The Youthtown centre in Auckland will be temporarily shut down after elevated levels of lead were detected as a result of a rifle range which used to operate in the building's basement.
The problem was first discovered when a member of the Central Shooters Inc (CSI) club had a blood test and his doctor complained to health authorities.
The club was shut down and the basement sealed off in 2012, which it was hoped would protect Youthtown from the poison.
Initial testing of Youthtown's facilities found no traces of lead but its chief executive Paula Kearns said recent further testing had revealed elevated levels.
"It's just a precautionary measure. We're really disappointed but the work that they did in 2012 didn't solve the problem so we're actually going to undertake a full-scale remediation and fix it once and for all."
There had been no reports of adverse health effects from anyone who used Youthtown's premises, she said.
Youthtown's programmes had been moved to other locations and it was hoped the facility would reopen by July.
Lead poisoning is more harmful to children than adults, affecting developing nerves and brains, but in severe cases can still cause vomiting, staggering, muscle weakness, seizures and comas among adults.
At least 10 gun club members were found to have high levels of lead.
A member told the Herald in last year that he saw a doctor after coming down with a series of bad headaches and feeling drowsy.
"I just felt miserable and grotty and I went along to the doctors and got a blood test. The doctor told me the test came back with high lead levels - which is a notifiable disease."
The member said he could not understand how that could be the case until his doctor asked about his weekly schedule.
"I told him I went to the shooting range every Friday night. He straight away wanted to know where we did the shooting. Other people had also contacted their doctors and they were notified, and so it was becoming more general."
The member was told to immediately stop going to the range.
"Lead is accumulative. But it will eventually work its way out of your system if you get away from whatever's causing it. I'm fine now. I stopped going straight away. But it was quite bad for a time."
Youthtown asked the shooting club to fix the ventilation problem in order to continue renting the basement level. The parties could not reach an agreement, so the shooting range closed in September 2012.
According to the Auckland Regional Public Health Service, lead fumes and dust generated by shooting may be breathed into the lungs or swallowed and then absorbed into the blood.