Berkeley — Children who were exposed to organophosphate pesticides while still in their mother’s womb were more likely to develop attention disorders (ADHD) years later, according to a new study by researchers at the University of California, Berkeley.

The new findings, to be published Aug. 19 in the journal Environmental Health Perspectives (EHP), are the first to examine the influence of prenatal organophosphate exposure on the later development of attention problems. The researchers found that prenatal levels of organophosphate metabolites were significantly linked to attention problems at age 5, with the effects apparently stronger among boys.

Earlier this year, a different study by researchers at Harvard University associated greater exposure to organophosphate pesticides in school-aged children with higher rates of attention deficit hyperactivity disorder (ADHD) symptoms.

“These studies provide a growing body of evidence that organophosphate pesticide exposure can impact human neurodevelopment, particularly among children,” said the study’s principal investigator, Brenda Eskenazi, UC Berkeley professor of epidemiology and of maternal and child health. “We were especially interested in prenatal exposure because that is the period when a baby’s nervous system is developing the most.”

The study follows more than 300 children participating in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a longitudinal study led by Eskenazi that examines environmental exposures and reproductive health. Because the mothers and children in the study are Mexican-Americans living in an agricultural community, their exposure to pesticides is likely higher and more chronic, on average, than that of the general U.S. population.

Yet, the researchers pointed out that the pesticides they examined are widely used, and that the results from this study are a red flag that warrants precautionary measures.

“It’s known that food is a significant source of pesticide exposure among the general population,” said Eskenazi. “I would recommend thoroughly washing fruits and vegetables before eating them, especially if you’re pregnant.”

Organophosphate pesticides act by disrupting neurotransmitters, particularly acetylcholine, which plays an important role in sustaining attention and short-term memory.

“Given that these compounds are designed to attack the nervous system of organisms, there is reason to be cautious, especially in situations where exposure may coincide with critical periods of fetal and child development,” said study lead author Amy Marks, who was an analyst at UC Berkeley’s School of Public Health at the time of the study.

Many of these same UC Berkeley researchers are also finding that children with certain genetic traits may be at greater risk, a finding that is being published the same day in a separate EHP paper. That study found that 2-year-olds with lower levels of paraoxonase 1 (PON1), an enzyme that breaks down the toxic metabolites of organophosphate pesticides, had more neurodevelopmental delays than those with higher levels of the enzyme. The authors suggest that people with certain PON1 genotypes could be particularly vulnerable to pesticide exposure.

In the study on attention problems, researchers tested for six metabolites of organophosphate pesticides in mothers twice during pregnancy and in the children several times after birth. Together, the metabolites represent the breakdown products of about 80 percent of all the organophosphate pesticides used in the Salinas Valley.

The researchers then evaluated the children at age 3.5 and 5 years for symptoms of attention disorders and ADHD using maternal reports of child behavior, performance on standardized computer tests, and behavior ratings from examiners. They controlled for potentially confounding factors such as birthweight, lead exposure and breastfeeding.

Each tenfold increase in prenatal pesticide metabolites was linked to having five times the odds of scoring high on the computerized tests at age 5, suggesting a greater likelihood of a child having clinical ADHD. The effect appeared to be stronger for boys than for girls.

While a positive link between prenatal pesticide exposure and attention problems was seen for 3.5-year-olds, it was not statistically significant, a finding that did not surprise the researchers.

“Symptoms of attention disorders are harder to recognize in toddlers, since kids at that age are not expected to sit down for significant lengths of time,” said Marks. “Diagnoses of ADHD often occur after a child enters school.”

The UC Berkeley researchers are continuing to follow the children in the CHAMACOS study as they get older, and expect to present more results in the years to come.

The findings add to the list of chemical assaults that have been linked to ADHD in recent years. In addition to pesticides, studies have found associations with exposure to lead and to phthalates, which are commonly used in toys and plastics.

“High levels of the symptoms of ADHD by age 5 are a major contributor to learning and achievement problems in school, accidental injuries at home and in the neighborhood, and a host of problems in peer relationships and other essential competencies,” said UC Berkeley psychology professor Stephen Hinshaw, one of the country’s leading experts on ADHD, who was not part of this study. “Finding preventable risk factors is therefore a major public health concern.”

Literature: University of California – Berkeley, Prenatal exposure to pesticides linked to attention problems, 19-Aug-2010.

Related Articles:

• Pesticides in kids linked to ADHD- Attention-Deficit/Hyperactivity Disorder, study finds
• Western Diet linked to ADHD
• Groups Seeking Ban on Organophosphate Pesticide Go to Federal Court
• Common household pesticides linked to childhood cancer cases in Washington area
• Anxiety in adult female mice following perinatal exposure to Chlorpyrifos

A new study from Perth’s Telethon Institute for Child Health Research shows an association between ADHD and a ‘Western-style’ diet in adolescents.

The research findings have just been published online in the international Journal of Attention Disorders.

Leader of Nutrition studies at the Institute, Associate Professor Wendy Oddy, said the study examined the dietary patterns of 1800 adolescents from the long-term Raine Study and classified diets into ‘Healthy’ or ‘Western’ patterns.

“We found a diet high in the Western pattern of foods was associated with more than double the risk of having an ADHD diagnosis compared with a diet low in the Western pattern, after adjusting for numerous other social and family influences,” Dr Oddy said.

“We looked at the dietary patterns amongst the adolescents and compared the diet information against whether or not the adolescent had received a diagnosis of ADHD by the age of 14 years. In our study, 115 adolescents had been diagnosed with ADHD, 91 boys and 24 girls.”

A “healthy” pattern is a diet high in fresh fruit and vegetables, whole grains and fish. It tends to be higher in omega-3 fatty acids, folate and fibre. A “Western” pattern is a diet with a trend towards takeaway foods, confectionary, processed, fried and refined foods. These diets tend to be higher in total fat, saturated fat, refined sugar and sodium.

“When we looked at specific foods, having an ADHD diagnosis was associated with a diet high in takeaway foods, processed meats, red meat, high fat dairy products and confectionary,” Dr Oddy said.

“We suggest that a Western dietary pattern may indicate the adolescent has a less optimal fatty acid profile, whereas a diet higher in omega-3 fatty acids is thought to hold benefits for mental health and optimal brain function.

“It also may be that the Western dietary pattern doesn’t provide enough essential micronutrients that are needed for brain function, particularly attention and concentration, or that a Western diet might contain more colours, flavours and additives that have been linked to an increase in ADHD symptoms. It may also be that impulsivity, which is a characteristic of ADHD, leads to poor dietary choices such as quick snacks when hungry.”

Dr Oddy said that whilst this study suggests that diet may be implicated in ADHD, more research is needed to determine the nature of the relationship.

“This is a cross-sectional study so we cannot be sure whether a poor diet leads to ADHD or whether ADHD leads to poor dietary choices and cravings,” Dr Oddy said.

ADHD is the most commonly diagnosed childhood mental health disorder and has a prevalence of approximately 5%. ADHD is known to be more common in boys.

Reference:

Telethon Institute for Child Health Research, Western diet link to ADHD, 29 July, 2010.

Related Articles:

• Pesticides in kids linked to ADHD – Attention-Deficit/Hyperactivity Disorder, study finds
• Common plastic chemicals linked to ADHD symptoms
• Our Planet, our Children – How are your children doing?

Chlorpyrifos – Outlawed in homes and gardens, pesticide is still sprayed on food crops

Community groups joined environmental advocates in filing a lawsuit at July 22th to force the Environmental Protection Agency to decide once and for all whether or not it will ban the toxic pesticide chlorpyrifos.

Chlorpyrifos — sprayed on corn, oranges, almonds and other crops — is acutely poisonous and is among a class of pesticides initially developed for World War II-era chemical warfare. Short term effects of exposure to chlorpyrifos include chest tightness, blurred vision, headaches, coughing and wheezing, weakness, nausea and vomiting, coma, seizures, and even death. Prenatal and early childhood exposure has been linked to low birth weights, developmental delays and other health effects.

In recognition of the particular risks the chemical presents for children, EPA banned residential uses of chlorpyrifos in 2001. But the pesticide is still widely used in fields and orchards across the country. This continued use puts nearby rural communities in harm’s way, and chlorpyrifos ends up in our nation’s food and water supplies, leading to even more widespread exposure (click here for a list of foods with documented chlorpyrifos residue.)

Luis Medellin has experienced the dangers of this pesticide firsthand. Medellin lives with his parents and three little sisters in the agricultural town of Lindsay, California, where chlorpyrifos is sprayed routinely on the orange groves surrounding his home. During the growing season, the family is awakened several times a week by the sickly smell of nighttime pesticide spraying. What follows is worse: searing headaches, nausea, vomiting. After undergoing testing for pesticides in his body, the 24-year-old Medellin discovered concentrations of chlorpyrifos breakdown compounds nearly five times the national average for adults, as calculated by the Centers for Disease Control and Prevention.

“When I found out I had this chemical in my body, it scared me. But what really worries me is how my little sisters might be affected.” said Medellin, a community organizer with the Lindsay-based El Quinto Sol. “I wish the growers would stop using such dangerous chemicals so my family and I can be safe.”

In September 2007, Natural Resources Defense Council (NRDC) and Pesticide Action Network North America (PANNA) filed a petition with EPA asking the agency to ban chlorpyrifos. In the nearly three years since, the agency has not responded. Today’s lawsuit, filed by the nonprofit environmental law firm Earthjustice on behalf of NRDC and PANNA, would force EPA to make a decision on the pesticide’s ban.

“This dangerous pesticide has no place in our fields, near our children, or on our food,” said Earthjustice attorney Kevin Regan. “We’re asking a court to rule so that EPA will finish the job and ban this poison.”

An estimated 8 to 10 million pounds of chlorpyrifos are applied to U.S. crops each year (click here for a map showing where this pesticide is used.)

“The overwhelming evidence shows that chlorpyrifos is dangerous, especially to children and fieldworkers,” said Aaron Colangelo, a senior attorney with NRDC. “There’s no good reason for EPA to take three years to decide what to do about it.”

Exposure to chlorpyrifos in agricultural communities is widespread. California Air Resources Board monitoring in the state’s San Joaquin Valley detected chlorpyrifos in one-third of all ambient air samples, sometimes at levels that pose serious health risks to young children. Monitoring by PANNA and community groups in Washington state and Luis Medellin’s hometown of Lindsay, California has shown that daily exposure to chlorpyrifos can be substantial, regularly exceeding the “acceptable” 24-hour acute dose for a one-year-old child established by the EPA.

In one 2000 incident, dozens of students and staff at an elementary school in Ventura, CA fell ill after chlorpyrifos applied to a nearby lemon orchard drifted onto school grounds.

“Chlorpyrifos is among a class of pesticides that targets developing nervous systems — in insects and humans alike. These pesticides are linked to a host of devastating diseases ranging from ADHD to childhood brain cancer,” said PANNA senior scientist Dr. Margaret Reeves. “Their human health costs are just too high and farmers are farming successfully without them. There’s no defensible reason for continuing to use chlorpyrifos.”

Reference: EarthJustice, Release: Groups Seeking Ban on Toxic Pesticide Go to Federal Court, New York, July 22, 2010.

BACKGROUND

• A copy of the lawsuit
• A fact sheet on chlorpyrifos
• A map documenting where chlorpyrifos is used
• A list of foods with documented chlorpyrifos residue
• A study linking chlorpyrifos to low birth weights
• A study linking chlorpyrifos to developmental delays

A new study led by Mount Sinai researchers in collaboration with scientists from Cornell University and the U.S. Centers for Disease Control and Prevention, has found higher prenatal exposure to phthalates—manmade chemicals that interfere with hormonal messaging—to be connected with disruptive and problem behaviors in children between the ages of 4 and 9 years. The study, which is the first to examine the effects of prenatal phthalate exposure on child neurobehavioral development, will be published January 28, on the Environmental Health Perspectives website.

“There is increasing evidence that phthalate exposure is harmful to children at all stages of development,” said Stephanie Engel, PhD, lead study author and Associate Professor of Preventive Medicine at Mount Sinai School of Medicine. “We found a striking pattern of associations between low molecular weight phthalates – which are commonly found in personal care products – and disruptive childhood behaviors, such as aggressiveness and other conduct issues, and problems with attention. These same behavioral problems are commonly found in children diagnosed with Attention-Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder, or Conduct Disorder.”

Phthalates are part of a group of chemicals known as endocrine disruptors, that interfere with the body’s endocrine, or hormone system. They are a family of compounds found in a wide range of consumer products such as nail polishes, to increase their durability and reduce chips, and in cosmetics, perfumes, lotions and shampoos, to carry fragrance. Other phthalates are used to increase the flexibility and durability of plastics such as PVC, or included as coatings on medications or nutritional supplements to make them timed-release.

“Recently, the government instituted regulations limiting certain phthalates in things like child care articles or toys that a young child might put in their mouth,” continued Dr. Engel. “But it’s their mother’s contact with phthalate-containing products that causes prenatal exposure. The phthalates that we found most strongly related to neurodevelopment were those commonly found in cosmetics, perfumes, lotions and shampoos. Current US regulations do not address these kinds of phthalates.”

For the study, phthalate metabolite levels were analyzed in prenatal urine samples of a multiethnic group of 404 women who were pregnant for the first time. The women were invited to participate in follow-up interviews when their children were between the ages of 4 and 9. The mothers were not informed of their phthalate metabolite levels and the researchers were unaware of their exposures when testing the children.

Follow-up visits were completed by 188 of the women and their children. At each follow-up visit, the mothers completed validated questionnaires designed to assess their behavior and executive functions. The researchers found that mothers with higher concentrations of low molecular weight phthalates consistently reported poorer behavioral profiles in their children. The strongest trends were in the categories of conduct and externalizing problems, characteristics typically associated with Oppositional Defiant Disorder, Conduct Disorder and ADHD.

“These are high level, chronic exposures that start before the child is even born, but continue throughout their life. More research is needed to examine the effects of cumulative exposure to phthalates on child development. But what this study suggests is that it’s not enough to regulate childhood exposure to these chemicals. The regulations need to include products that moms use,” said Dr. Engel.

Reference: The Mount Sinai Hospital / Mount Sinai School of Medicine, Mount Sinai finds prenatal exposure to certain chemicals affects childhood neurodevelopment, Jan. 28, 2010

Are phthalates really safe for children? 

Phthalates are important components of many consumer products, including toys, cleaning materials, plastics, and personal care items. Studies to date on phthalates have been inconsistent, with some linking exposure to these chemicals to hormone disruptions, birth defects, asthma, and reproductive problems, while others have found no significant association between exposure and adverse effects. 

A new report by Korean scientists, published by Elsevier in the November 15th issue of Biological Psychiatry, adds to the potentially alarming findings about phthalates. They measured urine phthalate concentrations and evaluated symptoms of attention-deficit/hyperactivity disorder (ADHD) using teacher-reported symptoms and computerized tests that measured attention and impulsivity. 

They found a significant positive association between phthalate exposure and ADHD, meaning that the higher the concentration of phthalate metabolites in the urine, the worse the ADHD symptoms and/or test scores. 

Senior author Yun-Chul Hong, MD, PhD, explained that “these data represent the first documented association between phthalate exposure and ADHD symptoms in school-aged children.” John Krystal, MD, the Editor of Biological Psychiatry, also commented: “This emerging link between phthalates and symptoms of ADHD raises the concern that accidental environmental exposure to phthalates may be contributing to behavioral and cognitive problems in children. This concern calls for more definitive research.” 

The U.S. Centers for Disease Control and Prevention, in the Summary of their 2005 Third National Report on Human Exposure to Environmental Chemicals, state that “very limited scientific information is available on potential human health effects of phthalates at levels” found in the U.S. population. Although this study was performed in a Korean population, their levels of exposure are likely comparable to a U.S. population.

The current findings do not prove that phthalate exposure caused ADHD symptoms. However, these initial findings provide a rationale for further research on this association. 

Reference: Elsevier, Common plastics chemicals linked to ADHD symptoms, November 19, 2009