Objectives of This Presentation

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1 Ecological Risk Benchmarks Protective of Aquatic Species for Gasoline and Some Diesel Petroleum Hydrocarbon Fractions Burt Shephard U.S. Environmental Protection Agency Seattle, WA Presented to the Northwest Environmental Business Council (NEBC) Seattle, WA October 29, 2014 Objectives of This Presentation Describe how petroleum mixtures elicit chemical toxicity to aquatic species Describe why petroleum benchmarks are derived from counting molecules in tissue, not environmental concentrations in water or sediment Summarize the methodology for deriving ecological risk benchmarks for TPH fractions in water and sediment Show why TPH analytical methods don t affect the toxicological model for deriving TPH fraction benchmarks Show the data that validates the approach for deriving TPH benchmarks Heckling bait for the already expert 1

2 Is This A Toxic Substance? Is This A Toxic Substance? Water poisoning (dilutional hyponatremia): Chemical toxicity, low internal electrolyte levels due to overhydration. Several deaths/year. 2

3 Is This A Toxic Substance? Water poisoning (dilutional hyponatremia): Chemical toxicity, low internal electrolyte levels due to overhydration. Several deaths/year. Drowning (physical toxicity): 359,000 deaths worldwide/year (WHO 2011) Everything Can Be Toxic All Things Are Poison and Nothing Is Without Poison; Only the Dose Makes That A Thing Is No Poison (Paracelsus 1538) The Dose Makes the Poison (popular short version) 3

4 What Do These Three Chemicals All Have In Common? Ethanol Nitrogen Petroleum Answer: They All Elicit Toxicity By A Mode Of Action Called Narcosis Ethanol Nitrogen Petroleum 4

5 So What s Narcosis? A non-specific mode of toxic action whose effects are general cellular disruption Symptoms include: Euphoria Wooziness Inability to concentrate Loss of equilibrium All chemicals are at least as toxic as their ability to elicit narcotic effects Chemicals with specific modes of action (e.g. dioxin, DDT) are more toxic than narcotics, i.e. adverse effects occur at lower concentrations Sublethal toxicity fully reversible if exposure terminated before lethality becomes inevitable Why This Is Important Because narcotic toxicity occurs at relatively constant chemical concentrations in the body Lethal concentration of narcotic chemicals: 2 8 millimoles/kilogram body weight (mmol/kg in tissue) Sublethal, reversible toxicity: threshold for sublethal narcotic effects begins at about 1 10 of the lethal concentration in tissue (roughly mmol/kg) 5

6 Chemistry 101 Refresher What s a Mole? Chemistry 101 Refresher What s a Mole? 6

7 Chemistry 101 Refresher What s a Mole? A chemical mass unit defined to be molecules (or atoms). The mass of a mole is the gram molecular weight of the chemical. Example: Molecular nitrogen (N 2 ) has a molecular weight of One mole of N 2 weighs grams, one mmol of N 2 weighs grams or 28 milligrams. Example: Ethanol has a molecular weight of One mole ethanol weighs grams. What Are The Lethal Concentrations Of These Three Chemicals In Tissue? Ethanol 43 mmol/kg Nitrogen 7.7 mmol/kg Petroleum See next slide 7

8 I Know You Can t Read All Of This Empirical Residue-Effects Data, But... Effect Effect Concentration Molecular Concentration Chemical mg/kg Weight mmol/kg Species Effect Reference Benzene Golden ide (Leuciscus idus) No effect on survivorship in 3 days Freitag et al Pacific herring (Clupea harengus) Decreased survival of larvae Struhsaker Goldfish (Carassius auratus) No effect on survivorship in bioconcentration experiment Ogata et al Cladoceran (Daphnia magna) Lethal body burden Pawlisz and Peters Green algae (Selenastrum capricornutum) 50% reduction in growth over 8 days Herman et al Rainbow trout (Oncorhynchus mykiss) Threshold for induction of serum sorbitol dehydrogenase Kaiser et al Rainbow trout (Oncorhynchus mykiss) 50% mortality Kaiser et al Rainbow trout (Oncorhynchus mykiss) 50% mortality in 96 hours Hodson et al n-butylcyclohexane Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Cyclooctane Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al n-decane Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Docosane Golden ide (Leuciscus idus) No effect on survivorship in 3 days Freitag et al n-dodecane Golden ide (Leuciscus idus) No effect on survivorship in 3 days Freitag et al > >1.19 Blue mussel (Mytilus edulis) Minimal reduction in feeding rate Donkin et al Dodecylcyclohexane Rainbow trout (Oncorhynchus mykiss) Reduced growth over 9 months Cravedi and Tulliez 1982 Ethylbenzene Manila clam (Tapes semidecussata) Increased mucus production, decreased feces production Nunes and Benville Goldfish (Carassius auratus) No effect on survivorship in bioconcentration experiment Ogata et al Green algae (Selenastrum capricornutum) 50% reduction in growth over 8 days Herman et al Heptadecane Blue mussel (Mytilus edulis) No effect on survivorship after 24 hours Lee et al Hexadecane Quahog (Mercenaria mercenaria) No effect on survival or filtering rate in 8 hours Boehm and Quinn 1976 Methylcyclohexane Flagfish (Jordanella floridae) Low end of lethal body burden range after 87 day exposure Jenkins et al n-nonane Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al n-octane Spiny dogfish (Squalus acanthias) No effect on mortality in 24 hours Guarino and Arnold Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Phenyldecane > >0.36 Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Phenylheptane Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Phenyloctane Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Phenylpentane Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Pristane Rainbow trout (Oncorhynchus mykiss) Reduced growth over 9 months Cravedi and Tulliez 1982 Toluene Blue mussel (Mytilus edulis) No effect on survivorship Lee et al Manila clam (Tapes semidecussata) Increased mucus production, decreased feces production Nunes and Benville Dolly Varden (Salvelinus malma) No effect on survival in 24 hours Varanasi et al Golden ide (Leuciscus idus) No effect on survivorship in 3 days Freitag et al Goldfish (Carassius auratus) No effect on survivorship in bioconcentration experiment Ogata et al Blue mussel (Mytilus edulis) 50% reduction in feeding rate Donkin et al Cladoceran (Daphnia magna) Lethal body burden Pawlisz and Peters Green algae (Selenastrum capricornutum) 50% reduction in growth over 8 days Herman et al Rainbow trout (Oncorhynchus mykiss) Median lethal dose Hodson et al n-undecane >69 >0.44 Blue mussel (Mytilus edulis) Minimal reduction in feeding rate Donkin et al m-xylene Manila clam (Tapes semidecussata) Increased mucus production, decreased feces production Nunes and Benville Goldfish (Carassius auratus) No effect on survivorship in bioconcentration experiment Ogata et al Green algae (Selenastrum capricornutum) 50% reduction in growth over 8 days Herman et al o-xylene Manila clam (Tapes semidecussata) Increased mucus production, decreased feces production Nunes and Benville Goldfish (Carassius auratus) No effect on survivorship in bioconcentration experiment Ogata et al Green algae (Selenastrum capricornutum) 50% reduction in growth over 8 days Herman et al p-xylene Goldfish (Carassius auratus) No effect on survivorship in bioconcentration experiment Ogata et al Green algae (Selenastrum capricornutum) 50% reduction in growth over 8 days Herman et al Part of the Empirical Residue- Effects Toxicity Database for TPH Components Effect Effect Concentration Molecular Concentration Chemical mg/kg Weight mmol/kg Species Effect Benzene Golden ide (Leuciscus idus) No effect on survivorship in 3 days Goldfish (Carassius auratus) No effect on survivorship in bioconcentration experiment Cladoceran (Daphnia magna) Lethal body burden Green algae (Selenastrum capricornutum) 50% reduction in grow th over 8 days Rainbow trout (Oncorhynchus mykiss) Threshold for induction of serum sorbitol dehydrogenase Rainbow trout (Oncorhynchus mykiss) 50% mortality Empirical data largely supports lethality between 2 8 mmol/kg 5 th percentile of available empirical chronic toxicity residue-effects data is 0.24 mmol/kg 8

9 A Tissue Residue Approach to Total Petroleum Hydrocarbon (TPH) Toxicity Reference Values for Water and Sediment TPH benchmark development historically a difficult problem TPH TRV development for alkanes, cycloalkanes, alkenes, BTEX and possibly some PAHs based on their narcotic toxic properties (CONCAWE 2001, Schultz 1997) Start with a critical body residue, use a bioaccumulation model run backwards to derive water column TRVs, use water TRVs with EqP approach to obtain sediment TRVs Total Petroleum Hydrocarbon Water and Sediment TRV Development Assumptions All individual chemicals in a TPH mixture elicit toxicity via narcosis Narcotic chemicals lethal at 2-8 mmol/kg in aquatic biota tissues, little or no chronic toxicity below 0.24 mmol/kg (5 th percentile of measured residue-effects data) 9

Total Petroleum Hydrocarbon Water and Sediment TRV Development Assumptions Based on concentration addition of narcotic chemical mixtures and constant body burden associated with effect Concentration

10 Total Petroleum Hydrocarbon Water and Sediment TRV Development Assumptions Based on concentration addition of narcotic chemical mixtures and constant body burden associated with effect Concentration addition implies that composition of mixture of narcotic chemicals causing toxicity is not important Toxicity of a mixture of narcotic chemicals occurs when the sum of individual chemical molar concentrations in tissue exceeds a critical body residue How Do We Know Most Petroleum Hydrocarbon Chemicals Are Narcotics? 10

(Polar narcosis) (Ester narcosis) So Here Is Why We Count Molecules In Tissue 1 mole = 6.02 10 23 molecules (Avogadro s number) 1 millimole = 1 1000 mole = 6.02 10 20 molecules 2 8 millimoles = 1.

11 (Polar narcosis) (Ester narcosis) So Here Is Why We Count Molecules In Tissue 1 mole = molecules (Avogadro s number) 1 millimole = mole = molecules 2 8 millimoles = to molecules/kg body weight is lethal millimoles = to molecules/kg body weight is sublethal (but adverse effects on growth, reproduction occur) 11

12 Derivation of TPH Water and Sediment TRVs Hydrocarbon Block Method Define carbon chain lengths, petroleum fractions or hydrocarbon blocks of interest Select a surrogate compound for each fraction Identify molecular weight, K OW, K OC and BCF values for surrogate within each fraction Use BCF and no effect residue to estimate no effect (or low effect) water concentration NOEC or LOEC in water is input into EqP calculation to define no effect sediment concentration Primary Equations Used to Calculate Water TRVs C water = C tissue /BCF(C tissue = critical body residue, C water = water TRV) log BCF = (0.85 log K ow ) (Alaska) log BCF = (0.91 log K OW ) (1.975 log(( K OW ) + 1)) (Oregon) BCF = bioconcentration factor K OW = octanol : water partitioning coefficient 12

13 Primary Equations Used to Calculate Sediment TRVs log K OC = (0.983 log K ow ) K p = f OC K OC ESB = K p C water (C water is the chronic petroleum fraction TRV from the previous slide) ESB is the equilibrium partitioning sediment quality benchmark in units of µg/g organic carbon f OC = fraction of organic carbon in sediment K OC = sediment organic carbon : water partitioning coeff. K p = sediment : water partitioning coefficient Why Did We Change BCF Equations For Oregon Derivation Of Water TRV? (Alaska) (Oregon) 13

14 Model Calibration to Predict Acutely Toxic Levels of Gasoline Using 2 8 mmol/kg as lethal body burden, back calculated concentration of gasoline predicted to be acutely toxic to aquatic species ranges between mg/l Model predictions within the lower end of the measured concentrations associated with short term lethality to aquatic species Measured Gasoline Toxicity Data in Closed Systems Without Head Space Species Conc. mg/l Endpoint Menidia beryllina h LC 50 Oncorhynchus mykiss h LC 50 Pimephales promelas h LC 50 Chaetogammarus marinus h LC 50 Daphnia magna h LC 50 Aquatic life (hexane as surrogate) 3.8 Mortality (this work) Selenastrum capricornutum h IL 50 Mysidopsis bahia h LC 50 Aquatic life (decane as surrogate) 0.95 Mortality (this work) mg/l can be considered comparable to an acute water quality criterion for gasoline range organics. This is the validation data set used to confirm model predictions based on empirical tissue residue-effects data. 14

15 Total Petroleum Hydrocarbon Water and Sediment TRVs for Protection of Aquatic Life - Alaska Fraction WQB µg/l SQB µg/g OC Gasoline Range Organics C 6 to C 10 Diesel Range Organics C 10 to C 25 Residual Range Organics NC 117,000 >C 25 Total Petroleum Hydrocarbon Water and Sediment TRVs for Protection of Aquatic Life - Oregon Fraction WQC µg/l SQC µg/g OC Aliphatic C 5 C Aliphatic C 6 C Aliphatic C 8 C Aliphatic C 10 C Aliphatic C 12 C 16 NC 138,874 Aliphatic C 16 C 21 NC NC Aliphatic C 21 C 34 NC NC 15

16 Pore Water Fluor. (ug/l) Total Petroleum Hydrocarbon Water and Sediment TRVs for Protection of Aquatic Life - Oregon Fraction WQC µg/l SQC µg/g OC Aromatic C 8 C Aromatic C 10 C 12 NC 393 Aromatic C 12 C 16 NC 575 Aromatic C 16 C 21 NC 1394 Aromatic C 21 C 34 NC 273,241 Can We Derive Sediment TRVs When The Maximum Water Solubility is Exceeded? Organic Sorbents in Sediment TIE Carbonaceous additives used in sediment TIE to reduce bioavailability of organic contaminants Ambersorb, coconut charcoal are examples Shown to work for a wide range of nonpolar organic chemicals in sediment Fluoranthene Spiked Sediment No Treatment Ambersorb 1500 (4%) 32 16

17 Coconut Charcoal Did Not Reduce Toxicity of PAH-Contaminated Sediments to Midge 1.6 Biomass (mg AFDW/individual) Intact Sediment With 5% Coconut Charcoal 0.0 Reference Site 1 Site 2 Site 3 Site 4 Site 5 33 Coconut Charcoal Did Reduce PAHs in Interstitial Water 50 Total PAH in Interstitial Water (ug/l) Intact Sediment With 5% Coconut Charcoal Reference Site 1 Site 2 Site 3 Site 4 Site

18 So if it s not PAHs, what is it? Realization that PAHs don t get to extremely high concentrations in sediments without a vehicle to get it there (oil, soot, coal) Maybe it s not the PAHs but the other stuff that comes with it Mineral Oil as a Model Oil So-called baby oil without the scents Comprised mainly of alkanes in the C 13 to C 24 range Essentially no PAH content Considered non-toxic Water-accommodated fraction not toxic to test organisms Intended to represent the oil part of contamination without the PAH part 36 18

19 Midge Are More Sensitive to Mineral Oil Than Are Oligochaetes 120 Biomass (% of control +/- SD) Lumbriculus variegatus Chironomus dilutus Hyalella azteca Mineral Oil Addition (g/kg dwt) 37 Charcoal Does Not Reduce Effect of Mineral Oil on Midge 120 Biomass (mg AFDW/individual) Intact Sediment With 5% Coconut Charcoal 0 Reference 2 g/kg spike 6 g/kg spike 38 19

20 Sensitivity to Oil Varies with Species Chironomus and Hyalella very sensitive to oil LC g oil/kg dry weight sediment (= mg/kg) Threshold for chronic narcotic effects at 1 10 of LC 50 (i.e mg/kg) Remember predicted Alaska diesel range organic sediment TRV was 91 mg/kg at 1% OC. Coincidence? Lumbriculus not affected LC 50 as high as 60 g oil/g dwt Ampelisca sensitivity much lower LC 50 ~ 20 g oil/kg dwt Conclusions about relative importance of PAHs 39 will vary depending on organism sensitivity to oil Implications/Future Directions Convincing case that oil in sediment has an effect on some invertebrates beyond that from PAHs alone Looking at only PAHs may miss some types of oil contamination (e.g., lubricating oils) Suggest including a measure of oil in monitoring/assessment programs This is where analytical chemistry issues come in Need a better measure of oil that relates to physical toxicity 40 20

$Approach covers only chemical toxicity of water soluble TPH fractions Physical toxicity of petroleum cannot be predicted from a chemical toxicity model Discussion Questions$ How do we handle physical toxicity? Can we obtain empirical sediment toxicity data to evaluate model predictions?

How do we handle physical toxicity? Can we obtain empirical sediment toxicity data to evaluate model predictions?

21 What About Us? Approach covers only chemical toxicity of water soluble TPH fractions Physical toxicity of petroleum cannot be predicted from a chemical toxicity model Discussion Questions How do we handle physical toxicity? Can we obtain empirical sediment toxicity data to evaluate model predictions? How good is the assumption that all TPH compounds elicit toxicity via narcosis? Particularly important for PAH compounds Is there a mechanism by which we can calculate sediment benchmarks when water TRV exceeds maximum solubility? We can do the math, but do the calculated sediment benchmarks have any real world utility? Where does the transition between chemical and physical toxicity occur? 21

22 Questions? 22

Assessing and Predicting Effects of Sediment Contamination

Assessing and Predicting Effects of Sediment Contamination David R. Mount U.S. Environmental Protection Agency Office of Research and Development Mid-Continent Ecology Division, Duluth, MN Why Study Sediments?