Children's Environmental Health Network
2011

 


June 2011


Title
7-Year Neurodevelopmental Scores and Prenatal Exposure to Chlorpyrifos, a Common Agricultural Pesticide

Author(s)
Virginia Rauh, Srikesh Arunajadai, Megan Horton, Frederica Perera, Lori Hoepner, Dana B. Barr, Robin Whyatt

Citation
Environmental Health Perspectives doi:10.1289/ehp.1003160
 
 
Abstract
BACKGROUND: Researchers of a longitudinal birth cohort study of inner-city mothers and children (Columbia Center for Children’s Environmental Health) have previously reported that prenatal exposure to chlorpyrifos (CPF) was associated with neurodevelopmental problems at child age 3 years.
 
GOALS: The goal of this study was to estimate the relationship between prenatal CPF exposure and neurodevelopment among cohort children at age 7 years.
 
METHOD: In a sample of 265 children, participants in a prospective study of air pollution, prenatal CPF exposure using umbilical cord blood plasma (picograms/gram plasma) and 7-year neurodevelopment using the Wechsler Intelligence Scales for Children (WISC-IV) were measured and compared.
 
RESULTS: On average, for each, Full-Scale IQ declined by 1.4%, and Working Memory declined by 2.8% as CPF exposure increased. Final covariates included maternal educational level, maternal IQ, and quality of the home environment. There were no significant interactions between CPF and any covariates, including the other chemical exposures measured during the prenatal period (environmental tobacco smoke and polycyclic aromatic hydrocarbons).
 
CONCLUSION: This study reports evidence of deficits in Working Memory Index and Full-Scale IQ as a function of prenatal CPF exposure at 7 years of age. These findings are important in light of continued widespread use of CPF in agricultural settings and possible longer-term educational implications of early cognitive deficits.
 
 
Policy Implications
The U.S. Environmental Protection Agency initiated regulatory action to phase out residential use of CPF and other organophosphates (OPs) beginning in 2001. Prior to this, applications of CPF were heavy in urban areas, particularly in residential buildings, and studies found detectable levels in nearly all personal and indoor air samples of pregnant study participants in New York City, as well as in the majority of participants’ cord blood samples taken at delivery.1,2,3 Previous studies have shown that OPs cross the placenta, and this study is consistent with a growing body of evidence that prenatal OP exposure is associated with cognitive and neurobehavioral deficits in young children.4,5,6,7,8
 
Despite the ban on most residential uses, and despite the fact that OPs are not considered to be persistent organic pollutants, ongoing residential exposure to OPs persists.9 In addition, OPs are still used to control mosquitoes and other insect pests in public spaces, and are commonly sprayed on agricultural crops. Exposure may occur via consumption of conventionally-grown produce10 as well as via inhalation and dermal contact.  These results indicate that further restrictions on the use of CPF should be considered.

Web link
Full article courtesy of Environmental Health Perspectives here.

Keyword(s)
pesticides, chlorpyrifos, neurodevelopment

May 2011


Title

A Comparison of PBDE Serum Concentrations in Mexican and Mexican-American Children Living in California

 

Author(s)

Brenda Eskenazi, Laura Fenster, Rosemary Castorina, Amy R. Marks, Andreas Sjödin, Lisa Goldman Rosas, Nina Holland, Armando Garcia Guerra, Lizbeth Lopez-Carillo, Asa Bradman

 

Citation 

Environ Health Perspect (2011): doi: 10.1289/ehp.1002874

 

Abstract

BACKGROUND: Polybrominated diphenyl ethers (PBDE), which are used as flame retardants, have been found to be higher in residents of California than of other parts of the U.S.

GOALS: This study investigated the role of immigration to California on PBDE levels in Latino children.

 

METHOD: The research group compared serum PBDE concentrations in a population of first generation Mexican-American 7-year old children (n=264), who were born and raised in California, with 5-year old Mexican children (n=283), who were raised in the states in Mexico where most mothers, having participated in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, had originated.

 

RESULTS: On average PBDE serum concentrations in the California Mexican-American children were three times higher than their mothers’ levels during pregnancy and seven times higher than concentrations in the children living in Mexico. The PBDE serum concentrations were higher in the Mexican-American children regardless of length of time their mother had resided in California or the duration of the child’s breastfeeding. These data suggest that PBDE serum concentrations in these children resulted primarily from postnatal exposure.

 

CONCLUSION: In the first study to assess the relationship between environmental levels of BTEX and NTDs, we found an association between benzene and spina bifida. Our results contribute to the growing body of evidence regarding air pollutant exposure and adverse birth outcomes.

 

Policy Implications

Two of the three commercially produced preparations of PBDEs have been phased out in the U.S. and Europe since 2004. However, the semi-volatile compounds continue to be released from old furniture, materials and equipment, and are bioaccumulative, persisting in humans and the environment for years. In addition, one preparation, decaBDE, is still used in consumer electronics and wire insulation, among other applications. This study found that the high PBDE body burdens in the 7 year olds in California were primarily due to postnatal exposure sources, including house dust and food. Previous biomonitoring studies indicated that children living in California have some of the highest documented PBDE serum levels worldwide, and exposure studies have revealed higher PBDE levels in house dust collected in California compared with other parts of the U.S. and Canada. These findings may be an unintended consequence of California’s furniture flammability standards, some of which were developed in the 1970’s. The regulations resulted in the addition of millions of pounds of flame retardants to various product materials during manufacturing. Attempts in other regions of the U.S. to meet California’s flammability standards have resulted in the spread of products containing high levels of PBDE throughout the U.S. Some studies indicate that PBDE levels may be higher in lower-income homes due to the presence of poorly manufactured products, aging and deteriorating products, and poorer ventilation.

 

PBDE crosses the blood-brain barrier and negatively impacts brain development, interferes with thyroid hormone levels, and may cause liver toxicity. Strict regulations of decaPBDEs at the federal and state levels are needed, and local consumer outreach, especially targeted to vulnerable populations, should provide information on potential sources of continuing exposure. Mandatory toxicological testing of other halogenated flame retardants or replacement chemicals should be required of chemical manufacturers prior to commercial use.

 


Web link

Full article available courtesy of Environmental Health Perspectives here.

 

Keyword(s)

DDE, DDT, Human Exposure, PBDEs

 


April 2011


Title

Maternal Exposure to Ambient Levels of Benzene and Neural Tube Defects among Offspring: Texas, 1999–2004

Author(s)

Philip J. Lupo, Elaine Symanski, D. Kim Waller, Wenyaw Chan, Peter H. Langlois, Mark A. Canfield, and Laura E. Mitchel

 

Citation 

Lupo PJ, Symanski E, Waller DK, Chan W, Langlois PH, et al. 2010 Maternal Exposure to Ambient Levels of Benzene and Neural Tube Defects among Offspring: Texas, 1999–2004. Environ Health Perspect 119(3): doi:10.1289/ehp.1002212

 

Abstract

BACKGROUND: Previous studies have reported positive associations between maternal exposure to air pollutants and several adverse birth outcomes. However, there have been no studies assessing the association between environmental levels of hazardous air pollutants, such as benzene, and neural tube defects (NTDs), a common and serious group of congenital malformations.

 

GOALS:  To conduct a case–control study assessing the association between ambient air levels of benzene, toluene, ethylbenzene, and xylene (BTEX) and the likelihood of NTDs to occur among offspring.

 

METHOD: The Texas Birth Defects Registry provided data on NTD cases (spina bifida and anen­cephaly) delivered between 1999 and 2004. The control group was a random sample of unaffected live births, frequency matched to cases on year of birth. Census tract–level estimates of annual BTEX levels were obtained from the U.S. Environmental Protection Agency 1999 Assessment System for Population Exposure Nationwide.

 

RESULTS: Mothers living in census tracts with the highest benzene levels were more likely to have off­spring with spina bifida than were women living in census tracts with the lowest levels. No significant associations were observed between anen­cephaly and benzene or between any of the NTD phenotypes and toluene, ethylbenzene, or xylene.

 

CONCLUSION: In the first study to assess the relationship between environmental levels of BTEX and NTDs, we found an association between benzene and spina bifida. Our results contribute to the growing body of evidence regarding air pollutant exposure and adverse birth outcomes.

 

Policy Implications

Benzene is known to cross the placenta. Previous studies found significant associations between maternal occupational exposure to benzene and other organic solvents and birth defects, including NTDs. This study found an association between prenatal exposure to benzene in ambient air and spina bifida, suggesting that adverse birth outcomes may not be limited to those whose mothers are occupationally exposed. Most of human exposure to benzene, aside from tobacco smoke, is from automobile exhaust and industrial emissions. Stricter industrial and motor vehicle emissions policies and regulations at the federal level are called for to reduce the general population’s exposure to benzene. In addition, adoption of innovative transportation policies, such as investment in sustainable transit programs, the creation of walkable neighborhoods and cities, and integrated bike paths, represent proactive approaches in reducing human exposure to benzene and other hazardous compounds from motor vehicle exhaust.



Web link

Full article available courtesy of Environmental Health Perspectives here.

 

Keyword(s)

Benzene, toluene, ethylbenzene, xylene

 

 

 


March 2011


Title

Environmental Chemicals in Pregnant Women in the US: NHANES 2003-2004

Author(s)

Tracey J. Woodruff, Ami R. Zota, Jackie M. Schwartz

 

Citation 

Woodruff TJ, Zota AR, Schwartz JM 2011. Environmental Chemicals in Pregnant Women in the US: NHANES 2003-2004. Environ Health Perspect :-. doi:10.1289/ehp.1002727

 

Abstract

BACKGROUND:

This study reviewed biomonitoring data from the National Health and Nutritional Examination Survey (NHANES) to characterize exposures in U.S. pregnant women to some chemicals linked to human health concerns.  NHANES is a nationally representative sample of the U.S. population.  Biomonitoring involves analyzing blood, urine and other samples from the survey participants for specific chemicals or their breakdown products. The chemicals analyzed included:

Polybrominated Diphenyl Ethers (PBDEs): a category of flame retardants commonly found in furnishings, computers and electrical appliances.  PBDEs can be toxic to the liver, thyroid, and developing nervous system.

Perfluorinated compounds (PFCs): a family of commonly used synthetic compounds with many applications, such as stain repellants.  PFCs accumulate in human tissues and emerging evidence suggests reproductive toxicity, neurotoxicity and hepatotoxicity, and some PFCs are considered to be likely human carcinogens.  Exposure to PFCs is widespread and some subpopulations, such as living in proximity to fluorochemical manufacturing plants, are highly contaminated. #

Organochlorine pesticides: an older class of pesticides.  Many of their uses have been banned due to their environmental persistence and potential adverse effects on wildlife and human health.

Phthalates: a class of chemicals used to soften some plastics, bind fragrances in products, and act as solvents and fixatives.  Phthalates have been linked to hormone disruption, developmental and reproductive problems, and other health concerns.  Some phthalates have been banned from children’s toys and products.

Polycyclic Aromatic Hydrocarbons (PAHs): a group of over 100 different chemicals that are formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat. PAHs are usually found as a mixture containing two or more of these compounds, such as soot.

Perchlorate: a naturally occurring and man-made chemical that is used to produce rocket fuel, fireworks, flares and explosives. Perchlorate can also be present in bleach and in some fertilizers. Perchlorate may have adverse health effects because scientific research indicates that this contaminant can disrupt the thyroid’s ability to produce hormones needed for normal growth and development.

Phenols: Phenol is a colorless-to-white solid when pure. Commercial phenol is a liquid that evaporates more slowly than water. Phenol has a distinct odor that is sickeningly sweet and tarry. Phenol is both a manufactured chemical and produced naturally. Phenol is used to make plastics. Phenol is also used as a disinfectant in household cleaning products and in consumer products such as: mouthwashes, gargles, and throat sprays.

 

METHOD:

Researchers analysed samples from 268 pregnant women from NHANES 2003-2004 . They looked for detectable levels of 163 chemical analytes in 12 chemical classes in the samples from these women.  RESULTS: The percent of pregnant women with detectable levels of an individual chemical ranged from 0 to 100 percent. Certain PCBs, organochlorine pesticides, PFCs, phenols, PBDEs, phthalates, polycyclic aromatic hydrocarbons (PAHs) and perchlorate were detected in 99 to 100% of pregnant women. We found, generally, levels in pregnant women were similar or lower than levels in non-pregnant women, adjustment for covariates tended to increase levels in pregnant women compared to non-pregnant women.

 

CONCLUSION:

Pregnant women in the U.S. are exposed to multiple chemicals. Further efforts are warranted to understand sources of exposure and implications for policy-making.

 

Policy Implications

Fetal development is a particularly sensitive period of human development, and this analysis confirms the reality of multiple chemical exposures for pregnant women in the U.S.  Other studies have shown that many chemicals can cross the placenta.  More research on the effects of multiple exposures is necessary. The National Academy of Science recommends that chemical risk assessments, which inform policy, account for the multiple exposures and for exposures that occur during these vulnerable periods of development. This is not currently occurring.  Reform of current Federal law that regulates industrial and consumer chemicals is needed to include a more protective approach to human health to better safeguard human health.



Web link

Full article available courtesy of Environmental Health Perspectives here.

 

Keyword(s)

chemicals, polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), organochlorine pesticides, phthalates.


 


February 2011


Title

Association of secondhand smoke exposure with pediatric invasive bacterial disease and bacterial carriage: a systematic review and meta-analysis.

  

Author(s)

Lee CC, Middaugh NA Howie SR Ezzati M.

 

Citation 

PLoS medicine. 2010;7(12):e1000374

 

Abstract

BACKGROUND:

A number of epidemiologic studies have observed an association between secondhand smoke (SHS) exposure and pediatric invasive bacterial disease (IBD) but the evidence has not been systematically reviewed. We carried out a systematic review and meta-analysis of SHS exposure and two outcomes, IBD and pharyngeal carriage of bacteria, for Neisseria meningitidis (N. meningitidis), Haemophilus influenzae type B (Hib), and Streptococcus pneumoniae (S. pneumoniae).

 

METHOD:

Two independent reviewers searched Medline, EMBASE, and selected other databases, and screened articles for inclusion and exclusion criteria. We identified 30 case-control studies on SHS and IBD, and 12 cross-sectional studies on SHS and bacterial carriage. Weighted summary odd ratios (ORs) were calculated for each outcome and for studies with specific design and quality characteristics.

 

RESULTS:  

Children with SHS exposure were more likely to be found with invasive meningococcal, pneumococcal disease, and Hib disease compared to those unexposed to SHS. The association between SHS exposure and invasive meningococcal and Hib diseases was consistent regardless of outcome definitions, age groups, study designs, and publication year. The effect estimates were larger in studies among children younger than 6 years of age for all three IBDs, and in studies with the more rigorous laboratory-confirmed diagnosis for invasive meningococcal disease.

  

CONCLUSION:

When considered together with evidence from direct smoking and biological mechanisms, our systematic review and meta-analysis indicates that SHS exposure may be associated with invasive meningococcal disease. The epidemiologic evidence is currently insufficient to show an association between SHS and invasive Hib disease or pneumococcal disease. Because the burden of IBD is highest in developing countries where SHS is increasing, there is a need for high-quality studies to confirm these results, and for interventions to reduce exposure of children to SHS.

 

Policy Implications

CHILDREN’S EXPOSURE TO SECONDHAND SMOKE SHOULD BE ELIMINATED.

Web link

Full article available courtesy of PLoS Medicine here.


Keyword(s)

tobacco, infection



January 2011


Title

Lead and PCBs as Risk Factors for Attention Deficit/Hyperactivity Disorder

  

Author(s)

Paul A. Eubig, Andréa Aguiar, Susan L. Schantz

 

Citation 

Environ Health Perspect 118(12): doi:10.1289/ehp.0901852

 

Abstract

BACKGROUND:

Attention deficit/hyperactivity disorder (ADHD) is the most common neurobehavioral disorder of childhood, with an estimated worldwide prevalence of 5.29% (Polanczyk et al. 2007). ADHD has an onset at early school age and is characterized by impulsive behavior and inattention.

 

This review highlights the parallels between the performance of ADHD children on tests of working memory, response inhibition, cognitive flexibility, planning, and attention and the performance of children and laboratory animals on similar tasks after developmental exposure to lead or polychlorinated biphenyls (PCBs).

 

OBJECTIVE:  

Although attention deficit/hyperactivity disorder (ADHD) is the most frequently diagnosed neurobehavioral disorder of childhood, yet its causes are not well understood. The researchers present evidence that environmental chemicals, particularly polychlorinated biphenyls (PCBs) and lead, are associated with deficits in many neurobehavioral functions that are also impaired in ADHD.

 

METHOD:

Human and animal studies of developmental PCB or lead exposures that assessed specific functional domains shown to be impaired in ADHD children were identified via searches of PubMed, an online database of the U.S. National Library of Medicine, using “lead” or “PCB exposure” in combination with key words, including “attention,” “working memory,” “response inhibition,” “executive function,” “cognitive function,” “behavior,” and “ADHD.”

 

RESULTS:  

 Children and laboratory animals exposed to lead or PCBs show deficits in many aspects of attention and executive function that have been shown to be impaired in children diagnosed with ADHD, including tests of working memory, response inhibition, vigilance, and alertness. Studies conducted to date suggest that lead may reduce both attention and response inhibition, whereas PCBs may impair response inhibition to a greater degree than attention. Low-level lead exposure has been associated with a clinical diagnosis of ADHD in several recent studies. Similar studies of PCBs have not been conducted.

  

CONCLUSION:

 The researchers speculate that exposures to environmental contaminants, including lead and PCBs, may increase the prevalence of ADHD.

 

Policy Implications

There is growing evidence that exposures to multiple toxicants, not just lead and PCBs, result in the same, or at least similar, outcomes. Exposure to mercury, alcohol in utero, arsenic, some pesticides, and some endocrine disrupting chemicals have all been associated with attention problems in animals and/or humans. Moreover, metals, inorganic compounds and various organic compounds including solvents, and some pesticides are all known to be neurotoxic, but there is rarely a specific neurotoxic syndrome that is linked to a specific chemical. Therefore, we need to prevent exposures to known toxicants and to identify the neurotoxicity of new compounds before they are brought to market. The current mechanism for regulating potential toxic substances, the Toxic Substances Control Act (TSCA), is totally inadequate for that purpose and is in urgent need of revision.

 

(1. Ahlbom J, Fredriksson A, Eriksson P. Exposure to an organophosphate (DFP) during a defined period in neonatal life induces permanent changes in brain muscarinic receptors and behaviour in adult mice. Brain Res. 1995;677:13–19. 2. Chasnoff IJ.  Wells AM.  Telford E.  Schmidt C.  Messer G. 2010. Neurodevelopmental functioning in children with FAS, pFAS, and ARND. Journal of Developmental & Behavioral Pediatrics.  31:192-201. 3. Diamanti-Kandarakis E Bourguignon JP. Giudice LC. Hauser R. Prins GS. Soto AM. Zoeller RT. Gore AC. 2009 Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement. Endocrine Reviews 30:293-342. 4. Gilbert SG. 2008. Scientific Consensus Statement on Environmental Agents Associated with Neurodevelopmental Disorders. Available at http://www.iceh.org/pdfs/LDDI/LDDIStatement.pdf. Accessed 30 November 2010. 5) Grandjean P, Landrigan PJ. 2006. Developmental neurotoxicity of industrial chemicals. Lancet.  368:2167-78. 6) Marks AR, Harley K, Bradman A, Kogut K, Boyd Barr D, Johnson C, Calderon N, Eskenazi B. 2010. Organophosphate Pesticide Exposure and Attention in Young Mexican-American Children. doi: 10.1289/ehp.1002056. Available at http://ehp03.niehs.nih.gov/article/info:doi/10.1289/ehp.1002056. Accessed 30 November 2010.  7) Mick, E., Biederman, J., Faraone, S., Sayer J. Kleinman S. (2002). Case-control study of attention-deficit hyperactivity disor­der and maternal smoking, alcohol use, and drug use during pregnancy. Journal of the American Academy of Child and Adolescent Psychiatry, 41, 378–385.)

 

Web link

Full article available courtesy of Environmental Health Perspectives here.


Keyword(s)

Lead - cehn.org/ lead



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