A leading toxicology scientist believes tighter regulations are needed to prevent chemicals leaking into the human body from common plastic drink bottles and packaging.

University of Canterbury professor of toxicology Professor Ian Shaw says it is crucially important to decrease the amount of the chemical BPA from New Zealanders' diets.

BPA, which leaches from food and drink containers into the body, has consistently been found in overseas tests in blood, urine and even the amniotic fluid protecting a foetus.

Such chemicals are linked to health problems that can include reduced sperm count in men, early puberty in girls and increased incidence of breast and testicular cancers - and countries such as the US, the UK and Canada have become alert to potential risks.

"We know we're getting much more exposure to these chemicals and we know we're getting a greater incidence of these weird effects on sexual development," said Professor Shaw. "It seems they are connected."

The Food Safety Authority says BPA is safe as long as the tolerable daily intake is not exceeded.

John Reeve, principal toxicology adviser to the NZFSA, said the problems were theories and there was no data.

The authority is now waiting on results of a new study commissioned by its US counterpart.

But the uncertainty has left one New Zealand businessman frustrated.

Mark Ward, owner of Extreme gear, imported bottles containing BPA from North America at 85 per cent off the normal price. When he discovered they were unwanted in Canada because of the health implications linked to BPA, he asked the NZFSA for guidance.

"I don't think we've had clear leadership from our so-called experts in this country," Mr Ward said. "I found it really difficult to find a credible source that tells it like it is. Somebody who is willing to stand up and say it is dangerous now."