Hair dye use and other risk factors for leukemia and pre-leukemia: a case-control study. Italian Leukemia Study Group

Association between cigarette smoking, genetic polymorphism and myelodysplasia: a multicentric case-control study

BACKGROUND

Both cigarette smoking (CGS), through its role as a benzene source, and some metabolic detoxyfiying enzymes (EDTOX) polymorphisms that hamper its inactivation, are considered as risk factors for the development of myelodysplastic neoplasms (MDS) and related disorders. This study aims to confirm such associations.

PATIENTS AND METHODS

We recruited 61 patients diagnosed with MDS following FAB Group criteria and 180 adults without peripheral blood cytopenia, and we analyzed: i) the crude odds-ratio (OR) for MDS between smokers and non-smokers, ii) the crude OR for MDS between homozygous individuals for the mutation NQO1609C-T, or harboring deletions in the genes codyfing for GSTM1 y GSTT1, and those who did not show such genotypes, and iii) the OR for MDS between smokers and non-smokers, adjusted for other potential risk factors.

RESULTS

Our data confirm the association between MDS with a 28 pack-year or greater CGS history (OR 3.10; IC 95% 1.38-6.96). Conversely, we did not observe any association between MDS diagnosis and the EDTOX genotypes analyzed.

CONCLUSIONS

Cigarette smoking history is more relevant than EDTOX genotype in MDS etiopathogenesis.

[Environmental and occupational risk factors for myelodysplastic syndrome]

Chemotherapy and radiotherapy for a previous cancer can lead to subsequent myelodysplastic syndrome (MDS). However, these therapy-related cases are hypothesized to explain only 5 % of diagnosed MDS cases. Environmental or occupational exposure to chemicals or radiations has also been reported to be associated with higher risk of MDS. The present review analyses those studies evaluating the association of MDS with environmental or occupational risk factors. There is sufficient evidence that environmental or occupational exposure to ionizing radiation or benzene can cause MDS. Tobacco smoking is also a sufficiently documented riskfactor for MDS. A positive association has been reported between exposure to pesticides and MDS. However, there is only limited evidence that this association could be causal.

Risks of Leukemia in Various Industrial Groups in Korea: A Retrospective National Cohort Study

It is known that occupational exposure to specific agents is associated with leukemia. However, whether the occupational risks of leukemia differ among various industrial groups remains unclear. Therefore, the purpose of this study was to elucidate the occupational risks of leukemia among different worker groups by industry. Data for a total of 11,050,398 people from the National Health Insurance System's claim data from 2007 to 2015 were analyzed. By cohort inclusion of workers whose industry had not changed for three years and with total workers as a control group, the risk for a specific industry group was expressed as an age-standardized incidence ratio (SIR). Among groups by industry, 'Manufacture of motor vehicles and engines for motor vehicles', 'Sale of motor vehicle parts and accessories', and 'Personal care services' showed significantly higher SIRs. In division analysis, the 'Manufacture of other machinery and equipment' and 'Waste collection, treatment and disposal activities' divisions showed significantly higher SIRs than other divisions. We identified an increased risk of leukemia in workers of certain industries in Korea. Based on the results of this study, it is necessary to create a policy to protect workers at risk of leukemia. Various additional studies are needed to protect workers by revealing more precise relationships between individual hazardous substances, processes, and leukemia.

Risk of Carcinogenicity Associated with Synthetic Hair Dyeing Formulations: A Biochemical View on Action Mechanisms, Genetic Variation and Prevention

Article tries to visualize the potential for carcinogenic trigger in humans with a preference for oxidative synthetic of hair dyeing formulations, especially which belong to the category of permanent colours. According to the International Agency for Cancer, hair dyes for personal use are not strictly classified as carcinogen to humans. However, some controversy exists that requires clarification. Some epidemiological studies support the association between the risk of cancer development and personal use of hair dyes (pooled relative risk RR = 1.50. 95% CI: 1.30-1.98). The world-wide sale of hair dyeing cosmetics have exceeded 15 billion dollars by the year 2012 and has maintained an annual growth rate of 8-10%. This raises concerns and need to be addressed. The review article briefly discusses about the different hair dye components based on their chemical nature, permanence, interaction of dye components with different parts of the hair shaft, action mechanisms, health risk assessment, associated challenges and possible alternatives. There appears variability towards the pathological changes incurred in the human system upon the use of synthetic hair formulations. This probably appears due to the presence of interindividual genetic variation of enzymes handling these xenobiotics. The redox mechanism of major hair dye components appears to be involved in the carcinogenic trigger. Most of the hair dye constituents pose serious health issues. However, we do have few better alternatives to prevent the toxicity associated with hair dye constituents without compromising the need of today's fashion statement and expectations of the youth.

Magnitude and Temporal Trend of the Chronic Myeloid Leukemia: On the Basis of the Global Burden of Disease Study 2019

PURPOSE

To map the magnitudes and temporal trends of chronic myeloid leukemia (CML) along with its attributable risk factors, providing the essential foundation for targeted public policies at the national, regional, and global levels.

MATERIALS AND METHODS

We retrieved annual data on CML burden in 204 countries and regions from the Global Burden of Disease Study 2019 in 1990-2019. The estimated annual percentage change (EAPC) was calculated to quantify the temporal trends of CML burden by region, sex, and age group.

RESULTS

Globally, the age-standardized incidence rate of CML declined weakly over the past few years (EAPC: -1.04), but the number of incident cases increased by 54.1% to 65.8 × 103 in 2019. By contrast, a dramatic drop in death and disability-adjusted life years (DALYs) rate (EAPCs: -2.55; -2.69) led to a reduction in deaths and DALYs, especially in high-income regions. In 2019, the highest age-standardized death rate was observed in Ethiopia (1.89 per 100,000). The death rate of CML was pronounced among the population age above 70 years. DALYs of CML worldwide were primarily attributable to smoking (12.2%), high body mass index (5.0%), occupational exposure to benzene (0.9%), and occupational exposure to formaldehyde (0.3%) in 2019.

CONCLUSION

Although the mortality rate of CML has decreased significantly, the management of patients with CML cannot be neglected, especially in elders and developing regions.

Etiology of Acute Leukemia: A Review

Simple Summary

Acute leukemias are some of the most common cancers affecting all age groups. Despite a significant improvement made in the treatment of acute leukemias, their cause remains unknown. A number of genetic and environmental factors for the development of acute leukemias have been proposed, but none have been proven. Undoubtedly, genetics have a major role in the development of these diseases. The effects of a variety of environmental factors, occupations and hobbies have been explored. A recent “two-hit” theory” for the development of acute lymphoblastic leukemia has been proposed. This combines genetic factors and exposure to infections for the development of this disease. Several genetic factors are suggested. Most recently, for the infection portion, exposure to a virus containing Aspergillus Flavus has been proposed. This review summarizes what is currently known about the factors that are proposed for the development of acute leukemias.

Abstract

Acute leukemias constitute some of the most common malignant disorders. Despite significant progress made in the treatment of these disorders, their etiology remains unknown. A large and diverse group of genetic and environmental variables have been proposed. The role of a variety of factors, including pre-existing and acquired genetic mutations, exposure to radiation and various chemicals during preconception, pregnancy and throughout life, have been explored. The effects of inherited genetic variations and disorders, pre-existing diseases, infectious agents, hobbies, occupations, prior treatments, and a host of other factors have been proposed, but none is universally applicable to all cases. Variation in the incidence and prognosis based on the age, sex, race, type of the disease, geographic area of residence and other factors are intriguing but remain unexplained. Advances in genomic profiling, including genome-wide gene expression, DNA copy number and single nucleotide polymorphism (SNP) genotype, may shed some light on the role of genetics in these disparities. Separate two-hit hypotheses for the development of acute myeloblastic and lymphoblastic leukemia have been proposed. The latter combines genetics and infection factors resulting in leukemogenesis. A number of pre- and post-natal environmental conditions and exposure to infections, including a mycovirus infected Aspergillus flavus, have been suggested. The exact nature, timing, sequence of the events and mechanisms resulting in the occurrence of leukemia requires further investigations. This review summarizes some of the above factors in acute lymphoblastic and myeloblastic leukemias and the direction for future research on the etiology of these disorders.

The importance of evaluating specific myeloid malignancies in epidemiological studies of environmental carcinogens

INTRODUCTION

Although myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), myeloproliferative neoplasms (MPN) - including chronic myeloid leukemia (CML) - and myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are largely clinically distinct myeloid malignancies, epidemiological studies rarely examine them separately and often combine them with lymphoid malignancies, limiting possible etiological interpretations for specific myeloid malignancies.

METHODS

We systematically evaluated the epidemiological literature on the four chemical agents (1,3-butadiene, formaldehyde, benzene, and tobacco smoking, excluding pharmaceutical, microbial and radioactive agents, and pesticides) classified by the International Agency for Research on Cancer as having sufficient epidemiological evidence to conclude that each causes "myeloid malignancies." Literature searches of IARC Monographs and PubMed identified 85 studies that we critically assessed, and for appropriate subsets, summarized results using meta-analysis.

RESULTS

Only two epidemiological studies on 1,3-butadiene were identified, but reported findings were inadequate to evaluate specific myeloid malignancies. Studies on formaldehyde reported results for AML and CML - and not for MDS or MPN - but reported no increased risks. For benzene, several specific myeloid malignancies were evaluated, with consistent associations reported with AML and MDS and mixed results for CML. Studies of tobacco smoking examined all major myeloid malignancies, demonstrating consistent relationships with AML, MDS and MPN, but not with CML.

CONCLUSIONS

Surprisingly few epidemiological studies present results for specific myeloid malignancies, and those identified were inconsistent across studies of the same exposure, as well as across chemical agents. This exercise illustrates that even for agents classified as having sufficient evidence of causing "myeloid malignancies," the epidemiological evidence for specific myeloid malignancies is generally limited and inconsistent. Future epidemiological studies should report findings for the specific myeloid malignancies, as combining them post hoc - where appropriate - always remains possible, whereas disaggregation may not. Furthermore, combining results across possibly discrete diseases reduces the chances of identifying important malignancy-specific causal associations.

Occupational pesticide exposure increases risk of acute myeloid leukemia: a meta-analysis of case-control studies including 3,955 cases and 9,948 controls

The impact of pesticides on health is a major public health concern. A higher risk to develop chronic lymphoid malignancies has been demonstrated to be associated with occupational pesticide exposure (OPE). By contrast, little is known of the impact of OPE on the occurrence of myeloid malignancies especially acute myeloid leukemia (AML). The purpose of this meta-analysis is to summarize data on the association between OPE and AML. A relevant dataset of case-control studies was extracted. Among 6784 references extracted, 14 were selected, representing 3,955 AML patients and 9,948 control subjects diagnosed between 1976 and 2010. An adverse association was found between OPE and AML (OR = 1.51; 95%CI: 1.10-2.08), not affected by sensitivity analyses. Funnel plot asymmetry suggested a publication bias underestimating OR. Stratified analysis showed the association to be driven by studies with: (1) monocentric AML patients and hospital-based control population, (2) Newcastle-Ottawa scale > 6 and the group of studies identified as with the lowest risk, (3) exposure assessment through peer-to-peer interview, (4) diagnosis in North America and Asia and after 1995, (5) restriction to de novo AML. Moreover, the association between OPE and AML was significant with insecticides. These findings broaden the spectrum of pesticide toxicity to myeloid malignancies.

Personal use of hair dyes and risk of leukemia: a systematic literature review and meta-analysis

The objective of this study was to examine the association between personal use of hair dyes and the risk of leukemia. We conducted a systematic literature review of epidemiology studies reporting leukemia‐specific cancer risks among hair dye users, and estimated the meta‐relative risk (meta‐RR) and corresponding 95% confidence interval (95% CI) of leukemia, comparing hair dye users to nonusers. When data from all 20 studies that met the inclusion criteria were combined, ever use of hair dye was associated with a nonstatistically significant increased risk of leukemia, meta‐RR = 1.09 (95% CI: 0.97–1.22). When restricted to studies that adjusted for smoking, ever use of hair dye was not associated with leukemia, meta‐RR = 0.99 (95% CI: 0.76–1.29). A statistically significant increased risk of leukemia was associated with permanent hair dye use (meta‐RR = 1.19 [95% CI: 1.07–1.33]), dark hair dye use (meta‐RR = 1.29 [95% CI: 1.11–1.50]), hair dye use among males (meta‐RR = 1.42 [95% CI: 1.01–2.00]), hair dye use pre‐1980 (meta‐RR = 1.49 [95% CI: 1.21–1.83]), and hair dye use for ≥15 years (meta‐RR = 1.35 [95% CI: 1.13–1.62]). Overall, findings suggest that ever use of hair dye is not a significant risk factor for leukemia. Certain hair dye use characteristics were associated with a statistically significant increased risk, but further research is required to determine whether these associations truly reflect a risk of leukemia due to methodological limitations in the underlying studies.

Smoking and alcohol and subsequent risk of myelodysplastic syndromes in Japan: the Japan Public Health Centre-based Prospective Study

Smoking and alcohol are important modifiable risk factors for human cancers. However, few epidemiological studies have investigated their association with the risk of myelodysplastic syndromes (MDS). Here, we investigated the association of smoking and alcohol consumption and the risk of MDS in a large-scale population-based cohort study in Japan. We included 95 510 Japanese subjects (45 451 men and 50 059 women; age 40-69 years at baseline) and identified 70 MDS cases (50 men and 20 women) during 18·3 years of follow-up. Hazard ratios (HRs) and 95% confidence intervals (95% CI) were estimated using a Cox regression model adjusted for potential confounders. Smoking was marginally associated with an increased risk of MDS among men, with a HR for current smokers relative to never smokers of 2·11 (95% CI: 0·91-4·89). In contrast, alcohol consumption was associated with a dose-dependent decrease in the risk of MDS among men (nondrinkers: reference, occasional drinkers: HR = 0·48, 0·16-1·41; 0-299 g/week: HR = 0·37, 0·19-0·73; ≥300 g/week: HR = 0·49, 0·22-1·08, P for trend = 0·010). This study showed that alcohol has a significant protective effect on the risk of MDS. In addition, this study might indicate that smoking increases the risk of MDS among Japanese population, as it does in Western populations.

Environmental nanoparticles are significantly over-expressed in acute myeloid leukemia

The increase in the incidence of acute myeloid leukemia (AML) may suggest a possible environmental etiology. PM2.5 was declared by IARC a Class I carcinogen. No report has focused on particulate environmental pollution together with AML. The study investigated the presence and composition of particulate matter in blood with a Scanning Electron Microscope coupled with an Energy Dispersive Spectroscope, a sensor capable of identifying the composition of foreign bodies. 38 peripheral blood samples, 19 AML cases and 19 healthy controls, were analyzed. A significant overload of particulate matter-derived nanoparticles linked or aggregated to blood components was found in AML patients, while almost absent in matched healthy controls. Two-tailed Student's t-test, MANOVA and Principal Component Analysis indicated that the total numbers of aggregates and particles were statistically different between cases and controls (MANOVA, P<0.001 and P=0.009 respectively). The particles detected showed to contain highly-reactive, non-biocompatible and non-biodegradable metals; in particular, micro- and nano-sized particles grouped in organic/inorganic clusters, with statistically higher frequency of a subgroup of elements in AML samples. The demonstration, for the first time, of an overload of nanoparticles linked to blood components in AML patients could be the basis for a possible, novel pathogenetic mechanism for AML development.

Do the smoking intensity and duration, the years since quitting, the methodological quality and the year of publication of the studies affect the results of the meta-analysis on cigarette smoking and Acute Myeloid Leukemia (AML) in adults?

BACKGROUND

The aim was to perform a systematic review and meta-analysis on the relationship between tobacco smoking and the onset of acute myeloid leukemia (AML) in adults.

METHODS

PubMed and Scopus databases were systematically searched. In the meta-analysis, random or fixed effects models were used according to the presence of heterogeneity. Study quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

Twenty-seven articles were included. Case-control and cohort meta-analyses show that current, ever and former smokers have a significant increased risk to develop AML compared to never smokers [current: OR=1.36 (1.11-1.66) and RR=1.52 (1.10-2.14); ever: OR=1.25 (1.14-1.38) and RR=1.45 (1.10-1.90); former: OR=1.21 (1.03-1.41) and RR=1.45 (1.08-1.94)]. Moreover, increasing smoking intensity and duration is associated with an increase of the risk, OR shift from 1.14 (1-20 pack/years) to 2.36 (>40 pack/years).

DISCUSSION AND CONCLUSION

Smoking may have a significant role in AML onset in a multistep pathogenesis.

Cigarette Smoking and the Risk of Adult Myeloid Disease: A Meta-Analysis

Background

The adult myeloid diseases, myelodysplastic syndrome and acute myeloid leukemia, have been reported to be associated with cigarette smoking, but the results have been conflicting. Previous studies may have ignored the relationship between myelodysplastic syndrome and acute myeloid leukemia, where approximately one-third of myelodysplastic syndrome cases will progress to acute myeloid leukemia, which could induce a serious bias in independent analyses. For the purposes of researching pathogenesis, we suggest that myelodysplastic syndrome and acute myeloid leukemia should be regarded as a single class of adult myeloid disease, and herein assessed the relationship between cigarette smoking and the risk of adult myeloid disease.

Methods

The PubMed, Cochrane Library, EBSCO, and EMBASE databases were systematically searched for reports published from 1990 to 2015. Two authors independently assessed the methodological quality and the extracted data. The odds ratios and adjusted odds ratios (OR), a sensitivity analysis, and the publication bias were analyzed using the CMA v2 (Comprehensive Meta Analysis Version 2) software program.

Results

Twenty-five studies were included in this meta-analysis. The publication dates ranged from 1990 to 2014. The pooled OR in current smokers and ever-smokers showed an increased risk of adult myeloid disease, with ORs of 1.45 (95% CI, 1.30–1.62; p<0.001) and 1.23 (95% CI 1.15–1.32; p<0.001) versus non-smokers, respectively. In the subset analyses, the OR of adult myeloid disease was increased regardless of the form of disease, geographical region, NOS (Newcastle Ottawa Scale) score, and source of controls. The smoking status was divided into <20 and ≥20 cigarettes per day, and these groups had ORs of developing adult myeloid disease of 1.24 (95% CI, 1.09–1.40; p = 0.001) and 1.32 (95% CI, 1.14–1.53; p<0.001), respectively. In the groups divided based on the number of years the subjects had smoked (<20 and ≥20 years), the ORs were 1.05 (95% CI, 0.90–1.23; p = 0.25) and 1.30 (95% CI, 1.16–1.45; p<0.001), respectively. Similarly, <20 and ≥20 pack-years were associated with ORs of 1.15 (95% CI, 1.03–1.29; p = 0.017) and 1.34 (95% CI, 1.18–1.52; p<0.001), respectively.

Conclusions

This meta-analysis, for the first time, combined myelodysplastic syndrome with acute myeloid leukemia to assess the overall risk of adult myeloid disease, and it demonstrated that cigarette smoking is associated with a significantly increased risk of adult myeloid disease.

Pesticide exposure as a risk factor for myelodysplastic syndromes: a meta-analysis based on 1,942 cases and 5,359 controls

OBJECTIVE

Pesticide exposure has been linked to increased risk of cancer at several sites, but its association with risk of myelodysplastic syndromes (MDS) is still unclear. A meta-analysis of studies published through April, 2014 was performed to investigate the association of pesticide exposure with the risk of MDS.

METHODS

Studies were identified by searching the Web of Science, Cochrane Library and PubMed databases. Summary odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated using random- or fixed-effect models.

RESULTS

This meta-analysis included 11 case-control studies, all of which demonstrated a correlation between pesticide exposure and a statistically significant increased risk of MDS (OR=1.95, 95% CI 1.23-3.09). In subgroup analyses, patients with pesticide exposure had increased risk of developing MDS if they were living in the Europe or Asia and had refractory anemia (RA) or RA with ringed sideroblasts (RARS). Moreover, in the analysis by specific pesticides, increased risk was associated with exposure to insecticides (OR=1.71, 95% CI 1.22-2.40) but not exposure to herbicides or fungicides.

CONCLUSION

This meta-analysis supports the hypothesis that exposure to pesticides increases the risk of developing MDS. Further prospective cohort studies are warranted to verify the association and guide clinical practice in MDS prevention.

The relation between cigarette smoking and risk of acute myeloid leukemia: an updated meta-analysis of epidemiological studies

Smoking has been postulated as an environmental risk factor for acute myeloid leukemia (AML). The primary objective of this meta-analysis of observational studies was to evaluate the epidemiologic relationship between smoking and the risk of development of AML. Twenty-three studies published between January 1993 and December 2013 were included in our analysis, and accounted for 7,746 cases of AML. The outcome of interest was the relative risk (RR) with 95% confidence interval (CI) of developing AML in adult cigarette smokers in comparison with non-smokers, and was estimated using the random-effects model. Our results showed that current and ever smokers have 40% (RR 1.40, 95% CI 1.22-1.60; P < 0.001) and 25% (RR 1.25, 95% CI 1.15-1.36; P < 0.001) increased risk of developing AML when compared with non-smokers. The increased RR of AML was increased regardless of sex, study design, geographical region, and quality of the studies. Intensity of smoking of <10, 10-20, 20-30, and >30 cigarettes per day was associated with RRs of AML of 1.27, 1.36, 1.55, and 1.77, respectively (P < 0.001 for trend). Duration of smoking of <20 and >20 years was associated with RRs of 1.07 and 1.44, respectively (P < 0.001 for trend). Cumulative smoking of <10, 10-20, 20-30, and >30 pack-years was associated with RRs of 1.13, 1.23, 1.39, and 1.71, respectively (P < 0.001 for trend). Overall, cigarette smoking proves to be a significant risk factor for the development of AML in adults.

Evaluation of epidemiological factors in survival of patients with de novo myelodysplastic syndromes

Myelodysplastic syndromes (MDS) prognosis is currently based solely on clinical parameters. The identification of additional factors associated with MDS outcome could be used to further improve the current scoring system such as the International Prognostic Scoring System (IPSS). The present study evaluates the role of epidemiological markers as predictors of survival for 365 adult de novo MDS patients. Multivariable Cox regression analysis was used to estimate overall survival. Median follow-up time was 22 months. At the time of last follow-up, 271 patients (74.3 %) had died. For all MDS patients, medium-high lifetime occupational agrochemical exposure (HR 1.85, CI 1.19-2.89) remained as an independent predictor of MDS survival. Stratified analysis by gender showed that ≥ 25 pack-years smoked (HR 1.44, CI 1.001-2.09) and medium-high lifetime occupational agrochemical exposure (HR 1.84, CI 1.15-2.97) were independent predictors of MDS survival in men, but not in women. For MDS patients stratified by IPSS categories, ≥ 25 pack-years smoked (HR 1.75, CI 1.005-3.06) was an independent predictor for intermediate 1 IPSS risk group only, and medium-high lifetime occupational agrochemical exposure was associated with increased mortality (HR 4.36, CI 1.20-15.8) in the high IPSS risk group. Smoking and lifetime occupational agrochemical exposure may play a role in MDS survival. Incorporating relevant epidemiological markers with known clinical predictors of outcome may help physician stratify patients and customize treatment strategies to improve the outcome of MDS.

Acute myeloid leukemia risk by industry and occupation

Acute myeloid leukemia (AML) is the most common type of leukemia found in adults. Identifying jobs that pose a risk for AML may be useful for identifying new risk factors. A matched case-control analysis was conducted using California Cancer Registry data from 1988 to 2007. This study included 8999 cases of AML and 24 822 controls. Industries with a statistically significant increased AML risk were construction (matched odds ratio [mOR] = 1.13); crop production (mOR = 1.41); support activities for agriculture and forestry (mOR = 2.05); and animal slaughtering and processing (mOR = 2.09). Among occupations with a statistically significant increased AML risk were miscellaneous agricultural workers (mOR = 1.76); fishers and related fishing workers (mOR = 2.02); nursing, psychiatric and home health aides (mOR = 1.65); and janitors and building cleaners (mOR = 1.54). Further investigation is needed to confirm study findings and to identify specific exposures responsible for the increased risks.

A Meta-Analysis of the Relationship between Cigarette Smoking and Incidence of Myelodysplastic Syndromes

BACKGROUND

In recent years, epidemiologic studies have reported controversial results relating cigarette smoking to myelodysplastic syndromes (MDS) risk. A meta-analysis was performed to assess such potential relationship between cigarette smoking and incidence of MDS.

METHODS

A search of literature published before October 2012 for observational studies evaluating the association between cigarette smoking and MDS, returned 123 articles and of these, 14 were selected for this study. The outcomes from these studies were calculated and reported as odds ratios (OR). Quality assessments were performed with the Newcastle-Ottawa Scale. Heterogeneity was evaluated by the I(2) index and source of heterogeneity was detected by sensitivity analyses. Finally, publication bias was assessed through visual inspection of funnel plots and Egger's test.

RESULTS

The pooled OR of developing MDS in ever-smokers was 1.45 (95% CI, 1.25 to 1.68) versus non-smokers. Current and former smokers had increased risks of MDS, with ORs of 1.81 (95% CI, 1.24 to 2.66) and 1.67 (95% CI, 1.42 to 1.96), respectively. In subset analyses, ever-smokers had increased risks of developing MDS if they were living in the United States, or in Europe, female in gender, had refractory anemia (RA)/RA with ringed sideroblasts (RARS) or RA with excess blasts (RAEB)/RAEB in transformation (RAEBt), respectively. Our results demonstrated that the association was stronger in individuals who smoked ≥20 cigarettes/day (OR, 1.62; 95% CI, 1.03 to 2.55) versus those who smoked <20 cigarettes/day (OR, 1.36; 95% CI, 1.13 to 1.64). Moreover, individuals who smoked more than 20 pack-years had increased MDS risk (OR, 1.94; 95% CI, 1.29 to 2.92).

CONCLUSION

Our outcomes show that smoking increases the risk of developing MDS in ever-smokers who are current or former smokers. We also demonstrate here that positive association between cigarette smoking and risk of MDS exists, and occurs in a dose-dependent manner.

Hair dye use and risk of human cancer

Over 50% of the adult population will use hair dyes at some point in their lifetimes. Hair dyes consist of various chemicals and the composition of these chemicals vary by hair dye types. Chemicals p-phenylenediamine and aminophenyl have been suggested as possible carcinogens or mutagens in experimental studies. The scientific community has been interested in this potential public health impact and the results of published epidemiological studies are summarized here. The current evidence provides limited evidences on the association between personal hair dye use and human cancer risk, except for the possibility of hematopoietic cancers and to a lesser extent, bladder cancer. Risk appears to be affected by time period of use and by specific genetic polymorphisms. Future studies should investigate potential gene and environment interaction to assess possible genetic susceptibility. Several methodological issues should also be considered in future studies including completed hair dye use information such as on timing, duration, frequency and type of hair dye product use.

Obesity, weight gain, and risk of chronic myeloid leukemia

To date, little is known about the risk factors for the development of chronic myeloid leukemia (CML). Obesity, measured as body mass index, has been identified as a possible risk factor for several solid tumors as well as some adult hematopoietic malignancies. This case-control study (N = 253 cases and 270 controls), conducted at the University of Texas M. D. Anderson Cancer Center, investigated the role of obesity and adulthood weight gain in CML risk. Cases and controls were similar with respect to smoking, alcohol consumption, and occupational solvent and ionizing radiation exposure. Cases were significantly more likely to have a history of occupational exposure to agricultural chemicals (11% cases versus 3% controls, P = 0.001). Cases were more likely to be obese during adulthood compared with controls at age 25 [odds ratios (OR) = 4.29; 95% confidence intervals (95% CI), 1.63-11.3], at age 40 (OR = 5.12; 95% CI, 1.92-13.6), and at diagnosis (OR = 3.09; 95% CI, 1.56-6.13). Obesity at all ages was found to be an independent risk factor, with a significant dose-response effect. Among participants > or =45 years, cases gained significantly more weight each year between ages 25 and 40 compared with controls (0.78 versus 0.44 kg/y, P < 0.001) with the association strongest among those who gained >1 kg/y between 25 and 40 years of age (OR, 3.63; 95% CI, 1.46-9.04). Our results suggest that obesity and adulthood weight gain play important roles in CML risk. Several plausible biological mechanisms have been proposed and warrant further investigation. In the future, cancer prevention interventions aimed at reducing the incidence of CML could be developed.

Parental smoking and childhood leukemia

Childhood leukemia is the most common cancer among children, representing 31% of all cancer cases occurring in children younger than the age of 15 years in the USA. There are only few known risk factors of childhood leukemia (sex, age, race, exposure to ionizing radiation, and certain congenital diseases, such as Down syndrome and neurofibromatosis), which account for only 10% of the childhood leukemia cases. Several lines of evidence suggest that childhood leukemia may be more due to environmental rather than genetic factors, although genes may play modifying roles. Human and animal studies showed that the development of childhood leukemia is a two-step process that requires a prenatal initiating event(s) plus a postnatal promoting event(s). Despite a substantial public health effort to reduce cigarette smoking, a large proportion of the US and world population still smoke. Tobacco smoke contains at least 60 known human or animal carcinogens, with the major chemical classes being volatile hydrocarbons, aldehydes, aromatic amines, polycyclic aromatic hydrocarbons, and nitrosamines; among these chemicals, only benzene is an established leukemogen, although other chemicals in the tobacco could interact with one another in a complex way to jointly attain a significant carcinogenic effect on the development of leukemia. Although tobacco smoke is an established risk factor for adult myeloid leukemia, the studies of association between parental smoking and childhood leukemia have produced inconsistent results. The majority of the studies on maternal smoking and childhood leukemia did not find a significant positive association and some even reported an inverse association. In contrast to studies of maternal smoking, studies of paternal smoking and childhood leukemia reported more positive associations but only by less than half of the studies. Future directions to be considered for improving the study of parental smoking and childhood leukemia are: 1) consider all sources of benzene exposure in addition to smoking, including occupational exposure and traffic exhausts; 2) childhood leukemia is a heterogeneous disease and epidemiologic studies of childhood leukemia can be greatly improved by grouping childhood leukemia into more homogeneous groups by molecular techniques (e.g., structural and numerical chromosomal changes); and 3) assess gene-environment interaction. It is hoped that through the continual effort, more will be uncovered regarding the causes of childhood leukemia. In the meantime, more effort should be spent on educating the parents to quit smoking, because parental smoking is known to affect many childhood diseases (e.g., asthma, respiratory tract infection, and otitis media) that are much more prevalent than childhood leukemia.

A systematic review of myeloid leukemias and occupational pesticide exposure

OBJECTIVE

To conduct a systematic review and meta-analyses of published studies examining the association between myeloid leukemias (ML) and occupational pesticide exposure.

METHODS

Studies were identified from a MEDLINE search through 31 May 2006 and from the reference lists of identified publications. Studies were summarized and evaluated for publication bias. Relative risk estimates for ML were extracted from 17 cohort and 16 case-control studies published between 1979 and 2005. Fixed- or random-effect meta-analysis models were used depending on the presence of heterogeneity between studies. Separate analyses were conducted after stratification for study design, occupational group, ML subtype or gender.

RESULTS

The overall meta-rate ratio estimate (meta-RR) for the cohort studies was 1.21 (95% confidence interval [CI] 0.99-1.48). Substantial heterogeneity existed among cohort studies (p=1.064 x 10(-5)), mainly reflecting the varying occupational categories examined. The meta-RR was 6.32 (95% CI: 1.90-21.01) for manufacturing workers and 2.14 (95% CI: 1.39-3.31) for pesticide applicators. After stratification of cohort studies by specific ML subtype, an increased risk of acute myeloid leukemia (AML) was found (meta-RR: 1.55; 95% CI: 1.02-2.34). No significant heterogeneity was detected among case-control studies and an increased risk of chronic myeloid leukemia (CML) was found among men (meta-RR: 1.39; 95% CI: 1.03-1.88) and farmers or agricultural workers (meta-RR: 1.38; 95% CI: 1.06-1.79).

CONCLUSION

The strongest evidence of an increased risk of ML comes from manufacturing workers and pesticide applicators. Further studies will be needed to correlate reliable exposure data within these specific occupational groups with well-defined subtypes of leukemia to refine this assessment.

Personal hair dye use and cancer: a systematic literature review and evaluation of exposure assessment in studies published since 1992

Hair dyes are widely used, and permanent hair dye is the most commonly used type of product. Permanent hair dye colors are formed by an oxidative process involving arylamines, giving rise to concerns about the potential adverse health effects of long-term exposure, especially cancer. A 1993 International Agency for Cancer Research (IARC) review concluded that evidence was inadequate to evaluate the carcinogenicity of personal hair dye use. This systematic review synthesizes the results from studies of personal hair dye use and cancer published since 1993, taking into consideration the quality of exposure assessment. Thirty-one English-language articles published in January 1992-February 2005 that investigated the association between personal hair dye use and cancer were identified through the PubMed search engine. Quality of exposure assessment was rated between 1+ (lowest quality: assessed ever use of hair dyes) and 4+ (highest quality: assessed dye type [permanent/nonpermanent], dye color/shade, frequency and duration of use). Because of the heterogeneity of the exposure assessment across the studies, a formal meta-analysis was not conducted. Associations between personal hair dye use and non-Hodgkin's lymphoma, multiple myeloma, acute leukemia, and bladder cancer were observed in at least one well-designed study with detailed exposure assessment (rated 3+ or 4+), but were not consistently observed across studies. Results for bladder cancer studies suggest that subsets of the population may be genetically susceptible to hair dye exposures, but these findings are based on small subgroups in one well-designed case-control study. Replication of these findings is needed to determine whether the reported associations are real or spurious.

Association between personal use of hair dyes and lymphoid neoplasms in Europe

Hair dyes have been evaluated as possibly being mutagenic and carcinogenic in animals. Studies of the association between human cancer risk and use of hair dyes have yielded inconsistent results. The authors evaluated the risk of lymphoid malignancies associated with personal use of hair dyes. The analysis included 2,302 incident cases of lymphoid neoplasms and 2,417 hospital- or population-based controls from the Czech Republic, France, Germany, Ireland, Italy, and Spain (1998-2003). Use of hair dyes was reported by 74% of women and 7% of men. Lymphoma risk among dye users was significantly increased by 19% in comparison with never use (odds ratio (OR) = 1.19, 95% confidence interval (CI): 1.00, 1.41) and by 26% among persons who used hair dyes 12 or more times per year (OR = 1.26, 95% CI: 1.00, 1.60; p for linear trend = 0.414). Lymphoma risk was significantly higher among persons who had started coloring their hair before 1980 (OR = 1.37, 95% CI: 1.09, 1.72) and persons who had used hair dyes only before 1980 (OR = 1.62, 95% CI: 1.10, 2.40). Personal use of hair dyes is associated with a moderate increase in lymphoma risk, particularly among women and persons who used dyes before 1980. Specific compounds associated with this risk remain to be elucidated.

Etiology of acute myeloid leukemia in the elderly

The biologic and epidemiologic study of acute myeloid leukaemia (AML) in the elderly is in its infancy. Most epidemiologic data attempting to ascertain the etiology of AML have been obtained from younger cohorts or patients with therapy-related AML. The increasing prevalence of deletional and complex karyotypes in elderly AML patients implies a cumulative genotoxicity over time for this subgroup, given the similar spectrum of abnormalities following exposure to known genotoxic agents such as alkylating chemotherapeutic drugs. Exposure to benzene, radiation, and tobacco smoke are clear but weak risk factors for AML. Polymorphic variants in several genes responsible for genomic protection and integrity are now also weak risk factors for AML. Future epidemiologic studies should correlate exposure data with well-defined biologic subtypes of AML.

Occupational exposures and haematological malignancies: overview on human recent data

OBJECTIVE

Occupational causes of haematological malignancies are relatively uncommon, under-studied and under-identified. They are also often unrecognized by clinicians. This review summarizes the principal epidemiologic studies on this topic.

METHODS

We analyzed the recent relevant human data found in the Medline, the Pascal and the BDSP databases.

RESULTS

Benzene and ionizing radiation are the only agents conclusively demonstrated to be carcinogenic to the haematopoietic system. In particular, both exposures are strongly associated with acute myeloid leukaemia. Low doses of both may also be related to myeloid malignancies. Infectious agents and pesticides are also thought to induce lymphoproliferative cancers. Some studies show an association between haematological malignancies and low-frequency electromagnetic fields and organic solvents. All of these suspected occupational causes must be confirmed by further studies.

CONCLUSIONS

Better knowledge and understanding of occupational causes of haematological malignancies are necessary to improve their prevention and compensation.

Risk of lymphatic or haematopoietic cancer mortality with occupational exposure to animals or the public

BACKGROUND

Occupational exposure to animals or the public could result in exposure to infectious agents, which may play a role in the aetiology of lymphohaematopoietic (LH) cancers.

AIMS

To conduct a population based, case-control study of death certificate data from 1984 to 1998 in 24 US states in order to evaluate the risk of mortality from LH neoplasms associated with occupational exposure to animals or the public.

METHODS

Cases were selected as those with an underlying cause of death of non-Hodgkin's lymphoma (NHL, n = 72,589), Hodgkin's disease (HD, n = 5479), multiple myeloma (n = 35,857), or leukaemia (n = 68,598); 912 615 controls were randomly selected from all remaining deaths, frequency matched on age, sex, race, and geographic region.

RESULTS

Occupational exposure to animals was associated with modest increased risks of mortality from all four LH cancers; these associations varied by region. Occupational exposure to the public was associated with only negligible increased risk with LH cancer outcomes. Occupations involving animal exposure were predominantly agricultural, and the risks associated with employment in the livestock industry exceeded the corresponding risks associated with the crop industry for all outcomes except HD.

CONCLUSIONS

Increased risks of NHL, HD, multiple myeloma, and leukaemia were associated with occupations that involved animal exposure. Regional differences in risk imply that the risks may be associated with exposure to specific livestock or farming practices. However, these associations may be confounded by other farming related exposures, such as pesticides. Because the use of death certificates to classify occupation may result in misclassification during aetiologically relevant time periods, these hypotheses should be further explored in studies with detailed information on lifetime occupation.

Occupation, hobbies, and acute leukemia in adults

Occupational and industrial exposures have been implicated in the etiology of leukemia, yet uncertainty remains regarding potential high risk occupations. We examined the associations between self-reported occupations and hobbies and acute leukemia risk using data from 811 cases and 637 controls participating in a case-control study in the U.S. and Canada. We found that several occupations may increase the risk of acute leukemia, particularly occupations related to petroleum products, rubber, nuclear energy, munitions, plastics, and electronics manufacturing. Differences were noted according to histological type. Other occupations and hobbies were not clearly associated with risk.

Regular use of hair dyes and risk of lymphoma in Spain

BACKGROUND

The use of hair dyes has been inconsistently associated with an increased risk of lymphomas. We explore hair dye use and lymphoma risk in a case-control study in Spain.

METHODS

We studied 574 incident lymphoma cases and 616 hospital controls in a multicentric study in Spain. Information on hair dye use was obtained through a personal interview together with information on other known or putative risk factors for lymphoma. Unconditional logistic regression analysis was used to estimate odds ratio (OR) and 95% confidence intervals (95% CI). All ORs were adjusted for pathology center, sex, age, and house ownership.

RESULTS

Ever use of hair dyes was associated with a non-significant 20% increased risk of lymphoma (OR = 1.2, 95% CI 0.9-1.7) with a slightly higher risk observed for those using permanent hair dyes (OR = 1.3, 95% CI 0.9-1.9). No association was observed with duration of use or lifetime doses of hair dyes. Among all lymphomas categories, only chronic lymphocytic leukaemia (CLL) was significantly associated with the use of hair dyes (OR = 2.3, 95% CI 1.1-4.7). The risk of CLL increased with lifetime doses received.

CONCLUSIONS

Ever use of hair dye products is unlikely to substantially modify the risk of lymphoma. The observed association with CLL needs to be replicated.

Risk of Acute Myeloid Leukemia After Exposure to Diesel Exhaust: A Review of the Epidemiologic Evidence

The objective of this study was to review the epidemiologic literature on exposure to diesel exhaust (DE) exposure and leukemia risk. No cohort studies, nine case-control studies, and nine studies based on routine statistics and record linkages provided results useful to assess the risk of leukemia, and in particular acute myeloid leukemia (AML), among exposed workers. No formal pooling of the results was possible. The available studies do not consistently suggest an increased risk of leukemia, and specifically AML, among workers exposed to DE. For none of the occupational groups potentially exposed to DE, the results suggest an association, and sporadic positive results are counterbalanced by negative associations and might result from reporting bias. DE exposure does not appear to be associated with increased risk of leukemia.

Hair dye use and risk of lymphoid neoplasms and soft tissue sarcomas

We analyzed the relation between hair dye use and the risk of Hodgkin's disease (HD), non-Hodgkin's lymphoma (NHL), multiple myeloma (MM) and soft tissue sarcomas (STS) in a hospital-based case-control study conducted between 1985 and 1997 in northern Italy. Cases included 158 patients with histologically confirmed incident HD, 446 with NHL, 141 with MM, 221 with STS and controls included 1,295 patients with acute nonneoplastic conditions. Compared to never use of any type of hair dyes, the odds ratio (OR) for ever use was 0.68 (95% confidence interval, CI, 0.40-1.18) for HD, 1.03 (95% CI 0.73-1.44) for NHL, 1.17 (95% CI 0.70-1.97) for MM and 0.73 (95% CI 0.45-1.17) for STS. The OR were close to unity for permanent and semipermanent dyes analyzed separately or when the analysis was restricted to women. Our study indicates that there is no appreciable association between ever use of any type of hair dyes and the risk of HD, NHL, MM or STS.

Oxidative stress and the myelodysplastic syndromes

The evolution of higher organisms from anaerobic to aerobic living has promoted an elaborate mechanism of defense against potentially toxic oxidants. Many environmental toxicants implicated in the pathogenesis of myelodysplastic syndromes (MDS), including benzene and ionizing radiation, exert toxicity via pro-oxidant mechanisms. The emerging data suggest a probable genetic susceptibility to environmental carcinogenesis through functional polymorphic variants in enzymes that metabolize toxicants and/or protect against oxidative stress. The most studied enzyme is NAD(P)H:quinone oxidoreductase (NQO1). CD34+ cells from individuals homozygous for the NQO1 C609T nonfunctional allelic variant are incapable of enzyme induction following exposure to benzene, thus potentially increasing the hematotoxicity of benzene metabolites. Serologic and molecular markers of oxidative stress are present in many patients with MDS and include an increased concentration of the lipid peroxidation product malondialdehyde and the presence of oxidized bases in CD34+ cells. Potential mechanisms of oxidative stress include mitochondrial dysfunction via iron overload and mitochondrial DNA mutation, systemic inflammation, and bone marrow stromal defects. The biological activity of the antioxidant aminothiol amifostine in vivo suggests that these pathways may be meaningful targets for future therapy in MDS patients.

Leukemia in childhood and adolescence and exposure to ionizing radiation in homes built from uranium-containing alum shale concrete

Concerns in Sweden about indoor radon around 1980 prompted measurements of gamma-radiation from the facades of houses to identify those constructed of uranium-containing alum shale concrete, with potentially high radon concentrations. To evaluate any possible risk of acute lymphocytic leukemia from exposure to elevated gamma-radiation in these homes, we identified the acute lymphocytic leukemia cases less than 20 years of age in Sweden during 1980-1989 as well as eight controls per case from the population registry, matching on age, gender, and county. Using the existing measurements, exposure was assessable for 312 cases and 1,418 controls from 151 properly measured municipalities. A conditional logistic odds ratio of 1.4 (95% confidence interval = 1.0-1.9) was obtained for those ever having lived in alum shale concrete houses, with the average exposure exceeding 0.10 microsieverts per hour. Comparing those who ever lived in alum shale concrete houses (divided by higher and lower annual average exposure) with those who never lived in such houses, we found a weak dose-response relation. The results suggest some risk of acute lymphocytic leukemia from indoor ionizing radiation among children and young adults.

Are occupational, hobby, or lifestyle exposures associated with Philadelphia chromosome positive chronic myeloid leukaemia?

OBJECTIVES

To investigate a broad range of occupational, hobby, and lifestyle exposures, suggested as risk factors for Philadelphia chromosome positive (Ph+) chronic myeloid leukaemia (CML).

METHODS

A case-control study, comprising 255 Ph+CML patients from southern Sweden and matched controls, was conducted. Individual data on work tasks, hobbies, and lifestyle exposures were obtained by telephone interviews. Occupational hygienists assessed occupational and hobby exposures for each subject individually. Also, occupational titles were obtained from national registries, and group level exposure-that is, the exposure proportion for each occupational title-was assessed with a job exposure matrix. The effects of 11 exposures using individual data and two exposures using group data (organic solvents and animal dust) were estimated.

RESULTS

For the individual data on organic solvents, an effect was found for moderate or high intensity of exposure (odds ratio (OR) 3.4, 95% confidence interval (95% CI) 1.1 to 11) and for long duration (15-20 years) of exposure (OR 2.1, 95% CI 1.1 to 4.0). By contrast, the group data showed no association (OR 0.69, 95% CI 0.27 to 1.8; moderate or high intensity versus no exposure). For extremely low frequency electromagnetic fields (EMFs), only individual data were available. An association with long occupational exposure to EMFs was found (OR 2.3, 95% CI 1.2 to 4.5). However, no effect of EMF intensity was indicated. No significant effects of benzene, gasoline or diesel, or tobacco smoking were found. OR estimates below unity were suggested for personal use of hair dye and for agricultural exposures.

CONCLUSIONS

Associations between exposure to organic solvents and EMFs, and Ph+CML were indicated but were not entirely consistent.

Smoking and acute myeloid leukemia: associations with morphology and karyotypic patterns and evaluation of dose-response relations

This case-control study of tobacco smoking and acute myeloid leukemia (AML), emphasizing specific associations with morphologic and cytogenetic subtypes, comprised smoking histories for 333 cases and 351 controls. Smoking status (ever smokers versus life-long non-smokers) showed no evident effect on AML risk. However, an effect of smoking was indicated at high cumulative smoking doses (pack-years), e.g. 40 pack-years was associated with an odds ratio (OR) of 1.5 [95% confidence interval (CI) 1.0-2.3]. Among morphologic subtypes, the smoking associated OR for acute erythroleukemia was 8.9 (95% CI 1.0-76). No clear associations between smoking and cytogenetic subtypes of AML were observed.

Occupation and leukemia: a population-based case-control study in Iowa and Minnesota

BACKGROUND

Studies have suggested that risk of leukemia may be associated with occupational or industrial exposures and risk may vary by the histological type of the disease.

METHODS

A population-based case-control study was conducted in Iowa and Minnesota to evaluate the association between various occupations, industries, and occupational exposures and leukemia risk. A total of 513 cases and 1,087 controls was included in the study. A lifetime occupational history and other risk factor information were collected through in-person interviews, and a job-exposure matrix was used to assess possible risks associated with specific exposures.

RESULTS

A significantly increased risk of leukemia was observed among agricultural service industries and among nursing and healthcare workers. Janitors, cleaners, and light truck drivers also experienced increased risk. Those employed in plumbing, heating and air conditioning industries, and sales of nondurable goods (such as paints and varnishes) had an increased risk. Printers, painters, and workers in the food and metal industries had a nonsignificantly increased risk of leukemia. Analyses by specific exposures and histology of leukemia showed that risk of leukemia associated with occupational or industrial exposures may vary by histological type of the disease.

CONCLUSIONS

An increased risk of leukemia among workers employed in agricultural industries, nursing and healthcare workers, and in a few occupations with possible exposure to solvents is consistent with earlier studies. Associations of risk with occupations not observed previously deserve further assessment. Published 2001 Wiley-Liss, Inc.

Epidemiological features of myelodysplastic syndromes: results from regional cancer surveys and hospital-based statistics

Although myelodysplastic syndromes (MDS) have been increasingly diagnosed in recent years, precise data on their prevalence and incidence are still lacking. Due to difficulties of diagnosis and classification, large-scale population-based studies that are required for obtaining truly representative data on the epidemiology of MDS are currently not available. Our present knowledge of the incidence and other epidemiological characteristics of MDS is based on a few regional studies performed by authors with a long-lasting interest in these hemopathies. Despite certain limitations, these studies have consistently shown that MDS are relatively common hematological malignancies. Their crude incidence varies from 2.1 to 12.6 cases per 100,000 people per year. Among the age group that is mainly affected, people older than 70 years, we are now faced with incidence rates of about 15 to 50 cases per 100,000 people per year. The recent increase in MDS incidence observed in some studies is probably not the result of an actual increase in the number of cases, but reflects improvements in geriatric medical care and diagnosis.

Cancer mortality patterns among hairdressers and barbers in 24 US states, 1984 to 1995

We evaluated cancer mortality patterns among hairdressers and barbers, according to occupation, coded on 7.2 million death certificates in 24 states from 1984 to 1995. Of the 38,721 deaths among white and black hairdressers and barbers of both sexes, 9495 were from all malignant neoplasms. Mortality odds ratios were significantly elevated for all malignant neoplasms, lung cancer, and all lymphatic and hemopoietic cancers among black and white female hairdressers. White female hairdressers had significant excess mortality from cancers of the stomach, colon, pancreas, breast, and bladder and from non-Hodgkin's lymphoma and lymphoid leukemia; mortality from these cancers was also elevated among black female hairdressers. White male hairdressers had significantly elevated mortality from non-melanoma skin cancer and non-Hodgkin's lymphoma. Mortality from all malignant neoplasms, although significantly elevated among both white and black female hairdressers, was significantly below the null for white male hairdressers. Black and white male barbers had significantly elevated mortality from stomach and pharyngeal cancer, respectively. A significant deficit in mortality from all neoplasms and cancers of the pancreas, lung, and prostate was noted for white male barbers. This large study of cancer mortality among hairdressers and barbers showed some differences in mortality patterns by gender and race. Further studies are required to determine if specific occupational exposures may explain some of the elevated cancer rates.

A multicenter case-control study in Italy on hematolymphopoietic neoplasms and occupation

We conducted a population-based, case-control study on hematolymphopoietic malignancies in 12 areas in Italy to investigate associations between different hematolymphopoietic malignancies and exposure to solvents and pesticides. We collected all incident cases 20-74 years of age from 12 areas, with a combined population of approximately 7 million residents. The control group was formed by a random sample of the study population. Data presented in this paper refer to 2,737 interviewed cases of 3,357 eligible cases and to 1,779 of 2,391 eligible controls. We analyzed risks associated with occupation using job-title information to evaluate disease pattern according to job category. An earlier publication presented results for women; here, we report the findings for men and discuss the overall patterns in both genders. The most consistent overall finding was an approximate doubling in relative risk for all four types of malignancies among male managers and related occupations. Several additional occupations were associated with elevated risk of one or more malignancies among men. These included cooks, waiters, and bartenders, and building caretakers and cleaners, for non-Hodgkin's lymphoma; textile workers and machinery fitters for Hodgkin's lymphoma; metal processors, material handlers, rubber workers, and painters for leukemia; and hairdressers, metal processors, tailors, electrical workers, and plumbers for multiple myeloma. The finding of increased risk of non-Hodgkin's lymphoma among both male and female cooks, waiters, and bartenders has not been previously reported; nor has the elevated risk of leukemia among material handlers. Among people engaged in agriculture, those employed as tractor drivers and as "orchard, vineyard, and related tree and shrub workers" appeared to be at increased risk for hematolymphopoietic malignancies.

Use of hair dyes, hematopoietic neoplasms, and lymphomas: a literature review. I. Leukemias and myelodysplastic syndromes

We review published epidemiologic studies on personal use of hair dyes and leukemias and myelodysplastic syndromes (MDS). A subsequent article will review studies on lymphomas and multiple myeloma. A computerized literature search for the years 1966 through 1996 was completed using MEDLINE. Data were extracted using a standardized form that recorded study design, study population, type of cases, comparison group, sources of data on personal exposure to hair dyes, method of data collection, type of exposure data collected, covariates, and results. The above search identified 13 epidemiologic studies on the possible association between personal use of hair dyes and leukemias and MDS. Although there are some reports of positive associations, overall the evidence linking personal use of hair dyes to various leukemia and MDS subgroups is weak. One cannot definitively rule out an association, however, because of the methodologic limitations, such as small numbers of exposed cases and lack of detailed exposure information. Any further research would need much better assessment of hair dye use, including product type, color frequency, duration, and changes in use over time, and adequate statistical power.