Downstream Drugs

Q. Have any studies been done on possible environmental risks from drugs used for chemotherapy after they pass through the body?

A. At least one study, a 2008 opinion paper by British scientists, assessed the discharge of a commonly used cancer drug, 5-fluorouracil, and raised concern about possible contamination of the water supply.

Chemotherapy agents to fight cancer can pass through the body unaltered and enter the water supply through the sewer system. The drugs are easily soluble in water.

Like many cancer drugs, 5-flourouracil acts by killing dividing cells, and its toxicity to cells makes even small concentrations potentially risky.

The study, published in The Journal of Hydrology, focused on a water treatment project on the Aire and Calder Rivers in northern Britain. According to the study’s statistical model, measurable concentrations, 5 to 50 nanograms per liter of water, could be expected on long stretches of the catchment area at low flow.

The study concluded that it was “unclear to what extent the predicted low concentrations would affect flora and fauna in receiving waters,” but added that there may be an additive effect from a mixture of cell-killing drugs. It also said that exposure of pregnant women and their fetuses to such drugs through drinking water should be minimized.

Water treatment technology gives grounds for optimism about the removal of such compounds, the study said, but there is not enough data to be sure.