Advisory CommitteeAdvisory CommitteeMeeting #3Meeting #3

September 16, 2008September 16, 2008

North San Francisco BayNorth San Francisco BaySelenium TMDLSelenium TMDL

Draft Numeric TargetDraft Numeric TargetBarbara BaginskaBarbara Baginska

San Francisco BaySan Francisco BayRegional Water Quality Control BoardRegional Water Quality Control Board

Presentation OverviewPresentation Overview

Background:Background: Numeric targets in TMDL contextNumeric targets in TMDL context Problem in North SFBProblem in North SFB Exposure types and bioaccumulationExposure types and bioaccumulation

Target DevelopmentTarget Development Species at risk in North SFBSpecies at risk in North SFB Toxicity thresholds for local ducks and fish (exposure Toxicity thresholds for local ducks and fish (exposure

levels, local data, mitigating conditions)levels, local data, mitigating conditions)

Fish tissue-based target: why and how?Fish tissue-based target: why and how? Proposed target and rationaleProposed target and rationale

Numeric Target - DefinitionNumeric Target - Definition

Numeric targets are specific goals for Numeric targets are specific goals for TMDLs that ensure protection of TMDLs that ensure protection of

designated beneficial uses of waters designated beneficial uses of waters and provide basis for data analysis and and provide basis for data analysis and

allocationsallocations

Numeric Target - SelectionNumeric Target - Selection

A numeric target can be:A numeric target can be: numeric water quality objectivenumeric water quality objective numeric interpretation of narrative objective; ornumeric interpretation of narrative objective; or numeric measure of some other parameter necessary numeric measure of some other parameter necessary

to meet water quality standardsto meet water quality standards

Usually expressed as specific water column, Usually expressed as specific water column, sediment and/or tissue indicator sediment and/or tissue indicator

Will demonstrate attainment of water quality Will demonstrate attainment of water quality standardsstandards

Easy to monitorEasy to monitor

Water Quality CriteriaWater Quality Criteria

San Francisco Bay and DeltaSan Francisco Bay and Delta Freshwater numeric criteria apply:Freshwater numeric criteria apply: Acute-Criterion Maximum Concentration : Acute-Criterion Maximum Concentration : 20 20 µµg Se/Lg Se/L Chronic-Criterion Continuous Concentration : Chronic-Criterion Continuous Concentration : 5 5 µµg Se/Lg Se/L

CaliforniaCaliforniaSaltwater numeric criteria:Saltwater numeric criteria: Acute -Criterion Maximum Concentration : Acute -Criterion Maximum Concentration : 290 290 µµg Se/Lg Se/L Chronic-Criterion Continuous Concentration : Chronic-Criterion Continuous Concentration : 71 71 µµg Se/Lg Se/L

Selenium does Selenium does NOTNOT exceed the CTR chronic criteria exceed the CTR chronic criteriaof 5 µg/L in North SFBof 5 µg/L in North SFB

Problem to SolveProblem to Solve

303(d) listing303(d) listing: : Affected use is one branch of the food chain most Affected use is one branch of the food chain most

sensitive indicator is hatchability in nesting diving sensitive indicator is hatchability in nesting diving birds birds

exotic species may have made food chain more exotic species may have made food chain more susceptible to accumulation of selenium susceptible to accumulation of selenium

health consumption advisory in effect for scaup and health consumption advisory in effect for scaup and scoter (diving ducks)scoter (diving ducks)

Se concentrations in benthic invertebrate, fish, and bird Se concentrations in benthic invertebrate, fish, and bird tissue collected from the Bay have been measured at tissue collected from the Bay have been measured at concentrations known to cause reproductive and concentrations known to cause reproductive and toxicological effects in some speciestoxicological effects in some species

Harmful versus BeneficialHarmful versus Beneficial

Adapted from NRC 2005

Where Does Where Does SeSe Come From? Come From?

Volcanic depositsVolcanic deposits Mining (copper, phosphate, coal)Mining (copper, phosphate, coal) Oil production and refiningOil production and refining By-product of coal burning power plantsBy-product of coal burning power plants Food (plant foods, grains, cereals and nuts) Food (plant foods, grains, cereals and nuts)

FOOD Micrograms % Daily Value

Rice, white, 1/2 cup 12 15

Egg, whole, 1 medium 14 20

Turkey, 3½ ounces 32 45

Beef, cooked, 3½ ounces 35 50

Brazil nuts, 1 ounce 544 780National Institutes of Health 2004

Water versus Dietary ExposureWater versus Dietary Exposure

Water column Se has marginal impact on toxicity Water column Se has marginal impact on toxicity to higher level aquatic organismsto higher level aquatic organisms

Observed selenium toxicity in fish results Observed selenium toxicity in fish results predominantly from dietary intakepredominantly from dietary intake

Type of diet contributes to exposure and Type of diet contributes to exposure and vulnerabilityvulnerability Filter-feeding benthic organisms ingest and assimilate Filter-feeding benthic organisms ingest and assimilate

particulate selenium to high concentrationsparticulate selenium to high concentrations Bioaccumulation by invertebrates (zooplankton and Bioaccumulation by invertebrates (zooplankton and

bivalves) is critical to fish and birdsbivalves) is critical to fish and birds

Not All Food Webs Are EqualNot All Food Webs Are Equal

It’s better to be a shrimp!

Terri Reeder, Selenium Game , San Diego 2005

Clams Have Lower Loss Rates Clams Have Lower Loss Rates Than Crustaceans Than Crustaceans

Food chainFood chain SpeciesSpecies  

AssimilationAssimilationEfficiency Efficiency

%%

Loss Rate Loss Rate constantconstantper dayper day

ClamClam PotamocorbulaPotamocorbula  

0.45-0.80.45-0.8 0.0250.025

   CorbiculaCorbicula ((Lee et al. unpublishedLee et al. unpublished))

0.800.80 0.0190.019

CrustaceanCrustacean CopepodsCopepods (zooplankton)(zooplankton) 0.600.60 0.1550.155

   NeomysisNeomysis (shrimp)(shrimp) 0.680.68 0.2550.255

What Do They Have in Common?What Do They Have in Common?

Target Development ApproachTarget Development Approach

Review of fish and avian selenium toxicityReview of fish and avian selenium toxicity 80 fish toxicity studies (1987 -2007)80 fish toxicity studies (1987 -2007) 46 avian toxicity studies 46 avian toxicity studies

Identify species of concern in North SFBIdentify species of concern in North SFB Establish species-specific toxicity Establish species-specific toxicity

thresholdsthresholds Consider mitigating factors (diet, length of Consider mitigating factors (diet, length of

exposure, sulfate content, loss rates)exposure, sulfate content, loss rates) Compare with known effect levelsCompare with known effect levels

Toxicity Thresholds in BirdsToxicity Thresholds in Birds

No direct toxicity No direct toxicity information for birds information for birds in North SFBin North SFB

Most data for Most data for chickens and chickens and mallardsmallards

Sensitive endpoint: -Sensitive endpoint: -reproductive success reproductive success egg hatchabilityegg hatchability egg fertilityegg fertility chick survivalchick survival

Conc

entra

tion

[mg/

kg-d

w]

0

2

4

6

8

10

12

14

16

Reproductive Success NOAEL Reproductive Success LOAEL Reproductive Success Effect Threshold

Chicken Mallard Duck

Diving Ducks Exposure in NSFBDiving Ducks Exposure in NSFB

Feeding pattern - benthic Feeding pattern - benthic mollusks, shellfish, crustaceansmollusks, shellfish, crustaceans

Clams in scoter diet (SB = Clams in scoter diet (SB = 100%, SPB = 25%) 100%, SPB = 25%)

Spend winter in SFB Spend winter in SFB Breed in Alaska and CanadaBreed in Alaska and Canada Rapid elimination rates – Rapid elimination rates –

background levels after 70 daysbackground levels after 70 days New dataNew data: Se in eggs of scoters : Se in eggs of scoters

from NSFB below levels of from NSFB below levels of concern for sensitive speciesconcern for sensitive species

No reproductive effects for No reproductive effects for muscle tissue concentrations muscle tissue concentrations (2.1 – 5.7(2.1 – 5.7µg/g-ww, Lemly 1998)µg/g-ww, Lemly 1998)

Toxicity Thresholds in FishToxicity Thresholds in Fish

White Sturgeon White Sturgeon

Identified as likely the most Identified as likely the most affected species in NSFBaffected species in NSFB

Feeding pattern - benthic Feeding pattern - benthic organismsorganisms

Clam eater (77% of stomach Clam eater (77% of stomach volume)volume)

Present year-round in NSFB Present year-round in NSFB Reproductive biology may Reproductive biology may

contribute to bioaccumulationcontribute to bioaccumulation Highly variable Highly variable

bioaccumulation ratesbioaccumulation rates Toxicity data availableToxicity data available Tissue concentrations exceed Tissue concentrations exceed

known thresholdsknown thresholds

0102030405060708090

100

1 10 100Selenium concentration in maternal whole

body (μg/g dry wt.)

Inc

ide

nc

e o

f e

de

ma

or

sk

ele

tal

de

form

itie

s in

larv

ae

(p

erc

en

t)

EC10 = 8.13 μg/g

White sturgeonLinville 2006Tashjian et al . 2006

regression: y=100/(1+(12.46/x)5.149)

After W. Beckon, pers. com

Sacramento Splittail Sacramento Splittail

Potentially affected fish in North SFBPotentially affected fish in North SFB Feeding patterns - benthic organismsFeeding patterns - benthic organisms Clam eater (34% of stomach volume)Clam eater (34% of stomach volume) Spawns in the upper Estuary Spawns in the upper Estuary Can cope with high-level short-term exposureCan cope with high-level short-term exposure Rapid elimination ratesRapid elimination rates Tissue concentrations below known thresholds and Tissue concentrations below known thresholds and

indicative of background level dietindicative of background level diet

Fish Exposure in NSFBFish Exposure in NSFB

Fish-Tissue Target – Why & How?Fish-Tissue Target – Why & How?

2004 EPA draft aquatic life criteria – fish tissue2004 EPA draft aquatic life criteria – fish tissue Fish considered to be the most sensitive to chronic Fish considered to be the most sensitive to chronic

selenium exposureselenium exposure Accounts for protection of wildlife from the harmful Accounts for protection of wildlife from the harmful

effects of seleniumeffects of selenium Expressed as whole-body tissue concentration on a dry Expressed as whole-body tissue concentration on a dry

weight basisweight basis Offers direct link to chronic endpoints andOffers direct link to chronic endpoints and Integrates many site-specific factors (chemical speciation, rates Integrates many site-specific factors (chemical speciation, rates

of transformation, temporal variations)of transformation, temporal variations) Easy to sampleEasy to sample

Numeric Target DerivationNumeric Target Derivation

Toxicity thresholdsToxicity thresholds

For sensitive environments numeric target For sensitive environments numeric target should be more protective than EC10should be more protective than EC10

Geometric mean of boundary concentrations Geometric mean of boundary concentrations

Numeric Target RationaleNumeric Target Rationale

Fish-tissue –Fish-tissue – 6 6 µg/gµg/g whole body dry weight whole body dry weight

Proposed numeric target:Proposed numeric target: Established for species most at risk in North SFB and Established for species most at risk in North SFB and

based on local databased on local data

• Waterfowl depurates Se quickly after leaving the BayWaterfowl depurates Se quickly after leaving the Bay• Se concentrations in bird eggs at background levelsSe concentrations in bird eggs at background levels• Clam-eating bottom feeders - Clam-eating bottom feeders - white sturgeonwhite sturgeon - most at risk - most at risk

Within range of known thresholds protective of Within range of known thresholds protective of aquatic wildlifeaquatic wildlife

Conservative and considers mitigating conditions in Conservative and considers mitigating conditions in North SFBNorth SFB

Protective of human health (fish consumption)Protective of human health (fish consumption)

Human HealthHuman Health

Fish Contaminant Goal (OEHHA 2008)Fish Contaminant Goal (OEHHA 2008)

Tissue Concentration (ppb) = Tissue Concentration (ppb) =

[(RfD * Body Weight)–BDL]/CR = [(RfD * Body Weight)–BDL]/CR = 7.47.4 ppm ww ( ppm ww (29.629.6 ppm dw) ppm dw)

Allowable duck tissue consumptionAllowable duck tissue consumption Original health advisory still in placeOriginal health advisory still in place Scaup and scoter tissue concentrations < 6ppm wwScaup and scoter tissue concentrations < 6ppm ww

QUESTIONSQUESTIONS

Screening of Available StudiesScreening of Available Studies

NOAEL and/or LOAEL reportedNOAEL and/or LOAEL reported chronic exposure testedchronic exposure tested selenium exposure was the only treatmentselenium exposure was the only treatment tissue data reportedtissue data reported laboratory experiments under controlled laboratory experiments under controlled

conditionsconditions dietary exposure scenario useddietary exposure scenario used

How our Numeric Target Compares How our Numeric Target Compares with Known Thresholds?with Known Thresholds?

a – Compiled from Presser and Luoma, 2006 (Table 13, 14 and 15) b – Lemly (1998) (Table 1), values represent measured concentrations showing whether adverse effects are likely to occurc – Values in parenthesis indicate concentrations typical for uncontaminated aquatic systems