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Effect of sodium pentachlorophenate on growth of fathead minnow

P.promelas.Rd

Fathead minnows (Pimephales promelas) were exposed to sodium pentachlorophenate concentrations ranging from 32 to 512 micro g/L in a 7-day larval survival and growth test. The average dry weight was measured.

Usage

data(P.promelas)

Format

A data frame with 24 observations on the following 2 variables.

conc

a numeric vector of sodium pentachlorophenate concentrations (micro g/L).

dryweight

a numeric vector dry weights (mg)

Details

The data are analysed in Bruce and Versteeg (1992) using a log-normal dose-response model (using the logarithm with base 10).

Source

Bruce, R. D. and Versteeg, D. J. (1992) A statistical procedure for modeling continuous toxicity data, Environ. Toxicol. Chem., 11, 1485–1494.

Examples

library(drc)

## Model with ED50 on log scale as parameter
p.prom.m1<-drm(dryweight~conc, data=P.promelas, fct=LN.3())

plot(fitted(p.prom.m1), residuals(p.prom.m1))


plot(p.prom.m1, type="all", broken=TRUE, xlim=c(0,1000))

summary(p.prom.m1)
#> 
#> Model fitted: Log-normal with lower limit at 0 (3 parms)
#> 
#> Parameter estimates:
#> 
#>                  Estimate  Std. Error t-value   p-value    
#> b:(Intercept)   -0.571777    0.187101 -3.0560  0.006001 ** 
#> d:(Intercept)    0.704855    0.025553 27.5845 < 2.2e-16 ***
#> e:(Intercept) 1145.654281  392.624568  2.9179  0.008223 ** 
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
#> 
#> Residual standard error:
#> 
#>  0.05467719 (21 degrees of freedom)
ED(p.prom.m1, c(10,20,50), interval="delta")
#> 
#> Estimated effective doses
#> 
#>       Estimate Std. Error     Lower     Upper
#> e:10  121.8002    59.4612   -1.8561  245.4565
#> e:20  262.9046    72.2694  112.6121  413.1970
#> e:50 1145.6543   392.6246  329.1468 1962.1618

## Model with ED50 as parameter
p.prom.m2<-drm(dryweight~conc, data=P.promelas, fct=LN.3(loge=TRUE))
summary(p.prom.m2)
#> 
#> Model fitted: Log-normal with lower limit at 0 (3 parms)
#> 
#> Parameter estimates:
#> 
#>                Estimate Std. Error t-value   p-value    
#> b:(Intercept) -0.571671   0.187187  -3.054  0.006028 ** 
#> d:(Intercept)  0.704852   0.025555  27.581 < 2.2e-16 ***
#> e:(Intercept)  7.044103   0.343117  20.530 2.221e-15 ***
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
#> 
#> Residual standard error:
#> 
#>  0.05467719 (21 degrees of freedom)
ED(p.prom.m2, c(10,20,50), interval="fls")
#> 
#> Estimated effective doses
#> 
#>      Estimate    Lower    Upper
#> e:10  121.795   44.111  336.290
#> e:20  262.930  148.437  465.735
#> e:50 1146.080  561.466 2339.410