Some 40 Canadian and US diplomats and their families stationed in Cuba may have not been victims of “sonic attacks” after all — but instead may have fallen ill from ingredients used in pesticides to ward off mosquitoes, a new study revealed.

The Canadian study, first obtained by Radio-Canada’s Enquête TV program, revealed that the culprit could be neurotoxic agents used in pesticides across the country to prevent the Zika virus from spreading.

Since 2016, dozens of people associated with the embassy in Havana have suffered problems including dizziness, ear pain and ringing and difficulty thinking — a health mystery that has stupefied officials and damaged US-Cuba relations.

Global Affairs Canada dug into the mystery — commissioning a clinical study by a team of multidisciplinary researchers in Halifax.

The study included 11 “recently exposed” individuals who were tested within a month after returning from Havana, 14 remotely exposed participants — tested up to 19 months after their return — and a control group of 12 who were never exposed.

The researchers monitored their symptoms through blood and brain imaging tests.

“[The results] all support the diagnosis of acquired brain injury in the Canadian diplomats and their families posted in Cuba,” the study report says.

To combat mosquitoes, the embassies sprayed pesticides in offices, as well as inside and outside diplomatic residences — an activity that often happened every two weeks, records obtained by the CBC show.

Toxicological analysis confirmed that pyrethroid and organophosphate — two compounds found in fumigation products — were present in the systems of the Canadian victims, the study revealed.

“There are very specific types of toxins that affect these kinds of nervous systems … and these are insecticides, pesticides, organophosphates — specific neurotoxins,” Dr. Alon Friedman, the study’s lead author, told the CBC.

Various theories on the mysterious illnesses — ranging from crickets to mass hysteria — have emerged over the years.

“I have interviewed all but one or two of [the victims] and I haven’t found any evidence of psychiatric disorder,” Cindy Calkin, a psychiatrist and member of the multidisciplinary research team, told the CBC. “This is a very strong group, very resilient and there is no evidence of mass hysteria. Part of the diagnostic of mass hysteria is that there is no underlying other medical cause that can be found. And we [found] underlying medical evidence.”

But despite the new findings, an official cause has yet to be determined.

“While we are exploring all avenues, including the research at Dalhousie, no definitive cause of the health incidents has been identified to date,” Canada’s Foreign Affairs and International Trade spokesperson John Babcock told the CBC.