Every year, say environmentalists, some 7 million to 8 million tons of industrial waste are dumped into the North Sea - nearly one-third of it by five large West European chemical companies.
Other firms discharge thousands of tons of harmful waste into the Rhine River , which runs through four countries, emptying into the North Sea at this huge port city. The Rhine provides drinking water for 20 million people.
Earlier this month, in a unique and determined effort, environmentalists from across Western Europe met here and took the companies to ''court,'' judging them before an independent Bertrand-Russell-style tribunal to be violating international agreements and national laws.
The week-long court - dubbed the International Water Tribunal (IWT) - has received wide publicity. Some militants have said its work will form the statistical base for a massive consumer boycott against the companies put on trial.
''In West Germany,'' says IWT organizer Dr. Jan Dogterom, ''the Greens are already preparing such action by drawing up lists of companies which do harm to the environment.''
The IWT was set up two years ago, and a budget (collected from donations) of more than $500,000 has enabled volunteers to prepare dossiers on waste-dumping companies. The information was compiled and presented in a massive hard-bound, loose-leaf volume detailing the various charges, including the names and addresses of the companies. The book is a popular seller, despite a 145 guilder (about $50) price tag.
One of the more important cases involved five West European producers of titanium dioxide (a whitener) - Kronos Titan GMBH, Pigment Chemie GMBH (West Germany), Bayer Antwerpen NV, NL Chemicals SA (Belgium), and TDF Tiofine BV (the Netherlands) - which, according to environmentalists, together dump 1.89 million tons of acid waste a year into the North Sea.
Another case claimed that Shell Chemie - a Dutch subsidiary of the Anglo-Dutch giant - was dumping ''drins'' (the collective name for a group of pesticides that are toxic and almost nonbiodegradable) near Rotterdam.
''These companies and many others have continuously delayed research into other, innocuous methods of production,'' says IWT organizer Dr. Dogterom.
''It is now economically feasible to use alternative methods,'' he added. ''The dumping of titantium-dioxide waste into the sea has been forbidden in Japan, for example, since 1970 - and the industry nevertheless has remained competitive.''
The companies were invited to defend themselves before the tribunal - but they refused. IWT officials said replies were received from about half the companies invited, and that it was clearly a ''coordinated'' refusal to participate, judging from how similar the responses were.
''It shows they certainly must have something to hide,'' an IWT official said.
But a company official said firms were under no obligation to appear before ad hoc ''courts.''
''At this tribunal,'' the official added, ''it was clear the jury was in even before the cases were presented. . . .''