A research team from North York General Hospital and partner institutions analyzed data from 6,140,595 people living in Ontario, Canada. Participants were between 15 and 105 years old and lived in 10,574 neighborhoods from April 2017 through December 2022. The team examined whether living near a cannabis retail store after legalization in October 2018 influenced neighborhood-level rates of cannabis-related emergency department (ED) visits.

To define exposure, the researchers used provincial records on cannabis store locations. Neighborhoods were considered exposed if they were located within 1000m of a cannabis retail store and unexposed if they were situated more than 1000m away. The main measure of health impact was the rate of cannabis-attributable ED visits per 100,000 people aged 15 years or older.

The analysis showed that exposed neighborhoods were more commonly located in major urban centers and were disproportionately represented in the lowest income quintile compared to unexposed neighborhoods. After a cannabis store opened nearby, exposed neighborhoods did not show a rise in monthly cannabis-attributable ED visits. By contrast, unexposed neighborhoods experienced a decline in monthly ED visits over the same period.

When the two groups were compared directly, exposed neighborhoods had a 12% increase (CI, 6% to 19%) in the absolute rate of cannabis-attributable ED visits relative to unexposed areas. The researchers also observed that neighborhoods with several cannabis stores located within 1000m experienced greater increases in ED visits than areas with fewer stores. According to the authors, these findings suggest that the combination of legalization and retail expansion may introduce public health risks that differ from legalization on its own.

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Supported by FAPESP, the study showed that many of the toys failed to meet the safety requirements established by Brazil's National Institute of Metrology, Quality, and Technology (INMETRO) as well as those set by the European Union. The most concerning violations were linked to barium. In 44.3% of the samples, barium levels surpassed the permitted limit, reaching concentrations up to 15 times higher than allowed. Exposure to this element can lead to serious heart and nervous system issues, including arrhythmias and paralysis.

High Levels of Lead, Chromium, and Antimony

Elevated amounts of lead, chromium, and antimony were also detected. Lead, which is associated with irreversible neurological harm, memory problems, and reduced IQ in children, exceeded the limit in 32.9% of the samples, with some measurements reaching nearly four times the accepted threshold. Antimony, which can trigger gastrointestinal problems, and chromium, a known carcinogen, were present above acceptable levels in 24.3% and 20% of the toys, respectively.

"These data reveal a worrying scenario of multiple contamination and lack of control. So much so that in the study we suggest stricter enforcement measures, such as regular laboratory analyses, product traceability, and more demanding certifications, especially for imported items," says Bruno Alves Rocha. The research stems from Rocha's postdoctoral work, supported by FAPESP, carried out during his period as a visiting professor at UNIFAL.

Toy Selection and Testing Methods

To ensure the study reflected the broader market, researchers intentionally selected toys aimed at families from different socioeconomic backgrounds. Purchases took place in both large shopping centers and small discount shops in Ribeirão Preto. "We chose toys intended for children aged 0 to 12, many of which were sized and shaped to facilitate oral exploration -- that is, they could be put in the mouth -- which increases the risk of exposure to toxic substances," Rocha told Agência FAPESP.

The team used inductively coupled plasma mass spectrometry (ICP-MS) to detect and measure the presence of metals and non-metals, including extremely small quantities. They also used microwave-assisted acid digestion to simulate how chemicals might be released when toys come into contact with a child's saliva.

Twenty-One Toxic Elements Identified

This approach revealed the presence of 21 toxic elements: silver (Ag), aluminum (Al), arsenic (As), barium (Ba), beryllium (Be), cadmium (Cd), cerium (Ce), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), lanthanum (La), manganese (Mn), nickel (Ni), lead (Pb), rubidium (Rb), antimony (Sb), selenium (Se), thallium (Tl), uranium (U), and zinc (Zn).

Using bioavailability (acid digestion) tests, the researchers developed two different exposure scenarios. One represented typical exposure levels based on median concentrations, while the other considered the highest levels detected. According to Rocha, "Exposure varies according to the concentrations of toxic elements, but it can also vary greatly from one child to another depending on how long they play with or keep the object in their mouth."

Chemical Release and Safety Concerns

Extraction rates, referring to how much of a substance is released when exposed to gastric juice, ranged from 0.11% to 7.33%. These values indicate that only a small portion of the total contaminants actually leaches out under conditions mimicking oral contact. However, Rocha notes that this does not eliminate health concerns. "While this is positive, the finding doesn't eliminate safety concerns, particularly given the high total concentrations detected in many samples," he says.

Tracing Contamination Sources and Additional Risks

The investigation also offered insight into how contamination may enter the toy production chain. "We found correlations between nickel, cobalt, and manganese, suggesting a common manufacturing origin. Beige-colored toys had higher metal concentrations, possibly due to the paint supplier, which is a relevant clue for future enforcement actions," he explains.

Beyond toxic metals, the same research group has previously examined chemicals that interfere with the hormonal system. These include bisphenols, parabens, and phthalates, which are widely recognized as endocrine disruptors.

"This isn't the first study with such alarming results, which only reinforces the need for urgent action to protect children's health," Rocha concludes.