ON THE INFLUENCE OF THE POLARITY INDEX OF ORGANIC-MATTER IN PREDICTING ENVIRONMENTAL SORPTION OF CHEMICALS

Data on the correlation of partition coefficients and the polarity ind ex (PI = (O+N)/C) of sorbents is compiled from literature and discusse d with respect to the possible influence on the calculation of predict ed environmental concentrations in risk assessment. When artificial su bstrates are used a linear correlation between PI and sorption of chem ical substances is observed. However, sorption to natural organic matt er extracted from soil and water is not correlated to the PI of the so rbent. Therefore, the origin of the sorbent should be taken in account when estimating the sorption from the log P-ow of the substance. In t erms of risk assessment purposes the equation log K-oc approximate to log P-ow -1 is adequate for estimating the sorption to organic matter extracted from soil, and the equation log K-oc approximate to log P-ow -2 is adequate for estimating the sorption to organic matter in surfa ce waters.