{] Learning and Developmental Disabilities Linked to Environmental Toxins

[Guest guest]

Learning and Developmental Disabilities Linked to Environmental Toxins

Roman Bystrianyk, " Learning and Developmental Disabilities Linked to

Environmental Toxins " , Health Sentinel, February 25, 2008,

Autism, attention deficit hyperactivity disorder (ADHD), dyslexia,

mental retardation, lowered IQ and other learning and behavior

disorders are very common in today's American children. The

occurrence of these learning and developmental disabilities (LDDs)

appears to be rising with between 5 to 15 percent of all children

under the age of 18 in the United States affected. In general, these

disabilities have significantly increased over the past 40 years and

now affect more than 12 million children in the United States.

On February 20, 2008 The Collaborative on Health and the

Environment's Learning and Developmental Disabilities Initiative

published a Scientific Consensus Statement on Environmental Agents

Associated with Neurodevelopmental Disorder. This statement signed by

more than 50 national and international health professionals and

scientists summarizes the most recent science about environmental

contaminants associated with learning and developmental disabilities.

The report that was drafted by this prestigious group contains over

200 scientific references.

" We know enough now to move on with taking steps to protect our

children. This document pulls that knowledge together to further this

vital effort, " said reviewer Martha Herbert, PhD, MD, an assistant

professor of neurology at Harvard Medical School and a pediatric

neurologist with subspecialty certification in neurodevelopmental

disabilities at the Massachusetts General Hospital in Boston.

Exposure to a wide variety of chemicals is now an unavoidable fact of

modern life. Approximately 3,000 chemicals are manufactured in

amounts over 1,000,000 pounds each year. The vast majority of these

chemicals have little to no information on their potential to effect

learning and development. According to the report, " there is good

evidence that about 200 of these chemicals are adult neurotoxicants

and another 1,000 are suspected of affecting the nervous system.

Overall there has been a gross failure to require developmental

neurotoxicity testing. "

Historically, of all the factors that contribute to learning and

developmental problems, chemical contaminants have been the least

studied, although ironically the most preventable. The report states

that, " we now have solid scientific evidence that a variety of

environmental agents can adversely affect the nervous system, " and

that " a child's developing nervous system is more sensitive to

chemical exposure than the adult nervous system. "

Children that lack certain nutrients are more susceptible to these

chemical toxicants. For instance, iron and/or calcium deficiencies

can affect the absorption and toxicity of heavy metals such as lead

and manganese. " The role of nutrition in mitigating exposure to

environmental agents is an important public health issue. "

The following environmental contaminants have been " conclusively

shown " to affect the developing nervous system and cause a range of

performance deficits.

Alcohol – The effects of alcohol on the brain are well

recognized. " Fetal Alcohol Syndrome (FAS), now considered part of the

Fetal Alcohol Spectrum Disorder (FASD), is the most preventable form

of behavioral and learning disabilities. Even low or moderate

consumption of alcohol during pregnancy can cause subtle and

permanent performance deficits. "

Mercury – There is no doubt that mercury causes learning and

developmental disorders. " We are all exposed to some form of mercury.

Inorganic mercury is the liquid silver form and is used in dental

amalgams. Mercury is also present in coal, and coal-burning electric

utilities facilities are a significant source of atmospheric

environmental mercury. "

PCBs – Polychlorinated biphenyls (PCBs) are mixtures of chlorinated

compounds that were once used as cooling and insulating fluids in

electrical transformers and other electronic components. " Numerous

studies have documented that PCB exposure can adversely affect motor

skills, learning and memory as shown in lower full-scale and verbal

IQ scores and reading ability. "

PBDEs – Polybrominated diphenyl ethers (PBDEs) have been used

commonly as flame-retardant chemicals for years. " Recent studies have

left little doubt that PBDEs are developmental neurotoxicants in

animals and lead to changes in motor activity and reduced performance

on learning and memory tests. "

Manganese – Manganese is a trace element which is essential in small

quantities for normal growth and development. " Recent studies

indicate that high levels of manganese exposure, either from

inhalation or through drinking water, can damage the developing

nervous system. "

Arsenic – Arsenic is frequently found in drinking water around the

world. " Recent studies have found a dose-response relationship

between exposure to arsenic and intellectual impairment. While

additional studies assessing the impact of low levels of arsenic in

drinking water are needed, it is clear that arsenic affects the

neurodevelopment of children.

Solvents – Solvents include a broad array of different compounds

including toluene, benzene, alcohol, turpentine, acetone and

tetrachloroethylene. More than 50 million metric tons are used in the

United States with more than 10 million people exposed in the

workplace. " Several reports have documented that the adverse

developmental effects of maternal toluene exposure include low birth

weight, decreased head circumference and developmental delays. "

PAHs – Polycyclic aromatic hydrocarbons (PAHs) are widely dispersed

air pollutants and well-recognized human mutagens and carcinogens.

PAHs are generated during combustion of fuels from motor vehicles,

coal-fired power plants, residential heating and cooking and are also

present in tobacco smoke. " Recent studies have indicated that

elevated exposure to PAHs results in lower birth weight and affects

cognitive development. "

Pesticides – Pesticides are ubiquitous in our modern environment.

Agricultural and residential application of pesticides totals more

than 1 billion pounds each year in the United States. " There is now

evidence that childhood exposure to pesticides, such as

organophosphates, enhances the risk for developmental disorders

including deficits in memory, poorer motor performance and an array

of other conditions. "

Nicotine and environmental tobacco smoke (ETS) – Many studies link

maternal smoking to behavior disorders in children. The developmental

delays caused by ETS are costly and preventable. " Furthermore, new

data indicates that childhood exposure to ETS is associated with

neurobehavioral effects. There is growing recognition of subsequent

behavioral disorders in young adults following exposures either

prenatally or as children. "

Unfortunately, it is not possible to address all the chemicals that

might be associated with LDDs. Again, it's important to note that for

the majority of chemicals " we do not have the data necessary to

conclude there are no adverse developmental effects. " There are an

estimated 200 chemicals that are known to cause neurotoxic effects in

adults, but for many of these chemicals " developmental effects have

not been examined. "

The following are number of agents that are of significant concern:

Endocrine disruptors – " Animal studies have documented that a wide

range of chemicals have the ability to disrupt endocrine function in

animals and affect cognitive function. Endocrine disruptors include

phthalates, PCBs and polychlorinated dibenzodioxins, brominated flame

retardants, dioxins, DDT, perfluorinated compounds (PFCs),

organochlorine pesticides, bisphenol A and some metals. The

controversy around the effects of endocrine disruptors is perhaps

best illustrated by research on bisphenol A whose estrogenic activity

was first reported in 1936. It was subsequently found to stabilize

polycarbonates and resins and is now widely used in many products

including food-can liners. There is a growing body of evidence

related to the very low-dose effects of bisphenol A "

Fluoride – Fluoride is commonly added to drinking water across the

United States in an effort to reduce dental decay. Fluoride is also

found in a range of consumer products including toothpastes and

mouthwashes. " Excessive fluoride ingestion is known to lower thyroid

hormone levels, which is particularly critical for women with

subclinical hypothyroidism: decreased maternal thyroid levels

adversely affect fetal neurodevelopment. In addition, a study in

China reported decreased child IQ levels associated with fluoride in

drinking water. The primary concern is that multiple routes of

exposure, from drinking water, food and dental care products, may

result in a high enough cumulative exposure to fluoride to cause

developmental effects. "

Food additives – Artificial food colors and additives are found

throughout the modern food supply and have long been suspected as

causing conduct disorders. Diets, such as the Feingold Diet removes

food additives from the diets of individuals with ADHD. " Previous and

recent carefully conducted double-blind human studies have confirmed

that artificial food colorings such as sunset yellow, tartrazine,

carmoisine and ponceau, as well as the preservative sodium benzoate,

can cause conduct disorders. Recent studies using well-designed

randomized, double-blind, placebo-controlled, crossover trials show

that artificial food colors and additives cause increased

hyperactivity in three-year-old children. This has the potential to

become a serious issue given the large number of children diagnosed

with ADHD. "

" Accepting childhood exposure to contaminants that result in

compromised learning and behavioral abilities violates the basic

tenets of biomedical ethics. The principle of beneficence ( " do good " )

requires that the benefits be maximized while the harm be minimized

or eliminated. Respect for autonomy or personhood is violated when

children are unnecessarily exposed to harmful substances. Respect of

person also implies informed consent, and no child has given the

informed consent for exposure to harmful chemicals. Finally, the

principle of justice requires that burdens be shared equally, and

because children are more vulnerable they endure a greater burden. It

is wrong to allow the exposure of children to environmental agents

that cause learning and developmental disorders. "

We are still dealing with the health effects of adding lead to paint

and gasoline, even though at the time the toxic effects of lead were

well known. " To protect children, a precautionary approach is

required that shifts the burden of responsibility to producers or

manufacturers to demonstrate safety prior to potential exposure. "

" We could cut the health costs of childhood disabilities and disease

by billions of dollars every year by minimizing contaminants in the

environment, " said Phil Landrigan, MD, MSc, of the Children's

Environmental Health Center at the Mount Sinai School of

Medicine. " Investing in our children's health is both cost-effective

and the right thing to do. "

" The overwhelming evidence shows that certain environmental exposures

can contribute to life-long learning and developmental disorders, "

noted Ted Schettler, MD, MPH, with the Science and Environmental

Health Network. " We should eliminate children's exposures to

substances that we know can have these impacts by implementing

stronger health-based policies requiring safer alternatives. Further,

we must urgently examine other environmental contaminants of concern

for which safety data are lacking. "

" The proportion of environmentally induced learning and developmental

disabilities is a question of profound human, scientific and public

policy significance, " said lead author G. Gilbert, PhD, DABT,

of the Institute of Neurotoxicology & Neurological Disorders, " and

has implications for individuals, families, school systems,

communities and the future of our society. The bottom line is it is

our ethical responsibility to ensure all children have a healthy

future. "

The authors of the study do not include all the hazards that affect

the brains of our children. Nutritional deficiencies of omega-3 fatty

acids, B vitamins, selenium, vitamin E, and others are documented in

the medical literature as affecting brain health and development. The

avoidance of dairy, wheat, and artificial sweeteners in the diet have

been shown to positively change neurologic problems. Excessive

television viewing has also been associated with behavior and

attention problems. Thimerosal, found in vaccines and other products,

has been shown that it " induces oxidative stress and apoptosis by

activating mitochondrial cell death pathways " and to have " induced

DNA strand breaks, caspase-3 activation, membrane damage and cell

death " (NeuroToxicology, Vol. 26, 2005)

The authors conclude, " The scientific evidence we have reviewed

indicates environmental contaminants are an important cause of

learning and developmental disabilities. The proportion of

environmentally induced LDDs is a question of profound human,

scientific and public policy significance. Existing animal and human

data suggest that a demonstrated with scientific certainty. The

consequences of LDDs are most significant for the affected individual

but also have profound implications for the family, school system,

local community and greater society. Despite some uncertainty, there

is sufficient knowledge to take preventive action to reduce fetal and

childhood exposures to environmental contaminants. Given the serious

consequences of LDDs, a precautionary approach is warranted to

protect the most vulnerable of our society. "

The over 50 scientists of this report state they are developing a

companion document outlining specific policy recommendations based on

the current scientific knowledge that was used to assemble this

report.

We as individuals can act now. We can avoid alcohol and tobacco

smoke. We can get water and air filters to minimize exposure to lead,

mercury, and other contaminants. We can avoid using pesticides on our

lawns and by choosing to eat organic foods. We can avoid processed

foods that contain artificial colors and ingredients. We can use

fluoride free products. We can use natural cleaners that don't

contain harmful solvents in our homes. We can use products that don't

contain phthalates and other harmful chemicals. We can ensure we get

enough nutrients by avoiding nutritionally deficient junk foods and

focus on getting enough omega-3 fatty acids and key vitamins and

minerals in our diets. We can minimize our exposure to television and

instead focus on positive activities such as exercise, reading,

playing, and creating.

We can make the changes that help our children and reverse course on

an epidemic of neurologic problems. We can make a difference one life

and one child at a time if we have the ethics and will to do so.

SOURCE: Scientific Consensus Statement of Environmental Agents

Associated with Neurodevelopmental Disorders,

http://www.iceh.org/pdfs/LDDI/LDDIStatement.pdf