"Less than 1/1000th of the amount in coatings, organotins cause molluscs to change sex and/or become behaviourally castrated," warned Daniel Rittschof, a specialist in barnacles at North Carolina's Duke University.
Prof Rittschof said this caused male to follow male pheromones and female to follow female pheromones.
"Organotins at very low levels alter enzymes that process steroids, which is why molluscs change sex," he said.
While use of the organotin tributyltin (TBT) was outlawed as an active biocide a decade ago, the IMO is claimed to "have left the door open" for tin as a catalyst.
"I have seen for myself that something strange happened with the formulation of these foul release coatings," said Rik Bruer, managing director of Finsulate, a manufacturer of a non-toxic antifouling wrap.
While shipowners may have thought the use of organotins in marine hull coatings was completely outlawed in 2008 with the ban on tributyltin (TBT), they can still be used as a catalyst if organotin content does not exceed the allowable limit of 250mg/1kg of paint, said the report. Dibutyltin and dioctyltin are the organotins under most scrutiny.
"There are studies available in the public domain that should have already raised alarm bells," said Boud Van Rompay, chairman of Subsea Industries, the manufacturer of the Ecospeed hull coating system.