### Selenium effect levels for selected representative/surrogate species

William Beckon

U.S. Fish and Wildlife Service

July 31, 2009Table 1 . Summary: Selenium effect levels for selected representative/surrogate species

### Mallard ( Anas platyrhynchos )

Tissue

Figure 1

. Relationship between hatchability of fertile eggs and concentration of selenium in on e egg from

each clutch laid by mallard ducks after exposure to dieta ry selenium in the form of seleno

- DL

- methionine

(H einz et al

. 19 89 ; see Table 2 ). The biphasic model is that of B eckon et al

. ( 2008 ).

Table 2

. Selenium concentration in mallard eggs (average for each treatment, one egg per hen ) and

proportion of fertile eggs hatch ed (average for each treatment) after exposure of hens to dietary selenium

in the form of seleno

- DL

- methionine

. Data are from Tables 2 and 4 in Heinz et al . (1989). Concentrations

of seleniu m, reported on wet

- weight basis, were converted to dry weight assuming 70% moisture, in

accordance with Ohlendorf (2003).

x y

Selenium

concentration

in eggs (ug/g

dry weight) Hatchability

(pro portion

of eggs

hatched)

0.59 0.596

2.74 0.707

5.28 0.6

11.2 0.534

36.3 0.369

59.4 0.022The a nalysis was that presented in Beckon et al . 2008 Supporting Information.

Diet

Figure 2

. Relationship between hatchability of fertile eggs and concentration of selenium in the diet of the

parent female mallard duck after exposure to dietary selenium in the form of seleno

- DL

- methionine

(H einz et al

. 19 89 ) . The biphasic model is that of Beckon et al

. ( 2008 ).Table 3 . Hatchability of fertile eggs and concentration of selenium in the diet and in one egg from each

female mallard duck after exposure to dietary selenium in the form of seleno

- DL

- methionine. Data are

from Gary Heinz (pers. com) with calculat ions (in red) using data in Heinz et al . (1989) with control diet

data from Heinz and Fitzgerald (1993) . Dietary concentration on a dry weight basis was calculated from

reported nominal wet weight concentration converted to dry weight based on percent moi sture reported as

about 10%, added to the control diet wet concentration (geometric mean of 0.33, 0.41, and <0.2 [treated as

0.1] μg/g wet weight) reported in Heinz and Fitzgerald (1993) converted to dry weight based on 10%

moisture.

x y

Pen

no. Dietary

Se

nominal

wet wt. Dietary

Se

calculated

dry wt.

incl.

control Egg

Se

(wet

wt) Egg Se

(dry wt

calculated

using

70%

moisture) %

hatch Hatchability

(proportion

hatched)

1 0 0.26 86.7 0.867

3 0 0.26 69.2 0.692

8 0 0.26 20 0.2

10 0 0.26 53.3 0.53 3

18 0 0.26 80 0.8

23 0 0.26 86.7 0.867

24 0 0.26 86.7 0.867

35 0 0.26 60 0.6

43 0 0.26 20 0.2

44 0 0.26 20 0.2

48 0 0.26 100 1

55 0 0.26 60 0.6

59 0 0.26 60 0.6

61 0 0.26 50 0.5

72 0 0.26 64.3 0.643

74 0 0.26 75 0.75

7 5 0 0.26 46.2 0.462

85 0 0.26 35.7 0.357

91 0 0.26 46.7 0.467

92 0 0.26 66.7 0.667

93 0 0.26 40 0.4

98 0 0.26 93.3 0.933

101 0 0.26 80 0.8

103 0 0.26 50 0.5

105 0 0.26 80 0.8

106 0 0.26 100 1

111 0 0.26 20 0.2

5 0 0.26 0.11 0.37 41.7 0.417

37 0 0.26 0.16 0.53 60 0.6

67 0 0.26 0.18 0.60 18.2 0.182

53 0 0.26 0.21 0.70 36.4 0.364

15 0 0.26 0.23 0.77 26.7 0.267

49 1 1.38 0.36 1.20 100 1

13 1 1.38 0.58 1.93 73.3 0.733

88 1 1.38 0.60 2.00 71.4 0.714109 1 1.38 0.67 2.23 46 .2 0.462

115 1 1.38 0.71 2.37 100 1

40 1 1.38 0.73 2.43 20 0.2

114 1 1.38 0.77 2.57 73.3 0.733

62 1 1.38 0.79 2.63 71.4 0.714

11 1 1.38 0.82 2.73 78.6 0.786

14 1 1.38 0.87 2.90 21.4 0.214

16 1 1.38 0.90 3.00 93.3 0.933

22 1 1.38 1.10 3.67 100 1

34 1 1.38 1.10 3.67 26.7 0.267

25 2 2.49 1.10 3.67 33.3 0.333

70 2 2.49 1.10 3.67 60 0.6

32 1 1.38 1.20 4.00 100 1

38 1 1.38 1.20 4.00 0 0

80 2 2.49 1.20 4.00 46.7 0.467

90 2 2.49 1.20 4.00 66.7 0.667

58 2 2.49 1.30 4.33 46.7 0.467

84 2 2.49 1.40 4.6 7 41.7 0.417

82 2 2.49 1.50 5.00 61.5 0.615

12 2 2.49 1.60 5.33 0 0

31 2 2.49 1.60 5.33 80 0.8

51 2 2.49 1.60 5.33 78.6 0.786

26 2 2.49 1.80 6.00 80 0.8

78 2 2.49 1.90 6.33 61.5 0.615

86 2 2.49 1.90 6.33 60 0.6

42 2 2.49 2.00 6.67 100 1

17 2 2.49 2.10 7.00 76.9 0.769

97 4 4.71 2.20 7.33 0 0

73 4 4.71 2.30 7.67 20 0.2

41 4 4.71 2.70 9.00 53.3 0.533

79 4 4.71 2.70 9.00 35.7 0.357

108 4 4.71 3.10 10.33 40 0.4

4 4 4.71 3.30 11.00 73.3 0.733

95 4 4.71 3.30 11.00 90.9 0.909

83 4 4.71 3.40 11.33 9 3.3 0.933

33 4 4.71 3.50 11.67 46.7 0.467

81 4 4.71 3.60 12.00 61.5 0.615

56 4 4.71 3.90 13.00 57.1 0.571

64 4 4.71 4.00 13.33 73.3 0.733

21 4 4.71 4.10 13.67 66.7 0.667

36 4 4.71 4.30 14.33 66.7 0.667

68 4 4.71 4.30 14.33 35.7 0.357

6 8 9.15 4.90 16.33 42.8 0.428

7 8 9.15 6.20 20.67 73.3 0.733

113 8 9.15 6.70 22.33 50 0.5

57 16 18.04 8.50 28.33 26.7 0.267

112 8 9.15 9.30 31.00 60 0.6

27 8 9.15 10.00 33.33 73.3 0.733

47 8 9.15 11.00 36.67 13.3 0.13371 8 9.15 11.00 36.67 0 0

87 8 9.15 11.00 36.67 88.9 0.889

89 8 9.15 11.00 36.67 100 1

45 8 9.15 12.00 40.00 0 0

9 8 9.15 13.00 43.33 53.3 0.533

20 8 9.15 13.00 43.33 0 0

69 8 9.15 13.00 43.33 0 0

77 8 9.15 13.00 43.33 26.7 0.267

100 16 18.04 13.00 43.33 26.7 0.267

104 16 18.04 13.00 43.33 0 0

52 8 9.15 14.00 46.67 53.3 0.533

65 16 18.04 18.00 60.00 13.3 0.133

19 16 18.04 19.00 63.33 0 0

46 16 18.04 21.00 70.00 0 0

96 16 18.04 23.00 76.67 0 0

110 16 18.04 23.00 76.67 0 0

63 16 18.04 25.00 83.33 0 0

nls(start=list(eUp=0.0452,bUp=0. 1417,eDn=10.0533,bDn=

- 2.659),

control=list(tol=.06,maxiter=50,minFactor=1/1024,printEval=FALSE,warnOnly

=FALSE),data = SeMallardHeinzRawDiet, trace=TRUE

, formula =

y~1/((1+(eUp/x)^bUp)*(1+(eDn/x)^bDn)))

Parameters:

Estimate Std. Error t value Pr(>|t|)

eUp 0.0452 0.1402 0.322 0.7478

bUp 0.1417 0.1665 0.851 0.3968

eDn 10.0533 2.0246 4.966 2.93e

- 06 ***

bDn

- 2.6590 1.2940

- 2.055 0.0426 *

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Re sidual standard error: 0.2708 on 97 degrees of freedom

Number of iterations to convergence: 0 (manually fitted)

Achieved convergence tolerance: 0.05054

### White sturgeon ( Acipenser transmontanus )

Note: unpublished data from UC Davis indicate that g reen sturgeon are more sensitive

to selenium than white sturgeon.

Tissue

Figure 3 . The relationship between selenium in the muscle tissue of adult female white sturgeon and the

occurrence of edema and/or skeletal deformities i n the larvae (at the end of yolk sac absorption) that hatch

from their eggs. The data are from Table 3

- 18 in Linville 2006 ( Table 4 below)

.

Table 4

. Selenium in the diet and muscle tissue of adult fem ale white sturgeon and the occurrence of

edema and/or skeletal deformities in the larvae (at the end of yolk sac absorption) that hatch from their

eggs (from Table 3

- 18 in Linville 2006). Corresponding selenium in diet and whole

- body (in red) were

calcula ted using data from Tables 2 and 3 in Tashjian et al

. ( 2006 )

.

diet y

Selenium

concentration

in maternal

diet ( μ g/g

dry wt.) Selenium

concentration

in maternal

muscle ( μ g/g

dry wt.) Selenium

concentration

in diet ( μ g/g

dry wt.) Selenium

concentration

in whole

body ( μ g/g

dry wt.) Incidence

of edema

or skeletal

deformities

in larvae

(percent)

1.42 1.28 0.0020 1.211 0

1.42 1.22 0.0017 1.161 0

1.42 1.48 0.0031 1.373 0

34.04 9.93 0.9990 7.147 0

34.04 11.1 1.4007 7.872 13.33

34.04 15.3 3.7082 10.396 27. 78y~100/(1+(e/x)^(b))

e=20,b=1

Formula: y ~ 100/(1 + (e/x)^(b))

Parameters:

Value Std. Error t value

e 18.85050 1.51369 12.45330

b 4.46565 1.18170 3.77899

Residual standard error: 3.60266 on 4 degrees of freedom

Figure 4 . Relationship between muscle and whole

- body concentrations of selenium in young white

sturgeon ( initially weighing about 30 g) exposed for 56 days to dietary selenium in the form of seleno

- L

methionine . Dat a are from Tables 2 and 3 in Tashjian et al . 2006.Table 5 . Diet, muscle, and whole body concentrations of selenium in young white sturgeon (initially

weighing about 30 g) exposed for 56 days to dietary selenium in the form of s eleno

- L

- methionine. Data

are from Tables 2 and 3 in Tashjian et al . 2006.

diet musc WB

Selen ium

in diet

(μg/g

evidently

essentially

dry) Selenium

in

muscle

(μg/g dry

wt.) Selenium

in

sturgeon

(μg/g

whole

body dry

wt.)

0.4 8.2 5.2

9.6 17.2 11.8

20.5 22.9 14.7

41.7 36.8 22.5

89.8 52.9 34.4

191.1 54.8 27.5

Figure 5 . The relationship between selenium in the whole bodies of adult female white sturgeon and the

occurrence of edema and/or skeletal deformities in the larvae (at the end of yolk sac absorption) that hatch

from their eggs. The data are from Table 3

- 18 i n Linville 2006, using Tashjian et al . (2006) data (Figure 4

above) to convert muscle selenium concentrations to whole body selenium concentrations.

nls(formula = y~100/(1+(e/diet)^b),

data = WhiteSturgeonEffects,

start = list(e=5,b=1.9),trace=TRUE)

Parameters:Estimate Std. Error t value Pr(>|t|)

e 6.9847 1.7016 4.105 0.0148 *

b 1.4719 0.3895 3.779 0.0195 *

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 3.603 on 4 degrees of freed om

Number of iterations to convergence: 6

Achieved convergence tolerance: 2.548e

- 06

Diet (adult)

Figure 6 . Relationship between diet and muscle concentrations of selenium in adult white sturgeon

exposed for six month s to die tary selenium in the form of selenized yeast . Data are from Table 1

- 3 in

Linville ( 2006 )

. ( Figure 4 above)

lm(formula = log10(musc) ~ log10(diet), data = WhiteSturgeonEffects)

Residuals:

1 2 3 4 5 6

- 0.01407

- 0.03492 0.04898

- 0.07871

- 0.03033 0.10904

Coefficients:

Estimate Std. Error t value Pr(>|t|)

(Intercept) 0.01594 0.04866 0.327 0.759729

log10(diet) 0.69173 0.04470 15.475 0.000102 ***---

Signif . codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 0.07553 on 4 degrees of freedom

Multiple R

- squared: 0.9836, Adjusted R

- squared: 0.9795

F

- statistic: 239.5 on 1 and 4 DF, p

- value: 0.0001018

Diet (juvenile)

Figure 7 . Relationship between diet and muscle concentrations of selenium in young white sturgeon

(initially weighing about 30 g) exposed for 56 days to dietary selenium in the form of seleno

- L

- methionine.

Data are from Table 3 in Tashjian et al . 2006.

Call:

lm(formula = log10(musc) ~ log10(diet), data = WhiteSturgeonTTF)

Residuals:

1 2 3 4 5 6

0.04788

- 0.08533

- 0.06962 0.03475 0.08255

- 0.01023

Coefficien ts:

Estimate Std. Error t value Pr(>|t|)

(Intercept) 0.99709 0.05515 18.081 5.5e

- 05 ***

log10(diet) 0.32961 0.03549 9.288 0.000748 ***

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1Residual standard error: 0.07508 on 4 degrees of freedom

Multiple R

- squared: 0.9557, Adjusted R

- squared: 0.9446

F

- statistic: 86.26 on 1 and 4 DF, p

- value: 0.0007476

Figure 8 . The relationship between selenium in the diets of white sturgeon and the o ccurrence of edema

and/or skeletal deformities in the larvae (at the end of yolk sac absorption) that hatch from their eggs.

The data ( Table 4 above) are from Table 3

- 18 in Linville 2006, using Tashjian et al . (2006) data (Figu re 7

above) to convert muscle selenium concentrations to dietar y selenium concentrations.

nls(formula = y~100/(1+(e/diet)^b),

data = WhiteSturgeonEffects,

start = list(e=5,b=1.9),trace=TRUE)

Parameters:

Estimate Std. Error t value Pr(>|t|)

e 6. 9847 1.7016 4.105 0.0148 *

b 1.4719 0.3895 3.779 0.0195 *

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 3.603 on 4 degrees of freedom

Number of iterations to convergence: 6

Achieved conver gence tolerance: 2.548e

- 06

### Chinook salmon ( Oncorhynchus tshawytscha )

Tissue

Figure 9

. Relationship between survival of juvenile Chinook salmon and concentration of selenium in

their tissues after 90 days exposure to dietary selenium in the form of wild

- caught fish (red dots) or seleno

DL

- methionine (blue dots) (H amilton et al

. 19 9 0). The biphasic model is that of Brain and Cousens ( 1989 ).

Atlantic salmon data from Poston et al . (1976) w ere not used in the model, but are sho wn here as

validation of the generality of the model.Table 6 . Survival of juvenile Chinook salmon and concentration of selenium in their diet and in their

tissues after 90 days exposure to dietary selenium in the form of wild

- c aught fish (SLD) or seleno

- DL

methionine (SeMet). The data are from Tables 3 and 5 in H amilton et al . ( 19 9 0).

diet y

nls(start = list(f=1.7,e=.8,b=

- 1.67),control=

list(tol=.001,maxiter=50,minFactor=1/1024,printEval=FALSE,warnOnly

=FALSE),trace=TRUE,

data = ChinookSalmon,formula = y~f*x/(1+(e/x)^b ))

Parameters:

Estimate Std. Error t value Pr(>|t|)

f 1.7143 0.4684 3.66 0.00640 **

e 0.7993 0.2103 3.80 0.00524 **

b

- 1.6657 0.0955

- 17.44 1.19e

- 07 ***

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 0.0531 on 8 degrees of freedom

Number of iterations to convergence: 2

Achieved convergence tolerance: 0.0001288 Diet

type Selenium

in diet

(μg/g dry

wt.) Selenium

in fish

(μg/g

whole

body dry

wt.) Survival

SLD 3.2 2.7 0.56

SLD 5.3 4 0.447

SLD 6.9 6.5 0.312

SLD 18.2 14.3 0.209

SLD 35.4 33.4 0.182

Control 1 0.8 0.667

SeMet 3.2 1.7 0.725

SeMet 5.3 2.6 0.45

SeMet 6.9 5. 4 0.375

SeMet 18.2 10.8 0.224

SeMet 35.4 27.8 0.107Diet

Figure 10

. Relationship between concentration of selenium in the diets of juveni le Chinook salmon and

survival and after 90 days exposure to dietary selenium in the form of wild

- caught fish (red dots) or

seleno

- DL

- methionine (blue dots) (H amilton et al

. 19 9 0). The biphasic model is that of Brain and Cousens

( 1989 ).

nls(start = li st(f=1.7,e=.8,b=

- 1.67),control=

list(tol=.001,maxiter=50,minFactor=1/1024,printEval=FALSE,warnOnly

=FALSE),trace=TRUE,

data = ChinookSalmon,formula = y~f*diet/(1+(e/diet)^b))

Parameters:

Estimate Std. Error t value Pr(>|t|)

f 1.0945 0.2367 4.625 0.00170 **

e 1.3180 0.2858 4.611 0.00173 **

b

- 1.7583 0.1148

- 15.315 3.28e

- 07 ***

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 0.05906 on 8 degrees of freedom

Number of iterations to convergence: 5

Achieved convergence tolerance: 0.0001085

### Rainbow trout ( Oncorhynchus mykiss )

Tissue

Figure 11

. Relationship between growth of juvenile rainbow trout and concentration of selenium in their

tissues after 140 da ys exposure to dietary selenium in the form of sodium selenite (Hilton et al. 1980 ; Table

7 below ). The biphasic model is that of Beckon et al. (2008).

Table 7 . Weight of juvenile rainbow trout and co ncentration of selenium in their tissues after 140 days

exposure to dietary selenium in the form of sodium selenite

. Data are from Tables 2 and 3, and

transcribed from Fig. 2 in Hilton et al

. (1980). Whole body selenium was calculated from reported

conce ntrations in carcass, kidney and liver.

Selenium

in diet

( μg/g dry

diet) Carcass

Concen

tration

Factor

(from

Hilton

et al

. Fig.2) Selenium

concen

tration

in fish

(μg/g

carcass

dry wt.) Liver

Concen

tration

Factor Hepato

somatic

index at

wk 4 Liver

Se

correc

tion Kidney

Concen

tration

Factor Kidney

Se

correc

tion Selenium

in fish

(μg/g

whole

body dry

wt.) Weight

of

whole

fish (g)

0.07 3.55 0.249 8.5 1.4 0.0036 11.35 0.00282 0.2523 32

0.15 2.95 0.442 6.3 1.3 0.0061 9 0.00478 0.4489 35

0.38 1.35 0.513 6.5 1.3 0.0161 6.7 0.00902 0.5362 37

1.25 0.52 0.650 9.65 1.3 0.0784 2.9 0.01285 0.7386 41

3.67 0.37 1.358 11.9 1.3 0.2839 2.6 0.03381 1.6697 41

13.06 0.35 4.571 7.9 1.4 0.7222 2.8 0.12959 5.4037 14nls(start = list(max=81.9998,eUp=0.82232,bUp=0.4387,eDn=3.3428,bDn=

- 2.56175),

control= list(tol=29,maxiter=50,minF actor=1/1024,printEval=FALSE,warnOnly =FALSE),

trace=TRUE, data = RainbowTroutTTF, formula = y~1.28+((max

1.28)/(1+(eUp/x)^bUp))/(1+(eDn/x)^bDn))

Parameters:

Estimate Std. Error t value Pr(>|t|)

max 81.9998 658.7795 0.124 0.921

eUp 0.8223 29.7913 0.028 0.982

bUp 0.4387 2.4779 0.177 0.888

eDn 3.3428 4.5195 0.740 0.595

bDn

- 2.5618 2.1202

- 1.208 0.440

Residual st andard error: 1.783 on 1 degree of freedom

Number of iterations to convergence: 0

Achieved co nvergence tolerance: 28.12

residual sum

- of

- squares: 3.178 (minimized manually)

Diet

Figure 12

. Relationship between dietary concentration of selenium (as selenite) and weight (mass) of

young rainbow trout (average initial m ass 1.28 g) fed diets spiked with sodium selenite for 140 days

(Hilton et al. 1980 ; Table 7 above )

.nls(start = list(max=75,eUp=.1,bUp=.17,eDn=14,bDn=

- 2.4),control=

list(tol=.0001,maxiter=50,minFactor=1/1024,printEval=FALSE,warn Only

=FALSE),trace=TRUE,data = RainbowTroutTTF,formula = y~1.28+((max

1.28)/(1+(eUp/diet)^bUp))/(1+(eDn/diet)^bDn))

Parameters:

Estimate Std. Error t value Pr(>|t|)

max 74.8106 125.7177 0.595 0.658

eUp 0.4701 9.5920 0.049 0.969

bUp 0.1684 0.2653 0.635 0.640

eDn 9.1007 1.2964 7.020 0.090 .

bDn

- 2.7285 0.5476

- 4.983 0.126

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 0.654 on 1 degree of freedom

N umber of iterations to convergence: 8

Achieved convergence tolerance: 2.743e

- 05

Figure 13 . Relationship between dietary concentration of selenium (as seleno

- L

- methionine equivalent)

and weight (mass) of young rainbow trout (av erage initial mass 1.28 g) fed diets spiked with sodium

selenite for 140 days (Hilton et al . 1980)

. The seleno

- L

- methionine equivalent diets were calculated by

using the whole body selenium concentration data in Hilton et al

. ( 1980) and the bioaccumulati on data

from the experiment of Vidal et al . (2005) in which larval rainbow trout were fed seleno

- L

- methionine for

9 0 days ( Figure 14 and Table 8 below)

.Figure 14 . Selenium in the whole body tissue of young rainbow trout as a function of selenium in the diet

in the form of either selenite ( Hilton et al . 1980 ) or seleno

- L

- methionine (Vidal et al . (2005).

Table 8 . Selenium in the diets of larval rainbo w trout and selenium in their whole body tissue after 90

days of exposure to dietary selenium in the form of seleno

- L

- methionine . Data are from Table 2 in Vidal et

al . (2005) , with dietary selenium (in red) calculated by adding background (control) seleni um analysis to

nominal (added) selenium

. Whole body selenium on a dry weight basis (in red) was calculated from

reported wet weight concentrations using 75.84 percent moisture as used in USEPA (2004).

Selenium

in diet

( μ g/g dry

wt.) Selenium

concentrati on

in fish ( μ g/g

whole body

wet wt.) Selenium

concentration

in fish ( μ g/g

whole body

dry wt.) Weight

of

whole

fish (g)

0.23 0.31 1.28 5.17

4.83 0.58 2.40 3.45

12.23 1.2 4.97 3.45

18.23 1.41 5.84 3.82nls(start = list(max=77.073,eUp=0.03730,bUp=0 .15925,eDn=5.5995,bDn=

- 0.8558),control=

list(tol=30,maxiter=50,minFactor=1/1024,printEval=FALSE,warnOnly

=FALSE),trace=TRUE,data = RainbowTrout,formula = y~1.28+((max

1.28)/(1+(eUp/dietr)^bUp))/(1+(eDn/dietr)^bDn))

Parameters:

Estimate Std. Error t va lue Pr(>|t|)

max 77.0730 513.0790 0.150 0.905

eUp 0.0373 3.1269 0.012 0.992

bUp 0.1593 0.8301 0.192 0.879

eDn 5.5995 22.1013 0.253 0.842

bDn

- 0.8558 0.7089

- 1.207 0.440

Residual standard error: 1.808 on 1 d egrees of freedom

Number of iterations to convergence: 0

Achieved convergence tolerance: 29.92References

Beckon WN, Parkins C, Maximovich A, Beckon AV. 2008 . A general approach to modeling

biphasic relationships. Environ Sci Tech nol 42:1308

- 1314.

Brain P, Cousens R. 1989. An equation to describe dose responses where there is stimulation

of growth at low doses. Weed Res 29:93

- 96.

Heinz GH, Hoffman DJ, Gold LG. 1989. Impaired reproduction of mallards fed an organic

form of selenium. J Wildl Manag 53:418

– 428.

Heinz GH, Fitz g erald MA. 1993. Overwinter survival of mallards fed selenium. Arch

Environ Toxicol 25:90

- 94

.

Hilton JW, Hodson PV, Slinger SJ. 1980. The requirements and toxicity of selenium in

rainbow trout ( Salmo gairdneri ). J Nutr 110: 2527

- 2535.

Linville RG. 2006. Effects of excess selenium on the health and reproduction of white

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