Death of fathead minnow larvae after exposure to fluoranthene

Fathead minnow larvae were exposed to fluoranthene, a polycyclic aromatic hydrocarbon, under two different algal densities resulting in different levels of ambient ultraviolet radiation. Number of dead larvaes were reported.

Usage

data(fluoranthene)

Format

A data frame with 24 observations on the following 4 variables.

algalconc: a numeric vector
conc: a numeric vector
totalnum: a numeric vector
mortality: a numeric vector

Source

M. W. Wheeler, R. M. Park, and A. J. Bailer (2006). Comparing median lethal concentration values using confidence interval overlap or ratio tests. Environmental Toxicology and Chemistry, 25:1441–1444.

Examples

library(drc)

## Displaying the data
head(fluoranthene)
#>   algalconc conc mortality totalnum
#> 1       0.7    5         0       23
#> 2       0.7    5         0       19
#> 3       0.7    5         0       20
#> 4       1.5    5         0       22
#> 5       1.5    5         0       25
#> 6       1.5    5         0       24

## Fitting a two-parameter log-logistic model for binomial response
## with different curves per algal concentration
fluoranthene.m1 <- drm(mortality/totalnum ~ conc, algalconc, weights = totalnum,
data = fluoranthene, fct = LL.2(), type = "binomial")
summary(fluoranthene.m1)
#> 
#> Model fitted: Log-logistic (ED50 as parameter) with lower limit at 0 and upper limit at 1 (2 parms)
#> 
#> Parameter estimates:
#> 
#>       Estimate Std. Error t-value   p-value    
#> b:0.7 -4.61836    0.53249 -8.6731 < 2.2e-16 ***
#> b:1.5 -5.14932    0.64726 -7.9556  1.78e-15 ***
#> e:0.7 15.24767    0.73337 20.7914 < 2.2e-16 ***
#> e:1.5 17.88383    0.77174 23.1735 < 2.2e-16 ***
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

## Plotting the fitted curves
plot(fluoranthene.m1, xlab = "Fluoranthene concentration",
ylab = "Proportion dead")