httk (version 2.6.0)

calc_half_life: Calculates the half-life for a one compartment model.

Description

This function calculates the half life from the three compartment steady state model where elimination is entirely due to metabolism by the liver and glomerular filtration in the kidneys.

Usage

calc_half_life(
  chem.cas = NULL,
  chem.name = NULL,
  dtxsid = NULL,
  parameters = NULL,
  species = "Human",
  model = "3compartmentss",
  suppress.messages = TRUE,
  ...
)

Value

Half life

Units of h.

Arguments

chem.cas

Either the cas number or the chemical name must be specified.

chem.name

Either the chemical name or the cas number must be specified.

dtxsid

EPA's 'DSSTox Structure ID (https://comptox.epa.gov/dashboard) the chemical must be identified by either CAS, name, or DTXSIDs

parameters

Chemical parameters from parameterize_steadystate or 1compartment function, overrides chem.name and chem.cas.

species

Species desired (either "Rat", "Rabbit", "Dog", "Mouse", or default "Human").

model

The model used to calculate elimination rate (defaults to "3compartmentss")

suppress.messages

Whether or not the output message is suppressed.

...

Additional parameters passed to parameterize function if parameters is NULL.

Author

Sarah E. Davidson

Details

Half life is calculated by dividing the natural-log of 2 by the elimination rate from the one compartment model.

See Also

calc_elimination_rate

Examples

calc_half_life(chem.name="Bisphenol A")
# \donttest{
calc_half_life(chem.name="Bisphenol A",species="Rat")

calc_half_life(chem.cas="80-05-7")

# Volatiles are outside the domain of default model:
try(calc_half_life(
     chem.name="toluene"))

# We can turn off physchem checking:
calc_half_life(
     chem.name="toluene",
     physchem.exclude=FALSE)

# Or use an appropriate model for volatiles:
calc_half_life(
     chem.name="toluene",
     model="sumclearances")

# PFAS are outside the domain:
try(calc_half_life(
     dtxsid="DTXSID8031865",
     model="sumclearances"))

# Can turn off chemical class checking:
calc_half_life(
  dtxsid="DTXSID8031865",
  model="sumclearances",
  class.exclude=FALSE,
  suppress.messages=TRUE)

# For a metabolized compound, non-restrictive clearance should be faster:
h1 <- calc_half_life(
  chem.name="toluene",
  model="sumclearances",
  suppress.messages=TRUE)
h2 <- calc_half_life(
  chem.name="toluene",
  model="sumclearances",
  restrictive.clearance=FALSE,
  suppress.messages=TRUE)
# Check that h2 < h1:
if (!(h2 < h1)) stop("h2 not less than h1")

# Change species: 
calc_half_life(
  dtxsid="DTXSID8031865",
  species="rat",
  model="sumclearances",
  default.to.human=TRUE,
  class.exclude=FALSE,
  physchem.exclude=FALSE,
  suppress.messages=TRUE)
# }