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Environmental Chemicals= Neurodevelopmental Disorders

Project TENDR ( Targeting Environmental Neuro-Development Risks) , which started in 2015 is a unique collaboration of leading scientists, health professionals and children's and environmental advocates. Project TENDR was developed out of concern, now substantial scientific evidence, that toxic environmental chemicals are linked to neurodevelopmental disorders such as autism spectrum disorder, attention deficits, hyperactivity, intellectual disability and learning disorders. Their mission is to reduce exposures to toxic chemicals that can contribute to the prevalence of neurodevelopmental disabilities in American's children. They agree that widespread exposures to toxic chemicals in our air, water, food, soil, and consumer products can increase the risks for cognitive, behavioral, or social impairment.

A 2011 analysis of the U.S. Centers for Disease Control and Prevention's biomonitoring data found that 90% of pregnant women in the United States have detectable levels of 62 chemicals in their bodies, out of 163 chemicals for which the women were screened. Among the chemicals found in the vast majority of pregnant women are PBDEs, polycyclic aromatic hydrocarbons, phthalates, per fluorinated compounds, polychlorinated biphenyls, perchlorate, lead and mercury. Many of these chemicals can cross the placenta during pregnancy and are routinely detected in cord blood or other fetal tissues. Many toxic chemicals can interfere with healthy brain development, some at extremely low levels of exposure. Research in the neurosciences has identified "critical windows of vulnerability" during embryonic and fetal development, infancy, early childhood and adolescence. During these windows of development , toxic chemical exposure may cause lasting harm to the brain that interferes with a child's ability to reach his or her full potential.

We are witnessing an alarming increase in learning and behavioral problems in children. Parents report that 1 in 6 children in the United States, 17% more than a decade ago, have developmental disabilities. As of 2012, 1 in 10 (about 5.9 million) children in the United States are estimated to have ADHD. As of 2014, 1 in 68 children in the United States has an autism spectrum disorder. The economic costs associated with neurodevelopmental disorders is staggering. On average, it costs twice as much in the United States to educate a child who has a learning or developmental disability as it costs for a child who does not.

Evidence of neurodevelopmental toxicity of any type-epidemiological or toxicological or mechanistic- by itself should constitute a signal sufficient to trigger prioritization and some level of action. Such an approach would enable policy makers and regulators to proactively test and identify chemicals that are emerging concerns for brain development and prevent widespread human exposure. Failures to protect children from harm underscore the urgent need for a better approach to developing and assessing scientific evidence and using it to make decisions. We as a society should be able to take protective action when scientific evidence indicates a chemical is of concern, and not wait for unequivocal proof that a chemical is causing harm to our children. To help reduce the unacceptably high prevalence of neurodevelopmental disorders in our children , we must eliminate or significantly reduce exposures to chemicals that contribute to these conditions . We must adopt new framework for assessing chemicals that have potential to disrupt brain development and prevent the use of those that may pose a risk.

The following list provides examples of toxic chemicals that are most common and have lasting effects on the developing brain. (This is a small list with explanations)

What are organophosphate pesticides?

Organophosphate pesticides (OPs) are a class of neurotoxic chemicals initially developed for use as warfare nerve agents in the 1930-40s. Many OPs, including malathion, dichlorvos, azinphos-methyl, and chlorpyrifos were licensed for insecticidal use during 1950-60 before there were requirements for evaluation of the potential human health or environmental impacts of pesticides. OPs are currently used on a wide variety of crops including fruit trees, vegetables, wheat, soy, corn, and cotton. While agriculture use of OPs has been declining in the United States, 33 million pounds were still applied in 2007 alone.

What are the effects of OP exposure on children’s brain development?

OPs are neurotoxins that inhibit the activity of acetylcholinesterase, an enzyme necessary for the proper functioning of nerves. During an acute poisoning incident, the enzyme is suppressed and nerve impulses fire uncontrollably, resulting in symptoms such as muscle spasms, confusion, dizziness, loss of consciousness, seizures, abdominal cramps, vomiting, diarrhea, cessation of breathing, paralysis, and death in extreme cases. Long-term exposure to lower OP concentrations may not cause the same severe symptoms, but are still hazardous. The developing fetus and young child are particularly sensitive to OP exposure because the brain is growing and developing at an exceedingly rapid pace. Exposure during pregnancy is associated with developmental abnormalities, reduced motor function, and decreased IQ. Studies have also found associations between prenatal exposure and increased risk for neurobehavioral problems such as Attention Deficit Hyperactivity Disorder (ADHD)-like behaviors and autism spectrum disorder. Studies have found similar, serious neurodevelopmental effects from OP exposures in both rural and urban populations.

What are polybrominated diphenyl ethers (PBDEs)?

Polybrominated diphenyl ethers (PBDEs) are a group of industrial chemicals used as “flame retardant chemicals” and added to products in order to meet flammability standards established in the 1970s. Like a family, the group of PBDEs contains many related chemicals. There were two main commercial mixtures of PBDEs that were added to many household products including upholstered furniture, plastic casings for computers and televisions, carpet padding, baby products (e.g. changing pads and car seats), fabrics, and wire and cable coatings. PBDEs are found in animals and people throughout the world, with some of the highest levels in North America. Due to health and environmental concerns, a number of U.S. states banned PBDEs and these chemicals stopped being made in the U.S. between 2004 and 2013. Even though PBDEs are no longer made in the U.S., furniture, TVs, and other products that were made with PBDEs remain in our homes, schools, and workplaces. Several countries still manufacture some PBDEs, including China, India, and Japan.

What are the effects of PBDEs on children’s brain development?

Studies show that some PBDEs are associated with harm to children’s brain capacities that are critical for thinking and success in school. These effects include loss of IQ and problems with verbal comprehension, perceptual reasoning, motor coordination, hyperactivity, impulsivity, and attention. These associations are seen with PBDE exposures before birth (when mom is pregnant) and in young children. These effects may not be a significant problem for any individual child. But when you look at the bigger picture, such effects can pose a substantial burden on the population as a whole because almost everyone has some level of these chemicals in their body. Scientists have found that PBDEs disrupt hormones in the body that are essential for normal brain development; however, PBDEs may affect the developing brain in other ways too. Scientists are also concerned about the toxicity of the flame retardant chemicals used as replacements for PBDEs.

What is air pollution?

Most air pollution is the result of burning fossil fuels, such as coal, oil, natural gas, and gasoline to produce electricity and power cars, buses and trucks. Wood and other materials burned for cooking or heating also emit air pollutants. Combustion-related air pollutants can include polycyclic aromatic hydrocarbons (PAHs), nitrogen dioxide, particulate matter (a mixture of small solid particles and liquid droplets), and many other toxic chemicals including formaldehyde and benzene. The World Health Organization (WHO) reports that two million worldwide people die prematurely from exposure to air pollution every year.

What are the effects of air pollution on children’s brain development?

Prenatal and early childhood exposure to certain air pollutants is associated with developmental delays, reduced IQ, symptoms of anxiety, depression and inattention. Some emerging evidence suggests that prenatal exposure to traffic-related air pollutants may be risk factors for autism spectrum disorder. Research has linked air pollution with preterm birth and low birth weight, which are known risk factors for an array of neurodevelopmental disorders in children. Exposure to air pollution in early life may affect brain function across the lifespan.

What is lead? Lead, a toxic metal mined from the earth, has been used in many products for hundreds of years. Lead was removed from gasoline in the 1970s, but it can still be found in the soil, especially near roadways. Leaded paint was banned from sales to consumers in 1978, but it can still be found in many older houses, especially those built before 1960 and those in low-income neighborhoods and in poor repair. Lead can be found in some water pipes installed before 1986, and water can also be contaminated by lead solder previously used in pipes and with use of brass faucets and fixtures. Lead emissions from car battery or electronics recycling or other industrial sources can also contaminate soil and air. Lead can be found in a range of products, including aviation gas, wheel weights, industrial paints, fishing weights, bullets, car batteries, lubricants and toys, as well as in imported products often used in Latino and Asian communities such as folk remedies, cosmetics, contaminated foods and spices and lead-glazed cookware.

Over the past forty years, blood lead levels in American children have declined rapidly after the lead was removed from gasoline, paints, and other consumer products. Still, 1 in 50 preschool American children have lead poisoning (a total of about 535,000 U.S. children), which is defined as having a blood lead level above 5 micrograms per deciliter or 50 parts per billion. Lead exposure costs about $50 billion every year .

What are the effects of lead on children’s brain development? There is no safe level of lead in children’s blood. Blood lead levels < 5 μg/dL, which is 50 parts per billion, are associated with lower intelligence quotient scores, learning deficits, developmental delay, school problems and school failure, attention deficits, and problem behaviors, like delinquency and conduct disorders. Children who have higher blood lead levels are more likely to have attention deficit hyperactivity disorder (ADHD), making them act impulsively, and become hyperactive and disorganized in their schoolwork. Lead exposure has also has been associated with preterm birth and lower birth weight, which are risk factors for learning and developmental problems.

What are phthalates?

Phthalates are synthetic, high production-volume chemicals used in a wide range of products, including building materials, food production and packaging, medical devices, personal care products such as cosmetics and other consumer products. It is estimated that 4.9 million metric tons of phthalates are produced annually worldwide.

What are the effects of phthalates on children’s brain development?

Human studies have linked prenatal exposure to some phthalates with altered neurodevelopment in children. Effects seen include Attention Deficit Hyperactivity Disorder (ADHD)-like behaviors, problems with conduct and aggression, as well depression and other internalizing behaviors. In addition, prenatal exposure has been associated with deficits in child IQ, working memory and executive functioning, as well as with problems in emotional regulation. In a large Swedish population-based study the presence of PVC flooring in the parents’ bedroom, which is a known source of phthalate exposure, was associated with autism.

*Information provided by Project TENDR