Could Toxic Chemicals Lower Our Child’s IQ?

April 11, 2023 by Dr. Steve Chaney

Is The Science Solid?

Author: Dr. Stephen Chaney

As Earth Day approaches, our thoughts turn to our environment. Most of the concern is with global warming, and rightly so. But should we be concerned about the effects of toxic chemicals in our environment on our health – or, more importantly the health of our children?

The short answer is, “Maybe.” But let’s delve a little deeper.

In a past issue of “Health Tips From the Professor” I examined the evidence suggesting that toxic chemicals in the home could cause childhood asthma. That is alarming because asthma can predispose individuals to other diseases and affects quality of life.

But what if that were only the tip of the iceberg? For example, a recent headline stated: “More Toxic Chemicals [In Our Environment] Are Damaging Children’s Brains”. If that headline is true, it’s downright scary.

The authors of this study suggested that toxic chemicals which are abundant in our environment can cause decreases in IQ and aggressive or hyperactive behavior in children – and that those changes may be permanent.

The Study Behind The Headlines

The paper that generated the headlines (Grandjean & Landrigan, The Lancet Neurology, 13: 330-338, 2014) was a review of the literature, not an actual clinical study.

Based on published clinical studies, the authors identified 11 chemicals commonly found in the environment as developmental neurotoxins (toxins that interfere with normal brain development) based.

This finding compares with 6 developmental neurotoxins that they were able to identify in a similar study in 2006.

The authors were not claiming that the number or amount of neurotoxic chemicals changed between 2006 and 2014. They were saying that science has advanced to the point where we can classify six more chemicals that have been in our environment for years as developmental neurotoxins.

Even more worrisome, the authors postulate that many more environmental neurotoxins remain undiscovered, and these environmental neurotoxins come from many sources.

Some are industrial pollutants.

Some are persistent groundwater contaminants.

Some are insecticides and herbicides used in agriculture.

Some are found in common household products and furnishings.

Could Toxic Chemicals Lower Our Child’s IQ?

To answer that question, you need to look at some of the studies they cited in their review. For example:

Elevated blood lead levels in children are associated with as much as a 7-point decrease in IQ (Lamphear et al, Environmental Health Perspectives, 113: 894-899, 2005).

The effects of many of the neurotoxic chemicals they identified on IQ were difficult to quantify. However, the authors estimated that average exposure of US children to just 3 of the best studied chemical neurotoxins (lead, methylmercury, and organophosphate pesticides) was sufficient to lower their average IQ by 1.6 points.

The authors spoke of the environmental neurotoxins they identified as representing a “silent pandemic of a chemical brain drain” that could cost the US economy billions of dollars.

One of the blog posts I read on this topic summarized the consequences in a very graphic manner. It said:

If one child’s IQ is reduced by 5 points, it doesn’t appear to make a big difference. For example, that child might be:

A little slower to learn.
A little shorter of attention.
A little less successful at tests and at work.

That might result in $90,000 in lost lifetime earnings.

However, if the average IQ of every child in the US were decreased by 5 points, the effect becomes significant:

Only half as many members of the next generation would be “intellectually gifted”.
Twice as many of the next generation would be “intellectually impaired”.
Lost productivity could be in the billions.

Of course, statements like that are a bit over the top. Drs. Grandjean and Landrigan did not claim that the net effect of the chemicals they identified was a 5-point drop in IQ. Nor did they claim that all US children were affected equally.

Still, it’s enough to make you think.

Are Toxic Chemicals Causing Behavior Problems?

The authors cited numerous studies linking the chemical neurotoxins they identified to aggression and hyperactivity. But perhaps the most compelling reason to suspect that environmental chemicals may be affecting brain development is the spiraling incidence of developmental disorders such as autism and ADHD. For example:

Autism has increased by 78% since 2007 and now affects 1 of 88 eight-year-old children.

ADHD has increased by 43% since 2003 and now affects 11% of children aged 4-17.

Some of this increase could be due to better diagnosis of these conditions, but nobody believes that all of it is due to improved diagnosis. The authors claim that much of this increase is likely due to environmental exposure to the kinds of developmental neurotoxins they identified.

Is The Science Solid?

Of course, you have seen these kinds of warnings before. Is this crazy talk, or is it something you should take seriously? What is the truth? Is the science solid?

The problem is this is a very difficult area of research. You can’t do a gold standard double-blind, placebo-controlled clinical trial. Nobody in their right mind would give one group of children toxic chemicals and the other group a placebo.

The studies cited in this paper were mostly population studies. Basically, this means that they compared children with exposure to certain toxic chemicals to a control group that was as similar as possible to the first group except that their exposure to the toxic chemicals was less.

The limitation of this kind of study is obvious. We are usually comparing children from different locations or of different backgrounds. We almost never know if we have controlled for all possible variables so that the groups are truly identical.

Consequently, it becomes important to ask how many studies come to the same conclusion. For some of the toxic chemicals, such as lead, methylmercury, and organophosphate pesticides, the weight of evidence is very strong. For some of the newer additions to their list of developmental neurotoxins, it is clear that the chemicals have neurotoxic properties, but the significance of those effects on the developing human brain are hard to quantify at this point.

So, rather than ask, “Is this true?”, we should ask, “What if it were true?” The consequences of lowered IQ and developmental behavioral problems are so significant that it may not make sense to wait until we have unassailable scientific evidence before we act.

We don’t need to panic. The science isn’t that strong. But we should take sensible precautions. The developmental neurotoxins identified in this study come from many sources. Here are the sources and sensible precautions we can take.

Some are industrial pollutants. For these, we need to lobby for better environmental regulation.

Some are persistent groundwater contaminants. For these we need to drink purified water whenever possible.

Some are insecticides and herbicides used in agriculture. For these we need to buy organic, locally grown produce whenever possible.

Some are found in common household products and furnishings. For these we need to become educated label readers and use non-toxic products in our home whenever possible.

The Bottom Line:

1) A recent review claims that there is a good scientific basis for classifying at least 11 environmental chemicals as developmental neurotoxins that are likely to reduce IQ and contribute to behavioral problems in US children.

2) The science behind the claims in this review is solid, but not iron clad. This is an area of science where it is virtually impossible to come up with a definitive conclusion.

3) However, there are times when we need to simply ask ourselves: “What if it were true?” The consequences of lowered IQ and developmental behavioral problems are so significant that it may not make sense to wait until we have unassailable scientific evidence before we act.

4) We all need to be guardians of our personal environment. The article above identifies practical steps each of us can take.

For more details and to learn what practical steps you can take to reduce your family’s exposure to toxic chemicals, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

How Did Our Bodies Get So Contaminated?

March 1, 2022 by Dr. Steve Chaney

Would You Like Phthalates With Your Burgers?

Author: Dr. Stephen Chaney

Every once in a while, a scientific study grabs the headlines and causes a paradigm shift in our thinking. One such study, published in 2016, showed that babies’ umbilical cords contained over 200 toxic chemicals.

That study created instant headlines. It grabbed our attention. People were asking, “How did our bodies get so contaminated?”

Sure, there were clues. There were many studies showing that individual toxic chemicals in our environment were making their way into our bodies. But no one anticipated the full scope of the problem. Nobody anticipated that our bodies had become toxic waste dumps.

And the very thought that newborn babies were starting their lives with so many toxic chemicals in their bodies was frightening. No one knows what the long-term health consequences will be.

What Are Phthalates And Why Should You Care?

Phthalates are a class of compounds that are widely used in the manufacture of household products we use every day. For example, in shampoos and hair gels they increase spreadability, enhance absorption, and help make fragrances last longer. In hairsprays they make the hair softer and more flexible. And from shampoos, hair gels, and hairsprays they can be absorbed into our bodies through our scalp.

They are also used as “plasticizers” to make certain plastics more flexible and more durable. This is an issue because phthalates are added to some food packaging and materials used to handle and process food. And from there they can migrate into the food. This is especially true for fast foods and highly processed foods.

So, most of us are exposed to phthalates. We accumulate them in our bodies. The question is, “How harmful are these chemicals? Should we be concerned?” As with many other chemicals in our environment, the answer isn’t clear.

Phthalates belong to a class of chemicals called “hormone disruptors”. In animal studies phthalates disrupt the reproductive system, especially in males. They can cause developmental problems in the offspring. And they appear to increase the risk of some cancers.

In humans there is emerging evidence that phthalate exposure during pregnancy may impair a child’s brain development and increase their risk for learning, behavioral, and attention disorders.

At the other end of the spectrum, a recent study found a link between increased phthalate exposure and premature death in older Americans. The authors of that study estimated that phthalate exposure may lead to roughly 100,000 premature deaths each year, resulting in an economic burden of between $40 and $47 billion per year.

Would You Like Phthalates With Your Burger?

That question brings me to the study (L Edwards et al, Journal of Exposure Science & Environmental Epidemiology, October 27, 2021) I want to discuss today. This was a preliminary study, so the authors focused on only a few fast foods from 6 fast food chains in the San Antonio area and a single source of phthalate contamination. They measured levels of 11 different phthalates in:

Hamburgers, chicken nuggets, and French fries from two hamburger chains.

Chicken burritos from two Tex-Mex chains.

Cheese pizzas from two pizza chains.

Plastic gloves from two hamburger chains and one Tex-Mex chain.

Each of the phthalates they tested has different properties and different risks. But for purposes of simplicity, I will only discuss total phthalate levels for this review.

Here is what the study found:

10 of the 11 phthalates they analyzed were found in the foods they tested.

86% of the foods they tested were contaminated with one or more phthalate.

Chicken burritos were the most contaminated food, followed by hamburgers, French fries, and chicken nuggets. Cheese pizza was the least contaminated food.

High levels of phthalates were found in the plastic gloves in all 3 locations tested, indicating that the plastic gloves used for handling the foods are one likely source of food contamination.

The authors concluded, “Our findings suggest that phthalates…are abundant in prepared meals available at popular fast-food restaurants. In addition, they are found in food handling gloves, which may be a source of food contamination. These data support prior observations that consumption of highly processed and prepared foods contribute to human exposure of phthalates. Many of these chemicals have been associated with adverse health outcomes or, based on in vitro data, have the potential to be harmful to human health. These results, if confirmed, may inform individual and regulatory reduction strategies.”

In summary, while the evidence is not yet definitive, it is strong enough for us to ask how we might reduce our exposure to phthalates.

How Did Our Bodies Get So Contaminated?

The sobering thought is that this study is just the tip of the iceberg. It looked at 11 chemicals found in 5 foods from 6 fast-food chains and identified one potential source of the chemical contamination of those foods. The problem is much larger.

Crops are sprayed with pesticides and herbicides. Contaminants can also come from polluted surface and ground water.

Hormones and chemicals are used to make animals grow faster, and some of these chemicals make their way into the meats.

Chemicals are added to processed and fast foods to prevent spoilage and give them the desired properties.

Processed and fast foods are produced in factories, often packaged in plastic, and shipped to distant locations where they will be handled by people wearing plastic gloves.

We are even starting to see meats and produce sold in grocery stores prewrapped in plastic.

And, of course, we are exposed to chemicals in our cosmetics, personal care products, and household products. We are even exposed to chemicals through outgassing of our household furnishings.

Once you start to think about all the ways we are exposed to chemicals in our daily lives, it is easy to understand how we can end up with over 200 chemicals in an infant’s umbilical cord blood. It’s easy to understand how our bodies got so contaminated.

Each chemical is present at very low levels. If you look at each chemical individually, you might be tempted to conclude the risk is too small to be concerned about. But when you have hundreds of these chemicals in your body, their effect is cumulative. The risk can become significant.

What Can We Do?

Phthalates are so pervasive in our environment that it would be impossible to completely eliminate our exposure to them. However, there are some ways we can minimize our exposure:

1) Buy organic whenever possible.

2) Eat as close to nature as possible. By that I mean:

- Buy your produce at your local farmer’s market whenever possible.

- Choose grocery stores that source locally and do not wrap meat and produce in plastic.

3) Avoid fast foods and highly processed foods. You already know they are unhealthy. If you needed one more reason to avoid them, this would be it.

4) Read the labels of personal care products and cosmetics and choose those without phthalates.

The Bottom Line

In humans there is emerging evidence that phthalate exposure during pregnancy may impair a child’s brain development and increase their risk for learning, behavioral, and attention disorders. At the other end of the spectrum, a recent study found a link between increased phthalate exposure and premature death in older Americans.

Some previous studies have suggested that processed and fast foods may be contaminated with phthalates. The study discussed in this article looked at 11 phthalates found in 5 foods from 6 fast-food chains and looked at the plastic gloves used to handle the food as one potential source of phthalate contamination. The study found:

86% of the foods they tested were contaminated with one or more phthalate.

Chicken burritos were the most contaminated food, followed by hamburgers, French fries, and chicken nuggets. Cheese pizza was the least contaminated food.

High levels of phthalates were found in the plastic gloves, indicating that the plastic gloves used for handling the foods are one likely source of food contamination.

The authors concluded, “Our findings suggest that phthalates…are abundant in prepared meals available at popular fast-food restaurants. In addition, they are found in food handling gloves, which may be a source of food contamination. These data support prior observations that consumption of highly processed and prepared foods contribute to human exposure of phthalates. These results, if confirmed, may inform individual and regulatory reduction strategies.”

I discuss how to minimize our exposure to phthalates in the article above.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Are Toxic Chemicals Lowering Our IQ?

February 25, 2014 by Dr. Steve Chaney

Is Chemical Brain Drain A Pandemic?

Author: Dr. Stephen Chaney

But, what if that were only the tip of the iceberg? For example, a recent headline stated: “More Toxic Chemicals [In Our Environment] Are Damaging Children’s Brains”. If that headline is true, it’s downright scary.

The Study Behind The Headlines

The paper that generated the headlines (Grandjean & Landrigan, The Lancet Neurology, 13: 330-338, 2014) was a review of the literature, not an actual clinical study.

Based on published clinical studies, the authors identified 12 chemicals commonly found in the environment as developmental neurotoxins (toxins that interfere with normal brain development) based. [If you would like to find out what those “Dirty Dozen” chemicals are and where they are found, click here.]

This finding compares with 6 developmental neurotoxins that they were able to identify in a similar study in 2006.

The authors were not claiming that the number or amount of toxic chemicals changed between 2006 and 2014. They were saying that science has advanced to the point where we can classify six more chemicals that have been in our environment for years as developmental neurotoxins.

Even more worrisome, the authors postulate that many more environmental neurotoxins remain undiscovered.

Are Toxic Chemicals Lowering Our IQ?

To answer that question, you need to look at some of the studies they cited in their review. For example:

Elevated blood lead levels in children are associated with as much as a 7 point decrease in IQ (Lamphear et al, Environmental Health Perspectives, 113: 894-899, 2005).

Elevated fluoride levels in drinking water are also associated with as much as a 7 point decrease in IQ (Choi et al, Environmental Health Perspectives, 120: 1362-1368, 2012).

The effects of many of the toxic chemicals on IQ were difficult to quantify, but the authors estimated that exposure of US children to just 3 of the chemicals (lead, methymercury and organophosphate pesticides) was sufficient to lower their average IQ by 1.6 points.

What Are The Potential Consequences?

The authors spoke of the environmental neurotoxins they identified as representing a “silent pandemic of a chemical brain drain” that could cost the US economy billions of dollars.

One of the blog posts I read on this topic summarized the consequences in a very graphic manner. It said:

If one child’s IQ is reduced by 5 points, it doesn’t appear to make a big difference. For example, that child might be:

A little slower to learn
A little shorter of attention
A little less successful at tests and at work

That might result in $90,000 in lost lifetime earnings

However, if the average IQ of every child in the US were decreased by 5 points, the effect becomes significant:

Only half as many members of the next generation would be “intellectually gifted”.
Twice as many of the next generation would be “intellectually impaired”
Lost productivity could be in the billions

Of course, statements like that are a bit over the top. Drs. Grandjean and Landrigan did not claim that the net effect of the chemicals they identified was a 5 point drop in IQ. Nor did they claim that all US children were affected equally.

Still, it’s enough to make you think.

Are Toxic Chemicals Causing Behavior Problems?

Autism has increased by 78% since 2007 and now affects 1 of 88 eight year old children.

ADHD has increased by 43% since 2003 and now affects 11% of children age 4-17.

Is The Science Solid?

This is a difficult area of research. You can’t do the gold standard double-blind, placebo-controlled clinical trial. Nobody in their right mind would give one group of children toxic chemicals and the other group a placebo.

The studies cited in this paper were mostly population studies. Basically this means that they compared children with exposure to certain toxic chemicals to a control group that was as similar as possible to the first group except that their exposure to the toxic chemicals was less.

As a consequence it becomes important to ask how many studies come to the same conclusion. For some of the toxic chemicals, such as lead, methymercury and organophosphate pesticides, the weight of evidence is very strong. For some of the newer additions to their list of developmental neurotoxins, it is pretty clear that the chemicals have neurotoxic properties, but the significance of those effects on the developing human brain are hard to quantify at this point.

The Bottom Line:

1) A recent review claims that there is a good scientific basis for classifying at least 12 environmental chemicals as developmental neurotoxins that are likely to reduce IQ and contribute to behavioral problems in US children. [If you would like to find out what those “Dirty Dozen” chemicals are and where they are found, click here.]

2) The science behind the claims in this review is solid, but not iron-clad.

4) We all need to be guardians of our personal environment. But, it is not easy. The “Dirty Dozen” chemicals identified in this study come from many sources:

Some are industrial pollutants. For those, we need lobby for better environmental regulation.

Some are persistent groundwater contaminants. For those we need to drink purified water whenever possible.

Some are insecticides and herbicides used in agriculture. For those we need to buy organic, locally grown produce when feasible.

Some are found in common household products and furnishings. For those we need to become educated label readers and use non-toxic products in our home whenever possible.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

The Dirty Dozen

February 25, 2014 by Dr. Steve Chaney

Environmental Toxins That Affect Brain Development

Author: Dr. Stephen Chaney

In a recent review, Drs. Grandjean and Landrigan (The Lancet Neurology, 13: 330-338, 2014) identified 12 toxic chemicals which are abundant in our environment and are developmental neurotoxins.

These are all chemicals that damage brain development. They can cause decreases in IQ and aggressive or hyperactive behavior in children – and that those changes may be permanent.

Let’s look at these developmental neurotoxins and where they are found.

The Dirty Dozen

In their review Grandjean & Landrigan identified 6 developmental neurotoxins that were known in 2006, and 6 more chemicals that have been confirmed to be developmental neurotoxins between 2006 and 2023.

Developmental Neurotoxins Known in 2006 and their sources:

Lead

Main Sources: paint, gasoline, solder and consumer products such as toys & jewelry

Current status: Lead has been banned in paint since 1978 and from gasoline since 1996. Millions of houses still contain lead paint. Other current sources are inexpensive toys and costume jewelry imported from China and other countries without tight regulations.
The EPA estimates that 1 million children in the US are affected by elevated lead levels.

Methylmercury

Main Sources: discharges into air & water from coal-burning power plants, mining, pulp & paper industries.

Polychorinated biphenyls (PCBs)

Main Sources: transformers and many commercial products

Current status: Banned in 1979, but continues to be a common environmental contaminant because this group of chemicals is very long-lived.

Arsenic:

Main Sources: extraction of metals from rock (smelting), algaecides, herbicides, pesticides and pressure-treated wood.

Current status: Pressure treated wood banned in 2003 for residential use. Still found in some playgrounds and older buildings.

Toluene:

Main Sources: gasoline. It is also a solvent for paints, paint thinners, spot removers, adhesives, antifreeze, & some consumer products like fingernail polish removers.

Current status: Common in consumer products. Read labels and make sure windows are open if you use.

Developmental Neurotoxins Identified Since 2006 and their sources:

Manganese

Main Sources: municipal wastewater discharge, emissions generated during alloy, steel & iron production, emissions from burning of fuel additives

Flouride

Main Sources: naturally elevated in groundwater in certain regions, added to municipal water supply, most bottled beverages and toothpaste.

The American Academy of Pediatrics has warned that children drinking fluoridated water, fluoridated beverages, using fluoridated toothpaste and receiving fluoride treatments for their teeth may be receiving excess fluoride.

Chlorpyrifos

Main Sources: insecticide

Current status: Banned for use in homes in 2001. Still one of the most widely used insecticides in agriculture.

DDT

Main Sources: insecticide

Current status: Banned for use in this country in 1972. DDT and its breakdown products still found in our water supply. DDT still in use in agriculture and insect control in some countries.

Trichloroethylene (TCE)

Main Sources: widely used in dry cleaning fabrics, the textile industry and metal degreasing

Current status: Found in groundwater due to discharge from factories and dry cleaners.

Polybrominated diphenyl ethers (PBDEs)

Main Sources: flame retardants – used in building materials, electronics, mattresses & household furniture, plastics, polyurethane foams & textiles.

Current status: Readily leached into the environment. Found in dust, water, food & human breast milk

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.