FOR the first 56 years of his life, Samuel Bemerguy had no greater pleasure than to go fishing near his hometown of Itaituba, on Brazil's Tapajos River, one of the main tributaries of the Amazon. But since last year, he has not only stopped fishing, he has refused even to eat fish. The reason is simple - he discovered that both he and the whole Amazon river system have been poisoned with mercury. About two years ago, Mr. Bemerguy and dozens of other people in the area became seriously ill. Local doctors were at a loss to explain the epidemic, but Bemerguy, a comparatively wealthy man, thanks to his supermarket business, decided to spend whatever it cost to solve the mystery. He flew to Sao Paulo for medical evalution: The results showed mercury levels well above those that can cause violent disorders.
It wasn't hard for Bemerguy and his friends along the river to figure out where the mercury had come from. Itaituba is right in the middle of the new Brazilian gold rush, and wherever gold is extracted in Brazil these days, mercury is sure to be left in its place. About 500,000 gold prospectors roam the Amazon, taking out more than 100 tons of gold each year. But because this gold rush is dominated by individuals and small groups, rather than big mining companies, methods are crude and expedient. That's where the mercury comes in.
Most prospectors who comb the Amazon and its tributaries are little more advanced than their predecessors in California in the 1850s. Mud that has been dug from the fields, or pumped from the riverbeds, is examined by hand for any traces of glitter. If there is gold present, the next step is to add mercury to the mixture, because the toxic liquid metal attaches itself to gold. It's the quickest way the miners have to separate the gold from the accompanying mud.
The resulting alloys of gold and mercury are subjected to blowtorches, which burn off the mercury, contaminating the air in the immediate vicinity. But a much worse problem is that the prospectors often pour mercury while standing in, or right next to, the rivers, thereby poisoning the water and the fish that swim in it.
Mercury is added to gold at ratios ranging from 2:1 to 10:1, meaning that from 200 to 1,000 tons of mercury is being burned or dumped in the Amazon region each year.
Most of the miners know that mercury is classified as toxic, but because few of them have fallen ill - many miners are comparative newcomers to the region - they tend to ridicule the idea that the Amazon is being poisoned. One prospector explained it this way: ``Look, mercury is heavy, right? So it sinks to the bottom of the river, where neither we nor the fish will drink it.''
Whether the miners actually believe that, or are simply excusing their actions, the fact is that they are wrong - perhaps fatally wrong.
``We've been finding Amazon fish with up to five times the World Health Organization safety level of mercury,'' says Bruce Forsberg, an American biologist working for Brazil's Institute of Amazon Research.
``Wherever there's gold mining, the fish are contaminated, and there's gold mining now across an area half as big as the United States,'' he explains.
Dr. Forsberg says that contrary to the miners' theory, some fish do eat from the bottom of the river, and that mercury's heaviness exacerbates the overall problem. ``Because it sits at the bottom of the river, it becomes a reservoir of poison, constantly leaching into the system,'' he says.
The scenario conjures up visions of Minamata in Japan, where mercury dumping into Minamata Bay by a plastics factory in the 1950s caused a wave of poisonings over the next decade that killed 700 people and caused injury to 9,000.
``They're dumping more mercury into the rivers here than they were at Minamata,'' says Forsberg; ``but because the Amazon system is so huge - it contains 20 percent of the world's fresh water - it's too early to tell if the poisoning will be as concentrated. Nevertheless, it's a health time bomb, because there is no way a consumer can tell which fish contain mercury.
``On top of that, the rivers flood onto the nearby plains, sending mercury into the food chain via crops and animals,'' Forsberg says.
Because communications and regulations in the Amazon are generally poor, there is no way of telling how many people may have been killed already by mercury. But Samuel Bemerguy, who is recovering after special treatment for the poisoning, says that many hundreds are ill in his home region alone. And he's begun a crusade to prevent the problem from spreading.
``I tell everyone not to eat any fish at all,'' he says. ``Many are starting to listen, but many others prefer to try to wish the problem away. This thing could end up being worse for Brazil than an atom bomb blast.''
The Brazilian government recently issued an order banning the use of mercury by miners, but there are not nearly enough inspectors to enforce the law.
In Forsberg's view, there seem only two likely ways for the mercury poisoning to stop.
He says, ``Either the gold will have to run out, which does not seem likely for at least a decade, or so many people will have to get sick, including politicians, that the truth will finally hit home. But by then it could be too late.''