You could follow different regulatory body guidelines. The USEPA uses Raphidocelis subcapitata as test alga. Follow this link to the article. The methodology is detailed.Article Modifications to the algal growth inhibition test for use as...

You could also try OECD GUIDELINE FOR TESTING OF CHEMICALS. The document is attached. Chlorella vulgaris is also used here in addition to the alga earlier mentioned. Please note: Raphidocelis subcapitata was formerly Selenastrum capricornutum.

I am not sure exactly what might be covered in a formal ecological risk assessment, but likely substantially more than supported with algal testing. I have attached this link, and you might review and consider using some of the citations. The toxicity of pesticides can be very specific, but ecologically more potential to affect other areas than one might realize.

https://en.m.wikipedia.org/wiki/Pyrethroid

One might also also look up the pesticide label as it often has added information about effects, conditions for use, toxicity, citations, etc. If having algal problems, there might be biological controls available to consider such as infertile green carp, or water quality evaluation to check and manage pollutants or chemistry supporting excessive algal growth.

P.S. Kayshap: I am affraid that the results of algal growth inhibition tests are not enough for environm,ental risk assessment. There are rules how to perform environmental risk assessment. It is a complex task and results of algal growth inhibition test are not enough to perform it (environmental risk assessment).

Please see:

https://www.efsa.europa.eu/sites/default/files/161115-p03.pdf

https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/overview-risk-assessment-pesticide-program

Article Environmental risk assessment of pesticides: state of the ar...

Best regards

Vit

Dear P.s.,

for the risk assessment of an active ingredient in the environment many different test species are necessary. For the EU, please have a look to the data requirements for active ingredients and to the risk assessment of aquatic organisms of EFSA (European Food safety Agency). The principle is that you determine an acute endpoint (e.g. EC50) and/or a chronic endpoint (e.g. No-observed-effect-concnetration (NOEC)) in a lab test system, calculate a predicted no-effect concentration (PNEC) by applying an assessment factor and finally calculate a risk quotient by applying PNEC and the predicted environmental concentration (PEC). Please note that for the risk assessment analytically measured concentrations are highly recommended. Based on your test results, you will be able to assess the risk for your tested green alga species.

Kind regards, Thomas

Thank you all for your response.

I agree with Thomas Schmidt answer.....

• EU_2013_No 283_Data requirements for active substances.pdf1.74 MB
• EFSA_2013_Guidance on tiered risk assessment for plant protection products for aquatic organisms in edge-of-field surfacewaters.pdf

I agree with the other answers but the imprtant thing to remember re Ecorisk is you need to use the EC or LC50 for the most sensitive trophic level. In the case of permethrin algae are not the most sensitive trophic level. Usinf algae for permethrin will result in an ineffective ecorisk as you need to protect the invertebrates communtiy who are typically the most sensitive for pyrehtroids

Following the contribution. It would be interesting to know.