Sublethal level

Munoz, M.J., M. Carballo, and J.V. Tarazona. 1991. The effect of sublethal levels of copper and cyanide on some biochemical parameters of rainbow trout along subacute exposition. Comp. Biochem. Physiol. 100C 577-582. 

Selenium, in the form of selenate or selenite, is toxic to D. desulfuricans (Tomei et al. 1995) and Wolinella succinogenes (Tomei et al. 1992) at elevated levels. At sublethal levels of 0.1-1. OmM selenite or 10 mM selenate, minimal levels of growth is observed with both D. desulfuricans and Wolinella succinogenes. With both selenate and selenite, colloidal elemental selenium (Se°) is produced inside the cell and released into the culture fluid after cell death. This reduction of Se(VI) and Se(IV) by these anaerobes is not coupled to growth and proceeds by mechanisms that have not yet been identified. Selenite and selenate reduction with formation of elemental selenium by these nonrespiratory processes serve to detoxify the environment for future bacteria and may be important for the geochemical cycle of selenium. 

Prokaryotes are sensitive towards aminoglycosides. In E. coli sublethal levels suppress auxotrophic mutations and increase the frequency of misincorporation obtained in vitro (Gorini and Kataja 1964 Davies et al. 1965). Yeast is normally quite resistant toward aminoglycosides, but mutant strains expressing translational suppressors display increased sensitivity in vivo and increased mistranslation frequencies in vitro (Palmer et al. 1979 Singh et al. 

Anthony J, Banister E, Oloffs PC. 1986. Effect of sublethal levels of diazinon histopathology of liver. Bull Environ Contam Toxicol 37(4) 501-507. 

Toxicity is an important biological test and is also a signpost that other types of activity will be noted for the toxic compound at sublethal levels. 

Guinea pigs were exposed to sublethal levels of GB by IV, IH, and SC routes. Serial blood samples were collected... 

Researchers were also able to establish the link between declines of other predatory species such as the European sparrowhawk and the use of organo-chlorine pesticides other than DDT. For instance, the cyclodiene insecticides aldrin, dieldrin, and he-ptachlor used as seed treatments caused massive mortality of both seed-eating species and their predators. All of the insecticides had the following points in common they were highly soluble in fats and refractory to metabolism. The impacts on the predatory species typically take place in periods of food stress when fat soluble residues are released from fat stores and returned into general circulation. In a food-stressed individual, the brain remains as the most lipid rich tissue and this is where contaminants move to. Toxicity results when threshold values in brain tissue are exceeded. At sublethal levels, documented effects of cyclodiene insecticides in birds have included changes in their reproductive, social, and avoidance behaviors. 

In general, a greater proportion of aquatic organisms are exposed to sublethal concentrations of toxics compared to acutely lethal concentrations. There is general acceptance that chronic exposure of fish to sublethal levels of toxics makes them more prone to disease states. Although scientifically controversial, intuitively one can grasp how individual responses such as growth, reproduction rates, and survival probability, as a function of age, could relate to population level responses. 

In laboratory animals exposed orally or cutaneously to sublethal levels of various PCB mixtures, common findings are severe atrophy of 1° and 2° lymphoid organs, lower circulatory immunoglobulin levels, and decreased specific antibody responses following immunization with antigens. Both augmentation and suppression of cell-mediated immunity on exposure to PCBs have been reported. 

It had been found by Allcroft71 that certain isolated extracts of the milk produced by lactating cattle that had been fed sublethal levels of the aflatoxins, induced the formation of the liver lesions reminiscent of aflatoxicosis72,73. The toxins were isolated and called the milk toxins , which were later redesignated as the aflatoxins 18,74,75). Indeed, it was also demonstrated that the milk toxins were present in the original Aspergillus flavus mold as minor components72. ... 

McGee, B.L., C.E. Schlekat, and E. Reinharz. 1993. Assessing sublethal levels of sediment contamination using the estuarine amphipod Leptocheirus plumulosus. Environ. Toxicol. Chem. 12 577-587. 

Dimethirimol and ethirimol are effective fungicides at concentrations in the plant of approximately 10M. At the sublethal level concentration in the fungi is probably half that in the plant. Hence, it is assumed that these active substances act as noncompetitive enzyme inhibitors (Bent, 1970 Sampson, 1969 Calderbank,... 

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