Accumulating in humans, mercury can enter the central nervous system, causing loss of muscle control, brain damage and death.

In pregnant women, mercury can enter the placenta, causing birth defects.

As a vapor, however, elemental mercury rapidly enters the bloodstream once breathed in.

Unfortunately, the mercury often enters and contaminates creeks.

Metallic mercury, the kind the teen-agers found and played with here, enters the blood when vapors given off by the heavy liquid are inhaled.

The D.E.P. said mercury enters Connecticut waterways primarily from atmospheric contamination, which sinks into sediment.

When released in the air as a byproduct of burning coal, mercury drifts over lakes and rivers and enters the food chain through fish and shellfish.

In combination with other studies showing that mercury vapor can seep out of dental fillings, they presented a picture of how mercury might enter the intestines.

The short-life cyanide was undetectable within a few years, but the residual mercury remained in the sediment and entered the food chain.