Firefighting crews off the coast of southeast China are frantically working to prevent what has potential to become an environmental nightmare.

An oil tanker carrying 150,000 tons, nearly a million barrels, of a highly combustible substance called condensate caught fire Saturday. The tanker, named Sanchi, flies under a Panamanian flag and weighs more than 85,000 tons, according to the site Maritime Traffic. A statement from the Chinese government reports that the ship was transporting oil-based condensate to South Korea for National Iranian Oil Company subsidiary Bright Shipping Limited.

The fire sprang to life after Sanchi collided with a freight carrier.

As of Monday, Reuters is reporting that the remains of one crew member have been found, but 31 remain missing.

What sort of environmental damage the accident and fire could cause remains to be seen.

Condensate has different definitions depending on its source. According to the Energy Information Administration, the term broadly refers to gas from oil or natural gas that condenses into a liquid when it's extracted. In this case, the condensate came from crude oil.

For comparison, the Exxon Valdez oil spill leaked 260,000 barrels of heavy crude in 1989. Sanchi's oil slick is expected to be smaller than that of the Exxon Valdez spill because it's lighter and could burn off.

Just how much the Sanchi's condensate could pollute the region largely depends on if the tanker sinks or not, Babatunde Anifowose, a lecturer at the University of Coventry, told CNN.

Should the ship sink, more of the material will spill beneath the water, making it more difficult to clean. If the ship does not explode, much of the condensate spilled is expected to evaporate, he says.

An explosion also has the potential to spread more toxic fumes from the condensate, and the ship's own fuel could spill as well.

In a safety fact sheet by oil company Conoco Phillips, it notes any contact with condensate can cause respiratory problems and would likely require immediate medical attention.

The toxic fumes also represent a danger to those conducting cleanup and containment efforts.

It's unclear exactly how much condensate has been spilled into the ocean.