Dr. Gideon Koren: The Motherisk Hair-Testing Scandal at Toronto's Hospital for Sick Children

Gideon Koren, an Israeli-Canadian pediatrician, clinical pharmacologist, and toxicologist, founded the Motherisk Program while still in medical school in 1971. Based at Toronto's Hospital for Sick Children (SickKids) and affiliated with the University of Toronto, Motherisk grew into a widely trusted counselling service advising pregnant and breastfeeding women on the safety of medications, and Koren became one of Canada's most published and internationally recognized researchers in his field, authoring more than 1,500 papers over four decades.

The "Poison Pen" Letters

Fifteen years before the scandal that would ultimately end his career, Koren was already the subject of a serious disciplinary finding SickKids chose not to act on. In the late 1990s, Koren's SickKids colleague Dr. Nancy Olivieri went public with concerns that a drug company, Apotex, was suppressing her findings that one of its drugs posed risks to young thalassemia patients — a dispute that became a landmark Canadian case study in research independence and corporate influence over academic science. During the fallout, anonymous "poison pen" letters were sent to SickKids staff and the media, disparaging Olivieri and her supporters in vulgar terms. Koren denied writing them for months, until DNA testing on a mailed envelope proved otherwise. A 2000 disciplinary finding by the former presidents of SickKids and the University of Toronto concluded Koren's conduct amounted to "gross misconduct" providing "sufficient grounds for dismissal," citing his "repeatedly lying" and "reckless dereliction of duty." He was not dismissed, and continued to lead Motherisk for another 15 years.

The Motherisk Hair-Testing Scandal

Beginning in the late 1990s, the Motherisk Drug Testing Laboratory (MDTL), a separate arm of the program that Koren founded and directed, began accepting requests from child protection agencies across Canada to perform hair-strand testing — used to determine whether a parent or caregiver had been using drugs or alcohol. For more than a decade, these results were treated by courts and child welfare agencies as reliable scientific evidence, directly shaping custody decisions, criminal prosecutions, and cases where parents' children were removed from their homes.

In 2014, a Toronto Star investigation began raising serious questions about the accuracy of MDTL's methods. The hospital launched an internal review, and the Ontario government commissioned an independent review led by retired Court of Appeal Justice Susan Lang. The lab was closed in 2015 while the review proceeded. Justice Lang's 366-page report, delivered in December 2015, concluded that MDTL's hair testing was "inadequate and unreliable" for use in criminal or child protection proceedings and did not meet internationally recognized forensic standards, warning that its use in such cases had "serious implications for the fairness" of the proceedings involved. Her review also flagged five of Koren's studies as questionable, prompting a broader look at the integrity of his research output. Separately, in 2015 SickKids temporarily reassigned oversight of Motherisk amid questions about undisclosed funding the program had received from Duchesnay, a pharmaceutical company whose morning-sickness drug Diclectin was heavily promoted in Motherisk-branded materials Koren co-authored.

Aftermath

Koren stepped down from SickKids in 2015 and relocated to Israel. In 2019 he relinquished his licence to practise medicine in Ontario. A subsequent review of more than 400 of his published papers has, to date, led to five retractions, four corrections, and at least three formal expressions of concern from academic journals — including a 2026 expression of concern on a long-disputed 2006 case report in which Koren claimed an infant died of morphine poisoning transmitted through breast milk, a claim a New Yorker investigation scrutinized at length. As of 2026, roughly 70 active lawsuits from affected families remained before the Ontario courts, with SickKids and Koren arguing that the statute of limitations had passed and that their work should be immune from liability as expert evidence. Koren has not responded to media interview requests regarding the case; his lawyer has declined to comment given the ongoing litigation.

Timeline

• 1971Founds the Motherisk Program while in medical school.
• Late 1990sAnonymously sends "poison pen" letters disparaging whistleblower colleague Dr. Nancy Olivieri during the Olivieri/Apotex affair.
• 2000SickKids and University of Toronto find grounds for dismissal after DNA evidence confirms Koren wrote the letters; he is not dismissed.
• Late 1990s onwardThe Motherisk Drug Testing Laboratory (MDTL) begins performing hair-strand testing relied on in child protection and criminal cases across Canada.
• 2014Toronto Star investigation raises questions about the accuracy of MDTL's hair testing.
• 2015MDTL is closed; SickKids temporarily reassigns Motherisk's oversight amid Duchesnay funding-disclosure concerns; Koren steps down.
• Dec 2015Justice Susan Lang's independent report finds MDTL's hair testing "inadequate and unreliable" for legal proceedings.
• 2019Koren relinquishes his licence to practise medicine in Ontario.
• 2021–2026Journals retract or flag several of Koren's published studies following a review of over 400 papers; roughly 70 lawsuits from affected families remain active.

Note: this page covers the Motherisk hair-testing scandal and the earlier Olivieri "poison pen" letters affair as reported. Litigation over the affected families' claims remains ongoing as of this writing.