A general dose-response relationship for chronic chemical and other health stressors and mixtures based on an emergent illness severity model

PLoS One. 2019 Feb 15;14(2):e0211780. doi: 10.1371/journal.pone.0211780. eCollection 2019.

Abstract

Current efforts to assess human health response to chemicals based on high-throughput in vitro assay data on intra-cellular changes have been hindered for some illnesses by lack of information on higher-level extracellular, inter-organ, and organism-level interactions. However, a dose-response function (DRF), informed by various levels of information including apical health response, can represent a template for convergent top-down, bottom-up analysis. In this paper, a general DRF for chronic chemical and other health stressors and mixtures is derived based on a general first-order model previously derived and demonstrated for illness progression. The derivation accounts for essential autocorrelation among initiating event magnitudes along a toxicological mode of action, typical of complex processes in general, and reveals the inverse relationship between the minimum illness-inducing dose, and the illness severity per unit dose (both variable across a population). The resulting emergent DRF is theoretically scale-inclusive and amenable to low-dose extrapolation. The two-parameter single-toxicant version can be monotonic or sigmoidal, and is demonstrated preferable to traditional models (multistage, lognormal, generalized linear) for the published cancer and non-cancer datasets analyzed: chloroform (induced liver necrosis in female mice); bromate (induced dysplastic focia in male inbred rats); and 2-acetylaminofluorene (induced liver neoplasms and bladder carcinomas in 20,328 female mice). Common- and dissimilar-mode mixture models are demonstrated versus orthogonal data on toluene/benzene mixtures (mortality in Japanese medaka, Oryzias latipes, following embryonic exposure). Findings support previous empirical demonstration, and also reveal how a chemical with a typical monotonically-increasing DRF can display a J-shaped DRF when a second, antagonistic common-mode chemical is present. Overall, the general DRF derived here based on an autocorrelated first-order model appears to provide both a strong theoretical/biological basis for, as well as an accurate statistical description of, a diverse, albeit small, sample of observed dose-response data. The further generalizability of this conclusion can be tested in future analyses comparing with traditional modeling approaches across a broader range of datasets.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 2-Acetylaminofluorene / adverse effects*
  • 2-Acetylaminofluorene / pharmacology
  • Animals
  • Benzene / adverse effects*
  • Benzene / pharmacology
  • Bromates / adverse effects*
  • Bromates / pharmacology
  • Chloroform / adverse effects*
  • Chloroform / pharmacology
  • Dose-Response Relationship, Drug
  • Mice
  • Models, Biological*
  • Oryzias
  • Rats
  • Toluene / adverse effects*
  • Toluene / pharmacology

Substances

  • Bromates
  • Toluene
  • Chloroform
  • 2-Acetylaminofluorene
  • Benzene