Fish samples contained up to 4.4 parts per million of methyl mercury, more than four times what the Federal Government considers safe.

Scientists are puzzled by the discovery of methyl mercury in the Everglades.

The enzyme converts methyl mercury to the much less toxic elemental form of the metal.

The form found in water, methyl mercury, is the most toxic.

Mercury enters into the human food chain in the form of methyl mercury through fish, etc.

(Whale has levels of methyl mercury somewhere between those in tuna and shark.)

Its most toxic form when ingested, known as methyl mercury, occurs in combination with organic compounds.

As it moves up the food chain, methyl mercury increases in concentration as much as 10 million times.

It is not methyl mercury, which is much more dangerous.

Mercury is a persistent substance and can change in the environment into methyl mercury, which has enormously adverse effects on human health.