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ONE of the strongest infrared light sources ever created is giving scientists
in California an unprecedented view of the damage inflicted on living cells by
radiation and toxic chemicals. Their findings could spark changes in safety
regulations for nuclear power workers and those exposed to hazardous chemicals
and drugs.

A team at the Lawrence Berkeley National Laboratory near San Francisco is
using a powerful light source originally used for making advanced microchips to
blast single living cells with a beam that can be focused on an area smaller
than the cell. Each type of cell reflects the infrared beam in a unique way,
because particular molecules in the cell absorb characteristic amounts of light.
Analysing the frequencies in the spectrum of the reflected signal can provide a
wealth of information: for example, the scientists can use this 鈥渟ignature鈥� to
determine whether DNA strands have been damaged, or if cells have recently
died.

Michael Martin, who presented the work at last week鈥檚 American Physical
Society meeting in Minneapolis, Minnesota, recently looked at the effect of
ionising radiation on cells. His group鈥檚 work has shown that previous radiation
studies, which were based on less sensitive methods using dyes, may have
overestimated the effect of the low doses of radiation to which nuclear plant
workers are typically exposed.

These studies may have overlooked an exposure threshold below which no damage
occurs, says Martin. If the team鈥檚 preliminary results are mirrored in larger
studies, they could lead to changes in safety regulations. And the researchers
have already determined the specific damage that some chemicals cause.