Critical organ toxicological

Kjellstrom T. Critical organs, critical concentrations, and whole body dose-response relationships, in Cadmium and health a toxicological and epidemiological appraisal. Volume II effects and response. Friberg L, Elinder C-G, Kjellstrom T, Nordberg GF (editors). CRC Press, Boca Raton, Florida 1986 p. 231-246. 

Toxicology studies attempt to determine both the threshold and the critical organs for toxic substances. The resultant information can be used to ensure that levels of exposures are low enough to avoid reaching the threshold and damaging the critical oigan. 

It is a first principle of toxicology that no chemical substance is a poison at all concentrations toxicity occurs only when a critical concentration is reached within vital cells. Whether or not an economic poison will exert a particular deleterious effect depends on the relative rates of absorption as compared with detoxication and elimination, its inherent toxicity, and the physiologic status of the organism. 

The Critical concentrations with respect to the soil organisms should be related to a low effect level on the most sensitive species. The effects on the process of metabolism and other processes within the organisms should be considered and also the diversity of the species, which is most sensitive to the heavy metals, has to be accounted. Critical limits must refer to the chronic or accumulated effects. For assessment of the critical concentrations in crops and in drinking water, human-toxicological information is required. In general, for establishing critical loads we should also account the additive effects of the different metals and combination effect between the acidification and biogeochemical mobilization of the heavy metals in soils and bottom sediments. 

High doses of DEHP have been found to cause liver cancer in rats and mice and it is on the Reasonably Anticipated to Be Human Carcinogens list. In 2000 a report by the National Toxicology Program found serious concern that DEHP in vinyl medical devices may harm the reproductive organs of critically ill and premature male infants exposed during medical treatment. They also expressed concern that development of male unborn babies would be harmed by the pregnant mothers exposure to DEHP or that... 

Preclinical and clinical process laboratories serve a critical function in the development and organization of toxicology data, animal testing results, and ultimately of human test results. Again, the GLPs provide guidance and assure both minimization of misinterpretation and control of both the potential risks to human subjects and the suffering of test animals. 

The reviews Toxicological Indications of the Organic Fraction of Aerosols A Chemist s View by Van Cauwenberghe and Van Vaeck (1983) and Atmospheric Reactions of PAH by Van Cauwenberghe (1985) provide critical assessments and extensive literature references of the status of research to 1985 in the complex area of heterogeneous photochemical reactions and of the interactions of PAHs on laboratory substrates, primary combustion particles, and ambient particulate matter with ozone and NOz in air. In the following sections, we briefly summarize results from this earlier era and address subsequent studies on heterogeneous atmospheric reactions of PAHs in simulated and real atmospheres. 

These considerations indicate that there is no perfect solution to the toxicological evaluation of the organic contamination of various water sources or the drinking water that might be prepared from them. A number of pieces of critical information can help decide which of the approaches might be the most cost-effective ... 

Dose-response concepts. Dose-response assessment for hazardous chemicals that can cause deterministic effects begins with the toxicology data developed during the hazard identification step described in Section 3.1.4.1.2. In many cases, hazard identification and dose-response assessment occur simultaneously. For each chemical, the critical response (a specific response in a specific organ) is identified in the hazard identification process. Using the available data for the critical response, one of the following is established ... 

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