Autism and Lead Toxicity

There has been much debate about the causes of autism, from genetics to diet. Many have suspected a link to heavy metals. According to a 2017 NIH study, strong evidence of this link has been found in the baby teeth of children with autism, indicating early life lead exposure (see below).

The question is why would autism rates be increasing if lead toxicity rates are not increasing. One thing to keep in mind that, though lead pollution has declined, the environment remains filled with lead and other heavy metals — in the soil, paint, and pipes. Lead exposure still is extremely common and even low doses can be damaging.

That brings us to a recent congressional investigation released a couple of days ago (see below). Most of us may not be breathing more lead pollution and paint dust, or drinking more lead in our water. But we might still be getting excessive levels of lead in our food. The congressional investigation specifically found toxic levels in nearly all baby food.

What is uncertain is if this represents some kind of change. Has there been a change in farming practices or a change somewhere else in the food supply that is increasing heavy metal concentration? Or is it some combination of other factors that is somehow worsening the effect of already present heavy metals accumulated in the soil?

Basically, why does the autism rate appear to be on the rise? That is a mystery, if we invoke lead toxicity as the central cause. Overall, lead toxicity rates have been on a decline, compared to the heavy toll of lead toxicity that spiked with the childhood of GenXers and young Boomers during the 1960s and 1970s, prior to environmental regulations.

Looking at baby teeth and baby food might help to grasp the key factor. It’s not about lead exposure in general but at a specific period of development. What we need to be looking at is the lead toxicity rates of babies and pregnant mothers, but such testing is not standard. Children typically are only tested after, not before, they show health and developmental problems.

So, it’s possible that, even though there is less lead exposure on average across childhood and adulthood, lead exposure in infancy might have gone up. This could be caused, for example, by increasing import of baby food from countries with weak environmental regulations and more heavy chemical use in farming.

This is concerning, as the long-term affects of heavy metal toxicity are diverse and sometimes devastating — besides autism: behavioral issues, impulse control issues, aggression, lowered IQ, etc; along with physical health problems. We might be seeing another generation or two of lead toxicity damage, exacerbated by the poor communities still struggling with already high rates of lead toxicity from old housing and industrial residue.

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Baby teeth link autism and heavy metals, NIH study suggests
from National Institutes of Health

Baby teeth from children with autism contain more toxic lead and less of the essential nutrients zinc and manganese, compared to teeth from children without autism, according to an innovative study funded by the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health. The researchers studied twins to control genetic influences and focus on possible environmental contributors to the disease. The findings, published June 1 in the journal Nature Communications, suggest that differences in early-life exposure to metals, or more importantly how a child’s body processes them, may affect the risk of autism.

The differences in metal uptake between children with and without autism were especially notable during the months just before and after the children were born. The scientists determined this by using lasers to map the growth rings in baby teeth generated during different developmental periods.

The researchers observed higher levels of lead in children with autism throughout development, with the greatest disparity observed during the period following birth.

Leading baby food manufacturers knowingly sold products with high levels of toxic metals, a congressional investigation found
by Sandee LaMotte, CNN

Four leading baby food manufacturers knowingly sold baby food that contained high levels of toxic heavy metals, according to internal company documents included in a congressional investigation released Thursday.

“Dangerous levels of toxic metals like arsenic, lead, cadmium and mercury exist in baby foods at levels that exceed what experts and governing bodies say are permissible,” said Democratic Rep. Raja Krishnamoorthi of Illinois, chair of the House Subcommittee on Economic and Consumer Policy, which conducted the investigation, signed by the Democratic members.

Krishnamoorthi said the spreadsheets provided by manufacturers are “shocking” because they show evidence that some baby foods contain hundreds of parts per billion of dangerous metals. “Yet we know that in a lot of cases, we should not have anything more than single digit parts per billion of any of these metals in any of our foods,” he told CNN.

Chemicals of concern for children

Arsenic, lead, cadmium and mercury are in the World Health Organization’s top 10 chemicals of concern for infants and children.

As natural elements, they are in the soil in which crops are grown and thus can’t be avoided. Some crop fields and regions, however, contain more toxic levels than others, partly due to the overuse of metal-containing pesticides and ongoing industrial pollution.

“There was a time where we used metals as the predominant pesticide for many years, assuming it was safe,” said Dr. Leonardo Trasande, chief of environmental pediatrics at NYU Langone.

All of these heavy metals have been linked to cancer, chronic disease and neurotoxic effects, but it’s the devastating damage that can be done to a developing baby’s brain that makes baby food toxicity so critical.

The US Food and Drug Administration has not yet set minimum levels for heavy metals in most infant food. The agency did set a standard of 100 parts per billion inorganic arsenic for infant rice cereal, but even that level is considered much too high for baby’s safety, critics say, especially since the FDA has already set a much lower standard of 10 parts per billion of inorganic arsenic for bottled water.

From the time of conception through the age of 2, babies have an extremely high sensitivity to neurotoxic chemicals, said Jane Houlihan, the national director of science and health for Healthy Babies Bright Futures, a coalition of advocates committed to reducing babies’ exposures to neurotoxic chemicals.

“Their brain is forming rapidly, and so when they’re exposed to metals that can interrupt those natural processes, the impacts range from behavioral problems to aggression to IQ loss and all kinds of cognitive and behavioral deficits that can persist throughout life,” Houlihan said.

“Pound for pound, babies get the highest dose of these heavy metals compared to other parts of the population,” she said. “So the consequences are serious.”

Healthy Babies Bright Futures published a report in 2019 that found toxic metals in 95% of the baby foods randomly pulled off supermarket shelves and tested — that exposé was the “inspiration” for the subcommittee’s work, Krishnamoorthi told CNN.