Electromagnetic waves and autism, a questionable link?

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Autism spectrum disorders (ASD) have increased dramatically in recent decades in Western societies. In Quebec, about 0.8 in 1,000 children ages 1 to 17 were diagnosed with autism in 2000-2001, compared to 17 out of 1,000 in 2019, according to Health Canada.

This increase is largely due to changes in the definition itself of what the autism spectrum is: the evolution of this definition since the 1990s depends on a better understanding of these disorders. For this reason, many cases in the past may have gone under the radar, labeled as “intellectual disability.”

But the fact of better prognosis does not prevent the causes of autism spectrum disorder from remaining poorly understood. Among the suspected risk factors: certain genetic mutations, metabolic imbalances, and exposure to heavy metals and environmental toxins. Can electromagnetic fields be added to the list?

Mainly thermal effects

Of the thousands of studies conducted over the past 30 years on cells, animals or humans, the only quantified effect of radio waves and electromagnetic fields has been the potential heating of tissues. In 2021, a Franco-Italian study, for example, concluded that people feel skin tissue overheating as they age, and when electromagnetic fields are high. Older people tend to have thinner skin and less blood flow.

Due to current standards for electromagnetic fields, tissue heating is too low to damage cells. However, a review of the research, published in 2019, raises the possibility of biological effects that would not be related to heating their tissues. According to the authors, about 70% of studies using frequencies from 6 to 100 GHz — Wi-Fi uses frequencies between 2 and 5 GHz while 5G technology ranges between 0.5 and 30 GHz — would have detected such “non-thermal” effects on living organisms. live, regardless of energy density (58% of those made on animals).

The authors note, however, that the majority of these studies do not meet the quality criteria necessary to draw satisfactory conclusions. Which means more research will be needed to determine if and how 5G can affect human tissue.

Cognitive effects?

One such study, published in 2017, wanted to examine whether heavy mobile phone use could affect cognitive functions. The researchers divided about 60 female students, ages 18 to 25, into two groups, depending on how much time they reported using their phones: 30 minutes or less per day for the past five years, or 90 minutes and more per day. They concluded that the second group was associated with greater difficulties paying attention. However, this study has several limitations: the small number of people observed, the fact that it is based on an estimate of usage time by the students themselves, and that several indirect effects associated with mobile phone use may be involved, without EMF being responsible. for noticeable changes.

The conclusions of another review of the scientific literature published in 2018 go in the opposite direction. After reviewing 43 studies looking at EMF exposure and cognitive function, the authors concluded that there is no strong link.

and autism ?

in these cases, It’s hard to find evidence linking this to autism. An internet search turns up numerous articles and studies that claim to link exposure to electromagnetic radiation. The problem is that many of these posts come from groups or researchers who advocate reduced exposure to waves, overshadowing their writing.

These publications have been ignored, there are still some studies that have explored the effect of waves on the development of autism.

In 2004, someone suggested that exposure of a fetus or newborn to radiation could be associated with an increased incidence of autism. The hypothesis was analyzed again in 2009, in a study conducted in the context of the increase in autism diagnoses, but the authors were unable to substantiate the claim, due to the limited data available.

At the same time, during the first decade of the 21st century, the weight of environmental factors in the development of autism has been called into question. In a US study published in 2011, the authors suggest that genes account for less than half the risk of autistic disorders – not 90% as previously suggested.

If electromagnetic fields play a role as one of these environmental factors, what could they be? These fields are said to have the potential to modify the epigenome, that is, all epigenetic modifications of a cell, during the first trimester of pregnancy, which can lead to autism in infants who carry genetic abnormalities, three researchers speculated in an article published in 2013.

The hypothesis is gaining ground, and in 2014, researchers from Bahrain proposed a causal link between exposure to very low-frequency electromagnetic fields and autism…in rats. However, if autism is indeed difficult to diagnose in humans, one can imagine how it is diagnosed in mice is still a matter of debate.

It is in this spirit that an article was published in 2017 in Child growth Those who hypothesized such a link were quickly decried by experts who went so far as to call it “pseudoscience”. The authors have been criticized for extrapolating inappropriately from rodent data, as well as relying on poor quality data. The journal would publish a critical commentary a few months later denouncing the original article.

Rule

Low-frequency electromagnetic fields may have the biological effect of increasing skin temperature, but there is no evidence that they can promote cognitive impairment, let alone the development of autistic disorders.

Image: NCI