title: From more to less than Haber's law.
abstract: We show how reformulating a first-order response theory with respect to both toxicant concentration and exposure time, in terms of relative instead of absolute increments, leads to a generalized version of Haber's law and to a combined sigmoid model for concentration and time response, derived on analytical rather than empirical grounds. More general presuppositions of Haber's law (without assuming sigmoid response) are briefly discussed. The relative intensities of time response and concentration response are measured by a single dimensionless parameter, characterizing each quadruple {toxicant, route, species, adverse effect}. Cross-species and cross-toxicant variability of this parameter is discussed and illustrated by new findings on algae and Daphniae exposed to selected inorganic and organic pollutants.
authors.affiliation: GSF Research Centre, Institute of Ecological Chemistry, Ingolstadter Landstrasse 1, PO Box 11 29, D-85758 Oberschleißheim, Germany.
authors.forename: Karl-Werner
authors.initials: KW
authors.lastname: Schramm
authors.forename: Iulia
authors.initials: I
authors.lastname: Ghergut
authors.forename: Akbar
authors.initials: A
authors.lastname: Behechti
authors.forename: Karl K
authors.initials: KK
authors.lastname: Rozman
authors.forename: Antonius
authors.initials: A
authors.lastname: Kettrup