A biomedical scientist has warned that the chemicals found in the gooey tar balls that are being produced as a result of the Gulf oil spill can cause cancer in humans.
Professor Bongsup Cho said the saturated hydrocarbons found in crude oil, such as methane, hexane and octane, evaporate quickly once in the ocean because they have low boiling points - and may disappear even before humans get a whiff of them.
But the tar balls and remaining thick ooze washing ashore and into marshes are a reason for worry, as toxins in them can cause mutations in DNA and cause birth defects.
"The tar balls contain the non-volatile, benzene-like, heavily unsaturated hydrocarbons with high boiling points," Cho said.
"That's where there are a lot of toxins, such as benzo[a]pyrene. This is a known human carcinogen, and it is used as a biomarker to detect human exposure to toxins," he added.
Another worrisome phenomenon is the orange sheen seen on the surface of the gulf, which according to the scientist is a result of a chemical reaction involving the sun, the crude oil and the oil dispersants.
"But nobody knows what's in that color and how toxic the chemicals are. Companies keep the chemical makeup of the dispersants secret," he said.