(Describer) Streams of light collide to create a globe filled with water. Title: Science Nation. By a river flowing around rocks, several people get out of a car and walk down to it.

(male narrator) Email from a colleague tipped off environmental engineer Detlef Knappe to possible trouble brewing in the Cape Fear River Basin, the largest watershed in North Carolina. A newly-detected chemical called 1, 4-dioxane was turning up in rivers and streams that provide drinking water to many communities.

(Describer) Cylinders are lowered into the river to take samples.

Do we put sample location here?

(narrator) After collecting and analyzing samples at various locations, including here at the Haw River, his fears were confirmed.

(Describer) Knappe:

The concern is that the 1, 4-dioxane levels in this particular watershed are very high. They're probably the highest in the United States.

(narrator) With support from a National Science Foundation Rapid Response Grant, Knappe and his team at North Carolina State University are investigating how the chemical is getting into the watershed and affecting drinking water.

(male) This chemical shouldn't be in the water in the first place. It is a probable human carcinogen. If we would drink water with elevated 1, 4-dioxane levels over a lifetime, our risk of contracting some form of cancer would go up.

(Describer) White smoke drifts around a factory.

(narrator) Knappe says 1, 4-dioxane is an industrial solvent and a by-product in manufacturing everything from laundry detergent to cosmetics to plastics. Water treatment plants typically don't test for it.

(male) Our current technologies, the ones that are typically found in wastewater and drinking water plants, are not able to remove or transform 1, 4-dioxane.

(Describer) Samples are tested in a lab.

(narrator) Knappe's team wants to work with industry to develop methods to treat the problem at the source before the chemical ever reaches rivers and streams.

(male) The whole equation is very tricky. On one hand, manufacturing activities create jobs, manufacturing activities lead to pollution. Ideally, we would avoid this pollution at the source. If that doesn't happen, then in the end, we all have to pay for it.

(narrator) They're also investigating the effectiveness of low-cost carbon filters people might use in their homes.

(male) One of the goals is to find out whether home filtration devices will actually remove 1, 4-dioxane from the water. We want to see how long they will last.

(Describer) The team walks on a ramp away from the river past a man with a fishing pole.

I think we're good.

(narrator) Knappe is working with managers at water treatment plants and state policy makers to improve testing and treatment standards in North Carolina for 1, 4-dioxane. Perhaps soon the water here in the Cape Fear Watershed will be as clean as it looks.

(Describer) A globe turns by the title.

For Science Nation, I'm Miles O'Brien.