Fatores químicos e físicos que afetam a contaminação por chumbo e cobre em água potável: uma abordagem para o estudo de caso em química analítica

Lead and copper concentrations in drinking water increase considerably on going from municipality reservoirs to the households sampled in Ribeirão Preto (SP-Brazil). Flushing of only 3 liters of water reduced metal concentrations by more than 50%. Relatively small changes in water pH rapidly affected corrosion processes in lead pipes, while water hardness appeared to have a long-term effect. This approach aims to encourage University teachers to use its content as a case study in disciplines of Instrumental Analytical Chemistry and consequently increase knowledge about drinking water contamination in locations where no public monitoring of trace metals is in place.

Avaliação audiológica em crianças com baixo nível de exposição cumulativa ao chumbo

OBJETIVO: verificar a ocorrência de perda auditiva sensorioneural em crianças com baixo nível de exposição cumulativa ao chumbo. MÉTODO: 156 crianças intoxicadas por chumbo, 94 do sexo masculino e 62 do sexo feminino, na faixa etária entre 18 meses a 14 anos e 5 meses, foram submetidas a análise longitudinal do nível de Plumbemia em sangue, bem como audiometria tonal liminar e emissões otoacústicas evocadas por estímulo transiente. RESULTADOS: a população pesquisada apresentou um valor médio de Plumbemia estimada de 12,2±5,7mg/dL (faixa entre 2,4-33mg/dL); todas as crianças apresentaram resposta normal na audiometria tonal liminar em 20 dBNA nas frequências testadas, 0,5; 1; 2 e 4 kHz, para ambas as orelhas; as emissões otoacústicas evocadas por estímulo transiente estiveram presentes para todas as frequências bilateralmente, nas 79 crianças pesquisadas. CONCLUSÃO: não foi constatada perda auditiva sensorioneural em crianças com histórico de baixo nível de exposição cumulativa por chumbo, assim como não foi encontrada lesão de células ciliadas externas na cóclea, mesmo que subclínicas.

Relação entre nível de chumbo no sangue e desempenho nas habilidades do processamento auditivo

INTRODUÇÃO: A contaminação por chumbo afeta todos os sistemas do corpo humano, principalmente o sistema nervoso. OBJETIVO: Investigar se há correlação entre o nível de plumbemia e o desempenho em testes do processamento auditivo. MÉTODO: Estudo retrospectivo. 73 crianças, com idade entre 7 a 15 anos, residentes em uma área onde houve emissão de partículas de chumbo acima do permitido, com nível de plumbemia maior ou igual a 10 microgramas/dL, exames audiológicos (audiometria e timpanometria) dentro dos padrões de normalidade. Para avaliar o processamento auditivo foram utilizados o Teste de Fusão Auditiva-Revisado (AFT-R), subteste 1, e o Teste Dicótico de Dígitos (etapa de integração binaural). Foi utilizado o teste de Spearman para verificar a correlação entre os dados. RESULTADOS: O nível de plumbemia variou de 10 a 30,2microgamas/dL, sendo a média correspondente a 15,8 microgramas/dL (desvio-padrão de 4,8). Dessas crianças, 60,3% apresentaram desempenho ruim no teste AFT-R, ou seja, resultados superiores a 60ms. Quanto ao Teste Dicótico de Dígitos, 46,2% das crianças apresentaram desempenho ruim para a orelha direita e 67,3% apresentaram desempenho ruim na orelha esquerda. Conforme o resultado do teste de correlação de Spearman, não houve significância estatística entre o nível de chumbo e os resultados dos testes do processamento auditivo. CONCLUSÃO: Não houve correlação entre o nível de plumbemia e o desempenho nas habilidades do processamento auditivo, entretanto crianças contaminadas pelo chumbo apresentaram desempenho inferior nas habilidades do processamento auditivo.

Environmental lead poisoning among children in Porto Alegre state, Southern Brazil

OBJECTIVE: To estimate the prevalence of lead poisoning in children and to identify associated factors, as well as possible local sources of contamination. METHODS: A cross-sectional prevalence study conducted in 2006 with a random sample of 97 children age zero to five years from a neighborhood in Porto Alegre, Southern Brazil. Blood lead levels were measured and a questionnaire administered to collect information on sociodemographics, recycling and dwelling. A preliminary environmental evaluation was carried out with direct analysis of soil and indirect analysis of air pollution with bioindicators to identify possible sources of contamination. To analyze lead concentrations from the different collection sites, for each type of material studied, ANOVA was performed with a Brown-Forsythe adjustment for heteroscedasticity and with Dunnett's T3 procedure for multiple comparisons of unequal variances. RESULTS: Blood lead levels >= 10.0 mu g/dL was found in 16.5% of children. Recycling of waste at home, low father's education level, and increased age of children were associated with increase blood lead levels. High lead levels were found in soil, and there was little indication of lead air pollution. CONCLUSIONS: A high prevalence of lead poisoning was identified, and the potential sources of contamination in this community appear related to waste recylcing activities. Studies should be conducted with other populations of Brazilian children and evaluate potential sources of local and general contamination, to accurately characterize this issue in Brazil.

Correlation analysis of the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in children

Introduction: The effects of lead on children’s health have been widely studied. Aim: To analyze the correlation between the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in Brazilian children. Methods: This retrospective study evaluated 20 children ranging in age from 7 to 14 years at the time of audiological and electrophysiological evaluations. We performed periodic surveys of the lead concentration in the blood and basic audiological evaluations. Furthermore, we studied the auditory evoked potential long latency N2 and cognitive P3 by analyzing the absolute latency of the N2 and P3 potentials and the P3 amplitude recorded at Cz. At the time of audiological and electrophysiological evaluations, the average concentration of lead in the blood was less than 10 ug/dL. Results: In conventional audiologic evaluations, all children had hearing thresholds below 20 dBHL for the frequencies tested and normal tympanometry findings; the auditory evoked potential long latency N2 and cognitive P3 were present in 95% of children. No significant correlations were found between the blood lead concentration and latency (p = 0.821) or amplitude (p = 0.411) of the P3 potential. However, the latency of the N2 potential increased with the concentration of lead in the blood, with a significant correlation (p = 0.030). Conclusion: Among Brazilian children with low lead exposure, a significant correlation was found between blood lead levels and the average latency of the auditory evoked potential long latency N2; however, a significant correlation was not observed for the amplitude and latency of the cognitive potential P3

Availability of heavy metals in contaminated soil evidenced by chemical extractants

Heavy metals have been accumulating in Brazilian soils, due to natural processes, such as atmospheric deposition, or human industrial activities. For certain heavy metals, when in high concentrations in the soil, there is no specific extractant to determine the availability of these elements in the soil. The objective of the present study was to evaluate the availability of Cd, Cu, Fe, Mn, Pb and Zn for rice and soybeans, using different chemical extractants. In this study we used seven soil samples with different levels of contamination, in completely randomized experimental design with four replications. We determined the available concentrations of Cd, Cu, Fe, Mn, Pb and Zn extracted by Mehlich-1, HCl 0.1 mol L-1, DTPA, and organic acid extractants and the contents in rice and soybeans, which extracts were analyzed by ICP-OES. It was observed that Mehlich-1, HCl 0.1 mol L-1 and DTPA extractants were effective to assess the availability of Cd, Cu, Pb and Zn for rice and soybeans. However, the same was not observed for the organic acid extractant.