Björn Ekwall, an outstanding Swedish cell toxicologist

Abstract

Dr. Björn Ekwall (1940–2000) was an outstanding Swedish cell toxicologist who made pioneering contributions to the field of in vitro toxicology. In particular, he formulated the so called “basal cytotoxicity concept” (1983) which provided a conceptual basis for the estimation of acute systemic toxicity of chemicals in humans by the use of in vitro tests. Björn Ekwall formulated, initiated and, together with a group of dedicated Scandinavian toxicologists, guided the MEIC project (Multicentre Evaluation of In Vitro Cytotoxicity Programme, 1989–1999), in which 50 reference chemicals were voluntary tested in 100 laboratories worldwide by 61 different in vitro assays. This project was unique because human sub-lethal and lethal blood concentrations were used for a first time as a reference system for the evaluation of predictability of in vitro tests for human acute systemic toxicity. The results of MEIC project have shown good correlation between human LC 50 values (50% lethal concentrations) and IC 50 values (50% inhibitory concentrations from basal cytotoxicity tests), by the use a battery of three 24-h basal cytotoxicity tests ( R 2 = 0.77). The MEIC project paved the way to the present validation projects, under EU 6th Framework programme, such as ACuteTox, Sens-it-iv, and ReProTect.