However, the Dunedin-based centre has rejected the accusation, saying its system was ''robust''.
Grant Hall, of the Star Trust, contacted the Otago Daily Times following a story of a father speaking out about legal highs after his son ended up on life-support.
His 24-year-old son was taken to Dunedin Hospital after smoking the legal high Karma recently.
A spike of calls to the National Poisons Centre has led to five legal-high products being pulled from New Zealand shelves. The products - AK47, Anarchy, Northern Lights, Primo and Voodoo - appeared to all contain the same active ingredient.
The industry was committed to better health outcomes, but with each recall costing legal-high brand owners in the ''hundreds of thousands of dollars'', it was important that system was robust.
''This is a pretty serious investment and these decisions should not be made lightly,'' Mr Hall said.
''The industry needs the opportunity to look at the evidence, what can we learn from the evidence and what can it tell us,'' he said.
He questioned whether vodka would be pulled off the shelves if someone suffered chest pains and ended up in hospital.
The Star Trust's research showed many incidents of harm occurred when users combined legal highs with other drugs or were underage, against the industry's own guidelines Mr Hall said the National Poisons Centre should be audited, as the reporting system was ''clearly flawed''.
''We just want to look and validate these claims so we know what the evidence is and therefore we can extract some good information and make future products even safer.''
National Poisons Centre toxicologist Dr Leo Schep said the centre recorded each call, and the name and number of each person.
''We have a robust paper trail ... and have for years.''
Associate Health Minister Peter Dunne said the public could have confidence in the regime.
''I can assure you that regulatory action does and will occur whenever warranted.''
The monitoring of adverse side-effects through the risk assessment framework meant products such as Karma and four other legal highs had been ordered from shelves.
The overriding purpose of the Psychoactive Substance Act was to minimise harm to members of the public who chose to use those approved products.
Asked if he was concerned that people had to become ill before a legal product was recalled, Mr Dunne replied ''It is because people were being harmed that the Act was brought in''.
The present set of interim product applications had been assessed. and only those that did not have reports of adverse effects were granted interim approval. ''These products are subject to active and ongoing scrutiny and testing by health professionals and police,'' he said.
When Karma was approved by authorities, its risk score did not indicate more than a low risk of harm, he said.
''It is the ongoing monitoring and data collected subsequently that has led to a change in score and the recall action.''
