contaminated-cruise-water (Updated 1:10 p.m. EST) -- Could your cruise ship's drinking water be contaminated? That's the question the Sunday Times of London raised in a recent article about a 2004 issue with a possibly carcinogenic coating on the inside of cruise ship water tanks.

Here's the backstory: According to the newspaper report, paint inspector Brian Bradford found black residue inside the potable water tanks of two Norwegian Cruise Line ships (Norwegian Dawn and Norwegian Star) in 2004. He believed the residue could be from the coating leaching acrylonitrile into the water. (If you're curious, the insides of water tanks on cruise ships are painted for corrosion protection and for quicker, easier cleaning.)

What's acrylonitrile? According to the Web site of the Agency for Toxic Substances and Disease Registry (ATSDR), a U.S. public health agency, acrylonitrile is a "colorless, liquid, man-made chemical with a sharp, onion or garlic-like odor" that can cause health problems, including death, from prolonged exposure and "may reasonably be anticipated to be a carcinogen."

After Bradford told the paint's manufacturer and his employer, Hempel, about the issue, he said he was sacked; later, the company won an injunction against Bradford, prohibiting him from talking about the possible problems with the paint.

That Was Then…

First, let's address the 2004 situation. Despite the injunction, the impacted cruise lines were alerted to the problem. An official Norwegian Cruise Line statement e-mailed to Cruise Critic says "this situation ... was completely remediated at that time" and that its drinking water "has always been and remains safe, meeting or exceeding the required United States Public Health safety requirements and standards."

Likewise, in February 2004, Royal Caribbean was alerted by Hempel that Radiance of the Seas and Brilliance of the Seas could also be affected, as water tanks on those ships used the problematic paint. That line was more specific in its statement. "Once we were alerted to this concern, the coating on the potable water tanks on Royal Caribbean International's Radiance of the Seas and Brilliance of the Seas [was] replaced," the statement said. "During the period of time between when we were notified and [when] the coatings were replaced, experts from the Centers for Disease Control & Prevention and the Florida Poison Information Center confirmed that the water aboard the two ships did not pose a risk to public health."

While the cruise lines report that they remedied the situation immediately, it remains unclear whether passengers were ever actually at much risk.

Royal Caribbean's statement states that "following a life time exposure to excessive limits of [acrylonitrile], the risk of cancer could increase for one in every 10,000 people." And any amounts passengers may have been exposed to on a seven-night cruise would have been far less. The ATSDR agrees, saying the highest risks are for high-level, short-term exposure or lower-level, long-term exposure -- neither of which would have been the case for cruise travelers. And, for short-term exposure, the biggest problems -- such as headaches and nausea -- seem to be temporary.

To put things into perspective, acrylonitrile is used to make plastic food containers; the FDA simply regulates the amount of the substance that can enter the food stored inside.

…This Is Now

But what about cruise travelers today? Are they at risk from carcinogens the cruise lines are hiding from them?

We spoke with two experts from the Cruise Lines International Association (CLIA), who reported that drinking water on cruise ships is, in all likelihood, quite safe, given how carefully it's monitored. According to Michael Crye, executive vice president of technical and regulatory affairs, and Bud Darr, director of environmental and health programs, there are many regulations, on both the international and national levels, on potable water onboard cruise ships.

Many are spelled out in the CDC's Vessel Sanitation Program. The same folks who bring us surprise inspections and cruise ship health ratings have plenty to say about how ships need to monitor their potable water supplies. The Vessel Sanitation Program's 2011 Operations Manual dedicates an entire chapter (17 pages) to potable water, including information on bunkering, monitoring, inspecting and storing water onboard. The CLIA execs say that Europe and Brazil are working on their own ship sanitation programs, modeled after the United States'.

As an example, here's what Royal Caribbean spokeswoman Cynthia Martinez said in an e-mail about her line's safety procedures: "To protect the cleanliness of our water supplies, potable water is only bunkered from reputable destinations where we know the water is safe -- otherwise it is produced onboard. ... All bunkered water is also tested for coliforms and held in a tank until negative test results demonstrate it is safe for shipboard consumption. ... We also test potable and recreational water for the presence of Legionella (a bacteria that causes a form of pneumonia), even though it is not required by CDC/VSP. Every six months, our crew members test an average of 50 - 60 samples of water from different areas on each ship."

We asked the CDC for its take on cruise ship potable water and how often its inspectors found problems onboard. Jay Dempsey, a CDC health communication specialist, responded via e-mail, "Major potable water system violations, such as the filling of drinking water tanks at port without adding additional chlorine, are rare in our inspections. Cruise lines have alarm-enabled, fail safe second dosing systems incorporated into the potable water distribution system in case of failure. VSP also requires cruise ships to use backflow preventers onboard that have secondary failure points, such as intermediate atmospheric vents." However, problems can occur; when Cunard's Queen Mary 2 flunked its CDC inspection in June, one of the violations cited was the improper maintenance of the ship's potable water tanks.

If you're worried about transparency -- i.e., will you know if there's a public health issue onboard -- Crye and Darr say that the various public health regulations include obligations to notify passengers about public health risks in certain areas.

Martinez adds that Royal Caribbean has "a number of tools at our disposal including our onboard television system, as well as the ship's newsletter, announcements, and even letters to all guests in their staterooms. If necessary, we can also communicate with guests after their cruise has concluded."

The Bottom Line

From our research, it seems that there is a low probability that any tainted water -- if there was any at all -- contained enough chemicals to cause serious harm to travelers. Still, people can and do get sick on cruise ships with everything from Norovirus to Legionnaires' disease, so it's up to you to decide whether the risk to your health is great enough to take precautionary measures -- just as you would when deciding whether to eat in a restaurant that might give you food poisoning or sleep in a hotel that might have bed bugs. If you want to see how your cruise ship fared during its latest CDC inspection or want to read what standards ships are supposed to adhere to, visit the CDC's Web site.

--by Erica Silverstein, Features Editor