Table 3.
Summary of studies investigating the effect of lead exposure in childhood.
| Reference | Study Design | Procedures | Results |
|---|---|---|---|
| Buchanan et al. (2011) [2] | Cross-sectional cohort without a control group | Pure-tone audiometry and DPOAE | No association found. |
| Osman et al. (1999) [5] | Cross-sectional without a control group | Pure-tone audiometry | Association between blood lead levels and hearing thresholds. Children with the highest blood lead levels presented with a significantly increased latency of ABR wave I (adjusted for age) when compared to children with lowest blood lead levels. |
| Otto et al. (1985) [64] | Cross-sectional without a control group | ABR | Association between blood lead levels and absolute wave latencies for waves III and V. |
| Abdel Rasoul et al. (2012) [65] | Cross-sectional without a control group | Pure-tone audiometry | Blood lead levels were significantly correlated with pure-tone thresholds. |
| Schwartz and Otto (1987) [66] | Cross-sectional study without a control group | Pure-tone audiometry | Blood lead levels were significantly associated with increased right and left hearing thresholds at 500, 1000, 2000 and 4000 Hz. |
| Schwartz and Otto (1991) [67] | Cross-sectional study without a control group | Pure-tone audiometry | Significant association between blood lead levels and pure-tone thresholds at 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz. |
| Kamel et al. (2003) [68] | Cross-sectional study without a control group | Pure-tone audiometry | Significant correlation between blood lead level and PTA. |
| Baumann et al. (1987) [69] | Cross-sectional study without a control group | Long latency AEP | Significant association between blood lead level and the positive peak of the long latency AEP. |
| Zou et al. (2003) [70] | Cross-sectional without a control group | ABR | Significant association between high blood lead levels and longer peak-latencies for I, III and V. Significant positive correlations between peak-latencies for waves I, III and V in both ears and blood lead levels. |
| Counter et al. (1997) [72] | Cross-sectional with a control group | Pure-tone audiometry and ABR | No association found. |
| Counter (2002) [73] | Pure-tone audiometry and ABR | No association found. | |
| Counter et al. (2012) [74] | Cross-sectional without a control group | ABR | No significant association between blood lead levels and ABR wave latencies. |
| Buchanan et al. (1999) [75] | Cross-sectional without a control group | Pure-tone audiometry and DPOAE | No association found |
| Alvarenga et al. (2015) [76] | Cross-sectional cohort without a control group | pure-tone audiometry, ABR and TEOAE | No association found. |
| Counter et al. (2011) [77] | Cross-sectional without a control group | Acoustic reflex thresholds, amplitude growth and decay | No significant correlations between blood lead levels and various acoustic reflex tests at any of the frequencies tested. |
| Rothenberg et al. (1995) [78] | Repeated measures without a control group | ABR | Association between higher maternal blood lead level at 20 weeks of pregnancy and increased ABR I–V and III–V IPL in 1-month-old babies. |
| Rothenberg et al. (2000) [80] | Cohort without a control group | ABR | Maternal blood lead levels at 20 weeks of pregnancy significantly associated with ABR I–V and III–V IPL in 5 year-old children. |
| Geng et al. (2014) [81] | Cross-sectional with a control group | ABR | Infants with cord-blood lead concentrations above 2 µg/dL did not present differences in amplitudes for event-related potential (P2, P750) and late slow wave when using their mother’s voice versus strangers’ voices as eliciting stimuli as opposed to infants with cord-blood lead concentrations below 2 µg/dL. |