Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 1

Bioaccumulation of PFOS in Freshwater Fish: Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments

Presented by Daniel R. Opdyke, Joseph Volosin, Sarah L. LaRoe, John P. Connolly, and Jennifer Benaman

June 25, 2015

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 2

• Context • Overview of bioaccumulation • PFOS preferentially accumulates in liver, blood, and

other tissues • PFOS depuration from fish is relatively rapid • Early estimates of PFOS bioaccumulation subject to

significant uncertainty • Bioaccumulation estimates span orders of

magnitude

Outline

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 3

• Recent EU Environmental Quality Standards (EQS) for PFOS – 9,1 ng/g ww biota (fish; for protection of human health) – 0,65 ng/L freshwater – 0,13 ng/L saltwater – Requires increased monitoring – Goal is to achieve good chemical status by 2027

Context

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 4

• Various metrics are used to describe bioaccumulation – BCF: bioconcentration factor – BAF: bioaccumulation factor – BMF: biomagnification factor

𝐵𝐵𝐵𝐵𝐵𝐵 = 𝐵𝐵𝐵𝐵𝐵𝐵 × 𝐵𝐵𝐵𝐵𝐵𝐵

• BCF criteria for bioaccumulative designation by European Chemicals Agency (ECHA): 2000 L/kg

Bioaccumulation

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 5

• Laboratory studies indicate that PFOS associates most strongly with certain proteins, not fats (lipids)

• Field studies show PFOS accumulates in blood and liver (and certain other tissues) more than in fillet (muscle)

• Accordingly, estimates of bioaccumulation will depend on tissue analyzed

Specific Nature of PFOS Bioaccumulation

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Pan, 2014 Labadie, 2011 Murakami, 2011 Shi, 2012

PFO

S Co

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ww

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Fillet Liver Blood

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 6

PFOS is Rapidly Depurated by Fish

• Much faster than from most PCBs • Tissue concentrations reflect recent exposure • Temporal pairing

of fish and water concentrations are key in predicting BAFs

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0 10 20 30 40 50 60 70 80 90 100Perc

ent o

f Ori

gina

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cent

rati

on

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PFOS (liver)

PCB 66

Estimated Depuration of PFOS and PCBs from Trout

Based on Niimi et al. (1983)

Based on Falk et al. (2015)

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 7

• Many papers do not adequately pair fish and water samples they use – Borga et al. (2005): “A recurring problem in many studies is

that water and biota were not sampled simultaneously or from the same locations”

– Boulanger et al. (2004): Fish from Michigan collected in 1990s; water from Lakes Erie and Ontario collected in 2003

– Quinete et al. (2009): Water and fish samples are 34 to 250 km apart

Importance of Geographical and Temporal Pairing

Water samples taken here

Fish samples taken here

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 8

• Interlaboratory studies were conducted in 2004/2005, 2009, and 2011

• Early results subject to substantial uncertainty • Improvements have been realized, but some

uncertainty remains

Evolution of PFOS Analytical Procedures

Sources include: van Leeuwen et al. (2006), van Leeuwen et al. (2009), and Weiss et al. (2013)

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Fish Water

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fici

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Interlaboratory Coefficients of Variation by Year of PFOS in Fish and Water

2004/200520092011

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 9

• Martin et al. (2004): Oldest paper, widely cited

– Exhibits higher bioaccumulation

• Asher et al. (2012): More recent – Exhibits lower bioaccumulation

• Data suggest improvements in analytical methods largely account for temporal patterns

Lake Ontario Pelagic Food Web

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 10

0

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Log

BAF

Rank Whole Body Fillet Liver/Blood Other

BAF used in EQS determination

Estimated BAF of PCB 66

Overview of BAF Values in the Recent Literature

Bioaccumulative as per ECHA

Sources include: de Solla et al. (2012), Kwadijk et al. (2010), Labadie et al. (2011), Asher et al. (2012), Pan et al. (2014), Zhou et al. (2012), Awad et al. (2011), Murakami et al. (2011), De Silva et al. (2011), Ahrens et al. (2015)

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 11

𝐵𝐵𝐵𝐵𝐵𝐵 = 𝐵𝐵𝐵𝐵𝐵𝐵 × 𝐵𝐵𝐵𝐵𝐵𝐵

• “The highest, reliable BCF value for whole fish was noted to be 2796.” EU (2011) – This value is from a 2001 laboratory study – Exposure concentration > 1 000x typical environmental

concentrations – Bluegill only

• BMF set to 5 – Based on studies with acknowledged low reliability – No studies newer than 2008 considered

• Resulting BAF = (2796 × 5) = 13 980

ECHA BAF value

Source: EU, 2011. PFOS EQS dossier. p. 22

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 12

• PFOS (and other PFAS) bioaccumulation is importantly different from most other organic chemicals

• Substantial uncertainty in PFOS BAF remains – Evolution of analytical methods – Rapid depuration from aquatic species complicates monitoring – Significant variations across tissues

• Rapid depuration provides opportunity for relatively rapid recovery of fish concentrations following cessation of sources

• Water-based EQS (0,65 ng/L) is below typical commercial laboratory reporting limits

• Many of the general concepts herein apply not just to PFOS, but other PFASs as well

Conclusions

Bioaccumulation of PFOS in Freshwater Fish Evolving Perspectives on an Emerging Contaminant and Implications for Risk Assessments 13

Questions/Discussion