CDX-403

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

Algae growth inhibition tends to be the most sensitive aquatic endpoint reported for enzyme preparations in the literature with EC50 concentrations ranging from 99 to >1,000 mg/L (HERA, 2005). However, the published data support that enzyme preparations are not highly inhibitory to the growth of aquatic algae.

Again, interpretation of test results is complicated due the fact that enzyme preparations are mixtures. It should be noted that enzymes are produced through a fermentation process where micronutrients which are important to the growth of the bacteria and fungal species producing the enzymes are the same nutrients that are likely to impact the growth of algae. This raises complications in the interpretation of the results and calls into question the applicability of an algal growth inhibition study design for testing enzyme preparations which are likely to contain similar micronutrients that are in the growth media for the algal controls.

In summary, previous aquatic toxicity studies have 1) demonstrated that enzyme preparations are not appreciably toxic to aquatic life and 2) the test designs of the current study protocols were not developed to handle complex mixtures like enzyme preparations.