Toxicity testing based on microcalorimetry

Microcalorimetry is a promising tool to fulfill the increasing need for more sensitive ecotoxicity test methods. A TAM (Thermo Activity Monitor) microcalorimeter was used for measuring the heat production  of various test organisms when getting in contact with toxic soils. Well known bacterial (Azotobacter agile), animal (Tetrahymena pyriformis, Panagrellus revividus, Folsomia candida) and plant test organisms (Sinapis alba) were tested for heat production.:, and were used as test organisms. Their heat response for forest soil contaminated with metals (Cu, Hg and Zn) and with organic pollutants (transformator oil, diesel oil, phenanthrene, cypermetrine, BDNPA and PCP) was measured, evaluated and interpreted.

To receive the best signals the characteristics (cell concentration, number of animals and plants, their age) of the used test organisms and the test conditions (temperature, moisture-content, etc.) were optimized. Both the total amount of heat transmitted by the organisms and the shape of the time-heat curve (height of the maximum and it appearance in time) are suitable for the prediction of soil toxicity: in a certain concentration range the higher the pollutant concentration of the soil the lower the maximum of the time-heat curve. The time elapse of the maximum is also informative. In certain cases at low pollutant concentrations an increase was measured compared to control. It can be interpreted as  “fight for survival”. The microcalorimetric test method offers a new option in toxicity testing. Nowadays high capacity equipments are available with 96 independent cells.