PubMed Health⌕ Search

Biomedical subjects

L H Buchanan

Publications and source records attributed to L H Buchanan.

13 recordsLinked to original sources
PubMed2000

Blood lead and hemoglobin levels in Andean children with chronic lead intoxication.

This study investigated blood lead (PbB) and hemoglobin (HbB) levels in 88 children (42 females and 46 males; ages: 2-15 years; mean age: 7.2) with chronic Pb exposure, living in a highly Pb-contaminated Andean village at above 2800 meters. The mean PbB level for 88 venous blood samples was 43.2 microg/dl (SD: 25.1; range: 6.2 - 128.2 microg/dl) measured by ICP-MS, and 42.0 microg/dl (SD: 26.0; range: 5.0 - 130.0 microg/dl) by GFAAS analysis. The mean PbB level for the 42 females was 41.0 microg/dl and for 46 males, 45.0 microg/dl. Multiple regression analysis showed a significant gender by age interaction (R2 = 0.099; F = 4.173, p = 0.044), indicating a relationship between age and PbB level for males, but not for females. Simple regression analysis showed a statistically significant positive correlation between PbB levels and age for males (r = 0.416, p = 0.004), but not for females (r = -0.042, p = .793). The measured mean HbB level for the 88 children was 12.6 g/dl (12.5 g/dl for females and 12.8 g/dl for males) and lower than expected for children living in the Ecuadorian Andes. The mean altitude-corrected HbB level was 10.9 g/dl (10.8 g/dl for females and 11.1 g/dl for males). A significant inverse correlation between PbB and HbB levels was observed for the group of 88 children (r = -0.292, p = 0.006). Multiple regression analyses indicated no significant age and gender interaction (R2 = 0.014; F = 0.025, p = 0.876) for HbB levels. In conclusion, the results of this investigation indicate that the children in this Pb-contaminated, high altitude study area had chronic elevated PbB levels, which increased with age for males, and probable Pb-induced anemia.

Adolescent↗
PubMed1999

Lead in plasma and whole blood from lead-exposed children.

In 31 children exposed to lead and 13 considerably less exposed children ("unexposed"), the plasma (Pb-P) concentrations ranged from 0.46 to 18.4 (median, 2.4) and from 0.14 to 0.38 (median, 0.21) microg/L, respectively. Corresponding whole-blood concentrations (Pb-B) were 99-920 (median, 370) and 39-120 (median, 66) microg/L, respectively. The relation between Pb-B and Pb-P was nonlinear; when Pb-P rose, the Pb-B increased relatively less. There was a close association between Pb-B and log Pb-P (r=0.95; P=0.0001). When these data were compared to previous data on adults, there was no major difference between children and adults in the Pb-B/Pb-P relation. Free erythrocyte protoporphyrins in blood were associated with Pb-P (r=0.75; P=0.0001) and Pb-B (r=0.90; P=0.0001). Also, there was an association between blood-hemoglobin concentration and Pb-P in both exposed (r=-0.67; P=0.0001) and unexposed (r=-0.67; P=0.01) children; the corresponding figures for Pb-B were r=-0.42; P=0.02, and r=-0.80; P=0.001, respectively. Thus, at least with regard to toxicity on hematopoiesis at high lead levels, Pb-P may be a more relevant indicator of exposure and risk than Pb-B. Because the curved Pb-B/Pb-P relation indicates a saturation of binding sites for lead in red cells, exposure and risk at high lead levels may easily be underestimated from Pb-B data.

Adolescent↗
PubMed1999

Distortion product oto-acoustic emissions in Andean children and adults with chronic lead intoxication.

Neuroauditory disorders and sensory-neural hearing loss have been suggested as possible etiologic factors in the neurodevelopmental learning disabilities attributed to lead (Pb) intoxication. However, studies relating hearing loss to Pb poisoning have presented disparate results, suggesting that auditory sensitivity may not be a reliable marker of Pb intoxication. Oto-acoustic emissions, sounds that can be recorded non-invasively from the ear canal and are preneural responses of the outer hair cells of the inner ear, have been found to be diminished in ears exposed to some toxic agents. In the current study, distortion product oto-acoustic emissions (DPOAEs) were obtained from 28 ears of 14 children and 10 ears of 5 adults living in a highly Pb-contaminated environment in remote villages in the Andes Mountains of Ecuador. Blood lead (PbB) levels for the children (ages: 5-14 years) ranged from 33.4 to 118.2 microg/dl (mean: 51.5; SD: 22.9 microg/dl), or 3-12 times higher than the U.S. Centers for Disease Control and Prevention's toxic level of 10 microg/dl. The PbB levels for the adults ranged from 19.2 to 55.7 microg/dl. Despite the high PbB levels, the children had normal hearing thresholds, and DPOAEs were present for the children at the following f2 frequencies: 1187, 1500, 1906, 2406, 3031, 3812, 4812 and 6031 Hz. Although there was a tendency for the children to have diminished DPOAEs, no consistent correlation of DPOAEs with PbB level was found. The adults had diminished DPOAEs that were consistent with their observed, probably noise-related hearing loss. Contrary to some reports in the literature, the current results show no unequivocal clinical or subclinical evidence that high PbB levels have a toxic effect on the cochlea.

Adolescent↗
PubMed1998

Neurocognitive effects of chronic lead intoxication in Andean children.

Lead (Pb) intoxication in children has been associated with neurodevelopmental disabilities which may result in motor and cognitive impairment. We conducted blood lead (PbB) measurements, neurological examinations and cognitive tests on children living in Ecuadorian villages where Pb is used extensively in the glazing of ceramics. Group I consisted of 55 children with a mean PbB level of 48.0 microg/dl (SD: 26.4, range: 9.2-119.1 microg/dl) who received PbB tests and complete neurological examinations. An appreciable number of the children with elevated PbB levels were normal on specific components of the neurological examination. Among the children who showed neurological deficits, higher PbB levels were associated with abnormal tendon reflexes, finger tapping, visual pursuit, size discrimination, draw-a-person, and math calculation skills. Group II consisted of 41 children with a mean PbB level of 47.4 microg/dl (SD: 22.0, range: 6.6-84.7 microg/dl) who were administered Raven's Coloured Progressive Matrices (RCPM) non-verbal reasoning test. Performance on RCPM was abnormal in 22 (53.7%) of 41 children. Children with abnormal RCPM scores had higher PbB levels (t-test: P=0.030). There was a significant inverse correlation between RCPM scores and PbB levels for children ages 9 years and older (r=-0.618, P=0.011). Males had higher mean PbB levels as a function of age than females (t-test: P=0.037), and more males showed neurocognitive deficits. The results demonstrate a range of neurological responses in children with chronically elevated PbB levels from apparent exceptional neuro-physiological tolerance of PbB intoxication, to some fine motor and cognitive deficits.

Ceramics↗
PubMed1998

Blood mercury and auditory neuro-sensory responses in children and adults in the Nambija gold mining area of Ecuador.

This study investigated blood mercury (B-Hg) levels and the auditory neuro-sensory status of children and adults in the remote Andean settlement of Nambija, Ecuador where Hg is used in the extensive gold mining operations. The mean B-Hg level in 75 Nambija (Study Area) inhabitants (36 children and 39 adults) was 17.5 micrograms/L (SD = 11.0) vs 3.0 micrograms/L (SD = 1.6) in a second group of 34 subjects (15 children and 19 adults) in a non-gold mining area (Reference Area), the difference being statistically significant (p < 0.0001). Neuro-otological examinations revealed 34 subjects (45%) with complaints of headaches and/or memory loss, 3 cases of severe neurological impairment and 4 cases of middle ear pathology. Audiological tests on 40 persons in the Study Area (21 children and 19 adults) showed hearing thresholds ranging from normal to mildly abnormal at 2, 3, 4, 6 and 8 kHz for children, and normal to severely abnormal for adults. Correlation coefficients showed a significant relationship between B-Hg level and hearing level in children at 3 kHz in the right ear, and at no frequency for adults. Auditory brainstem evoked responses (ABR) on subjects in the Study Area showed a significant correlation between B-Hg and the I-III interpeak latency on the right side. The results indicated that the study population of the Nambija gold mining area had abnormally elevated B-Hg levels, and may be at neurological risk from exposure to methylmercury (MeHg) from the consumption of contaminated food and possibly from elemental Hg vapors inhaled during amalgam burning in the gold extraction process.

Adolescent↗
PubMed1998

Field screening of blood lead levels in remote Andean villages.

Blood lead (PbB) levels were investigated in chronically lead (Pb) exposed Andean children and adults living in a highly Pb contaminated area of Ecuador where Pb glazing of ceramics is prevalent. A comparative study was made of the PbB levels of Pb-glazing and non-Pb-glazing families living in close proximity, using three PbB analysis techniques. Fifty-one, 50-microl blood samples from children and adults were analyzed in the field by a finger-stick capillary screening technique using the portable ESA LeadCare Blood Lead Testing System (LCS). Venous blood samples of 2-4 ml were collected from the same 51 participants and analyzed in the laboratory by inductively coupled plasma mass spectrometry (ICP-MS) and by graphite furnace atomic absorption spectrometry (AAS). The median PbB levels for the Pb-glazing group as determined by the ICP-MS, AAS and LCS techniques were 37.2 microg/dl (range 11.6-101.0), 32.0 microg/dl (range 8.0-70.0 microg/dl) and 44.0 microg/dl (range 19.0-105.0), respectively. The median PbB levels for the non-Pb-glazing group were 9.2 microg/dl (range 5.0-21.7) with ICP-MS, 9.0 microg/dl (range 4.3-32.0) with AAS, and 11.3 microg/dl (range 7.3-21.1) with LCS. The differences in PbB levels between the Pb glazing and non-Pb glazing groups were statistically significant (p = < .0001) for each PbB analysis method. Correlations between paired samples were: LCS and ICP-MS: r = 0.913, LCS and AAS: r = 0.829, and ICP-MS and AAS: r = 0.905. The results suggest that neighboring Pb glazing and non-Pb glazing families have significantly different PbB levels, and that the portable LCS field technique may be useful for screening and periodic monitoring of relatively low and high PbB levels of persons in remote high altitude Andean areas.

Adolescent↗
PubMed1997

Normal auditory brainstem and cochlear function in extreme pediatric plumbism.

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.

Adolescent↗
PubMed1997

Extensive lead exposure in children living in an area with production of lead-glazed tiles in the Ecuadorian Andes.

We have determined the concentrations of lead (Pb), cadmium (Cd), and mercury (Hg) in the blood of children living in two Andean villages in Ecuador with many family-owned cottage-type industries using Pb from discarded car batteries and occasionally, utility batteries containing Cd and Hg for the production of glazed tiles. The battery metals are ground together with water to a suspension, which is applied manually onto the tiles and then fused at about 1,200 degrees C in sawdust-fired kilns. Children aged 4-15 years were recruited from the schools with the assistance of the school-teachers. Children from homes with and without tile-glazing activities were to be included. Blood metal concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS). The children had extremely high blood lead concentrations (B-Pb), which ranged between 100 and 1,100 micrograms/l (median 510 micrograms/l, n = 82). Children from families engaged in tile-glazing production had significantly higher B-Pb (median 600 micrograms/l) than those living in homes with no such activity (median 210 micrograms/l), although the B-Pb of the latter were nonetheless clearly elevated. B-Cd and B-Hg were low (medians 0.25 microgram Cd/l and 1.6 micrograms Hg/l, respectively), indicating that the exposure from utility batteries containing Cd and Hg was low. The blood hemoglobin concentrations decreased significantly with rising B-Pb, indicating an effect on the heme synthesis. This was supported by a marked increase in the blood concentration of protoporphyrins with increasing B-Pb. It can be concluded that children from families with cottage industries producing glazed tiles are at risk for severe health effects due to high lead exposure.

Adolescent↗
PubMed1997

High lead exposure and auditory sensory-neural function in Andean children.

We investigated blood lead (B-Pb) and mercury (B-Hg) levels and auditory sensory-neural function in 62 Andean school children living in a Pb-contaminated area of Ecuador and 14 children in a neighboring gold mining area with no known Pb exposure. The median B-Pb level for 62 children in the Pb-exposed group was 52.6 micrograms/dl (range 9.9-110.0 micrograms/dl) compared with 6.4 micrograms/dl (range 3.9-12.0 micrograms/dl) for the children in the non-Pb exposed group; the differences were statistically significant (p < 0.001). Auditory thresholds for the Pb-exposed group were normal at the pure tone frequencies of 0.25-8 kHz over the entire range of B-Pb levels, Auditory brain stem response tests in seven children with high B-Pb levels showed normal absolute peak and interpeak latencies. The median B-Hg levels were 0.16 micrograms/dl (range 0.04-0.58 micrograms/dl) for children in the Pb-exposed group and 0.22 micrograms/dl (range 0.1-0.44 micrograms/dl) for children in the non-Pb exposed gold mining area, and showed no significant relationship to auditory function.

Adolescent↗
PubMed1990

Early onset of presbyacusis in Down syndrome.

Puretone threshold data are reported as a function of age for 152 subjects with Down syndrome (age range: 5.4 years to 59.1 years). Results for the Down syndrome subjects were compared to data collected on 53 non-syndrome mentally-retarded subjects, and to data previously collected by Jatho (1969) for normal individuals. The results revealed that Down syndrome subjects have an earlier onset of presbyacusis than both normal individuals and non-syndrome mentally-retarded subjects, and that presbyacusis is evident in Down syndrome by at least the second decade of life. The data imply that for Down syndrome subjects, early onset of presbyacusis is another manifestation of precocious aging. The study of presbyacusis in Down syndrome may give us additional insights on presbyacusis in the normal population. The results further imply that studies concerned with the incidence and type of hearing loss in Down syndrome need to take age into consideration.

Adolescent↗
PubMedDate not supplied

Gender differences in blood lead and hemoglobin levels in Andean adults with chronic lead exposure.

A field study of the prevalence of lead (Pb) intoxication was conducted in 158 adults (67 men and 91 women) living at 2,500-2,800 meters in Ecuadorian Andean villages with high Pb contamination from local small-scale Pb-glazing cottage industries. Venous blood samples showed mean blood lead (PbB) levels of 34.5 microg/dL (SD 22.2) for men and 27.0 microg/dL (SD 18.4) for women; this difference was significant (t-test, p = 0.022; Mann-Whitney U, p = 0.044). An ANOVA showed no significant main effect for gender (F = 0.118, p = 0.782) or age (F = 2.479, p = 0.117), and no significant gender-by-age interaction (F = 0.273, p = 0.602). In the Pb-glazing study group, 39% of the men had PbB levels > or = 40 microg/dL, while 41% of the women had PbB levels > or = 30 microg/dL (the WHO health-based biological limits). A reference group of 39 adults (24 men and 15 women) had a mean PbB level of 5.9 microg/dL (SD 2.8; range: 1.8-16.8), significantly different from that of the 158 subjects in the study group (t-test, p < 0.0001). The difference in mean PbB levels of men (6.8 microg/dL) and women (4.7 microg/dL) in the reference group was significant (t-test, p = 0.026; Mann-Whitney U, p = 0.019). The mean altitude-corrected hemoglobin levels in the study group were lower than normal, 11.3 g/dL for men and 10.9 g/dL for women.

Adolescent↗
PubMedDate not supplied

Environmental lead contamination and pediatric lead intoxication in an Andean Ecuadorian village.

Environmental lead (Pb) contamination was measured in samples of soil and locally grown food produce in a remote Ecuadorian village where Pb glazing of ceramics is the local cottage industry. The Pb concentration levels of local soil samples collected at varying distances from a cluster of backyard Pb baking kilns were 29,213 ppm (microg/g) at 0.001 km, 172 ppm at 0.005 km, 81 ppm at 0.01 km, 55 ppm at 1 km, 19 ppm at 2 km, and 1.4 ppm at 6 km, significantly higher than levels in control soil samples from non-Pb-glazing reference areas. Samples of locally grown food produce were also found to be Pb contaminated. Venous blood samples from 166 schoolchildren (ages 4 months to 15 years) in the study area and 56 children in the reference area showed mean blood lead levels of 40.0 microg/dl (SD: 24.5; range: 6.2. - 119.1 microg/dL) and 6.6 microg/dL (SD: 3.4; range: 1.9 - 18.1 microg/dL), respectively, which were significantly different (p = 0.0001). The Pb levels in milk from breastfeeding mothers ranged from 1.44 to 39 ng/g. Lead isotope ratios of the children's blood and of samples of village soil revealed a common Pb source or "fingerprint."

Adolescent↗