06-05-2025
Can heavy metals in toys trigger autism in your child? Here's what AIIMS study found
Imagine a toddler playing with her toys, running barefoot in the park, eating chips bought by her parents from the vendor and drinking water from a community tap that has been installed near a public sit-out. You wouldn't know that such innocuous activities would have exposed her to heavy metals like lead, cadmium, manganese, chromium and mercury.
All of this heightens her risk of developing autism spectrum disorder (ASD), a neurological and developmental malaise that could affect her social communication and behaviour. An ongoing study from the All India Institute of Medical Science (AIIMS), Delhi, has shown how the environment plays a key role in autism development in children. The findings were recently presented at the International Society for Autism Research.
Autism cannot be ascribed to a single inherited gene but is caused by the interaction of multiple genes and environmental factors.
What does the child study say?
Dr Shefali Gulati, faculty in-charge of the child neurology division in the department of paediatrics, AIIMS, conducted the study on 500 children with ASD and 100 control subjects, monitoring their blood, urine, hair and nail samples to study the impact of 21 heavy metals. While the hair and nail analysis is ongoing, high levels of lead, arsenic, cadmium, manganese and chromium were present in the urine samples of all 500 children with ASD compared to the control group.
'These impact brain development and IQ. It is very important to understand where they are coming from. Children play with toys or use paints which are contaminated with lead, are exposed to non-standardised batteries that power their devices, to cadmium that comes from their passive smoking, to arsenic, which is everywhere, including in water, and to mercury which exists in seafood,' she says.
Jewellery, cosmetics, drinking water from old lead pipes or plumbing fixtures, household dust, even traditional medicines are all laced with heavy metals and within easy reach of the child. 'It is worst for children living near factories or waste sites, where both the soil and water get easily contaminated,' says Dr Gulati. Some of the foods which grow on this soil — whole grains, broccoli, grape juice, potatoes, garlic, apples and green beans — have traces of chromium.
How is environment a risk factor for autism?
Although some children are born with genetic triggers for autism, how they manifest depends on the environment. 'These factors include exposure to air pollution, pesticides, or certain medications during pregnancy, as well as maternal health conditions like obesity or diabetes. The advanced age, stress level and lifestyle of the father can impact the genes in the sperm and be a trigger of autism. We did another study where we found the gut microbiome of children with ASD different from that of their siblings, which is another area that needs looking into,' says Dr Gulati.
That's why she is focussing on minimising environmental risks, focussing on heavy metals now. Earlier research has shown that children exposed to higher levels of air pollutants before and after birth were more likely to have autism. Other possible environmental factors include exposure to flame retardants, used in most home appliances and products to decrease the risk of fire. Scientists are also studying phthalates, used in plastics, soaps and shampoos among others.
