laboratory:
a scientist’s work place

mercury:
one of the basic natural substances (or ‘elements’). It is a silver-colored liquid. Dimethyl mercury is a special type of mercury.

substance:
‘substance’is a general, formal word that can refer to any sort of material or ‘stuff’

take chances:
do something that might have a bad result; take risks

Karen Wetterhahn (easy version)

In August 1997, Dr Karen Wetterhahn, a scientist, died. She died because she had been poisoned while working in her laboratory .

The accident had happened a year earlier, in August 1996, at Dartmouth University in the north-eastern US. Karen was working with a special kind of mercury, called "dimethyl mercury." When she was pouring some dimethyl mercury from one container to another, a few drops fell onto her rubber glove near her thumb. Because she knew this substance was poisonous, she quickly wiped it off. She was sure no mercury had got into her body

She didn't think about the accident any more until five months later when she suddenly couldn't walk properly or speak clearly. She realized then that she had been poisoned by the mercury, but it was too late to do anything about it. As time passed, things got worse and worse. She could see less and less, and finally she became completely blind. She also became deaf. Then she went to sleep and didn't wake up. By the time she died, she had been sleeping for a long time.

For many years before Karen died, people had known that mercury is a strong poison. Scientists also knew that dimethyl mercury was much more poisonous than ordinary mercury.

However, before Karen's accident, no one knew that dimethyl mercury could go very quickly through rubber gloves. Now the company that sells this kind of mercury warns buyers that it can kill people if it touches their skin even for a very short period of time. The company tells buyers that anyone working with dimethyl mercury must wear two pairs of special gloves.

Karen's boss at Dartmouth University said that because of what happened to her, in the future, no one would have to die because this kind of mercury got into their body. He also said, however that there will always be a danger of accidents in laboratories; there were fourteen million known substances and new ones were being made every day. He said the only way to learn which substances are very dangerous and which are not is to work with them. So scientists will always have to take chances.

-information from: The New York Times (97.10.03)