RESUMO
Counter, S. Allen, Leo H. Buchanan, Fernando Ortega, Anthony B. Jacobs, and Göran Laurell. Middle ear function and pathophysiology in Andean children living at high altitudes. High Alt Med Biol. 18:163-170, 2017.-The extent of altitude-related middle ear disorders in children native to high altitudes is unclear. This study examined middle ear pathophysiology in two groups of children living in high-altitude Ecuadorian Andean communities by investigating middle ear pressure (MEP), tympanic membrane compliance (TMC), and ear canal volume (ECV) using tympanometry, and by otological examination. Altitude I Group lived at 2850 m, and Altitude II Group resided at around 4000 m. The two high-altitude groups were compared with a reference group of children residing at sea level. Mean MEP was -3.6 daPa (SD: 39.2), 3.5 daPa (SD: 28.7), and 1.3 daPa (SD: 13.6) for Altitude I Group, Altitude II Group, and the Sea Level Group, respectively. The MEP was not significantly different among the three groups. Mean TMC was 0.63 cm3 (SD: 0.51), 0.60 cm3 (SD: 0.43), and 0.60 cm3 (SD: 0.24) for Altitude I Group, Altitude II Group, and the Sea Level Group, respectively. The TMC was not significantly different among the three groups. Mean ECV was 1.1 (SD: 0.26), 1.2 (SD: 0.26), and 1.0 (SD: 0.23) for Altitude I Group, Altitude II Group, and the Sea Level Group, respectively. The difference in ECV between Altitude I Group and Altitude II Group was significant (p = 0.043), as was the difference between Altitude II Group and the Sea Level Group (p = 0.001). ECV did not differ significantly between Altitude I Group and the Sea Level Group. Otological examination revealed a low incidence of ear canal and middle ear pathology. In conclusion, tympanometric and otological findings did not reveal a high incidence of middle ear pathophysiology in children living at altitudes as high as around 4000 m.
Assuntos
Altitude , Otopatias/epidemiologia , Orelha Média/fisiopatologia , Testes de Impedância Acústica/métodos , Adolescente , Criança , Pré-Escolar , Otopatias/etiologia , Otopatias/fisiopatologia , Equador/epidemiologia , Feminino , Humanos , Incidência , Masculino , Pressão , Membrana Timpânica/fisiopatologiaRESUMO
Counter, S. Allen, Leo H. Buchanan, Fernando Ortega, Anthony B. Jacobs, and Göran Laurell. Assessment of the brainstem-mediated stapedius muscle reflex in Andean children living at high altitudes. High Alt Med Biol. 18:37-45, 2017.-This study examined the physiological thresholds, amplitude growth, and contraction duration of the acoustic stapedius reflex (ASR) in Andean children aged 2-17 years living at altitudes of 2850 m (Altitude I Group) and 3973 m (Altitude II Group) as part of a general medical assessment of the health status of the children. The brainstem-mediated ASR reveals the integrity of the neuronal components of the auditory reflex arc, including the cochlea receptors, eight cranial nerves, and brainstem neural projections to the cochlear nuclei, bilateral superior olivary nuclei, facial nerve nuclei, and facial nerve and its stapedius branch. Uncrossed (ipsilateral) and crossed (contralateral) ASR thresholds (ASRT), ASR amplitude growth (ASRG) function, and ASR muscle contraction duration (decay/fatigue) (ASRD) were measured noninvasively with 500, 1000 Hz and broadband (bandwidth = 125-4000 Hz) noise stimulus activators using a middle ear immittance system. Oxygen saturation (SaO2) level and heart rate were measured in a subsample of the study group. Statistical analyses revealed that the Altitude I and Altitude II groups had ASRT, ASRG function, and ASRD rates comparable to children at sea level and that the two groups were not significantly different for any of the ASR measures. No significant association was found between SaO2 or heart rate and ASRT, growth, and muscle fatigue rate. In conclusion, the assessment of the ASR in children in the high-altitude groups revealed normal function. Furthermore, the results indicate no adverse oto-physiological effects of altitude on the brainstem-mediated ASR at elevations between 2850 and 4000 m and suggest normal middle ear and auditory brainstem function.
Assuntos
Altitude , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Reflexo Acústico/fisiologia , Estapédio/fisiologia , Testes de Impedância Acústica/métodos , Adolescente , Criança , Pré-Escolar , Equador/etnologia , Feminino , Voluntários Saudáveis , Humanos , MasculinoRESUMO
Lead (Pb) exposure in infants and children remains an international health concern. Blood lead (PbB) levels of a cohort of 130 Ecuadorian infants and young children aged 0.33 to 5.8 yr were compared to values reported for similar age groups in Africa, Asia, Europe, Latin America, and the United States. The mean PbB level for the total group of 130 Ecuadorian infants and young children in this study was 29.4 µg/dl (SD: 24.3; range: 3.0-128.2; median: 21.7; geometric mean: 20.7 µg/dl). The mean PbB level for the 0-2 yr age group (infants) was 33.6 µg/dl (SD: 28.9; median: 22.0; range: 3.9-119.7; geometric mean: 23.6 µg/dl), while the average PbB level for the 3-5 yr age group (young children) was 27.9 µg/dl (SD: 22.5: median: 22; range: 3-128.2; geometric mean: 19.8 µg/dl). The difference between the mean PbB levels for the infants and young children was not statistically significant. The average PbB level of 32.6 µg/dl for males was not statistically different from the mean PbB level of 26.3 µg/dl for females. The PbB levels observed in Ecuadorian infants and young children in this investigation were elevated above the World Health Organization (WHO) level of concern of 10 µg/dl and Centers for Disease Control and Prevention (CDC) current reference value of 5 µg/dl. Values were comparable to concentrations found in Pakistan, where occupational use of Pb is prevalent. These findings further indicate that infants and young children exposed to Pb from Pb glazing of ceramics in Andean Ecuadorian villages exhibit greater potential metal-mediated poisoning than children of similar ages in Asia, Europe, other Latin American countries, and the United States.
Assuntos
Chumbo/sangue , Cerâmica/análise , Pré-Escolar , Estudos de Coortes , Equador/epidemiologia , Exposição Ambiental , Feminino , Humanos , Indígenas Sul-Americanos , Lactente , Chumbo/análise , Masculino , PrevalênciaRESUMO
Concentrations of lead (Pb) in breast milk (PbM) and blood (PbB) were measured in a current cohort of lactating mothers living in Andean communities where women of childbearing age engage in the occupational use of Pb, and compared to results obtained in earlier studies. Mean PbM concentration in the current group of breastfeeding mothers tested in 2012/2013 was 3.73 µg/L (SD: 7.3; range: 0.049-28.04), and significantly lower than the 9.83 µg/L (SD: 12.75; range: 0.2-49) previously observed in breastfeeding mothers in the study area from 1999 to 2007. Breastfeeding women in the current cohort showed an average PbM/PbB ratio of 3.6%, which is in agreement with other studies. The mean PbB level obtained for the current cohort was 7.8 µg/dl (SD: 5.2; range: 1.4-21), and significantly lower than the mean PbB level of 20.8 µg/dl (SD: 16.4; range: 4-73) obtained for the comparison group of breastfeeding mothers tested between 1999 and 2007. A correlation of .687 between paired PbM and maternal PbB was found, indicating that maternal PbB level is a significant predictor of PbM. Current PbM levels remain higher than international averages, but indicate that maternal Pb exposure has declined over time in the environmentally Pb-contaminated study area. The current reduction in Pb in milk and blood of breastfeeding mothers may be due to adherence to a Pb-exposure education and prevention program initiated by the authors in the study area years earlier, as well as recent improvements in local health care delivery.
Assuntos
Exposição Ambiental/análise , Chumbo/sangue , Chumbo/química , Leite Humano/química , Adolescente , Adulto , Arsênio/análise , Cádmio/análise , Estudos de Coortes , Equador , Feminino , Humanos , Lactação , Mercúrio/análise , Mães , Protoporfirinas/sangue , Protoporfirinas/química , Adulto JovemRESUMO
The purpose of this study was to investigate current blood lead (PbB) and zinc protoporphyrin (ZPP) levels in adults presently living in environmentally Pb-contaminated Andean communities, and to compare the findings with the PbB and ZPP levels of Pb-exposed adult cohorts from the same study area tested between 1996 and 2007. Blood samples from 39 adults were measured for PbB and ZPP concentrations. The current mean PbB level (22.7 µg/dl) was significantly lower than the mean (37.9 µg/dl) of the initial 1996 cohort. PbB levels for the 1997, 1998, 2003, and 2006 cohorts were also significantly lower than the levels for the 1996 group. Elevated ZPP/heme ratios of 103.3, 128.4, and 134.2 µmol/mol were not significantly different for the 2006, 2007, and 2012 groups, indicating chronic Pb exposure. While ZPP levels of Andean Ecuadorian Pb-glazing workers have remained elevated, PbB levels declined. Lead exposure of the workers needs to be continually monitored.
Assuntos
Chumbo/sangue , Exposição Ocupacional/efeitos adversos , Protoporfirinas/sangue , Adolescente , Adulto , Idoso , Estudos de Coortes , Feminino , Humanos , Intoxicação por Chumbo/sangue , Masculino , Pessoa de Meia-Idade , América do Sul , Adulto JovemRESUMO
OBJECTIVES: This neurophysiological study compared brainstem auditory evoked responses (BAER) in children living at high elevations (2800 to 3000 meters) in the Andes Mountains of Ecuador with a reference group of children living at sea level in the U.S. METHODS: BAER absolute latencies of waves I through V; interpeak latencies I-III, III-V, and I-V; amplitudes of waves I and V; and the V/I amplitude ratio were measured by scalp electrodes at acoustic click stimulus rates of 10 and 50 pulses per second (pps). RESULTS: Statistical analysis showed that the high-altitude group had significantly longer absolute and interpeak BAER latencies than the sea-level reference group at both the 10 and 50 pps stimulus rates for most wave peaks. The amplitudes of waves I and V were significantly reduced for the high-altitude group at 10 and 50 pps, suggesting blood O2 saturation effects. CONCLUSIONS: The BAER of children in the high-altitude group suggested physiological anomalies in auditory neural conduction and summation compared with the sea-level group. The results further suggest that small physiological effects of altitude on BAER, especially at elevations near 3000 meters and higher, should be taken into consideration in the evaluation of brainstem auditory function.
Assuntos
Altitude , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Hipóxia/fisiopatologia , Adolescente , Estudos de Casos e Controles , Criança , Pré-Escolar , Equador , Feminino , Humanos , Masculino , Estados UnidosRESUMO
OBJECTIVES: To investigate current lead (Pb) exposure in children living in Andean Ecuadorian communities. Blood Pb (PbB) and zinc protoporphyrin (ZPP) levels were used respectively as biomarkers of acute and chronic Pb poisoning. The current PbB-ZPP levels were compared with previous pediatric PbB-ZPP levels recorded over years in the study area. DESIGN AND METHODS: Samples of whole blood were collected from 22 Andean children of Quechua and Mestizo backgrounds and measured for PbB concentrations by graphite furnace atomic absorption spectroscopy. ZPP/heme ratio and ZPP whole blood (ZPP WB) levels were measured with a hematofluorometer. RESULTS: The mean PbB level for children in the current study group was 14.5 µg/dL, which was significantly lower than the mean PbB level of 41.1 µg/dL found in the same study area in the 1996-2000 test period, and lower than the 22.2 µg/dL mean level found in the 2003-2007 period. The current mean ZPP/heme ratio was 102.1 µmol/mol, and the mean ZPP WB level was 46.3 µg/dL, both lower than values previously found in children in the study area. CONCLUSION: While the current pediatric PbB-ZPP levels in the study area remain elevated in some children, the overall levels indicate a decline relative to levels observed in the same Pb-contaminated area in the period between 1996 and 2007. The elevated ZPP levels suggest a history of chronic Pb exposure, and potential iron deficiency in some children. The overall reduction in PbB-ZPP levels suggests a positive outcome of a Pb-exposure education and prevention program, and the therapeutic intervention of succimer chelation therapy.
Assuntos
Intoxicação por Chumbo/sangue , Chumbo/sangue , Protoporfirinas/sangue , Criança , Equador , Feminino , Heme/metabolismo , Humanos , Chumbo/toxicidade , Masculino , Exposição OcupacionalRESUMO
CONCLUSION: The results suggested mercury (Hg)-induced anomalies in the brainstem-mediated acoustic stapedius muscle reflex in children. OBJECTIVES: Hg exposure has been associated with hearing impairment and brainstem anomalies. Acoustic stapedius reflex (ASR) thresholds, growth functions, decay/adaptation times, and behavioral auditory thresholds were used to screen Andean children and adults for Hg-induced auditory brainstem and facial nerve impairment. METHODS: Fifty-one participants, which included 22 children (aged 6-17 years) and 29 adults (aged 19-83 years) living in gold mining areas of Ecuador where Hg is widely used in amalgamation, were screened using ASR immittance procedures. RESULTS: Mean blood mercury (HgB) level in the children was 15.6 µg/L (SD, 21.3; median, 7 µg/L; range, 2.0-89 µg/L), and in the adults 8.5 µg/L (SD, 7.1; median, 6 µg/L; range, 2.0-32 µg/L). Mean contralateral ASR thresholds (ASRT) for the screening frequency of 2000 Hz in the children (39 ears) was 92.9 dB HL (SD, 6.1; range, 80-105 dB HL), and in the adults (53 ears) 90.0 dB HL (SD, 6.4; range, 65-105 dB HL). The ASRT in the children increased significantly with HgB level (rho = 0.433; p = 0.008).
Assuntos
Limiar Auditivo/fisiologia , Exposição Ambiental/efeitos adversos , Doença Ambiental/fisiopatologia , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Mercúrio/efeitos adversos , Mineração , Reflexo Acústico/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Limiar Auditivo/efeitos dos fármacos , Criança , Equador/epidemiologia , Doença Ambiental/induzido quimicamente , Doença Ambiental/epidemiologia , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Reflexo Acústico/efeitos dos fármacos , Adulto JovemRESUMO
Studies relating sensory hearing impairment to lead (Pb) exposure in children have presented inconsistent results. The objective of this study was to measure distortion product otoacoustic emissions (DPOAE), sounds emanating from the outer hair cells of the inner ear, in Pb-exposed children to determine the effects of Pb poisoning on the inner ear. DPOAE were recorded for 9 f(2) frequencies from 1187 to 7625 Hz on 102 ears of 53 Pb-exposed children (aged 6-16 yr) residing in Pb-contaminated environments in the Andes Mountains of Ecuador where Pb glazing of ceramics is the primary livelihood. Blood lead (PbB) levels ranged from 4.2 to 94.3 µg/dl (mean: 37.7; SD: 25.7; median: 36.4). The median PbB level was markedly higher than the Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) 10-µg/dl action level. Spearman rho correlation analyses of the relation between PbB level and DPOAE amplitude and between PbB level and DPOAE signal-to-noise ratio revealed no significant associations at any of the f(2) frequencies tested. In addition, no significant correlation (Spearman rho) between PbB level and hearing sensitivity for 6 pure-tone test frequencies from 1000 to 8000 Hz was found. Although the study group was found to have abnormally elevated PbB levels, in contrast to some earlier reports, the results of the current study showed no consistent Pb-induced sensory effects on the cochlea of Pb-intoxicated children.
Assuntos
Orelha Interna/efeitos dos fármacos , Exposição Ambiental/efeitos adversos , Intoxicação do Sistema Nervoso por Chumbo na Infância/epidemiologia , Intoxicação do Sistema Nervoso por Chumbo na Infância/fisiopatologia , Emissões Otoacústicas Espontâneas/efeitos dos fármacos , Adolescente , Limiar Auditivo/efeitos dos fármacos , Criança , Estudos Transversais , Equador/epidemiologia , Exposição Ambiental/prevenção & controle , Feminino , Células Ciliadas Auditivas Externas/efeitos dos fármacos , Audição/efeitos dos fármacos , Humanos , Chumbo/sangue , Intoxicação do Sistema Nervoso por Chumbo na Infância/sangue , Intoxicação do Sistema Nervoso por Chumbo na Infância/prevenção & controle , Masculino , Otoscopia , Prevalência , Saúde da População Rural , Espectrofotometria AtômicaRESUMO
The purpose of this study was to investigate the neurological integrity and physiological status of the auditory brainstem tracts and nuclei in children with chronic lead (Pb) exposure using non-invasive acoustic stapedius reflex (ASR) measurements of afferent and efferent-neuromuscular auditory function. Following audiological examinations, uncrossed (ipsilateral) and crossed (contralateral) brainstem ASR responses were evoked by pure tone (500, 1000, and 2000 Hz), and broadband noise (bandwidth: 125-4000 Hz) stimulus activators. The ASR threshold (ASRT), amplitude growth, and decay/fatigue were measured by conventional clinical middle ear immittance methods in a group of Andean children (age range: 2-18 years) with a history of chronic environmental Pb exposure from occupational Pb glazing. Blood lead (PbB) levels of the study group (n=117) ranged from 4.0 to 83.7 µg/dL with a mean PbB level of 33.5 µg/dL (SD: 23.6; median: 33.0: CDC III Classification). The PbB distribution data indicated that 77.8% (n=91) of the children had PbB levels greater than the CDC action line of 10 µg/dL. Repeatable, normal ASRTs were elicited for ipsilateral (mean: ≤90 dB HL) and contralateral (mean: ≤97 dB HL) stimulation for each acoustic activator. Spearman Rho correlation analysis indicated no significant association between PbB level and ipsilateral or contralateral ASRT for any of the stimulus activators. The ASR amplitude growth results showed typical growth functions with no Pb-associated aberrations. No statistical association was found between ASR decay/adaptation (ASRD) and PbB level for any of the stimulus activators. The results of stapedius muscle reflex testing using several stimulus activators showed no significant relationship between PbB level and the physiological integrity of the auditory brainstem mediated ASR responses in children with chronic Pb exposure and elevated PbB levels.
Assuntos
Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Intoxicação por Chumbo/patologia , Intoxicação por Chumbo/fisiopatologia , Reflexo Acústico/efeitos dos fármacos , Estapédio/fisiopatologia , Estimulação Acústica/métodos , Adolescente , Criança , Pré-Escolar , Equador , Exposição Ambiental , Potenciais Evocados Auditivos do Tronco Encefálico/efeitos dos fármacos , Feminino , Lateralidade Funcional , Humanos , Chumbo/sangue , Chumbo/toxicidade , Masculino , Psicoacústica , Reflexo Acústico/fisiologia , Estapédio/efeitos dos fármacosRESUMO
This study was designed to assess the utility of two psychometric tests with putative minimal cultural bias for use in field screening of lead (Pb)-exposed Ecuadorian Andean workers. Specifically, the study evaluated the effectiveness in Pb-exposed adolescents and young adults of a nonverbal reasoning test standardized for younger children, and compared the findings with performance on a test of auditory memory. The Raven Coloured Progressive Matrices (RCPM) was used as a test of nonverbal intelligence, and the Digit Span subtest of the Wechsler IV intelligence scale was used to assess auditory memory/attention. The participants were 35 chronically Pb-exposed Pb-glazing workers, aged 12-21 yr. Blood lead (PbB) levels for the study group ranged from 3 to 86 microg/dl, with 65.7% of the group at and above 10 microg/dl. Zinc protoporphyrin heme ratios (ZPP/heme) ranged from 38 to 380 micromol/mol, with 57.1% of the participants showing abnormal ZPP/heme (>69 micromol/mol). ZPP/heme was significantly correlated with PbB levels, suggesting chronic Pb exposure. Performance on the RCPM was less than average on the U.S., British, and Puerto Rican norms, but average on the Peruvian norms. Significant inverse associations between PbB/ZPP concentrations and RCPM standard scores using the U.S., Puerto Rican, and Peruvian norms were observed, indicating decreasing RCPM test performance with increasing PbB and ZPP levels. RCPM scores were significantly correlated with performance on the Digit Span test for auditory memory. Mean Digit Span scale score was less than average, suggesting auditory memory/attention deficits. In conclusion, both the RCPM and Digit Span tests were found to be effective instruments for field screening of visual-spatial reasoning and auditory memory abilities, respectively, in Pb-exposed Andean adolescents and young adults.
Assuntos
Cognição/efeitos dos fármacos , Intoxicação do Sistema Nervoso por Chumbo/psicologia , Testes Neuropsicológicos , Adolescente , Atenção/efeitos dos fármacos , Criança , Equador , Feminino , Heme/metabolismo , Humanos , Chumbo/sangue , Intoxicação do Sistema Nervoso por Chumbo/diagnóstico , Masculino , Memória/efeitos dos fármacos , Exposição Ocupacional , Protoporfirinas/sangue , Psicometria , Percepção Espacial/efeitos dos fármacos , Percepção Visual/efeitos dos fármacos , Escalas de Wechsler , Adulto JovemRESUMO
This report presents case profiles of three siblings in a family of lead (Pb) glazing workers living in a Pb-contaminated Andean village who presented with extreme plumbism (blood Pb levels: 47 to 128 microg/dl) from childhood to adolescence. These cases are examples of persons who have chronic Pb poisoning as a result of prolonged occupational and environmental exposure in a Pb-glazing ceramic cottage industry in the study area. Using behavioral and physiological techniques for measuring the integrity of the peripheral and central auditory systems, including otoacoustic emissions, and replicated auditory brainstem electrophysiological potentials, the authors found normal auditory neurosensory function in each patient, thus ruling out hearing impairment as a basis for adverse neurocognitive outcomes. This finding is contrary to the prevailing view regarding the detrimental effects of Pb poisoning on the cochlear and auditory brainstem of children. Performance on tests of visual spatial intelligence and auditory memory/attention was below average in these patients, which may underlie their reported learning disabilities. In two of the cases, there was an improvement in cognitive performance following a lowering of PbB levels from chelation therapy and Pb prevention education, suggesting some level of reversibility of their neurocognitive deficits. Nevertheless, these case profiles suggest that if the patients persist in Pb-glazing activities, in spite of repeated chelation therapy and family counseling, they may continue to be re-intoxicated and remain at risk for learning disabilities and other neurological impairments.
Assuntos
Poluentes Ambientais/toxicidade , Intoxicação do Sistema Nervoso por Chumbo na Infância/patologia , Adolescente , Cerâmica , Terapia por Quelação , Criança , Doença Crônica , Equador/epidemiologia , Poluentes Ambientais/química , Feminino , Audição , Humanos , Intoxicação do Sistema Nervoso por Chumbo na Infância/sangue , Masculino , Succímero/uso terapêuticoRESUMO
OBJECTIVES: To investigate the relationship between blood lead (PbB), zinc protoporphyrin (ZPP) levels and performance on a test of auditory memory in Andean children and adolescents with chronic lead (Pb) exposure. DESIGN AND METHODS: PbB and ZPP levels were measured in blood samples from 166 participants (aged 6-16 yrs.) exposed to Pb in a local ceramic glazing cottage industry in Ecuadorian villages. PbB levels and ZPP/heme ratios were analyzed in relation to performance on the Digit Span subtest of the Wechsler IV intelligence scale, a test of auditory memory. RESULTS: Mean PbB level for the study group was 18.0 microg/dL (S.D.: 15.1; range: 3.0-86.0), and the mean ZPP/heme ratio was 105.7 mumol/mol (S.D.: 100.9; range: 36.0-592.0). There was no significant difference in PbB and ZPP levels between the 84 females and the 82 males. The mean Digit Span scale score (DS SS) for the study group was 6.81 (S.D.: 2.95; range: 1.0-17.0), which is below the average score of 10 for the test, with the females performing significantly better than males (t=2.435; p=0.01). Regression analyses revealed statistically significant inverse associations between DS SS and PbB level (r=0.251, p=0.001), and between DS SS and ZPP/heme ratio (r=0.246, p=0.001). CONCLUSION: Elevated PbB levels, representing acute exposure, and ZPP levels, reflecting chronic Pb exposure in this cohort of Andean inhabitants were associated with poor performance on a test of auditory memory, suggesting that the children and adolescents in the study area have neurocognitive deficits that may affect learning.
Assuntos
Transtornos Cognitivos/diagnóstico , Cognição/fisiologia , Exposição Ambiental , Intoxicação do Sistema Nervoso por Chumbo na Infância/fisiopatologia , Chumbo/sangue , Protoporfirinas/sangue , Adolescente , Estudos de Casos e Controles , Criança , Transtornos Cognitivos/sangue , Transtornos Cognitivos/fisiopatologia , Equador , Feminino , Heme/análise , Humanos , Chumbo/toxicidade , Intoxicação do Sistema Nervoso por Chumbo na Infância/sangue , Masculino , Fatores de TempoRESUMO
OBJECTIVES: The objective of this study was to investigate the zinc protoporphyrin/heme ratio (ZPP/heme) as a biomarker for chronic lead (Pb) poisoning in children with a history of high Pb exposure. DESIGN AND METHODS: ZPP/heme ratio was measured in blood samples from 78 children (44 females and 34 males) with persistent Pb exposure from Pb glazing of ceramics in a local cottage industry in the Andes Mountains of Ecuador. RESULTS: Mean blood lead (PbB) level was 26.4 microg/dL (SD: 23.2; range: 4.0-107.0), and the mean ZPP/heme ratio was 152.4 micromol/mol (SD: 190.6; range: 36.0-1064.0). A regression analysis of PbB level and ZPP/heme ratio revealed a significant association (r=0.761, p= <0.0001), with the logZPP showing a higher correlation with PbB (r=0.869, p= <0.0001). The ZZP/heme ratio decreased significantly with increasing age (ANOVA, p=0.030). The mean ZPP/heme ratios for females and males were 139.6 and 169.0 micromol/mol, respectively, and were not statistically different (t-test, p=0.504). CONCLUSION: The elevated ZPP/heme ratios, coupled with high PbB levels observed in this cohort of Andean children of Pb-glazing workers, suggest chronic Pb intoxication and probable iron deficiency.
Assuntos
Intoxicação por Chumbo/sangue , Chumbo/sangue , Protoporfirinas/sangue , Adolescente , Distribuição por Idade , Criança , Pré-Escolar , Equador/epidemiologia , Feminino , Heme/metabolismo , Humanos , Lactente , Intoxicação por Chumbo/epidemiologia , MasculinoRESUMO
OBJECTIVE: To determine the current lead (Pb) concentration in blood (PbB) and breast milk (PbM) of mothers and the PbB of children living in Andean Ecuadorian villages with high Pb contamination. METHODS: Samples of whole blood from 93 participants (74 children and 19 adult women) were analyzed for Pb concentration by graphite furnace atomic absorption spectroscopy with Zeeman background correction, and milk samples from nursing mothers were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS: Mean PbB concentration in children in 2006 was 26.7 microg/dL (SD: 23.0), and significantly lower than the mean PbB level in 1996 to 2000, but similar to the PbB level found in 2003. The mean PbB level of 22.0 microg/dL (SD: 20.6) for the 19 women in the 2006 study group did not differ significantly from the women in the 1996 to 2000 or 2003 study group. The PbM levels (range: 1-49 microg/L) of nursing mothers in the 2006 group were similar to the PbM values observed in the breast milk of nursing mothers in the same study area in 2003, and matched high PbB levels in some mother-infant pairs. CONCLUSION: This study found elevated, but stable, PbB and PbM levels in mothers and elevated, but stable, PbB levels in children in 2006 that were consistent with the levels observed in 2003 in the same Andean villages.
Assuntos
Intoxicação por Chumbo/epidemiologia , Chumbo/sangue , Leite Humano/química , Exposição Ocupacional/prevenção & controle , Adolescente , Adulto , Aleitamento Materno/efeitos adversos , Criança , Pré-Escolar , Equador , Feminino , Seguimentos , Humanos , Lactente , Intoxicação por Chumbo/sangue , Intoxicação por Chumbo/prevenção & controle , Masculino , Espectrometria de Massas/métodos , Exposição Ocupacional/efeitos adversos , Valores de Referência , Estatísticas não ParamétricasRESUMO
Performance on Raven's Coloured Progressive Matrices (RCPM) test of visual-spatial reasoning was used to evaluate the effects of mercury (Hg) exposure on 73 Andean children aged 5 to 11 years (mean: 8.4) living in the Nambija and Portovelo gold mining areas of Ecuador, where Hg is widely used in amalgamation. Mean levels of Hg found in blood (Hg(B)), urine (Hg(U)), and hair (Hg(H)) samples were 5.1 microg/L (SD: 2.4; range: 1-10 microg/L), 13.3 microg/L (SD: 25.9; range: 1-166 microg/L), and 8.5 microg/g (SD: 22.8; range: 1-135 microg/g), respectively. Of the children in the Nambija area 67-84.9% had abnormal RCPM standard scores (i.e., < or = 25%tile), depending on the test norm used in the data analysis. Higher standard scores for Peruvian (t = 4.77; p = < 0.0001) and Puerto Rican (t = 4.51; p = < 0.0001) norms than for U.S. norms suggested a linguistic influence. No difference was found between Peruvian and Puerto Rican norms (t = 0.832; p = < 0.408), which showed a significant positive correlation (r = 0.915, p = < 0.0001). Children with abnormal Hg(B) and Hg(H) levels had significantly lower scores on the RCPM subtest B than did children with nontoxic Hg levels (t = -2.16; p = < 0.034). These results suggest that a substantial number of Hg-exposed children in the Nambija study area have neurocognitive deficits in visual-spatial reasoning.
Assuntos
Transtornos Cognitivos/etiologia , Exposição Ambiental , Intoxicação do Sistema Nervoso por Mercúrio/psicologia , Mercúrio/análise , Criança , Pré-Escolar , Equador , Ouro , Cabelo/química , Humanos , Indígenas Sul-Americanos , Mercúrio/sangue , Mercúrio/urina , Intoxicação do Sistema Nervoso por Mercúrio/sangue , Intoxicação do Sistema Nervoso por Mercúrio/urina , Mineração , Testes NeuropsicológicosRESUMO
This field study investigated mercury (Hg) levels in urine and hair of Andean children of indigenous Saraguro and Metizo gold miners in the Nambija, Ecuador gold mining settlement. Spot samples of urine and hair samples were collected concurrently from 80 children each. Urine samples were used to determine the inorganic Hg burden, while hair samples were used as an index of methylmercury (MeHg) exposure from consumption of Hg contaminated fish. The mean level of Hg in urine (HgU) was 10.9 microg/L, and the mean level in hair (HgH) was 6.0 microg/g. Regression analysis showed a significant association (r = 0.404, p = 0.0007) between matched HgU and HgH samples. Mean HgU and HgU levels tended to be higher for children aged 6-14 years than for a younger group. The wide range of Hg levels in the urine and hair of Andean children of gold miners may place them at risk for neurodevelopmental and learning disorders.
Assuntos
Exposição Ambiental , Mercúrio/urina , Mineração , Adolescente , Criança , Pré-Escolar , Equador , Feminino , Ouro , Cabelo/química , Humanos , Lactente , Recém-Nascido , Masculino , Mercúrio/análiseRESUMO
OBJECTIVE: The level of lead (Pb) exposure necessary to induce intellectual impairment has not been firmly established. Some studies using conventional language-based intelligence tests have reported that pediatric blood lead (PbB) levels lower than 10 microg/dL (0.483 micromol/L) are associated with neurocognitive impairment. However, these tests may introduce cultural biases in the assessment of intellectual functioning. The objective of this study was to assess the effects of PbB concentration on nonverbal intelligence in Andean children with chronic environmental Pb exposure using a nonlanguage-based test of cognitive functioning. METHODS: Using Raven Colored Progressive Matrices (RCPM) as a measure of nonverbal intelligence, this study investigated the effects of Pb exposure (biomarker: PbB levels) on intellectual functioning in 188 chronically Pb-exposed children (age range: 5.33-11.67 years) of Ecuadorian Andean Pb-glazing workers. RESULTS: The mean PbB level of the 188 children was 29.3 microg/dL (range: 3.5-94.3 microg/dL). Forty-seven children had PbB levels <10 microg/dL (Centers for Disease Control and Prevention [CDC] I classification), of which 30 had abnormal (ie, < or =25th percentile) RCPM standard scores. Of the 141 children with PbB levels > or =10 microg/dL, 97 had abnormal RCPM scores. A regression analysis revealed a statistically significant negative association (r = -0.331, P < 0.0001) between PbB level and RCPM standard score. Conversion of RCPM standard scores to estimated IQ scores showed an approximate two-point decrease in IQ for each 10-microg/dL increment in PbB level from 10 to >70 microg/dL. CONCLUSIONS: Performance on a test of nonverbal intelligence was inversely associated with chronic Pb exposure in Andean children with PbB levels below and above the CDC risk management level of 10 microg/dL, with the decline in test scores suggesting a dose-response relationship.
Assuntos
Desenvolvimento Infantil , Transtornos Cognitivos/etiologia , Intoxicação por Chumbo/complicações , Exposição Ocupacional , Adulto , Cerâmica , Criança , Pré-Escolar , Estudos de Coortes , Equador/epidemiologia , Feminino , Humanos , Testes de Inteligência , Masculino , Relações Pais-Filho , Medição de RiscoRESUMO
Prenatal and postnatal lead (Pb) exposure may induce neurodevelopmental disabilities in children. As part of an ongoing health-monitoring study, blood lead (PbB) levels were compared in 90 children tested in 2003 (current group) and 166 children tested between 1996 and 2000 (reference group) in Ecuadorian Andean villages with high Pb contamination. The mean PbB level for children in the reference group was 40 microg/dL (range, 6.2-119.1), and significantly higher than the mean PbB level of 25.5 microg/dL (range, 2.1-94.3) for the current group (t test, P = 0.0001). An analysis of variance revealed no significant main effects for age and gender and no significant interaction between age and gender for the current group but a significant age by gender interaction for the reference group (F = 5.96, P = 0.01). Regression analysis revealed a significant correlation (r = 0.258, P = 0.01) between PbB level and age for males but not for females in the reference group. The Pb levels in breast milk from nursing mothers ranged from 0.4-20.5 microg/L (mean, 4.6), and the PbB levels in the breastfeeding mothers ranged from 4.5-35.2 microg/dL (mean, 17.1). The PbB levels of mother-infant pairs ranged from 4.6-27.4 microg/dL for mothers and 3.9-33.5 microg/dL for infants. The results showed significantly reduced PbB levels in children in the study area and suggest that a Pb education and prevention program contributed to the current reduction in Pb intoxication.
Assuntos
Exposição Ambiental/efeitos adversos , Intoxicação por Chumbo/epidemiologia , Chumbo/sangue , Leite Humano/química , Adolescente , Adulto , Análise de Variância , Cerâmica , Criança , Pré-Escolar , Equador/epidemiologia , Feminino , Humanos , Lactente , Masculino , Vigilância da População , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Estatísticas não ParamétricasRESUMO
The authors studied children in Andean villages contaminated by a lead-glazing cottage industry. Mean blood lead (PbB) level in 35 exposed children, aged 3-14 years, a year before treatment, at the time of initiation of a comprehensive lead education and prevention program, was 53.4 microg/dL. PbB levels immediately before and three weeks after a ten-day regimen of succimer treatment of the 35 children were 43.4 microg/dL and 34.3 microg/dL, respectively, showing a 21% reduction and a significant difference between means (t = 5.09, p = 0.0001). PbB levels of the same children a year before treatment and immediately pre-treatment were also significantly different (t = 10.59, p = 0.0001). Thus, a ten-day course of succimer chelation effectively reduced PbB in children with moderate to severe Pb intoxication, and the education and prevention program, initiated with parents, health care providers, and educators, also contributed significantly to reducing PbB.