A comparison of plant toxicities of some industrial chemicals in soil culture and soilless culture.

The toxicities of 10 industrial chemicals to three types of plants were determined according to OECD Guideline 208. Apart from two types of soil, soilless culture was used in the test. The results with terrestrial plants in these tests were also compared with those of the same chemicals tested with aquatic plants (duck weed, algae) in nutrient solution. It was found that in soilless culture the EC50 values obtained were much lower than those in soil culture. Soilless culture of terrestrial plants and tests with aquatic plants yielded about the same results. It is concluded that adsorption of the chemicals to soil particles is the main factor governing the results. In an additional experiment with Cd, it was demonstrated that the Cd content of reacting plants was about the same in tests carried out in soil and in nutrient solution, pointing to the obvious fact that the amount of chemical taken up is the basis for the toxic effect. In the interpretation of tests carried out with chemicals added directly to soil, this should be taken into account. It is recommended that soilless culture of terrestrial plants be seriously considered in ecotoxicological testing.