Maleic anhydride

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.038 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.379 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.004 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

PNEC marine water (intermittent releases):

0.038 mg/L

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

44.6 mg/L

Assessment factor:

1

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.296 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.03 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:

0.037 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

The distribution of maleic anhydride in dogs was tested as part of a 90-day feeding study (60 mg/kg bw maleic anhydride in peanut oil). On day 1, the maleic anhydride plasma levels in the males ranged from 0.19 ppm to 0.78 ppm and in the females from 0.1 ppm to 0.88 ppm. Interpolation revealed that the blood concentration reached a plateau on day 55. After 90 days the plasma levels in the males ranged from 1.8 to 3.4 ppm and in the females from 1.9 to 3.5 ppm. The uptake rate constant was calculated to be 0.00349 per day, the elimination rate 0.0832 per day (OECD SIDS, 2005).

Considering the chemical structure of maleic anhydride, metabolism may consist of the hydrolysation to maleic acid in aqueous solutions and epoxidation of the double bond (estimated by means of the OECD Tool Box). These reactions lead to more polar and more water soluble products than the parent chemical (maleic acid is soluble in water (400 g/l at 20 °C) and has a log Pow of -0.48 at 25 °C (calculated by means of EPI Suite)) and are expected to be excreted predominantly via the urine. The epoxide is a reactive metabolite, but studies on genotoxicity (Ames test, chromosomal aberration test in vivo) were negative, i.e. there is no indication of reactivity of maleic anhydride or its metabolites under the test conditions.

The toxikokinetic study showed that maleic anhydride was ingested and distributed in the body. However, the elimination rate was considerably higher than the uptake rate. Taking also into account the log P_ow, the water solubility of the hydrolysation product maleic acid and the considerations on the metabolism, accumulation of maleic anhydride, and therefore secondary poisoning, is considered to be unlikely.

Conclusion on classification

Key data environmental classification (based on maleic anhydride):

* Short term fish: 96-h LC₅₀ for freshwater fish: 75 mg/L

* Short term daphnia: 48-h EC₅₀ for freshwater invertebrates: 37.9 mg/L

* Short term algae: 72-h E_rC₅₀ for freshwater algae: 65.8 mg/L

* Long term daphnia: 21-d NOEC for freshwater invertebrates: 10 mg/L (no reliable; secondary source)

* Long term algae: 72-h E_rC₁₀ for freshwater algae: 10.4 mg/L

* Effect on micro-organisms: EC₁₀ (18 h) for aquatic micro-organisms: 44.6 mg/L

* Biodegradability: Readily biodegradable

* Log K_ow: -2,61 (hydrolysis product maleic acid; hydrolysis DT50 = 0.3 min)

Short term aquatic hazard:

Category acute 1: no classification (all acute values > 1 mg/L)

Long term aquatic hazard:

(ii) Readily biodegradable, no bioaccumulation, adequate chronic toxicity data available; no classification (all chronic values > 1 mg/L)

Regarding all available data of the acute and/or chronic toxicity tests on aquatic organisms and taking into account the provisions laid down in Regulation 1272/2008 CLP (GHS), including ATP 790/2009 and ATP 286/2011, the substance does not have to be classified with respect to acute and chronic ecotoxicity.