Isopropylnaphthalene

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.26 µg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

1.5 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.026 µg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

2.22 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

197.1 µg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

19.71 µg/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:

39.15 µg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

49 mg/kg food

Assessment factor:

70

Additional information

Deduction of PNECs is based on the Guidance Document "Guidance on information requirements and chemical safety assessment - Chapter R.10: Characterisation of dose [concentration]-response for environment" (TGD R.10) published by the European Chemicals Agency, 2008.

PNECs aqua are derived from aquatic toxicity data for monoisopropylnaphthalene and diisopropylnaphthalene as supporting substance applying the appropriate assessment factors.

PNECs for sediment and soil are calculated using the equilibrium partitioning method. For these calculations, values for Koc and Henry's Law Constant (HLC) are required in addition to PNECs aqua. Values for Koc and HLC (see IUCLID Sect. 5.4.1 and Sect. 5.4.2) were estimated by calculation using the estimation program US EPA EPI Suite v4.1.

PNECs aqua (freshwater)

For monoisopropylnaphthalene short-term toxicity data are present for aquatic invertebrates (two tests) and fish (studies according to OECD TG 202 and 203). In addition, a NOEC was obtained in a 72-h algal growth inhibition test according to OECD TG 201. As data on long-term aquatic toxicity for monoisopropylnaphthalene could not be identified, data from diisopropylnaphthalene as supporting substance are used. For this substance, a daphnia immobilisation and reproduction test according to OECD TG 201, Part II (1984) was performed.

The following data are available for assessment of the aquatic toxicity of monoisopropylnaphthalene.  

	Monoisopropylnaphthalene		Diisopropylnaphthalene
	MIPN		DIPN
(values in mg/L)	L/EC50	NOEC	NOEC
Short term toxicity test to fish (96 h)	0.74
Short term toxicity test to aquatic invertebrates (48 h)	0.67
Short term toxicity test to aquatic invertebrates (48 h)	0.15
Algal growth inhibition test (72 h)	0.25	0.079
Daphnia immobilisation and reproduction test (21 d)			0.013

The data from the daphnia reproduction test with the supporting substance diisopropylnaphthalene (0.013 mg/L) is adopted for monoisopropylnaphthalene to characterise the inherent long-term aquatic toxicity.

There are toxicity data for all three trophic levels. In addition to short-term tests, results of a long-term study with daphnia are available. Daphnia is the most sensitive species regarding aquatic toxicity indicated by test results obtained for the three trophic levels. NOEC are available for algal growth inhibition and daphnia reproduction. As all three trophic levels are covered and two long-term results (NOEC) are available covering the most sensitive species, the PNEC aqua (freshwater) will be derived from long-term toxicity data of the most sensitive species. An assessment factor of 50 (see Guidance Document Chapter R.10.3.1.2. Table R.10-4) is applied to this value (daphnia reproduction test, NOEC = 13 µg/L, derived from data for diisopropylnaphthalene) to generate the PNEC aqua (freshwater).

PNEC aqua (marine water)

For monoisopropylnaphthalene, toxicity data with marine species are not available. The NOEC for daphnia reproduction (13 µg/L, lowest NOEC) adopted from the daphnia reproduction test of the supporting substance diisopropylnaphthalene is taken to derive the PNEC (aqua marine water). To compensate for a wider diversity of taxonomic groups and to allow for a broader distribution of sensitivities in the marine environment, an assessment factor of 500 is applied according to Guidance Document Chapter R.10.3.2.3, Table R.10-5.

PNEC STP

Toxicity data of isopropylnaphthalene to aquatic microorganisms are only available from a ready biodegradation test. No inhibition of biodegradation was observed in the toxicity controls at a MIPN concentration of 22.2 mg/L. An assessment factor of 10 is applied on this value in order to derive the PNEC STP.

PNEC sediment (freshwater)

According to chapter R.10.5.2.1 of TGD R.10,the PNEC sediment can provisionally be calculated in the absence of data for sediment-dwelling organisms using the equilibrium partitioning method (EPM).

PNEC derivation following procedures of TGD R.10 and R.16:

PNEC aqua (freshwater): 0.26 µg/L,

Koc:7544L/kg (US EPA EPI Suite estimate, program KOCWIN v2.00, Koc estimate from MCI; see IUCLID Sect. 5.4.1);

The PNEC sediment (freshwater) was calculated to 42.84 µg/kg ww. This value was converted to dry weight (conversion factor of 4.6) resulting in a PNEC sediment (freshwater) of 197.1 µg/kg sediment dw.

PNEC sediment (marine water)

According to chapter R.10.5.3.1 of TGD R.10,the PNEC sediment can provisionally be calculated in the absence of data for sediment-dwelling organisms using the equilibrium partitioning method (EPM).

PNEC derivation following procedures of TGD R.10 and R.16:

PNEC aqua (marine water): 0.026 µg/L,

Koc: 7544 L/kg (US EPA EPI Suite estimate, program KOCWIN v2.00, Koc estimate from MCI; IUCLID Sect. 5.4.1);

The PNEC sediment (marine water) was calculated to 4.284 µg/kg ww. This value was converted to dry weight (conversion factor of 4.6) resulting in a PNEC sediment (marine water) of 19.71 µg/kg sediment dw.

PNEC soil

According tochapter R.10.6.1 of TGD R.10, the PNEC soil can provisionally be calculated in the absence of data for soil organisms using the equilibrium partitioning method (EPM).

PNEC derivation following procedures of TGD R.10 and R.16:

PNEC water (freshwater): 0.26 µg/L,

Koc: 7544 L/kg (US EPA EPI Suite estimate, program KOCWIN v2.00, Koc estimate from MCI; IUCLID Sect. 5.4.1),

HLC: 147 Pa*m³/mol (US EPA EPI Suite estimate, program HENRYWIN v3.20, bond estimation method; IUCLID Sect. 5.4.2);

The PNEC soil was calculated to 34.65 µg/kg ww. This value was converted to dry weight (conversion factor of 1.13) resulting in a PNEC soil of 39.15 µg/kg soil dw.

Secondary poisoning

For monoisopropylnaphthalene, data concerning secondary poisoning are not available. As substitute, data from diisopropylnaphthalene as supporting substance are used.But secondary poisoning can only be assessed based on mammalian toxicity data, as information on toxicity to birds could not be identified.

Repeated-dose toxicity of DIPN has been tested in an oral 6-months repeated-dose toxicity study with rodents (rats) (see IUCLID Sect. 7.5.1 - Repeated-dose toxicity). A NOAEL of 170 mg/kg bw/day was determined. For use in the assessment of monoisopropylnaphthalene, this value is adopted.

Using a conversion factor of 20 for rats to obtain a NOEC(food) from NOAEL(oral) (Rattus norvegicus > 6 weeks - TGD R.10,Table R.10-12), a NOEC(mammal, food) of 3400 mg/kg food is calculated. According to TGD R.10, Table R.10-13, assessment factors of 90 or 30 should be applied to extrapolate from the NOEC to the PNEC oral (secondary poisoning), respectively, when toxicity data result from a subchronic or chronic study. To account for the differing time scale of the underlying oral rodent 180 days repeated-dose toxicity study (time scale between subchronic and chronic study), an assessment factor of 70 will be used for extrapolation. Thus, a PNEC oral (secondary poisoning) of 49 mg/kg food is calculated.

Conclusion on classification

Monoisopropylnaphthalene, isomer mixture [CAS no. 29253-36-9] shows acute aquatic toxicity below 1 mg/L on all three trophic levels: 0.15 =< EC/LC50 =< 0.7 mg/L.

According to Regulation (EC) No 1272/2008, this triggers classification 'Aquatic Acute 1', H400 (very toxic to aquatic life). In addition, chronic aquatic toxicity data (0.01 =< NOEC =< 0.1 mg/L) in combination with easy/rapid biodegradability leads to classification with 'Aquatic Chronic 2', H411 (toxic to aquatic life with long lasting effects).