanate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.009 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.087 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.001 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

100 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.015 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.001 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.001 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Lowest effect values reported in ecotox studies are as follows:

 

Fish:             LL0 >50 mg/L (Bayer Industry Services 2005a)

Daphnia:     EL0 >100 mg/L (Bayer Industry Services 2005b)

Algae:          E_rC50 8.744 mg/L, E_rC10 0.512 mg/L, NOEC_r0.073 mg/L (Bayer Industry Services 2006)

Considering the NOEC_rof 0.073 mg/L and the fact, that the substance is rapidly degradable (hydrolysis half time <1 hour), a classification of chronic cat. 2 (H411) according to Regulation EC No. 1272/2008 would be required. The reported NOEC value is indeed statistically significant, but not from a biological point of view. The reported E_rC10 of 0.512 mg/L is statistically and biologially valid. Based on this result, and as the substance is rapidly degradable, a classification chronic cat. 3 (H412) is required according to Regulation EC No. 1272/2008.

The concept of using the EC10 instead of a NOEC is discussed in relevant documents as presented in the following

• CLP [(EU) No 286/2011 "... The NOECs or other equivalent ECx (e.g. EC10) shall be used."
• Guidance on information requirements and chemical safety assessment, Chapter R.10: Characterisation of dose [concentration]-response for environment: " An EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis)will be used preferentially."
• OECD 201 "Recent scientific developments have led to a recommendation ofabandoning the concept of NOEC and replacing it with regression based point estimates ECx.")

Conclusion on classification

The classification of 1,5-naphthylene diisocyanate was based on the parent substance. Rapid hydrolysis of the substance was determined in an OECD 11 study on hydrolytical behaviour. While the formation of the reaction product 1,5 -naphthylene diamine was reported in this study it was demonstrated that this should be understood as the consequence of artificial test item preparation conditions (i.e. stirring). Under environmentally relevant conditions the final reaction product should be chemically inert poly-urea (for details see discussion in "hydrolysis" endpoint summary). The classification of 1,5 -naphthylene diisocyanate should, thus, be based on either poly-urea which is not classified according to Regulation (EC) No 1272/2008 or on the parent substance itself and the latter one was found to be appropriate.

Classification of 1,5-naphthylene diisocyanate based on Regulation (EC) No 1272/2008

 

- Category acute: There is only one acute category with the criterion: L/EC50 <= 1 mg/L. For 1,5-naphthylene diisocyanate there are studies on acute toxicity for fish, daphnids and algae and the lowest L/EC50 was reported as 8.74 mg/L (algae).

Result: The lowest L/EC50 was clearly higher than the criterion and, thus, there is no justification for a classification based on acute toxicity of 1,5-naphthylene diisocyanate.

 - Category chronic: There are data on short-term toxicity (fish, daphnids, algae) as well as chronic data (algae). With this dataset the classification has to be decided based on both acute and chronic data and the more critical classification has to be used for classification.

 a) Classification based on chronic data:

- Rapid degradation? Yes, due to rapid hydrolysis

- Lowest NOEC/EC10? Is in the range of 0.1-1 mg/L (= 0.512 mg/L for algae)

=> Result: Classification “category chronic 3” based on chronic data

 b) Classification based on acute data:

- Lowest L/EC50? Is in the range 1-10 mg/L (= 8.74 mg/L for algae)

- BCF >= 500? No, the experimental BCF is < 4.5

- Log Kow >= 4? No, the experimental log Kow is 0.91

=> Result: No chronic classification based on acute data

 Conclusion, 1,5-naphthylene diisocyanate does not need to be classified for acute toxicity but for chronic toxicity “category chronic 3” is justified (H412).