Uptake of Dietary PCBs by Rainbow Trout

Robert F. Carline and Patrick M. Barry

Penn. Coop. Fish & Wildlife Res. Unit

U.S.G.S. and Penn State University

H. George Ketola

U.S.G.S Tunison Lab. Aquatic Science

Background

• 1998 PCBs discovered in PA state trout hatcheries

• 1999 PCB concentrations exceed state’s consumption advisory limits

• PCB concentrations varied among hatcheries

Background

• 1999 Low concentrations of PCBs in fish feeds

• Feeds meet FDA standard, <200 ppb

Objectives

1. What is the relation between concentrations of PCBs in fish feed and concentrations in trout fillets?

Objectives

2. Of the PCBs consumed by trout, what proportion is assimilated ?

Objectives

3. If PCBs are present in hatchery supply water, what are the relative contributions of PCBs from the water and from the feed to the total found in trout?

Feed Formulations (*Aroclor 1260 added)

Diet Fish Meal MenhadenOil

PCB (ppb)

1 Herring Distilled 69

2 Menhaden Filtered 126

3* Menhaden Filtered 220

4* Menhaden Filtered 280

Sampling PCBs in water

Semi-permeable membrane device (SPMD)

Flattened polyethylene tubing

91 cm long by 2.5 cm wide

0.9 grams of triolein (purified lipid)

Experiments

• 6-month trial: 4 diets

• 3-week assimilation trial: 4 diets

6-Month Trial

• 4 diets

• 3 tanks of trout per diet

• Monthly sampling– Food

– Fish

– Water (SPMDs)

• PCB and lipid analyses conducted by Battelle Laboratories, Duxbury, Mass.

• Aroclor 1254/1260 standard

Initial Trout Size

• 124 mm total length (SD = 5.9)

• 22.6 grams (SD = 3.8)

6-Month Trial – Final Sizes

Diet Mean Length (mm)

Mean Weight (g)

1 248 197

2 242 183

3 243 185

4 246 194

0

40

80

120

0 100 200 300

Median PCB conc. in feed - ppb

Me

dia

n P

CB

co

nc

. in

fil

let

- p

pb

10th Percentile 90th Percentile

0

20

40

60

80

100

120

0 100 200 300

Median PCB conc. in feed - ppb

Med

ian

PC

B c

onc.

in fi

llets

- pp

b

Advisory

Objectives

2. Of the PCBs consumed by trout, what proportion is assimilated?

Assimilation Study

• Add chromic oxide to feed – 1% by wt.

• Feed fish for 2 weeks

• Strip feces

• Analyze feces for PCBs and chromic oxide

Assimilation Experiment

Diet % Assimilated

1 86.6

2 84.5

3 89.4

4 87.5

Mean = 87.0%

Objectives

3. If PCBs are present in hatchery supply water, what are the relative contributions of PCBs from the water and from the feed to the total found in trout?

SPMD Deployments

• 3 in source spring and 3 in tank with no fish

• Replace monthly

12-Month Average

Source Spring:

293 ng PCB/SPMD

Inside Tank:

200 ng PCB/SPMD

Mass Balance Approach

Initial Body Burden of PCBs

+

PCB uptake from feed

=

Expected Body Burden of PCBs

Actual body burden of PCBsminus

Expected body burden of PCBs=

Uptake of PCBs from water

Diet 2 – Month 1

Initial fillets 370 ng of PCBs

Initial carcasses 2134 ng

Absorbed from feed 1557 ng

Expected final total 4061 ng

Final fillets 754 ng

Final carcasses 3726 ng

Total final 4480 ng

Uptake from water 423 ng

24 Monthly Comparisons

• 8 comparisons: Actual > Expected– Uptake from water

• 16 comparisons: Expected > Actual– No evidence of uptake from water

– Overall: Average difference –8.8%, meaning on average, no evidence of uptake from water

Summary

• PCB concentrations in fillets were positively related to PCB concentrations in feed

• With feed that had 126 ppb PCBs, concentrations in fillets after 6 months did not exceed advisory limit of 100 ppb

Summary

• PCBs were detected in the source water and there was no indication that the hatchery infrastructure contributed additional PCBs to the water

• Preliminary analyses suggest that uptake of PCBs from water was not important

Summary

PCB uptake was primarily from the feed and trout assimilated a large a large proportion (87%) of PCBs in the feed