Table 1.
Summary of findings from the systematic review of exposures to chemical stressors related to childhood ADHD. Table was made using GRADEpro software.
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
|---|---|---|---|---|---|---|
| Risk with DSM criteria | Risk with chemical exposure | |||||
| Meta-analysis details for DSM ADHD (total), hyperactivity, impulsiveness and inattention diagnoses. | ||||||
| ADHD assessed with: Pb | 369 per 1,000 | 643 per 1,000 (463 to 733) | OR 3.08 (1.47 to 4.69) | 25253 (26 observational studies) | ⨁⨁⨁◯ MODERATE a,b | Lead (Pb) exposure likely results in an increase in DSM criteria-based ADHD diagnosis. |
| ADHD assessed with: PhPl | 62 per 1,000^ | 182 per 1,000 (133 to 226) | OR 3.36 (2.32 to 4.40) | 21594 (29 observational studies) | ⨁⨁⨁◯ MODERATE a,b | Phthalate exposure likely results in an increase in DSM criteria-based ADHD diagnosis. |
| ADHD (females) assessed with: PhPl | 35 per 1,000^ | 102 per 1,000 (80 to 122) | OR 3.12 (2.39 to 3.82) | 6036 (21 observational studies) | ⨁⨁⨁◯ MODERATE a,b | Phthalate exposure likely results in an increase in DSM criteria-based ADHD diagnoses in girls. |
| ADHD (males) assessed with: PhPl | 95 per 1,000^ | 267 per 1,000 (155 to 352) | OR 3.48 (1.76 to 5.20) | 6516 (21 observational studies) | ⨁⨁⨁◯ MODERATE a,b | Phthalate exposure likely results in an increase in DSM criteria-based ADHD diagnoses in boys. |
| ADHD assessed with: OCs | 144 per 1,000 | 148 per 1,000 (132 to 163) | OR 1.03 (0.90 to 1.15) | 15898 (29 observational studies) | ⨁⨁◯◯ LOW a,b | POP exposure may result in an increase in ADHD. |
| ADHD assessed with: Cigarette Smoke | 142 per 1,000 | 309 per 1,000 (133 to 425) | OR 2.70 (0.93 to 4.47) | 23602 (19 observational studies) | ⨁⨁⨁⨁ HIGH a,b | Cigarette smoke exposure results in large increase in DSM criteria-based ADHD diagnosis. |
| Meta-analysis details for DSM ADHD (total) diagnoses. | ||||||
| ADHD assessed with: Pb | 313 per 1,000 | 635 per 1,000 (425 to 733) | OR 3.82 (1.62 to 6.02) | 17158 (56 observational studies) | ⨁⨁⨁◯ MODERATE a,b | Lead (Pb) exposure likely results in an increase in DSM criteria-based ADHD diagnosis. |
The risk in chemical exposure group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the exposure OR (and its 95% CI).
CI: Confidence interval; OR: Odds ratio
Non-significant confidence intervals in original studies
Number of participants < 1000 in original studies.
Estimate is based on included studies that provided DSM ADHD and Control information for participants, actual risk may differ.
GRADE Working Group grades of evidence
High certainty: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect