According to the Karnataka State Pollution Control Board (KSPCB), about 30 city-based companies have been regularly flouting effluent discharge norms for the last five years, making use of legal loopholes. The PCB has repeatedly charged some of them with violations.

Since untreated effluents are know to be deadly to all forms of life, the KSPCB condcucts monthly checks- bio-assay tests- at its lab by introducing common carp fish into treaded effluent samples collected from industries named in the Environment Protection Act.

"Fish present in more than 20 samples invariably die much before the stipulated 96 hours at the lab, which means the treated effluents are unfit for discharge." scientists at the laboratory note.

A toxic index and a report summarising its findings of each industry is prepared after the monthly tests.

Ever since the bio-assay tests began five years ago, the seven regional offices in the city have been sending show-cause notices to erring industries.

"But all the industries need do to get away with it is pass the test the next month and show a clean record for at lest a few months a year," say environment officials. Thanks to this loophole, " KSPCB has to slap show-cause notice over and over again to remind the industries of their environment responsibilities," say these officers.

Nine categories of industries including pharmaceuticals, dye, cotton textiles, paint and pesticides have to undergo the bio-assay tests. In Bangalore, however, the Himalaya Drug Company Ltd and Cipla Ltd have maintained environment standards every month, according to the test results.