Residential pesticides and childhood leukemia: a systematic review and meta-analysis / Pesticidas residenciais e leucemia na infância: revisão sistemática e meta-análise

It is a systematic review and meta-analysis of previous observational epidemiologic studies examining the relationship between residential pesticide exposures during critical exposure time windows (preconception, pregnancy, and childhood) and childhood leukemia. Searches of Medline and other electronic databases were performed (1950-2009). Study selection, data abstraction, and quality assessment were performed by two independent reviewers. Random effects models were used to obtain summary odds ratios (ORs) and 95 percent confidence intervals (Cis). Of the 17 identified studies, 15 were included in the meta-analysis. Exposures during pregnancy to unspecified residential pesticides insecticides, and herbicides were positively associated with childhood leukemia. Exposures during childhood to unspecified residential pesticides and insecticides were also positively associated with childhood leukemia, but there was no association with herbicides. Positive associations were observed between childhood leukemia and residential pesticide exposures. Further work is needed to confirm previous findings based on self-report, to examine potential exposure-response relationships, and to assess specific pesticides and toxicologically related subgroups of pesticides in more detail.

Trata-se de uma revisão sistemática e meta-análise de estudos epidemiológicos observacionais anteriores que examinaram a relação entre a exposição de pesticidas residenciais durante as janelas de exposição crítica do tempo (pré-concepção, gravidez e infância) e leucemia infantil. Foram realizadas pesquisas de dados em diversas bases de dados eletrônicas como Medline e outras. Dois revisores independentes realizaram o estudo de seleção, abstração de dados e avaliação da qualidade. Foram utilizados modelos de efeitos aleatórios para obtenção de razões chances (odds ratio) e intervalos de confiança de 95 por cento (IC). Dos 17 estudos identificados, 15 foram incluídos na meta-análise. A exposição a pesticidas e inseticidas residenciais não especificados durante a infância foi positivamente associada com a leucemia infantil, mas não houve associação com herbicidas. Foram observadas associações positivas entre leucemia infantil e exposição a pesticidas residenciais. São necessários mais estudos para confirmar os resultados anteriores com base no autorrelato, para examinar possíveis relações exposição-resposta, e para a avaliação em detalhes de pesticidas específicos e subgrupos de pesticidas toxicologicamente relacionados.

Occupational Lymphohematopoietic Cancer in Korea

The purpose of this study was to review the existing studies on lymphohematopoietic (LHP) cancer in Korea, estimate the prevalence of workers exposed to carcinogens, and determine the population attributable fraction (PAF) of leukemia. Two case series and 4 case reports were reviewed. Using official statistics, the prevalence of benzene exposure and ionizing radiation exposure was estimated. Based on the prevalence of exposure and the relative risk, The PAF of leukemia was calculated. Between 1996 and 2005, 51 cases of LHP cancer were reported from the compensation system. Greater than 50% of occupational LHP cancer was leukemia, and the most important cause was benzene. In a cohort study, the standardized incidence ratio was 2.71 (95% CI, 0.56-7.91). The prevalence of exposure was 2.5% and 2.2% in 1995 and 2000, respectively. Using the 1995 prevalence, 3.6-4.8% and 0.1% of cases with leukemia were attributable to benzene and ionizing radiation exposure, respectively, which resulted in 39.7-51.4 cases per year. Benzene is the most important cause of occupational leukemia in Korea. Considering the estimated PAF in this study, the annual number of occupational LHP cancer (51 cases during 10-yr period), might be underreported within the compensation system.

Classification of risk occupation for benzene exposure by urine trans, trans-munconic acid level.

Leukemogenesis due to benzene exposure is of particular concern because of ongoing exposure to thousands of workers in industrial plants. Monitoring of at-risk workers is recommended and of several biomarkers, urine trans,trans-muconic acid (ttMA) determination is a helpful test. The aim of this work was to classify risk occupation for benzene exposure by urine ttMA level. Here, the author compared exposure risk ratios from 6 previous reports concerning urine ttMA determination. Of interest, the high risk occupations were found to be those which have direct contact with benzene in environmental ambient air, with petroleum fuel as the common source.

Induction of leukaemia in chloramphenicol-treated toads

Chloramphenicol has been associated with the development of aplastic anaemia. As it is still widely used in Egypt, we studied its effect on 100 Egyptian toads [Bufo regularis] given a dose of chloramphenicol of 5 mg/40 g body weight for 12 weeks. We found it induced numerous, severe ultrastructural changes in almost all types of leukocytes. These changes were similar to those induced by the chemical carcinogen 7,12-dimethylbenz[a]anthracene in 100 toads used as the carcinogen control group, and similar to those in leukocytes reported in humans with leukaemia. We recommend regulations be applied on the use of this antibiotic in countries where it is still widely used

Multiple myeloma terminating in acute leukemia: report of two cases and review of the literature

La presentación simultánea de mieloma múltiple y otras enfermedades hematológicas en un mismo paciente, se observa en muy rar as ocasiones. Se han publicado muy pocos casos en la literatura en que coexiste mieloma múltiple y leucemia aguda. En la mayoría de estos casos los pacientes presentaron la leucemia después de haber recibido tratamiento prolongado con agentes alquilantes, razón por la cual se ha implicado a estos como posible factor etiológico causal de la leucemia. Durante los últimos 14 años hemos seguido 141 pacientes con mieloma múltiple en el Hospittal Universitario, de los cuales 3 (2.1%) presentaron posteriormente leucemia aguda. Dos pacientes eran mujeres de 48 y 49 años y uno varón de 33 años. El diagnóstico de mieloma múltiple se estableció por la presencia de un pico protéico monoclonal en suero, lesiones óseas líticas y la presencia de una plasmacitosis inmafuera en la méfuela ósea. Los tres pacientes fueron tratados con agentes alquilantes por 2,9 y 10 años respectivamente antes del inicio de la leucemia. El evento inicial en dos de los casos fue trombocitopenia, alteraciones morfológicas de las plaquetas en uno de los pacientes y la presencia de células inmafueras en la sangre periférica. La transformación en los tres casos fue a leucemia aguda mielógena. Dos de los pacientes recibieron terapia antileucémica fuerante 9 y 11 meses respectivamente. El cuadro clínico de los tres pacientes se describe en detalle y se revisa la literatura pertinente