SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific...
Transcript of SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific...
![Page 1: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/1.jpg)
Using the SSD Toolbox to account for
interspecific variability in toxicity
M. Etterson
Center for Computational Toxicology and Exposure
Great Lakes Toxicology and Ecology Division
National Program: Chemical Safety for Sustainability
Research Areas: Ecotoxicological Analysis and Modeling
27 February 2020
K. Koehrn
Office of Pollution Prevention and Toxics
![Page 2: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/2.jpg)
What is an SSD?
• SSD = Species Sensitivity Distribution
• “A SSD is a statistical distribution
describing the variation among a set
of species in toxicity of a certain
compound or mixture” (Posthuma et
al. 2002)
![Page 3: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/3.jpg)
(selected) History of SSD
2008
EPA incorporates
SSDs into Web ICE
2002
Publication of
Reference
Book by
Posthuma,
Suter & Traas
(Eds.)
1985
Publication of
USEPA/OW
1985 guidelines
![Page 4: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/4.jpg)
An SSD = a statistical model
HC05
HC05
• Log10(LC50) ~ N(μ,σ)
• Log10(LC50) ~ μ + ε ; ( ε~ N(0,σ) )
• Inference usually is made on the 5th
percentile (HC05)
Log Toxicity Log Toxicity
Pro
ba
bili
ty D
en
sity
Cum
ula
tive
Pro
ba
bili
ty o
r
Pote
ntially
Affe
cte
d F
raction
![Page 5: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/5.jpg)
Example – DDT 14d avian LD50s
HC05
![Page 6: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/6.jpg)
SSD Toolbox - genesis
![Page 7: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/7.jpg)
Log10(LC50) ~ μ + ε ; ε~ N(0,σ)
Assumptions:
• All variation in sensitivity is random
• Toxicity data are an unbiased sample that is representative
of the set of species for which regulatory protection is
intended
• Toxicity test results for species in SSD are accurate
measurements of toxicity
• Field responses to exposure would be similar to laboratory
test results
![Page 8: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/8.jpg)
Questions we should ask about SSDs
▪ How does sample size influence bias and variance of the
estimated HC05?
▪ How do different estimation methods influence properties of the
estimated HC05?
▪ Is Akaike’s Information Criterion a useful method for identifying the
best distribution?
▪ Are goodness-of-fit tests reliable measures of performance?
▪ Does model-averaging across distributions improve estimates of
the HC05?
![Page 9: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/9.jpg)
SSD Toolbox - exodus
![Page 10: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/10.jpg)
Standalone Software
Design Criteria:
• Intuitive decision process for
model-fitting
• Methods vetted through peer-
review
• Standardized QA/QC
• Extensive help in User’s Guide
and Technical Manual
• Easy to use!
![Page 11: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/11.jpg)
(selected) History of SSD
2008
EPA incorporates
SSDs into Web ICE
2002
Publication of
Reference
Book by
Posthuma,
Suter & Traas
(Eds.)
1985
Publication of
USEPA/OW
1985 guidelines
2012-2018
SSD Toolbox Development
2019
SSD Toolbox
peer review
![Page 12: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/12.jpg)
SSD Toolbox Features
• Ability to fix six distributions accommodating differently “shaped”
data (normal, logistic, triangular, Gumbel, Weibull, & BurrIII)
• AICc methods for distinguishing among distributions
• Post-hoc Goodness of Fit (GoF) tests
• Extensive graphing and visualization tools
• Distribution-averaging of HC05 estimates
• Ability to use non-definitive toxicity values (e.g., LC50 > x)
![Page 13: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/13.jpg)
Software Demo!
![Page 14: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/14.jpg)
Using SSD Toolbox for the TSCA Risk
Evaluation for TCE• TSCA Background:
▪ Under TSCA, OPPT evaluates and regulates, as appropriate, the full life cycle of a chemical, i.e., manufacture (import), distribution in commerce, use and disposal.
▪ In 2016, TSCA was amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act
▪ Currently OPPT is drafting risk evaluations for the first 10 chemicals, including TCE, since the Lautenberg Act was signed.
• Used SSD Toolbox for aquatic toxicity data: algae data and acute toxicity data
![Page 15: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/15.jpg)
Algae toxicity data for TCE
• Algae toxicity data on TCE had a wide range of values.
• SSD was used as a line of evidence for assessing algae in this assessment.
• The resulting SSD calculated an HC05 of 52 mg/L or 52,000 µg/L.
Fig 1. SSD using EC50 algae data for TCE (triangular)
![Page 16: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/16.jpg)
Acute aquatic toxicity data for TCE
• SSD was also used as a line of
evidence for interpreting acute
toxicity data for other aquatic
organisms.
• The model-averaged HC05 from
all four distributions was 9.9
mg/L or 9,900 µg/L.
• The SSDs showed aquatic
invertebrates were the most
sensitive species.
Fig 2. SSDs using acute data for TCE (Gumbel, logistic, triangular, normal)
![Page 17: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/17.jpg)
The Future of SSD: Systematic Variation
Current usage SSDs are like
null models for taxonomic
variation in sensitivity
Log10(LC50) ~ μ + ε
▪ ε ~ N(0,σ)
Data from Fojut et al. 2012. Rev. Env. Contam. & Tox.
![Page 18: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/18.jpg)
The Future of SSD: Systematic Variation
Current usage SSDs are like
null models for taxonomic
variation in sensitivity
Log10(LC50) ~ μ + ε
▪ ε ~ N(0,σ)
▪ μ = f(invertebrate versus vertebrate)
Data from Fojut et al. 2012. Rev. Env. Contam. & Tox.
Fish↑
Inverts ↓
(mostly)
![Page 19: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/19.jpg)
Log10(LC50) ~ μ + ε
▪ ε ~ N(0,σ)
▪ μ = ?
The Future of SSD: Systematic Variation
HC05
Ulrich Prokop
Joseph C Boone
Ingrid Taylar
YathinAlan D. Wilson
Dariusz Kowalczyk
![Page 20: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/20.jpg)
HC05
Log10(LC50) ~ μ + ε
▪ ε ~ N(0,σ)
▪ μ = f(phylogeny + natural history + AOP + …?)
The Future of SSDPhylogeny from
Brusatte et al. 2015
Galloanseres:
~ 4.5% of birds
~ 66% of this SSD
![Page 21: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/21.jpg)
HC05
Log10(LC50) ~ μ + ε
▪ ε ~ N(0,σ)
▪ μ = f(phylogeny + natural history + AOP + …?)
The Future of SSDPhylogeny from
Brusatte et al. 2015
Galloanseres:
~ 4.5% of birds
~ 66% of this SSD
Nobu Tamura
![Page 22: SSD Toolbox presentation - US EPA€¦ · Using the SSD Toolbox to account for interspecific variability in toxicity M. Etterson Center for Computational Toxicology and Exposure Great](https://reader033.fdocuments.in/reader033/viewer/2022060517/604a524f0056354903631896/html5/thumbnails/22.jpg)
Future of the SSD Toolbox?
• www.epa.gov/chemical-research/species-
sensitivity-distribution-toolbox
• Further enhancement of visualization tools
• Increased model-fitting capacity using MCMC
sampler