As many as 2,300 people in Nova Scotia and New Brunswick had their hair tested for drugs and alcohol at a discredited Toronto lab, a CBC News investigation has found.

Hundreds of those people produced at least one positive test result between 1997 and 2015, findings the lab now admits may have been "inaccurate."

Many of the test results from the Motherisk lab at The Hospital for Sick Children were used as evidence in child protection cases, leaving critics across the country worried some children may have been taken from their families unnecessarily.

Norman Bossé, New Brunswick's child and youth advocate, said the damage in such a case could be difficult to repair.

"Government would have to look at the parents and say, 'OK, we messed up here. We don't know how to fix it,'" Bossé said.

CBC Investigates

Did you have your hair tested for drugs or alcohol between 1997 and 2015? Contact CBC News.

"Perhaps there's a solution. Perhaps you go back to the adoptive parents and they come to an agreement. I don't know. That is the danger of using this type of evidence that's not reliable."

Despite that, CBC News has learned the two Maritime provinces are doing little to review those cases to see if children were unfairly removed from their families.

Until this month, New Brunswick and Nova Scotia continued to use hair testing from another lab, even though Ontario told social services agencies to stop using the tests almost a year ago.

Now, both provinces admit the science of hair testing is in doubt.

Not reviewing cases

In Ontario, where the majority of Motherisk's tests were used, the provincial government has appointed an independent commissioner, Justice Judith Beaman, to pore over 25 years' worth of cases and identify people who may be affected.

Sick Kids hospital sign

As many as 2,300 people from New Brunswick and Nova Scotia had samples tested at the Motherisk lab at The Hospital for Sick Children in Toronto. (CBC)

Hundreds of pending adoptions have been put on hold until Beaman has completed her work.

Officials with Nova Scotia and New Brunswick can't say how hundreds of unreliable test results may have been used in their provinces because they are not doing a similar review.

Both provinces say they will only take a second look at closed cases if they receive a request from a person who was tested or their lawyer. No one from either provincial government was available for an interview about Motherisk.

Nova Scotia has received one request to look at an individual case. Heather Fairbairn, a spokeswoman with the Department of Community Services, said it didn't result in a change to the original decision.

In New Brunswick, all open child welfare cases are subject to an automatic review, said Dave MacLean, a spokesman with the Department of Social Development.

He couldn't say how many open cases might have used Motherisk testing.

A negative or positive drug test has never been the sole deciding factor to take a child from a parent, officials from both provinces say.

"A number of other factors inform such decisions," MacLean said.

New Brunswick's child and youth advocate wants the New Brunswick government to go back and check its records.

Bossé wants to be assured that children weren't taken away from their parents solely because of unreliable tests.

Without that assurance, he's left thinking about the worst-case scenario: a child, ripped from his or her parents, all because of a false positive drug test.

No forensic accreditation

The Motherisk lab tested about 2,000 samples per year for child protection agencies between 2005 and 2015, according to an independent review written by Susan Lang, a retired Ontario Court of Appeal judge.

Motherisk review, Susan Lang

Susan Lang, an independent reviewer appointed by the Ontario government, found serious shortcomings with the Motherisk lab. (Queen's Park)

While the lab provided test results that were used as evidence in court, she found the lab wasn't meeting forensic standards.

She determined the tests should have never been used in court for child protection or criminal cases.

Almost a year ago, Motherisk shut down its hair-testing program permanently.

The Ontario government told social services agencies to stop using hair testing from any lab.

Ontario lab still used

Despite the warning, New Brunswick and Nova Scotia continued to order tests from an Ontario-based lab called Dynacare.

The lab says its testing is "robust," providing "high-quality analytical toxicology service for analysis of drugs-of-abuse in hair."

New Brunswick reversed its position and stopped using hair tests on March 1, prompted by "concerns about the overall reliability of this type of testing."

Kymberly Franklin

Halifax-based lawyer Kymberly Franklin has called for a review of child protection cases where hair samples were tested in the Motherisk lab. (CBC)

​Last week, the Nova Scotia government said hair-strand testing was one of a number of tools that might be used in child protection cases.

But on Monday, officials admitted the science behind the tests "is coming into question."

Fairbairn said in an emailed statement to CBC News the government is reconsidering its value and "will be looking at alternative options."

He isn't the only one who has called for a review of Motherisk cases.

Last year, Halifax-based lawyer Kymberly Franklin called for the Nova Scotia government to review dozens of open child protection cases that used hair testing from Motherisk.

"It's a very serious issue to take a child away from its family, and it's permanent," Franklin told CBC in 2015.

Do you have a story tip you'd like CBC News to investigate? You can email reporter Karissa Donkin.