Figure 6-1

Polarity-volatility diagram for chemical contaminants.

Furthermore, a majority of the measured concentration for a given herbicide was in the form of its degradates, even for a relatively persistent compound such as atrazine. The degradates comprised 60 to over 99 percent of a herbicide's measured concentration. It was shown that potentially stable and persistent degradates are being formed in the environment before complete herbicide mineralization occurs. Kolpin and coworkers (1998) concluded that any investigation of herbicides such as their occurrence and effects on the environment and human health would be missing a significant piece of the puzzle if data on herbicide degradates are not also obtained. It can be extrapolated that for other pesticides similar observations will be made regarding the environmental occurrence of more polar metabolites.

In several European countries research activities have been accelerated that are aimed at enlarging our knowledge of environmental occurrences of pharmaceutical chemicals. Good overviews are given by Stun and Heberer (1997) and Ternes (1998a,b) as well as for a public audience by Raloff (1998).