Six people who worked at the Mapua toxic site have approached the Environment Ministry to ask for a medical assessment.

The Environment Ministry said it has now contacted all nine companies who employed workers on site during the cleanup of the Mapua toxic site.

Andrew Crisp, Environment Ministry deputy secretary, said the companies had agreed to contact workers and forward information to them about the offer of a medical assessment and how to contact the ministry.

A Labour Department report in May, which looked at the health and safety of four workers at the site, found they could have been made sick from working on the cleanup and may suffer further work-related health problems.

The Environment Ministry, as the main resource consent holders of the project, was advised that workers should be offered medical assessments.

The controversial $12 million Mapua cleanup at what was previously the most toxic site in New Zealand finished five years ago.

Thirty people are believed to have worked at the project.

In 2008, Parliamentary Commissioner for the Environment Jan Wright said contaminants may have been inadvertently released during the cleanup.

Mr Crisp said the medical assessment would be undertaken by a member of the Australian and New Zealand Society of Occupational Medicine.

The assessment was likely to include a review of the worker's role at the site, their duration of employment, a review of any monitoring done while the worker was employed or since they left, and a full medical history to document any issues.

A full examination might involve a range of blood tests and, depending on the exposures, a urine test.

Mr Crisp said the ministry was unable to comment on any support that would be available to the workers until they had received the results of their assessment.

- © Fairfax NZ News