http://ironman.com/mediacenter/press...ptember-1-2010
"Wetsuits may be worn in water temperatures up to and including 24.5 degrees Celsius/76.1 degrees Fahrenheit. Athletes who choose to wear a wetsuit in water temperatures exceeding 24.5 degrees C /76.1 degrees F will not be eligible for awards, including World Championship slots. Wetsuits will be prohibited in water temperatures greater than 28.8 degrees C/84 degrees F."
"Swimwear and swim apparel must be comprised of 100 percent textile material, such as nylon or lycra, and may not include rubberized material such as polyurethane or neoprene. Swimwear may not cover the neck or extend past the shoulders or knees. Swimwear may contain a zipper. A race kit or trisuit may be worn underneath swimwear."