[tristanstringer]

Hi David,

Thank you for the response.

I’m glad that you have some solutions available that will make using % dilution data in SSDs a lot more robust. While I do understand the basics of the transformation of the data, I will need to have a play with some dummy data to see how I go.

My next question is that when transforming % dilution data and using SSDTools, are we likely going to see a big change in SSD results, compared to just plugging in the % dilution data in to BurrliOZ which is the standard practice is now? This could be quite important with comparison of new data analyzed with the new methods in SSDtools to historical data. Especially in cases where the existing discharge mixing zones are based on SSD data from BurrloOZ.

Myself and my clients (especially the environmental consults) are doing SSDs on almost every DTA project that we do (as well as data from other labs) so the more guidance the better. Especially as currently the ANZG (2018) has no guidance on how to best do SSDs on % dilution DTA data, so we have had to default to the Warne et al. (2018) method. The obvious limitation is that this method was designed for a single toxicant not DTA data.

I would not be surprised that the if outside of the academic and WQG /ANZG application the most common use of BurrliOZ is on DTA data. (Though I may have a biased view as we don’t see a lot of single toxicant work). So, the more guidance we have on using the new methodologies in SSDTools the better.

Your point about the frequency of testing effluents due to the inherent variation is very true. This is obviously governed by the individual regulators which regulate the discharge. There is a lot of variation on how this is done through different frequencies of screening tests and “whole suite” (8 species) testing but perhaps there should be more attention to this in the future of the ANZG. I also think that this is where engagement with the regulators is important, especially when new methods are being developed. This would help with a better understanding on all sides of how to best implement DTA data.

Finally, about a turnkey software package, this is great news, obviously funding is always a limitation but if it helps, I will gladly pay a subscription fee to be able to use such a software package!

Many thanks and look forward to more discussion at SETAC.

[tristanstringer]

 

Thanks for the very informative SSD Session, I have two follow up questions:

• It was very informative with David’s comments on bimodal distribution, I have (perhaps wrongly) assumed when we see some bimodal distribution in DTA SSDs it was likely due to different species (or species types) being more or less sensitive to than the others to different contaminants present or some be more sensitive to the additive/ synergistic effects of the mixture.  This is probably a lot more complex than most of my clients want to get into though.
• Additionally, regarding concentration response data analysis I am interested in looking at alternative stat packages for deriving our statistical endpoints (ECx values) for our toxicity data. We like a few other labs are reliant on Toxcalc.  I know its limitations especially as really has no updates and support with it reliant on excel 2003 to run the plugin. I have looked at CETUS but again not sure about ongoing support and it was more difficult to use than ToxCalc for our purposes.   It would be great to have a nice plug and play stat package (perhaps as a R based package like BurrliOZ is?) as a replacement for ToxCalc for us that are not good with statistics and don’t know how to properly use R, but are good at running bioassays.

Many thanks,

Tristan Stringer

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