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Technical Challenges in the Development of the Clark Fork River Ecological Risk Assessment Dale J. Hoff, Ph.D. Region VIII, USEPA BTAG Coordinator.

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Presentation on theme: "Technical Challenges in the Development of the Clark Fork River Ecological Risk Assessment Dale J. Hoff, Ph.D. Region VIII, USEPA BTAG Coordinator."— Presentation transcript:

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2 Technical Challenges in the Development of the Clark Fork River Ecological Risk Assessment Dale J. Hoff, Ph.D. Region VIII, USEPA BTAG Coordinator

3 Clark Fork River Ecological Risk Assessment n Not Here to talk about the Results of the Assessment as much as to discuss technical aspects of multiple debates n IMPORTANT: NEED to acknowledge the incredible support that this project received from ORD: Drs. Erickson, Stephan and Mount from the Duluth Effects Lab.

4 Multiple Lines of Evidence were used to Answer Questions of Aquatic Risk n Weight of Evidence Approach –Predictive approach: n HQ= Site exposure / Reference Exposure –Site-Specific Toxicity Tests n WER Ratio tests…… n caged fish studies n dietary exposure studies –Direct Observations of Receptor Demographics

5 Major Findings from the CFRERA n Impacts to the Aquatic Community as a Whole from As, Cd, Cu, Pb and Zn –Comparison of AWQC values to Total and Dissolved Metals –Total and Dissolved metals concentrations compared to both acute and chronic criteria n Total recoverable concentrations of all metals exceeded AWQC n Dissolved concentrations of only Cu exceeded Chronic and Acute occasionally

6 Major Findings from the CFRERA n Impacts to Salmonids –Predictive: Few, < 10 out of 232 exceed salmonid surface water toxicity reference value –Toxicity tests: Toxicity tests completed by PRP and supported by trustee results for respiratory exposure were used to derive site specific surface water TRVs, 2 out of 232 exceeded chronic, O exceeded Acute. –Demographics: 2 replicates (multiple years) of 15 stations consistently had less fish on CFR compared to Reference

7 Major Findings from the CFRERA n Other Toxicity tests on Salmonids –Trout Feeding Studies n Conflicting results led to multiple analyses to reduce uncertainty. Oral TRVs were used from the lowest concentrations leading to effects (Woodward et al ). Very few exceedences occurred of little magnitude and only in the upper reaches n Tissue burdens in fish leading to effects in growth from other pathways of exposure were used to help support site-specific TRV. –Conclusion: supported decrease in demographics were more a result of Acute, not chronic exposure

8 Major Findings from the CFRERA n Other Toxicity tests on Salmonids –Caged fish studies n Hatchery fish were placed in cages in the river during spring flow. n No apparent or statistical correlation between ambient, measured levels of total recoverable and survival were noted, n Survival and growth were decreased on the CFR compared to reference –Conclusion: Caged fish studies support Acute exposures more than chronic exposures resulting in effects.

9 Major Findings from the CFRERA n Other Toxicity tests on Salmonids –Flow through Mobile Laboratory test n Multiple life stages of trout exposed to dilutions of CFR water and survival of eggs, swim-ups, and frys monitored. Water concentrations of metals quantified every 4 hrs for 6 weeks during spring runoff. n No difference among any endpoints and any dilutions. No high spikes from low-flow runoff year were noted. –Conclusions: Supportive of acute risks, not chronic risks

10 Major Findings from the CFRERA n Other Toxicity tests on Salmonids n Non-lethal Endpoints –Biomarkers n Metallothionein n lipid peroxidase n Clinical Pathology: liver enzymes, Blood Cell counts, etc –Avoidance n Laboratory avoidance is most likely real at concentrations as low as 1 ppb dissolved Cu. –Uncertainty: Evidence of exposure, not effects, principally in laboratory only, little concurrent evidence of exposure and effects in the field.

11 Major Findings from the CFRERA n Impacts to Benthic Invertebrates –Predictive: Some species should be impacted based off of Daphnia toxicity values –Toxicity tests: Sediment, SEM-AVS, pore- water analyses demonstrate and predict toxicity in upper portions –Demographics: A 12 yr data set collected by the same observer in the same locations consistent with finding that sensitive species are limited, but biomass unaffected

12 Major Findings from the CFRERA n Impacts to Benthic Invertebrates –statistical correlation between water concentrations, not sediment, and tissue concentrations positive –statistical correlation between water concentrations, not sediment, and species richness and EPT indexs were positive. n Conclusions: All three lines of evidence not consistent with a large magnitude of chronic risk to COMMUNITY, principle pathway was through the water, not sediment.

13 Major Findings from the CFRERA n Impacts to Algae –Predictive: Few exceedences of Surface water TRV –Toxicity tests: no direct toxicity studies available –Demographics: Algal populations are the same as reference stream. n Conclusion: Algal populations on the CFR are not impacted by metals

14 How can the following observations be concurrently occurring? n Trout population (k- selected, top level predator) be decreased up to 6 fold n Only the most metals sensitive species of Benthics be decreased (k- and r- selected) n Algal populations (r- selected) not impacted n Nearly random storm events in time and space prevent learned protective behavior n r-selected species can reproduce exponentially after acute events

15 Theoretical population relationship among exposure and effects Population Estimate (n) Time of n Estimate Time of Acute Pulse Event Time Trout Benthics Algae

16 Major Findings from the CFRERA n Impacts to the Aquatic Community –Risks to aquatic species are apparent from multiple lines of evidence –Risks are principally from acute exposure during storm events –Risks from non-lethal chronic exposures are of probable little consequence to receptors as exposures are of neither of sufficient duration or magnitude to impact growth………………..but…..uncertaintly precludes total exclusion of chronic risks.

17 Major Findings from the CFRERA n Soil organisms---weight of evidence –Predicted: risk is occurring and could be widespread, depending on what benchmark value is used –Toxicity experiments: microbes and earthworms are affected in slickens areas –Population Surveys: Limited information

18 Major Findings from the CFRERA n Plants--- weight of evidence –Predictive: Many soil samples had heavy metal levels greater than those found to have effects in other conditions –Toxicity Experiments: tests from soils on the site has found them to be toxic to at least some plants. –Population Surveys: Decreased number of different types of plants (species richness) n Notes –impossible to consider metals effects without pH-- acid soil is harmful to plants –Risk outside slickens areas is lower

19 Major Findings from the CFRERA n Wildlife--- weight of evidence –Predictive: Risks highest to small organisms that eat insects –Toxicity experiments: no info –Population Surveys: Frequency of sign for raccoon, mink, and otter was significantly less on the Clark Fork River compared to the Big Hole River n Notes: Conclusions are uncertain because of the lack of direct measurements and evidence of exposure and toxicity.

20 Major Findings from the CFRERA n Which metals are of most concern for terrestrial species –Varies for each species n Plants: best estimate is the sum of all metals in conjunction with pH best predict effects in the field n Microbes and worms: Copper and Arsenic primarily n Wildlife: Arsenic, cadmium and lead

21 Major Findings from the CFRERA n Impacts to the terrestrial system –Risks to vegetation and soil invertebrates associated with pH and exposed “slickens” tailings areas –Risks to wildlife predicted but highly uncertain n Conclusions: Risks focussed around the upper portions of the river, in and around exposed tailings...

22 Major Findings from the CFRERA n Common Themes among systems: –1. “Slickens”, exposed tailings bad for both aquatic and terrestrial species. –2. Chronic risks of relatively little concern, absolute risk immeasurable compared to potential impacts from acute exposures (> 500,000 ppb dissolved Cu flowing into river) –3. Focus of remedial action should be on “Slickens”, to prevent acute exposures in Aquatic system and decrease bioavailability of metals in terrestrial system.

23 Feasibility Study n Clearly, the focus for remedial action is on areas of exposed tailings n Secondarily, answering questions about the feasibility of addressing chronic risks

24 How to resolve issues ? n 1. USE GOOD SCIENCE !! –Doesn’t always make people feel good, but puts forth the evidence in a logical manner and provides the Agency with the most defensible document for enforcement actions n 2. Weight of Evidence to objectively describe strengths and weaknesses of given issues

25 Significant Issues n Burden of Proof –what is threshold for saying an effect is likely. n Significant Ecological Effect –lethal vs. non-lethal –growth vs. biomarker –individual vs. a population –population vs. a community

26 Significant Issues n Use of Water Effect Ratio testing in the Risk Assessment WER = Ratio of Site Water Toxicity and Lab water LD50 = 300 ug/L Cu (site water) 150 ug/L Cu (lab water) WER = 2

27 Use of Water Effect Ratio Testing in CERCLA Risk Assessments n Pros –Site-specifice toxicity tests –relative toxicity to literature values tested directly –relative toxicity can be measured throughout the year –data from multiple species required –Established protocols must be used n Cons –Some specifics of the test procedure –Differences on toxicity from the influence of Ca (lab) and Mg (field) –Influence from multiple metals –Ongoing remedial action will influence WER Results

28 Use of Water Effect Ratio Testing in CERCLA Risk Assessments n Resolution (The Duluth EP - A team) –Use of Raw data to establish site-specific thresholds of toxicity……forgot about an adjustment factor n Final equation for Acute number (Normalized to a 0.4 g fish): –Log (LC50)= x log (Calcium/10) x log (DOC) x log (Calcium / 10) x log (DOC)

29 Use of Water Effect Ratio Testing in CERCLA Risk Assessments n Points of Interest –Mass significantly influenced LC50 estimate (0.4 g is the most sensitive mass, smaller and larger fish less sensitive) –Ca/Mg ratio more important than Hardness estimate for the influence of toxicity –DOC also influences the toxicity –Need to use river water in same system, but outside the OU to establish credible relationships.

30 Use of Water Effect Ratio Testing in CERCLA Risk Assessments n ORD Research Need ? –Not basic research, but important to programs –What other criteria would benefit from weight adjustment/normalization? –What is the relative importance of different salts (measured as calcium carbonate equivalents) in their role on mediating the toxicity of metals in water?

31 Trout Feeding Studies n Pathway is real n Uncertainties around current studies: –Bioavailability: n Topically applied metals to trout chow vs. ground up benthics from the field n Multiple metal mixtures. One metal influencing the uptake of other metals –Confounding factors: n nutritional problems from benthic studies n food matrix leading to gut impaction not related to metals exposure

32 Trout Feeding Studies n Uncertainties –If have a TRV, what matrix do you compare it to. n Swim-up fry do not eat large mayflys, caddisflys etc. n what is the geographical representation of whatever matrix is measured ? –No from natural organism exposure (ie, not trout chow) has ever demonstrated a consistent dose-response.

33 Trout Feeding Studies n ORD Research Need ? –1. What techniques can be used to quantify wild fry diets? –2. What are the diets? –3. What factors influence bioavailability of the metals in the fish gut? –4. What factors need to be considered in designing a study around dietary exposure? –5. What standard procedures can be developed to prevent confounding factors

34 Non-lethal Endpoints n Biomarkers –Hypothesis is that responses by enzymatic biomarkers influence overall health n Principle mechanism is energy transfer to protein synthesis of biomarker away from growth related expenditures n Examples: Metallothioneins, lipid peroxidase, Clinical pathology n ORD Question: Is there any relationship between growth and biomarker response

35 Non-lethal Endpoints n ORD Research for biomarkers?? –Is there any relationship between growth and biomarker response? –Is there any relationship between growth effects and population decline? –Is there a threshold level of biomarker response that adds concern of effects ?

36 Non-lethal Endpoints n Avoidance Behavior –Avoidance behavior of trout to metals has been found repeatedly in laboratory settings. –Concentrations as low as 1 ppb Cu has caused avoidance in laboratory –Applicability of laboratory data is called into question in the field –Only examples of field avoidance behavior are at surface water metal concentrations well above those of chronic and even acute criteria!

37 Non-lethal Endpoints n Avoidance Behavior –ORD Research: n What other factors besides metals are quantifiably important in avoidance behavior –(cover, food, etc) n What relative importance is avoidance level concentrations in reference to other endpoints in the wild? n What magnitude of avoidance must occur before population level impacts are seen?

38 Theoretical population relationship among exposure and effects Population Estimate (n) Time of n Estimate Time of Acute Pulse Event Time Trout Benthics Algae

39 Theoretical population relationship among exposure and effects n Multi-component community analysis? n Can better decisions be made by looking at multiple levels? n Much work has been done on Benthic communities, but how do they fit into the bigger picture?

40 Wildlife Work n I did not think I would have a lot of time to go into these issues, but there are many, many more research questions related to wildlife toxicity. –Principle questions revolve around bioavailability n What factors are the most important to consider in the absorption of metals in different species?

41 ORD input into Superfund Risk Assessment: A Regional Perspective n Unfortunately………most of need is NOT basic research n Fortunately……….most of pragmatic need can be met through coordination of regional scientists with basic research questions n Example of Mount study: Use of CFR sediment in new trout feeding study.

42 ORD input into Superfund Risk Assessment: A Regional Perspective n Follow up on basic research important for applications in the Region. –Erickson’s paper on dissolved vs. total metals –Believe it or not: Unscrupulous scientists will intentionally misuse your DATA!!!! –Briefings through videoconference to primary program contacts (such as BTAG coordinators in Superfund) can help insure appropropriate use of ORD data and methods.

43 ORD input into Superfund Risk Assessment: A Regional Perspective n Remember that often what is boring to you all is NEWS to us!!!! n ORD needs to continue original research with ideas that are new and NOT necessarily applied. n However, all new research is built on old concepts. If sites can be used for new work, all the better. n Don’t forget about regional scientists as a source of ideas and even labor!!


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