Acrylaldehyde

Endpoint summary

Additional information

For freshwater fish reliable LC50-values were considered to be in the range of 14 to 90 µg/l, all based on measured concentrations. The LC50 of 19.5 µg/l is considered to be the most reliable LC50 value for freshwater fish because a detailed study report was available for the registrant. The most reliable LC50-value for marine fish is 179 µg/l (recalculation (geometric mean) from test results EC0 100µg/l and EC100 320µg/l).

The lowest reliable long-term fish toxicity study is a 60-days reproduction study with Pimephales promelas. A NOEC-value of 11.4 µg/l is reported (measured value) for effects on mortality of adults, number of spawning, number of eggs per female, number of eggs per spawn, length of offspring and hatchability.

For Daphnia magna the 48-hours LC50-values range from 22 to 93 μg/l. The EC50 of 90 µg/l is considered to be the most reliable value because a detailed study report was available for the registrant. For salt water invertebrates the lowest EC/LC50 values were 55 μg/l for Crassostrea (shell growth) and 100 μg/l for Penaeus aztecus. However, these values are reported in a review without further details. For this reason both results can only be used as supportive information. No effects were observed after three repeated short-term exposures of 24h to 0.24 mg/L acrolein followed by 6d recovery phases to adult animals of the crustcean Hyalella curvispina.

The lowest reported effect concentration in a three generation study is a 64-days NOEC-value of 16.9 μg/l for Daphnia magna.

The lowest 72h-EC50 value of 26 µg/l is found for Scenedesmus subspicatus and is based on the endpoint biomass (72h-EC50 = 61 µg/l based on the endpoint growth rate). The NOEC for growth rate was 10 µg/l. The study was considered to be reliable in the EU-RAR (2001), even though does not meet a main validity criteria, as the cell number in the controls increased by a factor of only ca. 15.

In tests with Potamogeton nodosus and Potamogeton pectinatus foliar damage of aquatic macrophytes exposed to acrolein is determined. The lowest NOEC of 10 µg/l was reported for Potamogeton pectinatus. When acrolein is used to clear unwanted vegetation from irrigation canals, its effective dose range is 1–15 mg/litre over an exposure period of 0.25–8 h.

For the bacterium Proteus vulgaris a 2 hour EC₅₀ of 20 μg/l was determined. The 0.5 h EC₅₀- value for activated sludge bacteria from municipal origin was found to be 400 mg/l (respiration inhibition).

In a 96-hours multiple species test a LC₅₀ of 7 μg/l is reported for the tadpole Xenopus laevis, based on measured concentrations.

Bufo arenarum larvae were subjected to three repeated exposures to acrolein up to 0.023 mg /L (based on initial measured concentration) for 24 h followed by 13d of recovery. No cumulative effects on mortality and completing metamorphosis were seen for the repeated exposures up to 0.023 mg/L of acrolein.

In many of the aquatic studies, the exposure solutions were periodically replenished via static renewal. In other cases, the organisms were exposed in a flow-through design to a continually renewed solution of acrolein. Dose–response relationships were frequently based on nominal concentrations of acrolein because of the ready volatilization and degradation of acrolein in aqueous solutions. The actual concentrations to which the organisms were exposed, particularly in the case of static renewal bioassays, may have been lower than reported. As a result, many of the existing data may underestimate the toxicity of acrolein to aquatic organisms. (WHO, 2002).

Biotransformation and kinetics

The fish species Lepomis macrochirus and Ictalurus punctatus, the clam Elliptio complanata and the crayfish Orconectes virilis were exposed to 20.2 µg/L (fish) and 101µg/L (clam, crayfish) acrolein in static exposure test systems, with two applications of acrolein made at 7-d intervals. Neither acrolein, acrylic acid, nor allyl alcohol were detected in the edible tissues of any of the test species. Metabolites of acrolein found in the water-extracted tissues were primarily alcohols and organic acids. These results suggest that the rapid biodegradation of acrolein in aquaria water is followed by the rapid and complete metabolism of the parent and water-borne metabolites in the tissues of all four species tested. They are able to further metabolize these compounds in their tissues to 10 identified metabolites, with a number of polar and nonpolar compounds being generally characterized as carbohydrates, amino acids, and peptides.

Additional ecotoxicological information

In a field study over a period of two years during spring and summer period exposure of irrigation channels with rates of 10 to 15 mg/L for 1 to 4 h (first year) and 2 to 8 mg/L for 4 to 12 h (second year) effected the benthic invertebrates inhabiting the channels. About two months after the last herbicide applications (late summer-autumn), the benthic invertebrate communities in treated channels recovered their biotic attributes, reaching values similar to those of controls, except for diversity which remained significantly lower (28% decrease vs control) in the second year. Immediately before initiating a new application campaign, treated channels did not show significant differences in the biotic attributes in reference to control channels. The community attributes of benthic invertebrates from drainage collector sites expected to receive the herbicide through percolation (downstream) did not differ from their upstream control sites. Recolonization by aerial flight and oviposition by adults (insects), vertical migration from deeper layers of the bottom used as refuge (sediment dwellers), and downstream drift from upstream unaffected areas are possible mechanisms for recovery, as Acrolein is unlikely to accumulate in the habitats due to biodegradation.

Summary:

Acute toxicity to aquatic species

Freshwater

Fish:                   96h-LC₅₀= 0.0195 mg/l for Pimephales promelas(OECD TG 203).

Invertebrates:      48 h-EC₅₀ = 0.090 mg/l for Daphnia magna (DIN 38412, part 11)

Algae:                 72 h-ErC50 = 0.061 mg/l for Scenedesmus subspicatus (DIN EN 28692/1993)

Marine

Fish:                   96h-LC₅₀= 0.179 mg/l for Pleuronectes platessa (Government Publishing Office, Netherlands (1980)).

Invertebrates:      no reliable data available

Algae:                 no data available

Chronic toxicity to aquatic species

Freshwater

Fish:                   60 d-NOEC = 0.0114 mg/l for Pimephales promelas (APHA 1971).

Invertebrates:      64 d-NOEC = 0.0169 mg/l for Daphnia magna (3 generation study; APHA 1971)

Algae:                 72 h-NOEC (growth rate) = 0.010 mg/l for Scenedesmus subspicatus (DIN EN 28692/1993)

Marine

Fish:                   no data available

Invertebrates:      no data available

Algae:                 no data available

Toxicity to microorganisms

2 h-EC₅₀ = 0.020 mg/l for Proteus vulgaris (no guideline reported)

30 min-NOEC = 400 mg/l for activated sludge (Pagga 1981)

Toxicity to other aquatic organisms

Tadpole:             96h-LC₅₀= 0.007 mg/l for Xenopus laevis (OECD TG 203).

The lowest long-term aquatic toxicity test result for acrolein covering four trophic levels is the ScenedesmusNOEC of 10 µg/l. This NOEC would normally be used for the derivation of the PNEC in water (using an assessment factor of 10). However, the available long-term tests do not cover the most sensitive species from the short-term tests, i.e. the LC50 for Xenopus laevisof 7 µg/l. Therefore the latter result is used for the derivation of the PNEC (EU, 2001; WHO, 2002).