Residential exposure to air pollution and incidence of leukaemia in the industrial area of Viadana, Northern Italy.

BACKGROUND: Exposure to air pollution has been proposed as one of the potential risk factors for leukaemia. Work-related formaldehyde exposure is suspected to cause leukaemia. METHODS: We conducted a nested register-based case-control study on leukaemia incidence in the Viadana district, an industrial area for particleboard production in Northern Italy. We recruited 115 cases and 496 controls, frequency-matched by age, between 1999 and 2014. We assigned estimated exposures to particulate matter (PM10, PM2.5), nitrogen dioxide (NO2), and formaldehyde at residential addresses, averaged over the susceptibility window 3rd to 10th year prior to the index date. We considered potential confounding by sex, age, nationality, socio-economic status, occupational exposures to benzene and formaldehyde, and prior cancer diagnoses. RESULTS: There was no association of exposures to PM10, PM2.5, and NO2 with leukaemia incidence. However, an indication of increased risk emerged for formaldehyde, despite wide statistical uncertainty (OR 1.46, 95%CI 0.65-3.25 per IQR-difference of 1.2 µg/m3). Estimated associations for formaldehyde were higher for acute (OR 2.07, 95%CI 0.70-6.12) and myeloid subtypes (OR 1.79, 95%CI 0.64-5.01), and in the 4-km buffer around the industrial facilities (OR 2.78, 95%CI 0.48-16.13), although they remained uncertain. CONCLUSIONS: This was the first study investigating the link between ambient formaldehyde exposure and leukaemia incidence in the general population. The evidence presented suggests an association, although it remains inconclusive, and a potential significance of emissions related to industrial activities in the district. Further research is warranted in larger populations incorporating data on other potential risk factors.

Occupational-related exposure to diesel exhaust and risk of leukemia: systematic review and meta-analysis of cohort studies.

PURPOSE: Diesel exhaust (DE) is an established lung carcinogen. The association with leukemia is not well established. We conducted a systematic review and meta-analysis of cohort studies to determine the association between occupational DE exposure and risk of leukemia. METHODS: A systematic literature review was performed to identify all cohort studies on occupational exposure to DE and associated risk of leukemia. STROBE guidelines and PECOS criteria were followed. Meta-analyses with fixed effects (and random-effects model in cases of high heterogeneity) were performed to calculate summary relative risks (RR) and 95% confidence intervals (CI), including subgroup analyses by outcome (mortality or incidence), sex, geographic region, industry type, and study quality. Study quality was assessed using the the Joanna Briggs Institute (JBI) critical appraisal checklist for cohort studies. RESULTS: Of the 30 studies retained, 20 (8 from North America, 12 from Europe) reported a total of 33 estimates of the risk of leukemia. Overall, the relative risk (RR) of leukemia was 1.01 (95% CI = 0.97-1.05, I2 = 21.2%, n = 33); corresponding results for leukemia incidence and mortality were RR = 1.02 (95% CI = 0.98-1.06, I2 = 27.9%, n = 19) and RR = 0.91 (95% CI = 0.81-1.02, I2 = 0.0%, n = 15), respectively. The main results were confirmed in analyses by sex and geographic area. A statistically significant association was detected for miners (RR = 1.58, 95% CI = 1.15-2.15, I2 = 77.0%, n = 2) but not for other occupational groups. Publication bias was not detected (p = 0.7). CONCLUSION: Our results did not indicate an association between occupational DE exposure and leukemia, with the possible exception of miners. Residual confounding cannot be excluded.

Cancer incidence in Swedish oil refinery workers exposed to benzene.

BACKGROUND: Oil refinery workers are exposed to benzene, which is a well-known cause of leukaemia, but results on leukaemia in oil refinery workers have been mixed, and the data on workers' exposure is limited. Oil refinery workers are also exposed to asbestos and several studies have shown increased risk of mesothelioma. AIM: The objective was to investigate cancer incidence, especially leukaemia, at low to moderate exposure to benzene in an update of a previous study of employees at three Swedish oil refineries. METHODS: Cancer incidence was followed up in 2264 men (1548 refinery operators) employed at three oil refineries in Sweden for at least one year. Job types and employment times were collected from complete company files. A retrospective assessment of the benzene exposure was performed by occupational hygienists in collaboration with the refineries using historic measurements as well as detailed information on changes in the industrial hygiene and technological developments. Cases of cancer were retrieved by a linkage with the Swedish Cancer Register through 35-47 years of follow-up and standardized incidence ratios (SIR) with 95% confidence intervals (CI) were calculated. RESULTS: In total, 258 tumors had occurred versus 240 expected (SIR 1.07; 95% CI 0.95-1.21). There were 10 cases of leukaemia, all in refinery operators (SIR 2.4; 95% CI 1.18-4.51). There were three cases of pleural mesothelioma, two of which in refinery operators. The mean estimated cumulative benzene exposure for the cases of leukaemia was 7.9 ppm-years (median 4.9, range 0.1-31.1). DISCUSSION: The study suggests that low to moderate average cumulative benzene exposure increases the risk of leukaemia. Limitations include the modest number of cases and potential misclassification of exposure. CONCLUSION: The present study indicated an increased risk of leukaemia in male oil refinery workers with low to moderate exposure to benzene.

Leukemia risk assessment of exposure to low-levels of benzene based on the linearized multistage model.

Objectives: To assess leukemia risk in occupational populations exposed to low levels of benzene. Methods: Leukemia incidence data from the Chinese Benzene Cohort Study were fitted using the Linearized multistage (LMS) model. Individual benzene exposure levels, urinary S-phenylmercapturic acid (S-PMA) and trans, trans-muconic acid (t, t-MA) were measured among 98 benzene-exposed workers from factories in China. Subjects were categorized into four groups by rounding the quartiles of cumulative benzene concentrations (< 3, 3-5, 5-12, ≥12 mg/m3·year, respectively). The risk of benzene-induced leukemia was assessed using the LMS model, and the results were validated using the EPA model and the Singapore semi-quantitative risk assessment model. Results: The leukemia risks showed a positive correlation with increasing cumulative concentration in the four exposure groups (excess leukemia risks were 4.34, 4.37, 4.44 and 5.52 × 10-4, respectively; Ptrend < 0.0001) indicated by the LMS model. We also found that the estimated leukemia risk using urinary t, t-MA in the LMS model was more similar to those estimated by airborne benzene compared to S-PMA. The leukemia risk estimated by the LMS model was consistent with both the Singapore semi-quantitative risk assessment model at all concentrations and the EPA model at high concentrations (5-12, ≥12 mg/m3·year), while exceeding the EPA model at low concentrations (< 3 and 3-5 mg/m3·year). However, in all four benzene-exposed groups, the leukemia risks estimated by these three models exceeded the lowest acceptable limit for carcinogenic risk set by the EPA at 1 × 10-6. Conclusion: This study demonstrates the utility of the LMS model derived from the Chinese benzene cohort in assessing leukemia risk associated with low-level benzene exposure, and suggests that leukemia risk may occur at cumulative concentrations below 3 mg/m3·year.

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.

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