S 3 The chronic tests may last over one or more generations

Last updated: 1/27/2023

S 3 The chronic tests may last over one or more generations Duration of chronic tests involving longer life span test organisms takes significant proportion of their life including gestational period of females and spermatogenesis of male test organisms Generally chronic and sublethal toxicity tests last for a significant portion of an organism s life expectancy Reproductive tests often examine the reproductive capabilities of an organism By their nature these tests must include 1 the gestational period for females and 2 a significant portion of the time for spermatogenesis for males Growth assays may include an accounting of biomass produced by protists and algae or the development of newly hatched chicks Sublethal endpoints including reproductive immune endocrine and developmental dysfunction are generally associated with chronic toxicity Nevertheless chronic exposure also can result in direct mortality not observed during acute exposure For example chronic exposure of highly lipophilic substances can result in the ultimate bioaccumulation of the chemical to concentrations that are lethal to the organisms In principle ecotoxicity tests can be carried out at any level in the biological hierarchy of systems ranging from molecules to ecosystems The methods range from single species studies through multispecies studies to tests which attempt to measure and determine the effect of chemicals in the field in natural ecosystems Single species toxicity tests apply one single species for testing the effect of chemicals These species are well known organisms deriving from controlled cultures Single species are used in most of the laboratory bioassays and toxicological tests Multispecies toxicity tests as their name implies involve the inclusion of two or more organisms and are usually designed so that the organisms interact The effects of a toxicant upon various aspects of population dynamics are a goal of these tests In the field of microbiology the competition test of two bacterial species uses the competing bacterial strains grown together in the test medium A special relation is tested in the prey predator tests Food chain effects can be tested using the members of the food chain