title: A proposal for calculating the no-observed-adverse-effect level (NOAEL) for organic compounds responsible for liver toxicity based on their physicochemical properties.
abstract: OBJECTIVE
  Both environmental and occupational exposure limits are based on the no-observed-adverse-effect level (NOAEL), lowest-observed-adverse-effect level (LOAEL) or benchmark dose (BMD) deriving from epidemiological and experimental studies. The aim of this study is to investigate to what extent the NOAEL values for organic compounds responsible for liver toxicity calculated based on their physicochemical properties could be used for calculating occupational exposure limits.
  
  
  METHODS
  The distribution coefficients from air to the liver (log K(liver)) were calculated according to the Abraham solvation equation. NOAEL and LOAEL values for early effects in the liver were obtained from the literature data. The descriptors for Abraham's equation were found for 59 compounds, which were divided into 2 groups: "non-reactive" (alcohols, ketones, esters, ethers, aromatic and aliphatic hydrocarbons, amides) and "possibly reactive" (aldehydes, allyl compounds, amines, benzyl halides, halogenated hydrocarbons, acrylates).
  
  
  RESULTS
  The correlation coefficients between log-log K and log NOAEL for non-reactive and reactive compounds amounted to r = -0.8123 and r = -0.8045, respectively, and were statistically significant. It appears that the Abraham equation could be used to predict the NOAEL values for compounds lacking information concerning their liver toxicity.
  
  
  CONCLUSIONS
  In view of the tendency to limit animal testing procedures, the method proposed in this paper can improve the practice of setting exposure guidelines for the unstudied compounds.
authors: Department of Chemical Safety, Nofer Institute of Occupational Medicine, Łódź, Poland.
authors: Marek
authors: M
authors: Jakubowski
authors: Sławomir
authors: S
authors: Czerczak
mesh_terms: D055598:Chemical Phenomena; D006801:Humans; D008099:Liver / Q000187:drug effects*; D008962:Models, Theoretical; D019055:No-Observed-Adverse-Effect Level; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis*; D018570:Risk Assessment / Q000379:methods*; D055549:Volatile Organic Compounds / Q000009:adverse effects / Q000032:analysis*
chemical_list: D055549:Volatile Organic Compounds