Ethyl acetate

Endpoint summary

Additional information

For acute toxicity to fish, two flow through studies with Pimephales promelas (Fathead minnow) were conducted using EPA methodology. The first study reported a 96-hr LC50 of 230 mg/L and 95% CLs were 220 to 250 mg/L. The second study reported no effects on larval fish survival within 96 hr at the highest concentration tested, 75.6 mg/l; therefore, no definitive LC50 was determined. Using static exposure conditions, a 96 -hr LC50 value of 212.5 mg ethyl acetate/L was reported in Heteropneustes fossilis (Catfish); 63.89 mg/L was considered to be a NOEC. A number of other studies have reported similar or higher acute toxicity values for ethyl acetate in fish. Another study reported a 48 -hr, static LC50 value of 210 mg/L for ethyl acetate in Poecilia reticulata (Guppy), although only limited information are available about this study. One study reported a 48 -hr LC50 value of 125 mg/L for ethyl acetate in Oryzias latipes (Medaka); however insufficient information is published to judge the reliability of this result and another study in the same species reported an LC50 of 900mg/l. The most reliable study is the one using the flow through methodology and measured concentrations. This reported an LC50 towards the lower range of those values reported. However, it should be noted that in general the reported LC50 values across 6 species and even more studies span a remarkably narrow range of values, indicating that toxicity is probably due to narcosis rather than a specific toxic effect . An experimental chronic fish toxicity study is available that did not establish a NOEC at the lowest tested dose of 9.65mg/l. However, a QSAR estimates the NOEC to be 6.9mg/l.

For acute toxicity to invertebrates, a total of 16 results from 8 different species are available from all studies identified. Two reliable 24-hour studies with the pelagic invertebrate Daphnia magna Straus were conducted using the DIN 38412 method and reported 24-h EC50 values of 2500 to 3090 mg/L. Lower LC50 values have been reported in Daphnia magna, but in each case there were a number of limitations with these studies precluding their designation as reliable for use. Lower values were also reported in Daphnia pulex (230 -290 mg/L) and in Daphnia cucullata (154 -175 mg/L) and an LC50 value of 590 mg/L in Gammarus pulex was reported in the same studies, but again only limited information is available. 24-h EC50 values in the marine invertebrate Artemia salina of 1590 mg/L and 349 -645 have been reported.  EC50 values reported for a number of other species were invariably above 1000 mg/l. The key parameter would normally be based on the reliable studies available. However, since these represent some of the higher values available and appear to be from a less sensitive species, the results from the supporting studies cannot be ignored, even though these are from studies whose reliability cannot be confirmed. As a conservative approach therefore, the key parameter is based on the lowest value reported, which is an EC50 of 165mg/l reported in Daphnia cucullata. Similarly, for salt water species, the key parameter is based on the EC50 of 346mg/l reported in 25% strength seawater again from an unratable study. A 21-day reproduction study in Daphnia magna using static renewal conditions reported a NOEC value of 2.4 mg/l (measured concentration) based on parental mortality and reproduction rate (Kuhn, et al., 1989).

For algae, a 72-hour GLP limit test study conducted according to OECD TG 201 using Scenedesmus subspicatus reported a NOEC in excess of 100 mg/l. A 48-hour study using Scenedesmus subspicatus reported an EC50value of 5600 mg/l and a NOEC of 2300mg/l. Studies which could not be rated for reliability due to a lack of information also reported consistent NOEC values of 1000mg/l or above in other algal species. Overall, the toxicity of ethyl acetate to algae appears to be very low. The key study is only a limit study. Only one study reports an EC50 and this is used for this key parameter. The EC10 is derived from the lowest reported actual value (which is greater than the value from the reliable limit test.) There is no reliable data for marine algae.

From a variety of studies in microorganisms where a weight of evidence approach is used, the lowest reported toxicity value was a 72-hr toxicity threshold (EC5) of 202 mg/L for ethyl acetate in Entosiphon sulcatum. Results from ciliated protozoa can be used to predict toxicity in a WWTP, but Entisiphon does not fall into this category. In the more commonly tested bacterium Pseudomonas putida, the lowest reported NOEC (a 16-hr EC3) was 650 mg/L. Results for all other protozoa and bacterium were in excess of this value.

The available measured short term toxicity data supports the conclusion that fish are not the most sensitive trophic level. From the acute toxicity data, invertebrates are more sensitive than fish or algae. This conclusion is made more robust by the fact that data is available from multiple species at each trophic level. This observation is also borne out in the data that is available for the chronic toxicity end points. A reliable 21-day reproduction study in Daphnia magna using static renewal conditions reported a NOEC value of 2.4 mg/l (measured concentration) based on parental mortality and reproduction rate. A 32-day early life-stage study with fathead minnows measured effects on survival and growth of the fish measured from the egg stage through to early life stages. The results do not allow a clear NOEC to be established, but it is clear that ethyl acetate is not a potent chronic toxicant; at 75mg/l, no mortality or adverse impact on hatching was seen, no mortality is evidence, and growth retardation was only reduced by 13% by length compared to controls. Based on the result however, it is reasonable to conclude that the study shows a NOEC<9.65mg/l. This can be considered a conservative approach. This study is supported by a reliable QSAR which estimates that the NOEC would be 6.9mg/l for a study of the same duration, which is very consistent with the experimental data.