Collective dose hypothesis

Estimating Risks Using the Collective Dose Hypothesis.937... 

All these comparisons support the hypothesis of an increase. The arithmetic means and thereby the collective doses seem to have increased by about a factor of four to six. If the aerated concrete based on alum-shale had not been used, the country-wide average has been estimated to be 30 % lower (Swedjemark 1985). 

Following intramuscular administration to sheep of 1 mg xylazine/kg bw, two-thirds of the injected dose could be absorbed within 10 min (113). The drug was rapidly distributed to different tissues, and rapidly eliminated. The rapid elimination of xylazine in sheep is probably related to its intense metabolism rather than to its rapid renal excretion. This hypothesis was supported by the lack of significant amounts of the intact drug in urine samples collected every 10 min from treated sheep. 

The most important parameter is a clear identification of the specific question that the toxicity test is supposed to answer. The determination of the LC50 within a tight confidence interval will often require many fewer organisms than the determination of an effect at the low end of the dose-response curve. In multispecies toxicity tests and field studies, the inherent variability or noise of these systems requires massive data collection and reduction efforts. It is also important to determine ahead of time whether a hypothesis testing or regression approach to data analysis should be attempted. 

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