'If you go to the hospitals around Taiji, you'll find evidence of people with mercury poisoning.'
These poisons are also having a shattering impact on whales and dolphins. Mercury damages their brains and nervous systems, too. And pesticides and other long-lived pollutants devastate their immune systems and cause cancer.
But perhaps the most insidious effect of all is the impact these pollutants have on fertility. Dolphin numbers are plummeting worldwide. Hunting obviously has a big impact, but reduced fertility plays an equally significant role.
And in recent years, yet another problem has begun to threaten dolphins and whales - noise pollution. Not only do both creatures use sound to 'see' underwater, they also rely on it to navigate and communicate.
Sound from ships' engines, oil exploration, and military sonar confuses them and can permanently damage their hearing.
The impact of noise pollution cannot be over-stated. The latest generation of sonar used by both the U.S and Royal navies can seriously harm whales and dolphins.
To put this in perspective, if a submarine uses its sonar at maximum power, then dolphins 100 miles away will hear an ear-splitting sound equivalent to standing next to a jet fighter on full thrust. Such noise pollution is believed to have led to many whale and dolphin strandings in recent years.
Whaling fears: Activists are also concerned about the continuing slaughter of the world's whales
Although the killing of dolphins at Taiji is undoubtedly horrific, campaigners fear that an equally horrific fate lies in store for the world's whales. For the International Whaling Commission - at the behest of the U.S government - is currently working on a 'compromise' agreement that would legalise commercial whaling.
For the past 23 years, Japan has ignored international law and hunted whales illegally. To try to bring Japan back into the fold, the IWC is proposing to allow them to kill as many whales as they choose in their own waters.
'If the Japanese get their way, they will have succeeded in slaughtering hundreds of thousands of dolphins in defiance of world opinion,' says Andy Ottaway, director of the UKbased welfare group Campaign Whale. 'They will also have won the right to kill thousands of whales.
'But there are also signs of hope. Japan has just voted out a government that was in power for more than 40 years. For the first time in decades, there's a chance that attitudes might begin to change.
'If this issue is raised at the highest level - preferably at Prime Ministerial level - then there is a chance that this slaughter, and that of the whales, might finally end.'
Until then, however, the waters of Taiji will continue to run red.