fitdistrplus (version 1.0-0)

endosulfan: Species Sensitivity Distribution (SSD) for endosulfan

Description

Summary of 48- to 96-hour acute toxicity values (LC50 and EC50 values) for exposure of Australian an Non-Australian taxa to endosulfan.

Usage

data(endosulfan)

format

endosulfan is a data frame with 3 columns, named ATV for Acute Toxicity Value (geometric mean of LC50 ou EC50 values in micrograms per liter), Australian (coding for Australian or another origin) and group (arthropods, fish or nonarthropod invertebrates).

source

Hose, G.C., Van den Brink, P.J. 2004. Confirming the Species-Sensitivity Distribution Concept for Endosulfan Using Laboratory, Mesocosms, and Field Data. Archives of Environmental Contamination and Toxicology, 47, 511-520.

Examples

# (1) load of data
#
data(endosulfan)

# (2) plot and description of data for non Australian fish in decimal logarithm
#
log10ATV <-log10(subset(endosulfan,(Australian == "no") & (group == "Fish"))$ATV)
plotdist(log10ATV)
descdist(log10ATV,boot=1000)

# (3) fit of a normal and a logistic distribution to data in log10
# (classical distributions used for SSD)
# and visual comparison of the fits
#
fln <- fitdist(log10ATV,"norm")
summary(fln)

fll <- fitdist(log10ATV,"logis")
summary(fll)

cdfcomp(list(fln,fll),legendtext=c("normal","logistic"),
xlab="log10ATV")

denscomp(list(fln,fll),legendtext=c("normal","logistic"),
xlab="log10ATV")


# (4) estimation of the 5 percent quantile value of 
# logistic fitted distribution (5 percent hazardous concentration  : HC5)
# with its two-sided 95 percent confidence interval calculated by 
# parametric bootstrap with 501 iterations
#
# in log10(ATV)
bll <- bootdist(fll,niter=501)
HC5ll <- quantile(bll,probs = 0.05)
# in ATV
10^(HC5ll$quantiles)
10^(HC5ll$quantCI)

# (5) estimation of the 5 percent quantile value of 
# the fitted logistic distribution (5 percent hazardous concentration  : HC5)
# with its one-sided 95 percent confidence interval (type "greater")
# calculated by 
# nonparametric bootstrap with 501 iterations
# 
# in log10(ATV)
bllnonpar <- bootdist(fll,niter=501,bootmethod = "nonparam")
HC5llgreater <- quantile(bllnonpar,probs = 0.05, CI.type="greater")
# in ATV
10^(HC5llgreater$quantiles)
10^(HC5llgreater$quantCI)

# (6) fit of a logistic distribution 
# by minimizing the modified Anderson-Darling AD2L distance
# cf. ?mgedist for definition of this distance
#

fllAD2L <- fitdist(log10ATV,"logis",method="mge",gof="AD2L")
summary(fllAD2L)
plot(fllAD2L)