Frequency distribution, toxicity data

SSD Species sensitivity distribution. A frequency distribution of the toxicity of a certain compound or mixture to a set of species that may be defined as a taxon, assemblage, or community. Empirically, the distribution is estimated from a sample of toxicity data for the specified species set. 

Accurate exposure and biological monitoring data are crucial to the evaluation of residential exposure and risk estimates since the potential health risks associated with a pesticide depend on the amount of exposure to the pesticide, its toxicity and the susceptibility of the exposed population. Prediction of whether adverse health effects will occur in humans can be made by comparing the exposure estimate to the No Observed Adverse Effect Level (NOAEL) derived from the animal toxicity data. Uncertainty arises from the input data used in an assessment, e.g. variability in time-activity patterns, contact with exposure media, bioavailability, exposure duration, frequency of product use and differences in the route of exposure in humans from that in the animal studies (since absorption, distribution, metabolism and elimination kinetics may differ substantially by exposure route). 

A frequency distribution of the toxicity data, which depicts at which contaminant levels toxicity has been observed, is calculated. The most important features of these frequency-distribution curves are the average toxicity, as reflected by the geometric mean of all toxicity values, and the width of the curve, reflected by the standard deviation. 

A substantial increase in the frequency and geographic distribution of toxic plankton blooms has occurred worldwide over the past two decades [5,6] however, incidence data for PSP... 

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