TABLE 21.
Key epidemiological studies on autism and As exposure.
| Reference study population age design | Outcome definition | Population size (n) case/control | Arsenic concentration/exposure | Results | Additional information/confounders |
|---|---|---|---|---|---|
|
Al‐Ayadhi (2005) Arab/up to 14 years Case–control study |
Autism spectrum disorder (autism, attention deficit disorder, Rett's syndrome, Asperger's syndrome) | 77/80 | Hair As |
Cases versus control mean ppm (SEM): 1.8 (0.16) versus 0.23 (0.05), p < 0.05 |
Age and sex matched controls. Also results for 12 cases in total with attention deficit disorder, Rett's syndrome, Asperger's syndrome |
|
Kern et al. (2007) USA 1–6 years, Case–control study |
Autism spectrum disorder, Autism severity (Childhood Autism Rating Scale (CARS)) | 45/45 | Hair As |
Cases versus control mean μg/g (SD): 0.06 (0.06) versus 0.09 (0.08), p < 0.05. No association between As levels and CARS |
Age, sex, race/ethnicity matched controls |
|
Blaurock‐Busch et al. (2011) Arab 3–9 years, Case–control study |
Autism spectrum disorder (ASD), autism severity (Childhood Autism Rating Scale (CARS)) | 25/25 | Hair As | Cases versus control mean μg/g (SD): 0.2 (0.26) versus 0.06 (0.04), p: 0.01 | Age and sex matched controls. Significant differences regarding the amount of sea food eaten per month by mothers during pregnancy and by infants in the infancy period were noted |
|
De Palma et al. (2012) Italy/mean 9 years Case–control study |
Autism spectrum disorder, autism severity (Childhood Autism Rating Scale (CARS) | 44/61 | Hair As |
Cases versus control median μg/g (IQR): 003 (0.01–0.06) versus 0.04 (0.012–0.07), p: NS |
Age matched controls |
|
Obrenovich et al. (2011) USA (authors)/under 6 years, Case–control study |
Autism spectrum disorder | 26/39 | Hair As | Cases versus control p < 0.001 | Age matched controls. No details for data |
|
Blaurock‐Busch et al. (2012) Arab 3–9 years, Case–control study |
Autism spectrum disorder, autism severity (Childhood Autism Rating Scale [CARS]) | 44/146 | Hair As |
Cases versus control mean μg/g (SD): 2.94 (4.05) versus 0.7 (95th percentile), p: 0.01 No correlation between total or any subscale of CARS and As (r: −0.2). |
Age matched controls. Expanded sample compared with Blaurock‐Busch but only hair As measurement |
|
Fido and Al‐Saad (2016) Arab 4–7 years, Case–control study |
Autism | 40/40 | Hair As |
Cases versus control median μg/g (IQR): 013 (0.12–018) versus 0.13 (0.11–0.16) p: NS. |
Age and sex matched controls |
|
Skalny et al. (2016) Russia/2–9 years, Case–control study |
Autism spectrum disorder | 74/74 | Hair As |
Cases versus control median μg/g (IQR): 0.034 (0.021–0.044) versus 0.031 (0.021–0.058), p: NS |
Age and sex matched controls. Additional data for selected age groups. Population of Skalny et al. (2016 and 2017) publications may partly overlap |
|
Skalny et al. (2017) Russia 3–8 years, Case–control study |
Autism spectrum disorder | 33/66 | Hair As |
Cases versus control median μg/g (IQR): 0.0343 (0.026–0.0434) versus 0.0426 (0.021–0.0862), p: NS |
Age and sex matched controls. Additional data for selected age groups and As correlation with age |
|
Zhai et al. (2019) China mean 5 years, Case–control study |
Autism spectrum disorder | 79/58 | Hair As |
Cases versus control median (μg/g) (IQR): 0.21 (0.16–0.29) versus 0.09 (0.0–0.16), p < 0.001 |
Age and site matched. Data also for gut microbiota |
|
Fiłon et al. (2020) Poland 2–8 years, Case–control study |
Autism spectrum disorder | 30/30 | Hair As |
Cases versus control mean μg/g (SD): 0.216 (0.09) versus 0.061 (0.03), p < 0.001 |
Controls < 8 years randomly selected |
Abbreviations: As, arsenic; ASD, autism spectrum disorder; CARS, Childhood Autism Rating Scale; IQR, interquartile range; n, number; NS, not significant; ppm, parts per million; SD, standard deviation; SEM, standard error of the mean; USA, United States of America.