Environmental Chemical Exposures and Autism Spectrum Disorders: A Review of the Epidemiological Evidence

In the paper

“Associations between maternal smoking during pregnancy and higher-functioning autism were elevated compared to associations with lower-functioning autism for two studies”

What the sources say

• Not checked yetcites [51] Lee, 2011, Brief report: maternal smoking during pregnancy and autism spectrum disorders, J Autism Dev Disord source
• Not checked yetcites [52] Kalkbrenner, 2012, Maternal smoking during pregnancy and the prevalence of autism spectrum disorders, using data from the autism and developmental disabilities monitoring network, Environ Health Perspect source

In the paper

“The published literature on the role of tobacco is currently limited by the absence of any measures of secondhand smoke exposure to the mother during pregnancy.”

In the paper

“The importance of social class confounding for studies of tobacco and autism was affirmed in the results: associations were altered after adjustment for factors such as maternal education or income.”

In the paper

“Two studies examining the continuous autism phenotype also suggested that tobacco may impact higher-functioning autism (Fig. 1).53,54”

What the sources say

• Not checked yetcites [53] Indredavik, 2007, Prenatal smoking exposure and psychiatric symptoms in adolescence, Acta Paediatr source
• Not checked yetcites [54] Ronald, 2010, Exploring the relation between prenatal and neonatal complications and later autistic-like features in a representative community sample of twins, Child Dev source

In the paper

“Seven publications of traffic-related and criteria air pollutants met our inclusion criteria for further consideration (Table 6).”

In the paper

“For almost every pollutant and every study, associations were stronger for exposures in the 3rd trimester of pregnancy and the 1st year of life compared to in earlier pregnancy (Fig. 3).”

In the paper

“a few groups of VOCs (paints and chlorinated solvents) showed elevated associations compared to other groups”

In the paper

“Results for VOC exposures and autism were scattered above and below the null, a pattern expected to result from sampling error when no causal relationship exists”

In the paper

“the published literature shows associations between traffic-related and criteria air pollutants and the development of autism”

In the paper

“most studies have not accounted for the correlations between multiple chemical pollutants or the differences in air pollutant mixtures between the West and East coasts of the U.S.”

In the paper

“Some individual VOCs had consistently elevated associations, although the VOC concentration comparisons differed somewhat across studies: methylene chloride, trichloroethylene, and styrene.”

In the paper

“Published results for this research question often had wide confidence intervals reflecting small numbers of exposed children with autism, especially for the occupational studies.”

In the paper

“This imprecision and uncertainty in estimates also resulted from the inherent measurement error of VOCs in these studies.”

In the paper

“possibly increased susceptibility when exposures occur in late pregnancy or early postnatal life”

In the paper

“Mercury from dental amalgams was also associated with increased autism severity”

What the sources say

• Not checked yetcites [97] Geier, 2009, A prospective study of prenatal mercury exposure from maternal dental amalgams and autism severity, Acta Neurobiol Exp (Wars) source

In the paper

“One exception to the pattern of no association was an estimate of thimerosal from multiple vaccines and Autism Spectrum Disorder with regression; this result was markedly protective/inverse but imprecise and inconsistent with biologic plausibility”

What the sources say

• Not checked yetcites [104] Price, 2010, Prenatal and infant exposure to thimerosal from vaccines and immunoglobulins and risk of autism, Pediatrics source

In the paper

“The second exception was from a study of thimerosal from hepatitis B vaccination in the 1st month of life, limited to males, that showed an elevated association”

What the sources say

• Not checked yetcites [102] Gallagher, 2010, Hepatitis B vaccination of male neonates and autism diagnosis, NHIS 1997–2002., J Toxicol Environ Health A source

In the paper

“these studies have not examined the potential influence of vaccine co-factors”

In the paper

“When patterns of autism risk were examined by the timing of the vaccine, more associations for prenatal vaccines were above null compared to the later postnatal vaccines”

What the sources say

• Not checked yetcites [104] Price, 2010, Prenatal and infant exposure to thimerosal from vaccines and immunoglobulins and risk of autism, Pediatrics source

In the paper

“The largest measured impacts were seen in a study of agricultural drift for two developmental windows: a period in the 1st trimester of pregnancy corresponding to central nervous system development (pregnancy weeks: 1–7), and a period that emerged, a posteriori, from the data (pregnancy weeks: 4–12)”

What the sources say

• Not checked yetcites [138] Roberts, 2007, Maternal residence near agricultural pesticide applications and autism spectrum disorders among children in the California central valley, Environ Health Perspect source

In the paper

“Associations between PCBs and autism from a pilot study in Finland were mostly elevated”

What the sources say

• Not checked yetcites [137] Cheslack-Postava, 2013, Maternal serum persistent organic pollutants in the Finnish prenatal study of autism: a pilot study, Neurotoxicol Teratol source

In the paper

“Associations between PCBs (individual congeners and mixtures) and autism were scattered above and below the null and so were not consistent with a causal relationship.”

In the paper

“Results for flame-retardant (PBDE) and non-stick (PFCs) chemicals, all from one publication, showed mixed findings”

What the sources say

• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source

In the paper

“the studies to date have not addressed numerous other chemicals that disrupt hormone signaling and are ubiquitous in the environment, such as dioxin and the anti-bacterial compound, triclosan.”

In the paper

“others may be associated with fewer autistic behaviors (e.g., PBDE-85 and PFOA)”

What the sources say

• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source

In the paper

“although results were not consistent across these studies”

What the sources say

• Not checked yetcites [58] Larsson, 2009, Associations between indoor environmental factors and parental-reported autistic spectrum disorders in children 6–8 years of age, Neurotoxicology source
• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source
• Not checked yetcites [158] Miodovnik, 2011, Endocrine disruptors and childhood social impairment, Neurotoxicology source

In the paper

“suggestions that some congeners may be associated with more autistic behaviors (e.g., PBDE-28)”

What the sources say

• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source

In the paper

“Several phthalate congeners, in contrast, appeared associated with increased autism across three different studies”

What the sources say

• Not checked yetcites [58] Larsson, 2009, Associations between indoor environmental factors and parental-reported autistic spectrum disorders in children 6–8 years of age, Neurotoxicology source
• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source
• Not checked yetcites [158] Miodovnik, 2011, Endocrine disruptors and childhood social impairment, Neurotoxicology source

In the paper

“Associations between autism and BPA from two studies were not consistent with a causal association.”

What the sources say

• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source
• Not checked yetcites [158] Miodovnik, 2011, Endocrine disruptors and childhood social impairment, Neurotoxicology source

In the paper

“evidence suggests that some criteria air pollutants, some metals, and several pesticides, with suggestions that some volatile organic compounds (e.g., methylene chloride, trichloroethylene, and styrene) and phthalates, may be linked to autism.”

In the paper

“evidence suggests that some criteria air pollutants, some metals, and several pesticides, with suggestions that some volatile organic compounds (e.g., methylene chloride, trichloroethylene, and styrene) and phthalates, may be linked to autism.”

In the paper

“evidence suggests that some criteria air pollutants, some metals, and several pesticides, with suggestions that some volatile organic compounds (e.g., methylene chloride, trichloroethylene, and styrene) and phthalates, may be linked to autism.”

In the paper

“evidence suggests that some criteria air pollutants, some metals, and several pesticides, with suggestions that some volatile organic compounds (e.g., methylene chloride, trichloroethylene, and styrene) and phthalates, may be linked to autism.”

In the paper

“a study finding no interaction between OP pesticide exposure and polymorphisms in the gene encoding the detoxifying enzyme, paraoxonase 1 (PON1) with autism risk.164”

What the sources say

• Not checked yetcites [164] Eskenazi, 2010, PON1 and neurodevelopment in children from the CHAMACOS study exposed to organophosphate pesticides in utero, Environ Health Perspect source

In the paper

“while reasons for this have been explored,159–162 there is currently no definitive explanation”

What the sources say

• Not checked yetcites [159] Baron-Cohen, 2010, Empathizing, systemizing, and the extreme male brain theory of autism, Prog Brain Res source
• Not checked yetcites [160] Cheslack-Postava, 2012, Autism spectrum disorders: toward a gendered embodiment model, Soc Sci Med source
• Not checked yetcites [161] Lai, 2013, Biological sex affects the neurobiology of autism, Brain J Neurol source
• Not checked yetcites [162] Schaafsma, 2014, Etiologies underlying sex differences in autism spectrum disorders, Front Neuroendocrinol source

In the paper

“Some studies reviewed here have addressed susceptibilities in males vs. females, without finding clear trends.70,136”

What the sources say

• Not checked yetcites [70] Roberts, 2013, Perinatal air pollutant exposures and autism spectrum disorder in the children of Nurses׳ Health Study II participants, Environ Health Perspect source
• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source

In the paper

“a study demonstrating interaction between traffic-related air pollutants and a functional variant of the Met receptor tyrosine kinase (MET) gene with regard to autism risk,163”

What the sources say

• Not checked yetcites [163] Volk, 2014, Autism spectrum disorder: interaction of air pollution with the met receptor tyrosine kinase gene, Epidemiology source

In the paper

“Although evidence for a discrete developmental window of susceptibility for autism is in its early stages”

In the paper

“the issue of potentiation due to chemical mixtures and autism, that is, whether the neurodevelopmental response to chemical X differs when combined with chemical Y (and Z, and so on), has only been addressed in a handful of reports.”

In the paper

“Increasingly, studies that examine exposures by developmental time period suggest that all windows are not equal.”

In the paper

“results shown here suggest that early pregnancy may be a period of susceptibility to pesticides”

In the paper

“whereas later pregnancy may be a period of susceptibility to criteria air pollutants”

In the paper

“evidence suggests that some criteria air pollutants, some metals, and several pesticides, with suggestions that some volatile organic compounds (e.g., methylene chloride, trichloroethylene, and styrene) and phthalates, may be linked to autism.”

In the paper

“it is now understood that environmental factors play a larger role in causing autism than previously thought”

• Also stated in: § Introduction and Scope of Review · hedged

  “Environmental chemical exposures are increasingly understood to be important in causing autism, with current theories positing that autism is caused by the interplay of multiple genetic and environmental contributions that differ from individual to individual.4,5”

What the sources say

• Not checked yet

  A check is scheduled.

  cites [4] Engel, 2011, On the complex relationship between genes and environment in the etiology of autism, Epidemiology source
• Not checked yet

  A check is scheduled.

  cites [5] Landrigan, 2010, What causes autism? Exploring the environmental contribution, Curr Opin Pediatr source
• Not checked yet

  A check is scheduled.

  cites [6] Sandin, 2014, The familial risk of autism, J Am Med Assoc source

In the paper

“including a study of over 14,000 children with autism in Sweden that demonstrated a heritability of 50%”

What the sources say

• Not checked yetcites [6] Sandin, 2014, The familial risk of autism, J Am Med Assoc source

In the paper

“Genetic and environmental factors may combine to disrupt the normal processes of nervous system development, interfering with neuron formation and migration, synapse formation, or neurological connectivity, ultimately causing autism.”

In the paper

“evidence from neuroanatomical, animal, and epidemiologic studies support the prenatal and early postnatal origins of autism.19–24”

What the sources say

• Not checked yetcites [19] Courchesne, 1988, Hypoplasia of cerebellar vermal lobules VI and VII in autism, N Engl J Med source
• Not checked yetcites [20] Herbert, 2005, Brain asymmetries in autism and developmental language disorder: a nested whole-brain analysis, Brain J Neurol
• Not checked yetcites [21] Hultman, 2002, Perinatal risk factors for infantile autism, Epidemiology source
• Not checked yetcites [22] Rodier, 1996, Embryological origin for autism: developmental anomalies of the cranial nerve motor nuclei, J Comp Neurol source
• Not checked yetcites [23] Shi, 2003, Maternal influenza infection causes marked behavioral and pharmacological changes in the offspring, J Neurosci source
• Not checked yetcites [24] Stoner, 2014, Patches of disorganization in the neocortex of children with autism, N Engl J Med source

In the paper

“these studies allow greater feasibility for prospective, and therefore more accurate, measurement of prenatal environmental exposures.”

In the paper

“Environmental chemical exposures may act through pathophysiologies, including the direct disruption of cells and structures of the nervous system, endocrine hormone- or immune system-mediated impacts, epigenetic changes, and more (Table 1).”

What the sources say

• Not checked yetcites [7] Hallmayer, 2011, Genetic heritability and shared environmental factors among twin pairs with autism, Arch Gen Psychiatry source
• Not checked yetcites [8] Lawler, 2008, The “environment” for autism research: signs of improvement?, Environ Health Perspect source
• Not checked yetcites [9] Daniels, 2006, Guest editorial: autism and the environment, Environ Health Perspect source

In the paper

“the continuous measures allow for robust statistical properties”

In the paper

“in earlier data from this same study, 100% of pregnant women had detectable levels of five chemical classes that were examined.13”

What the sources say

• Not checked yetcites [13] Woodruff, 2011, Environmental chemicals in pregnant women in the United States: NHANES 2003–2004, Environ Health Perspect source

In the paper

“Selection bias is common in studies of autism because children receiving an autism diagnoses may differ from the set of all children who could, under ideal conditions, receive a diagnosis.”

In the paper

“when these influences can be ruled out, epidemiological studies reporting associations can suggest a population-level causal association between the risk factor and autism.”

In the paper

“A critical period in early pregnancy was suggested from a study of autism cases suspected to be caused by thalidomide exposure in early pregnancy.22”

What the sources say

• Not checked yetcites [22] Rodier, 1996, Embryological origin for autism: developmental anomalies of the cranial nerve motor nuclei, J Comp Neurol source

In the paper

“it is believed to be exposures during these times that can exert causal influences on developmental disorders.14,27,28”

What the sources say

• Not checked yetcites [14] Lyall, 2014, Maternal lifestyle and environmental risk factors for autism spectrum disorders, Int J Epidemiol source
• Not checked yetcites [27] Rodier, 2000, The early origins of autism, Sci Am source
• Not checked yetcites [28] London, 2000, The environment as an etiologic factor in autism: a new direction for research, Environ Health Perspect source

In the paper

“recent reductions may be offset by future population growth, climate change63 and international transport of air pollutants.64”

What the sources say

• Not checked yetcites [63] Jacob, 2009, Effect of climate change on air quality, Atmospheric Environ source
• Not checked yetcites [64] Lin, 2014, China׳s international trade and air pollution in the United States, Proc Natl Acad Sci U S A source

In the paper

“In summary, evidence does not support a strong causal link between direct maternal smoking during pregnancy and autism.”

In the paper

“some likely cause additional pathophysiologies that have not yet been fully explored, such as epigenetic alterations.69”

What the sources say

• Not checked yetcites [69] Baccarelli, 2009, Rapid DNA methylation changes after exposure to traffic particles, Am J Respir Crit Care Med source

In the paper

“The residence-based metrics included measurement error due to inaccuracies in geo-locating residences, air modeling assumptions, and the inability to include time spent away from home, measurement error that would be expected to attenuate findings.”

In the paper

“the likelihood is low that exposure measurement error could have resulted in overestimated associations (possible if measurement error was related to autism status).”

In the paper

“Other metals, including arsenic, fluoride, and manganese, are increasingly recognized as also being human neurodevelopmental toxicants.”

What the sources say

• Not checked yetcites [11] Grandjean, 2014, Neurobehavioural effects of developmental toxicity, Lancet Neurol source
• Not checked yetcites [91] Wu, 2014, Arsenic
• Not checked yetcites [92] Lucchini, 2014, Other metals
• Not checked yetcites [93] Wasserman, 2014, A cross-sectional study of well water arsenic and child IQ in Maine schoolchildren, Environ Health source

In the paper

“It is therefore possible that these study results are conservative, that is, these air pollutants may have stronger associations with autism than suggested by the observed data.”

In the paper

“all of these methods provided only a rough approximation of the internal dose of VOCs to the developing nervous system”

In the paper

“The emissions-based NATA model is especially problematic for VOCs because it relies on proximity to sources emitting VOCs outdoors, such as traffic and large factories, ignoring the important unique indoor sources for several VOCs.”

What the sources say

• Not checked yetcites [79] Payne-Sturges, 2004, Personal exposure meets risk assessment: a comparison of measured and modeled exposures and risks in an urban community, Environ Health Perspect source

In the paper

“Petroleum-based VOCs like benzene, toluene, ethyl benzene, and xylenes have been widely detected in biological samples from a U.S. representative sample in 2013.”

What the sources say

• Not checked yetcites [12] US Department of Health and Human Services. Fourth National Report on Human Exposure to Environmental Chemicals, Updated Tables. Available at: http://www.cdc.gov/exposurereport/pdf/FourthReport_UpdatedTables_Sep2013.pdf; 2013 Accessed 16.12.13.

In the paper

“These health impacts are not restricted to high-exposure scenarios, but have been seen with typical exposure levels, leading to “silent toxicity.””

What the sources say

• Not checked yetcites [94] Lanphear, 2014, Lead

In the paper

“The only biomarker study took place in a high fish-consuming population with limited generalizability to other populations.”

What the sources say

• Not checked yetcites [96] Van Wijngaarden, 2013, Autism spectrum disorder phenotypes and prenatal exposure to methylmercury, Epidemiology source

In the paper

“The pattern of elevated associations was especially striking given the measurement error inherent in the emissions-based air pollutant model used in three of these studies, which would be expected to attenuate observed ORs.”

What the sources say

• Not checked yetcites [16] Kalkbrenner, 2010, Perinatal exposure to hazardous air pollutants and autism spectrum disorders at age 8, Epidemiology source
• Not checked yetcites [70] Roberts, 2013, Perinatal air pollutant exposures and autism spectrum disorder in the children of Nurses׳ Health Study II participants, Environ Health Perspect source
• Not checked yetcites [90] Windham, 2006, Autism spectrum disorders in relation to distribution of hazardous air pollutants in the San Francisco Bay Area, Environ Health Perspect source

In the paper

“air may constitute an important source of lead exposure for some families”

What the sources say

• Not checked yetcites [95] Richmond-Bryant, 2014, The influence of declining air lead levels on blood lead-air lead slope factors in children, Environ Health Perspect source

In the paper

“Concluding that a factor like thimerosal is not causative using epidemiological studies is difficult, however, and requires ruling out biases that may artificially attenuate ORs.”

In the paper

“of these, organophosphates (OP) and organochlorines (OC) have the most evidence of neurotoxicity”

In the paper

“Population-based human studies have shown some pesticides to cause neurodevelopmental decrements.”

What the sources say

• Not checked yetcites [118] Engel, 2007, Prenatal organophosphate metabolite and organochlorine levels and performance on the Brazelton Neonatal Behavioral Assessment Scale in a multiethnic pregnancy cohort, Am J Epidemiol source
• Not checked yetcites [119] Eskenazi, 2008, Pesticide toxicity and the developing brain, Basic Clin Pharmacol Toxicol source
• Not checked yetcites [120] Rauh, 2011, Seven-year neurodevelopmental scores and prenatal exposure to chlorpyrifos, a common agricultural pesticide, Environ Health Perspect source
• Not checked yetcites [121] Polańska, 2013, Review of current evidence on the impact of pesticides, polychlorinated biphenyls and selected metals on attention deficit/hyperactivity disorder in children, Int J Occup Med Environ Health source

In the paper

“the Institute of Medicine review from 2004, which concluded that “the body of epidemiological evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism,””

What the sources say

• Not checked yetcites [105] Institute of Medicine (US) Immunization Safety Review Committee, 2004

In the paper

“Many pesticides act to control insects through direct impacts on the insect nervous system, with suspected analogous impacts on humans.”

In the paper

“the published literature on thimerosal, although not consistently adjusted for some potential confounders and with other potential biases, does not suggest an association with autism”

In the paper

“Demonstrated biological mechanisms also suggest pesticides as candidate risk factors for autism.”

What the sources say

• Not checked yetcites [112] Shelton, 2012, Tipping the balance of autism risk: potential mechanisms linking pesticides and autism, Environ Health Perspect source

In the paper

“the results from these studies suggest that several types of pesticide exposures may, for some children, be part of what causes the emergence of autism”

In the paper

“Pesticide exposures occur together with factors that may harm or benefit the developing nervous system, factors that can act as confounders in studies of pesticides and autism.”

In the paper

“The elevated associations observed across this literature may also be attenuated compared to the true relationship, given that pesticide exposure measurement methods included error.”

In the paper

“Another attenuating influence may be negative confounding by nutrients in the fruit and vegetables that contribute pesticides, which could counter-balance the toxic impact of the pesticide given some evidence that nutrients like folate are associated with reduced risk for autism.”

What the sources say

• Not checked yetcites [141] Schmidt, 2012, Maternal periconceptional folic acid intake and risk of autism spectrum disorders and developmental delay in the CHARGE (CHildhood Autism Risks from Genetics and Environment) case-control study, Am J Clin Nutr source
• Not checked yetcites [142] Suren, 2013, Association between maternal use of folic acid supplements and risk of autism spectrum disorders in children, J Am Med Assoc source

In the paper

“Many different pesticides have been detected in fruits, vegetables, grains, and breast milk.”

What the sources say

• Not checked yetcites [125] USDA Agricultural Marketing Service. Pesticide Data Program. USDA, 2014.
• Not checked yetcites [126] Weldon, 2011, A pilot study of pesticides and PCBs in the breast milk of women residing in urban and agricultural communities of California, J Environ Monit source

In the paper

“Diet is a predominant source of exposure for many persistent pollutants (PCBs, PBDEs, and PFCs), because they bioaccumulate in predatory fish and breast milk.”

In the paper

“sociodemographic and neighborhood factors are plausible confounders for this question”

What the sources say

• Not checked yetcites [156] Braun, 2011, Variability and predictors of urinary bisphenol A concentrations during pregnancy, Environ Health Perspect source

In the paper

“Five studies, from different countries and using different valid measures of autism diagnosis or the continuous autism phenotype, met our inclusion criteria”

In the paper

“All of these chemicals, whether banned or not, or persistent or not, are near-universally detected in representative human biological samples from the U.S.”

What the sources say

• Not checked yetcites [12] US Department of Health and Human Services. Fourth National Report on Human Exposure to Environmental Chemicals, Updated Tables. Available at: http://www.cdc.gov/exposurereport/pdf/FourthReport_UpdatedTables_Sep2013.pdf; 2013 Accessed 16.12.13.

In the paper

“Pregnancy biomarkers are especially valid for the persistent pollutants (PCBs, PBDEs, and PFCs) because they have long half-lives and reflect exposures over the entire relevant period.”

In the paper

“these chemicals can be widely present in interior spaces because they are not chemically bound in the products in which they are used, and so are readily liberated into the environment, leading to further ingestion or inhalation”

In the paper

“biomarkers for phthalates and BPA may incur more measurement error because they only reflect exposure for a few days instead of the entire relevant period of development”

In the paper

“These persistent and non-persistent chemical groups are all suspected to interfere with hormone systems and have thus been termed endocrine-disrupting chemicals.”

What the sources say

• Not checked yetcites [145] Stroustrup, 2014, Endocrine disruptors

In the paper

“the modest sample (75 children with autism) did not allow for precise, conclusive results”

What the sources say

• Not checked yetcites [137] Cheslack-Postava, 2013, Maternal serum persistent organic pollutants in the Finnish prenatal study of autism: a pilot study, Neurotoxicol Teratol source

In the paper

“the emerging literature on autism and persistent and non-persistent endocrine-disrupting compounds does not allow definitive conclusions regarding a role for PCBs, flame retardants, non-stick chemicals, or BPA”

In the paper

“most lacked the statistical precision for conclusive results”

What the sources say

• Not checked yetcites [58] Larsson, 2009, Associations between indoor environmental factors and parental-reported autistic spectrum disorders in children 6–8 years of age, Neurotoxicology source
• Not checked yetcites [136] Braun, 2014, Gestational exposure to endocrine-disrupting chemicals and reciprocal social, repetitive, and stereotypic behaviors in 4- and 5-year-old children: the HOME Study, Environ Health Perspect source
• Not checked yetcites [158] Miodovnik, 2011, Endocrine disruptors and childhood social impairment, Neurotoxicology source

In the paper

“results for phthalates are more suggestive that exposures to some phthalates may be risk factors for autism”

In the paper

“the lack of adjustment for birth order may have slightly biased these findings”

What the sources say

• Not checked yetcites [137] Cheslack-Postava, 2013, Maternal serum persistent organic pollutants in the Finnish prenatal study of autism: a pilot study, Neurotoxicol Teratol source

In the paper

“If a genetically susceptible subgroup is combined with a non-susceptible group, the overall impact of the xenobiotic exposure on autism risk may be diluted or obscured.”

In the paper

“It is likely that the autism risk associated with a given xenobiotic exposure will differ based on the child’s genes or the mother’s genes.”

In the paper

“diagnostic definitions may not be ideal for causal research, a phenomena termed “etiological heterogeneity.”165–167”

What the sources say

• Not checked yetcites [165] Visser, 2012, Narrowly versus broadly defined autism spectrum disorders: differences in pre- and perinatal risk factors, J Autism Dev Disord source
• Not checked yetcites [166] Bill, 2009, Genetic advances in autism: heterogeneity and convergence on shared pathways, Curr Opin Genet Dev source
• Not checked yetcites [167] Hu, 2013, From genes to environment: using integrative genomics to build a “systems-level” understanding of autism spectrum disorders: integrative genomics of ASD, Child Dev source

In the paper

“The environmental chemical risk factors for a given phenotype, such as high-functioning autism, may be quite different from risk factors for children with severe autism and intellectual disability.”

In the paper

“Definitive causal conclusions cannot yet be drawn from this emerging body of literature.”

In the paper

“When multiple autism subtypes are combined in a given study, true causal impacts may be diluted or masked.”

In the paper

“autism, like other psychiatric disorders, is diagnosed based on observable symptom clustering, not causal pathways”

What the sources say

• Not checked yetcites [165] Visser, 2012, Narrowly versus broadly defined autism spectrum disorders: differences in pre- and perinatal risk factors, J Autism Dev Disord source
• Not checked yetcites [166] Bill, 2009, Genetic advances in autism: heterogeneity and convergence on shared pathways, Curr Opin Genet Dev source
• Not checked yetcites [167] Hu, 2013, From genes to environment: using integrative genomics to build a “systems-level” understanding of autism spectrum disorders: integrative genomics of ASD, Child Dev source

In the paper

“These associations have emerged despite difficulties of study in this area, most notably the error in accurately measuring exposure concentrations and obtaining sufficient sample sizes.”