Canadian government urged to test sick patients for herbicide

A neurologist who believes his patients are suffering from a suspicious illness has pleaded with the Canadian government to carry out environmental testing he thinks will show the involvement of the herbicide glyphosate.

For more than two years, dozens of people in the Canadian province of New Brunswick have experienced a distressing array of neurological symptoms, initially prompting speculation that they had developed an unknown degenerative illness – and that figure is believed to be far higher than official reports.

A year ago, the New Brunswick government announced that there was no mystery illness, and closed its investigation. An independent oversight committee, created by the province, determined the patients in the “cluster” were most likely misdiagnosed and were suffering from known illnesses like cancer and dementia.

The government also cast doubt on the work of neurologist Alier Marrero, who was initially referred dozens of cases from baffled doctors, and who has since become a fierce advocate for patients he feels have been neglected by the province.

On 30 January, Marrero sent a letter to both Canada’s top public health official and the province of New Brunswick’s chief medical officer, warning them of “troubling” new developments and pleading for action and warning some of his parents were in “advanced stages of clinical deterioration and near end of life”.

Among those developments, he said recent laboratory tests on a number of patients showed “clear signs of exposure” to glyphosate, as well as other compounds linked to herbicides, adding that many of those tested had levels “many times over the detection limit”, according to the letter obtained by the Guardian.

Marrero said he was not requesting the study of any “mysterious diseases” but was instead concerned the presence of glyphosate and other compounds could be linked to known toxins in the region, known for their harmful effects on the brain.

“Moreover, I underline again that many of our patients are young. This is concerning as it is quite rare for young patients to present with such symptomatology.”

Multiple patients have provided the Guardian with their recent test results, which show clearly detectable levels of glyphosate other metabolites.

It is unclear if the elevated levels of glyphosate, widely used by forestry companies in the province to limit vegetation growth, have had any bearing on the patients with neurodegenerative illnesses. And experts say more testing would be needed to determine how “elevated” these results are, compared with the community.

But in his letter, Marrero told officials he worried that the presence of glyphosate could be linked to blue-green algae blooms in water sources. In the past, these blooms have released toxins like BMAA (B-methylamino-L-alanine), which experts initially suspected could be a culprit for the unexplained cases that baffled officials two years ago.

Marrero referred to studies that have shown some species of cyanobacteria such as blue-green algae are resistant to glyphosate and even use the herbicide as a source of phosphorus, which in turn can create the toxic blooms.

More than 1,000 pages of internal documents obtained by freedom of information requests and seen by the Guardian show that early on in the investigation, the province’s department of environment and public health units began exploring the possibility of environmental causes, including blue-green algae.

The documents also demonstrate how officials were aware of numerous hazardous algae blooms throughout the province, including in three municipal reservoirs, including the city of Moncton.

Staff even flagged glyphosate, a controversial herbicide, as a possible avenue of investigation.

On 23 March 2021, a senior environmental epidemiologist requested information on the scope and quantity of glyphosate spraying in the province over a two-decade period, spanning 2000 to 2021.

In an email the next day, Dr Cristin Muecke, the province’s deputy chief medical officer of health, asked if there was “anything linking glyphosate to neurological disorders”.

Experts have previously cautioned that extensive environmental testing is more work that the public realises, including determining what an “elevated” level of a possible toxin is compared with the broader population.