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Normal auditory brainstem and cochlear function in extreme pediatric plumbism
S A Counter1, L H Buchanan, F Ortega
1Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Cambridge 02138, USA.
Insights
High lead (Pb) exposure in Ecuadorian children did not impair auditory brainstem responses or cochlear function. This study challenges assumptions linking lead intoxication to sensory-neural deficits in children.
Area of Science:
- Environmental Health
- Pediatric Toxicology
- Neuroscience
Background:
- Childhood lead (Pb) intoxication is linked to encephalopathy and neurodevelopmental impairments.
- Industrial Pb contamination from ceramics glazing using discarded batteries affects communities in Ecuador.
- Previous research suggests Pb exposure negatively impacts sensory and cognitive functions in children.
Purpose of the Study:
- To determine the prevalence and neuro-sensory effects of Pb exposure in children from Andean villages.
- To investigate the relationship between blood lead (PbB) levels and auditory function in exposed children.
Main Methods:
- Collected venous blood samples from 107 children in a Pb-glazing area and 39 controls.
- Measured blood lead (PbB) levels.
- Conducted auditory brainstem responses (ABR) and audiological/otological tests on the exposed group.
Main Results:
- Median PbB levels were significantly higher in the Pb-glazing group (40.0 microg/dL) vs. controls (6.0 microg/dL).
- ABR tests showed normal wave latencies and neural transmission times, with no correlation to PbB levels.
- Audiological tests revealed normal cochlear function, unrelated to PbB levels.
Conclusions:
- Elevated blood lead levels in these children did not impair auditory brainstem neural transmission.
- Sensory-neural cochlear function remained intact despite high PbB levels.
- Findings challenge the assumption that Pb exposure invariably causes auditory pathway deficits in childhood plumbism.
Abstract:
Lead (Pb) intoxication in children has been associated with encephalopathy, sensory and cognitive impairments. We investigated the prevalence and neuro-sensory effects of Pb exposure in children living in Andean villages of Ecuador with high Pb contamination from discarded automobile batteries used in the local ceramics glazing industry. Venous blood samples were collected from 107 children in the Pb glazing area and from 39 children living in a geographically distant area with no known Pb contamination and measured for blood lead (PbB) levels. Auditory brainstem responses (ABR) and audiological/otological tests were conducted on children in the Pb-Glazing Group. The median PbB level for children in the Pb-Glazing Group was 40.0 microg per dl (range: 6.2-128.2 microg per dl) and for the non Pb-Glazing Group 6.0 microg per dl (1.9-18.0 microg per dl). The differences in PbB levels for children in the study and control areas were statistically significant (t-test, P<0.0001). ABR tests on the Pb-Glazing Group indicated normal wave latencies and neural transmission times, and no statistical correlation between PbB level and interpeak latencies. Audiological tests showed normal cochlear function and no statistical relation between auditory thresholds and PbB level. Contrary to prevailing assumptions, elevated PbB levels in children do not invariably impair auditory brainstem neural transmission or sensory-neural cochlear function, both of which have been implicated as significant contributors to the neurodevelopmental disabilities associated with childhood plumbism.