A Marshall Islands environmental agency says it is hard for people to follow advice not to eat fish that may have been contaminated by pollutants from the US missile base on Kwajalein Atoll.
Reports declared the health risks from fish around the atoll to be unacceptable as they had been found to contain high levels of pollutants.
That led authorities to ban fishing around the military site and advise people on nearby islands not to eat fish.
But Environmental Protection Authority manager Moriana Phillip said it was hard to measure whether people were heeding the advice as fish makes up a substantial part of their diet.
"Marshallese rely on reef fish for subsistence, food security, and imported foods are often expensive and unhealthy," she said.
"Marshallese are among the highest diabetes rates in the world and if they can't eat fish what can they eat."
Moriana Phillip said it was a serious public health issue as the pollutants raised the risk of cancer and learning disabilities.