Risk of non-Hodgkin lymphoma associated with occupational exposure to solvents, metals, organic dusts and PCBs (Australia)

Investigation of occupational risk factors for the development of non-Hodgkin's lymphoma in adults: A hospital-based case-control study

Non-Hodgkin's Lymphoma (NHL) is a malignancy of the lymphoid lineage of the hematopoietic system has worldwide, especially in developed countries. Better diagnostic and recording techniques, longer life expectancy, and greater exposure to risk factors are hypotheses for this growing incidence curve. Occupational exposures to chemical, biological, and physical agents have also been associated with NHL development, but the results are still controversial. We have investigated the occupational and lifestyle case-control study design with 214 adult patients and 452 population controls. Socio-demographic, clinical, and occupational exposure data were obtained through individual interviews with a standardized questionnaire. Clinical, laboratory, and histopathological data were obtained through medical records. Risk of NHL (any subtype), B-cell lymphoma, DLBCL, Follicular lymphoma and T-cell lymphoma was elevated among the those who had ever been exposed to any solvents, hydrocarbon solvents, pesticides, meat and meat products, and sunlight and tended to increase by years of exposure. A significant upward trend with years of exposure was detected for any solvents and hydrocarbon solvents (NHL (any subtype) p-value for trend<0.001), B-cell lymphoma (p-value for trend<0.001), and T-cell lymphoma (p-value for trend<0.023), pesticides (NHL (any subtype), p for trend<0.001) and T-cell lymphoma (p for trend<0.002), meat and meat products (NHL (any subtype) (p for trend<0.001) and DLBCL (p for trend<0.001), and sunlight (B-cell lymphoma (p for trend<0.001). The results of this study agree line with other international studies, can be extrapolated to other countries that have the same socio-demographic and occupational characteristics as Brazil and support strategies for surveillance and control of work-related cancer.

Long-term exposure to ambient air pollution and risk of leukemia and lymphoma in a pooled European cohort

Leukemia and lymphoma are the two most common forms of hematologic malignancy, and their etiology is largely unknown. Pathophysiological mechanisms suggest a possible association with air pollution, but little empirical evidence is available. We aimed to investigate the association between long-term residential exposure to outdoor air pollution and risk of leukemia and lymphoma. We pooled data from four cohorts from three European countries as part of the "Effects of Low-level Air Pollution: a Study in Europe" (ELAPSE) collaboration. We used Europe-wide land use regression models to assess annual mean concentrations of fine particulate matter (PM2.5), nitrogen dioxide (NO2), black carbon (BC) and ozone (O3) at residences. We also estimated concentrations of PM2.5 elemental components: copper (Cu), iron (Fe), zinc (Zn); sulfur (S); nickel (Ni), vanadium (V), silicon (Si) and potassium (K). We applied Cox proportional hazards models to investigate the associations. Among the study population of 247,436 individuals, 760 leukemia and 1122 lymphoma cases were diagnosed during 4,656,140 person-years of follow-up. The results showed a leukemia hazard ratio (HR) of 1.13 (95% confidence intervals [CI]: 1.01-1.26) per 10 μg/m3 NO2, which was robust in two-pollutant models and consistent across the four cohorts and according to smoking status. Sex-specific analyses suggested that this association was confined to the male population. Further, the results showed increased lymphoma HRs for PM2.5 (HR = 1.16; 95% CI: 1.02-1.34) and potassium content of PM2.5, which were consistent in two-pollutant models and according to sex. Our results suggest that air pollution at the residence may be associated with adult leukemia and lymphoma.

Long-term occupational exposures on disability-free survival and mortality in older adults

BACKGROUND

The impact of long-term occupational exposures on health in older adults is increasingly relevant as populations age. To date, no studies have reported their impact on survival free of disability in older adults.

AIMS

We aimed to investigate the association between long-term occupational exposure and disability-free survival (DFS), all-cause mortality and cause-specific mortality in initially healthy older adults.

METHODS

We analysed data from 12 215 healthy participants in the ASPirin in Reducing Events in the Elderly (ASPREE) study whose mean age was 75 years. Their work history was collated with the 'ALOHA-plus JEM' (Job Exposure Matrix) to assign occupational exposures. The primary endpoint, DFS, was a composite measure of death, dementia or persistent physical disability. The secondary endpoint, mortality, was classified according to the underlying cause. Cox proportional hazard models were used to calculate hazard ratios and 95% confidence intervals, adjusted for confounders.

RESULTS

A total of 1835 individuals reached the DFS endpoint during the median 4.7 years follow-up period. Both ever-high and cumulative exposure to all dusts and all pesticides during a person's working years were associated with reduced DFS. Compared to no exposure, men with high exposure to dusts and pesticides had a reduced DFS. Neither of these exposures were significantly associated with all-cause mortality. Men with high occupational exposure to solvents and women exposed to dusts experienced higher all-cause and cancer-related mortality.

CONCLUSIONS

Long-term occupational exposure to all dusts and pesticides was associated with a reduced DFS and increased mortality in community-dwelling healthy older adults.

Cancer incidence among male construction workers in Korea: a standardized incidence ratio analysis, 2009-2015

OBJECTIVES

Construction workers face an elevated risk for several types of cancer. Nevertheless, there is a lack of large-scale epidemiological studies examining the risk of all cancers in construction workers. This study aimed to investigate the risk of various cancers in male construction workers using the Korean National Health Insurance Service (NHIS) database.

METHODS

We used data from the NHIS database from 2009 to 2015. Construction workers were identified using the Korean Standard Industrial Classification code. We calculated the age-standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for cancer occurrence in male construction workers compared to all male workers.

RESULTS

Compared to all male workers, the SIRs for esophageal cancer (SIR, 1.24; 95% CI, 1.07 to 1.42) and malignant neoplasms of the liver and intrahepatic bile ducts (SIR, 1.18; 95% CI, 1.13 to 1.24) were significantly higher in male construction workers. The SIRs for malignant neoplasms of the urinary tract (SIR, 1.19; 95% CI, 1.05 to 1.35) and non-Hodgkin lymphoma (SIR, 1.21; 95% CI, 1.02 to 1.43) were significantly elevated in building construction workers. The SIR for malignant neoplasms of the trachea, bronchus, and lung (SIR, 1.16; 95% CI, 1.03 to 1.29) was significantly higher in heavy and civil engineering workers.

CONCLUSIONS

Male construction workers have an increased risk for esophageal cancer, liver cancer, lung cancer, and non- Hodgkin's cancer. Our results indicate that tailored strategies for cancer prevention should be developed for construction workers.

Modeling historic environmental pollutant exposures and non-Hodgkin lymphoma risk

Environmental exposures to chemicals are suspected risk factors for non-Hodgkin lymphoma (NHL), but few studies have assessed historic environmental risk factors. In this study, we estimated the associations between NHL and 1) historic environmental pollutant emissions from the Risk Screening Environmental Indicators (RSEI) model, which uses a database from the Environmental Protection Agency of toxic release emissions to air, water, and land, and 2) chemical mixtures measured in house dust (groups of PCBs, PAHs, and two mixtures of pesticides) for study participants enrolled in the NCI-SEER population-based case-control study (1998-2000) at four SEER centers - Detroit, Iowa, Los Angeles County, and Seattle. We assigned 11 years of annual temporally-varying historic environmental exposure scores by intersecting residential locations from participants' residential histories with a fine grid from the RSEI model and by performing inverse distance weighting between facilities releasing specific carcinogenic chemicals and residential locations for spatially-precise exposure assignments. We used Bayesian index low-rank kriging multiple membership models to identify important lag times for RSEI scores, cumulative effects of RSEI scores, and specific carcinogenic chemical releases into the environment. We found a significant positive association between RSEI scores and NHL at the maximum time lag of 11 years (OR = 1.17, 95% CI (1.06, 1.32)) and a significant cumulative RSEI score effect (OR = 1.30, 95% CI (1.02, 1.84)) for long-term residents in Detroit, where benzene and trichloroethylene were the most important chemicals driving this association. Additionally, we identified significant inverse associations for two study centers and time lags that did not persist in cumulative exposure models. Large weights for dichloromethane and pentachlorophenol in models of cumulative exposure also support evidence for their association with NHL risk. These results underscore the importance of considering historic and cumulative environmental exposures and using residential histories for diseases with long latency periods such as NHL.

Childhood cancer risk in offspring of parents occupationally exposed to dusts: A register-based nested case-control study from Sweden of 5 decades

Background

Some largely inconsistent associations between parental occupational dust exposure and childhood cancer have been reported, with maternal exposures inadequately studied. The authors examined whether maternal or paternal occupational exposure to animal, wood, textile, or paper dust around a child's birth was associated with an increased risk of childhood cancer, both overall and by type (leukemias, lymphomas, central nervous system tumors, and other cancers).

Methods

In this nationwide, register‐based, case‐control study, children who were diagnosed with cancer from 1960 to 2015 were compared with up to 25 matched controls regarding maternal and paternal occupational dust exposure (9653 cases in maternal analyses and 12,521 cases in paternal analyses). Exposures were assessed using a job‐exposure matrix and occupational information from census and register data. By using conditional logistic regression models, adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated.

Results

Neither maternal nor paternal occupational exposure to animal, wood, textile, or paper dust was associated with childhood cancer overall, leukemias, or central nervous system tumors. Maternal, but not paternal, wood dust exposure was associated with an increased risk of lymphoma (OR, 1.42; 95% CI, 1.10‐1.84), particularly non‐Hodgkin lymphoma (OR, 2.03; 95% CI, 1.21‐3.40).

Conclusions

The current study did not confirm the associations reported previously but is the first to suggest a link between maternal occupational exposure to wood dust around pregnancy and lymphoma in the offspring.

This large study does not confirm associations reported previously for leukemia and central nervous system tumors but is the first to suggest a link between maternal occupational exposure to wood dust around pregnancy and lymphoma in the offspring.

Benzene exposure and non-Hodgkin lymphoma: a systematic review and meta-analysis of human studies

BACKGROUND

Non-Hodgkin lymphoma comprises a heterogeneous group of cancers with unresolved aetiology, although risk factors include environmental exposures to toxic chemicals. Although the ubiquitous pollutant benzene is an established leukemogen, its potential to cause non-Hodgkin lymphoma has been widely debated. We aimed to examine the potential link between benzene exposure and risk of non-Hodgkin lymphoma in humans by evaluating a wide array of cohort and case-control studies using electronic systematic review.

METHODS

We did a comprehensive systematic review and meta-analysis of all qualified human epidemiological studies that assessed the relationship between benzene exposure and non-Hodgkin lymphoma. We queried the PubMed and Embase databases for relevant articles published before June 5, 2019, and applied the SysRev platform for study selection. All peer-reviewed human cohort and case-control studies that reported non-Hodgkin lymphoma risk estimates specifically for benzene exposure were eligible for inclusion. Studies that calculated relative risks (RRs) for industries or job types without identifying those specifically exposed to benzene, that combined non-Hodgkin lymphoma with other cancer types, or that reported many different solvent exposures together were excluded. From each study, two investigators independently extracted information on the study design, location, years, sample size, participation rates, age, sex, sources of cases and controls, diagnosis, histological verification, exposure assessment, results, adjustment, and statistical analysis, and subsequently assessed study quality. We calculated the meta-analysis relative risk (meta-RR) and CIs using the fixed effect and random effect models, as well as assessing publication bias.

FINDINGS

Our search yielded 2481 articles. After screening and removal of duplicates, 20 case-control studies and eight cohort studies were included in our meta-analysis, which included a total of 9587 patients with non-Hodgkin lymphoma. We reported an increased meta-relative risk (meta-RR) of 33% in highly exposed groups, when data were available (meta-RR 1·33 [95% CI 1·13-1·57], n=28). The meta-RR rose to 1·51 (1·22-1·87, n=18) in the studies that provided results specifically for highly exposed individuals. In particular, we reported a doubling of this risk for diffuse large B-cell lymphoma, a major non-Hodgkin lymphoma subtype (1·67 [1·01-2·77]). We also detected increased risks for follicular lymphoma (1·47 [0·95-2·27]) and hairy cell leukaemia (1·77 [0·99-3·16]), though they were not statistically significant. Funnel plot, Egger's test (p=0·77) and Begg's test (p=0·98) did not show evidence of publication bias. We evaluated the major aspects of causal inference and found evidence to support all the Hill considerations for assigning causation.

INTERPRETATION

Our findings suggest a causal link between benzene exposure and non-Hodgkin lymphoma, especially for diffuse large B-cell lymphoma.

FUNDING

National Institute of Environmental Health Sciences.

Occupational exposure to organic dust and risk of lymphoma subtypes in the EPILYMPH case-control study

Objectives This study aimed to estimate the risk of lymphoma and its major subtypes in relation to occupational exposure to specific organic dusts. Methods We explored the association in 1853 cases and 1997 controls who participated in the EpiLymph case-control study, conducted in six European countries in 1998-2004. Based on expert assessment of lifetime occupational exposures, we calculated the risk of the major lymphoma subtypes associated with exposure to six specific organic dusts, namely, flour, hardwood, softwood, natural textile, synthetic textile, and leather, and two generic (any types) groups: wood and textile dusts. Risk was predicted with unconditional regression modeling, adjusted by age, gender, study center, and education. Results We observed a 2.1-fold increase in risk of follicular lymphoma associated with ever exposure to leather dust [95% confidence interval (CI) 1.01-4.20]. After excluding subjects who ever worked in a farm or had ever been exposed to solvents, risk of B-cell lymphoma was elevated in relation to ever exposure to leather dust [odd ratio (OR) 2.2, 95% CI 1.00-4.78], but it was not supported by increasing trends with the exposure metrics. Risk of Hodgkin lymphoma was elevated (OR 2.0, 95% CI 0.95-4.30) for exposure to textile dust, with consistent upward trends by cumulative exposure and three independent exposure metrics combined (P=0.023, and P=0.0068, respectively). Conclusions Future, larger studies might provide further insights into the nature of the association we observed between exposure to textile dust and risk of Hodgkin lymphoma.

Long-term exposure to PM2.5 and its constituents and risk of Non-Hodgkin lymphoma in Denmark: A population-based case-control study

BACKGROUND

Particulate matter (PM) air pollution is a complex mixture and the various PM constituents likely affect health differently. The literature on the relationships among specific PM constituents and the risk of cancer is sparse. In this study, we aimed to evaluate the association of PM_2.5 and its constituents with the incidence of non-Hodgkin lymphoma (NHL) and the two main NHL subtypes.

METHODS

We undertook a nationwide register-based case-control study including 20,847 cases registered in the Danish Cancer Registry with NHL between 1989 and 2014. Among the entire Danish population, we selected 41,749 age and sex-matched controls randomly from the Civil Registration System. We assessed modelled outdoor PM concentrations at addresses of cases and controls with a state-of-the-art multi scale air pollution modelling system and used conditional logistic regression to estimate odds ratios (ORs) adjusted for individual and neighborhood level socio-demographic variables.

RESULTS

The 10-year time-weighted average concentrations of PM_2.5, primary carbonaceous particles (BC/OC), secondary inorganic aerosols (SIA), secondary organic aerosols (SOA) and sea salt were 17.4, 2.3, 7.8, 0.3, and 4.1 μg/m³, respectively among controls. The results showed higher risk for NHL in association with exposure to BC/OC (OR = 1.03; 95% CI: 1.00, 1.07, per interquartile range (IQR)) and SOA (OR = 1.54; 95% CI: 1.13, 2.09, per IQR). The results indicated a higher risk for follicular lymphoma in association with several PM components. Including PM_2.5 (OR = 1.16; 95% CI: 0.98-1.38), BC/OC (OR = 1.05; 95% CI: 0.97-1.14), SIA (OR = 1.44; 95% CI: 0.80-1.08), SOA (OR = 4.52; 95% CI: 0.86-23.83) per IQR.

CONCLUSION

This is the first study on PM constituents and the risk of NHL. The results indicated an association with primary carbonaceous and secondary organic PM. The results need replication in other settings before any firm conclusion can be reached.

Benzene exposure-response and risk of lymphoid neoplasms in Chinese workers: A multicenter case-cohort study

BACKGROUND

While international agreement supports a causal relationship of benzene exposure with acute myeloid leukemia, there is debate about benzene and lymphoid neoplasm risks.

METHODS

In a case-cohort study with follow-up of 110 631 Chinese workers during 1972-1999, we evaluated benzene exposure-response for non-Hodgkin lymphoma (NHL), lymphoid leukemias (LL), acute lymphocytic leukemia (ALL), and total lymphoid neoplasms (LN). We estimated benzene exposures using state-of-the-art hierarchical modeling of occupational factors calibrated with historical routine measurements and evaluated cumulative exposure-response using Cox regression.

RESULTS

NHL and other specified LN were increased in exposed vs unexposed workers. However, there was no evidence of exposure-response for NHL or other specified LN. Based on a linear exposure-response, relative risks at 100 parts per million-years (RR at 100 ppm-years) for cumulative benzene exposure using a 2-year lag (exposure at least 2 years before the time at risk) were 1.05 for NHL (95 percent confidence interval (CI) = 0.97, 1.27; 32 cases), 1.11 for LL (95% CI < 0, 1.66; 12 cases), 1.21 for ALL (95% CI < 0, 3.53; 10 cases), and 1.02 for total LN (95% CI < 0, 1.16; 49 cases). No statistically significant exposure-response trends were apparent for these LN for 2 to <10-year or ≥10-year lags. NHL risks were not significantly modified by sex, age, or year at first exposure, attained age, or time since exposure.

CONCLUSION

Given the study strengths and limitations, we found little evidence of exposure-response for benzene and NHL, LL, ALL, or total LN, although NHL and other specified LN were increased in exposed vs unexposed individuals.

Case-control investigation of occupational exposure to chlorinated solvents and non-Hodgkin's lymphoma

OBJECTIVES

Although many studies have investigated the association between trichloroethylene (TCE) exposure and non-Hodgkin's lymphoma (NHL), less is known about other chlorinated solvents. We extended our previous analysis of occupational TCE exposure in a multicentre population-based case-control study of NHL to investigate associations with five additional chlorinated solvents: 1,1,1,-trichloroethane, carbon tetrachloride, chloroform, methylene chloride and perchloroethylene.

METHODS

Cases (n=1189) and controls (n=982) provided detailed information on their occupational histories and workplace exposure to chlorinated solvents for selected occupations using job-specific interview modules. An industrial hygienist used this information and a review of the literature to assess occupational exposure to chlorinated solvents. We computed ORs and 95% CIs for different exposure metrics, with the unexposed group as the referent. We also computed ORs by NHL subtype.

RESULTS

High cumulative hours exposed to carbon tetrachloride was associated with NHL (>520 hours: OR 1.9; 95% CI 1.0 to 3.6; Ptrend=0.04). This association remained after restricting to jobs with high-intensity exposure (OR 2.0; 95% CI 1.1 to 3.8; P=0.03) and ≥90% exposure probability (OR 2.1; 95% CI 1.0 to 4.3; P=0.03), adjusting for TCE (OR 2.1; 95% CI 1.0- to 4.1; P=0.04) and incorporating a 15-year lag (OR 1.9; 95% CI 1.0 to 3.6; P=0.06). The other evaluated chlorinated solvents were not associated with NHL.

CONCLUSIONS

This is the first study using high-quality quantitative exposure assessment methods to identify a statistically significant elevated association between occupational exposure to carbon tetrachloride and NHL. Our findings, although limited by a small number of exposed cases, offer evidence that carbon tetrachloride may be a lymphomagen.

Ranking occupational contexts associated with risk of non-Hodgkin lymphoma

BACKGROUND

Risk factors associated with non-Hodgkin lymphoma (NHL) remain unknown, but certain occupational contexts (OCs) have been implicated. The objective of this study was to inventory, from the accumulated knowledge, associations between OCs and NHL risk.

METHODS

Literature was used to identify the NHL-associated OCs. For each context, items were ranked both by scientific interest and the association strength.

RESULTS

Three ranked lists of OCs related to NHL were constructed. We found that NHL was associated with 31 occupational activities, 91 occupational exposures, and 35 occupational activity-exposure combinations. Among them, 5 activities, 2 exposures, and 3 combinations, involving agricultural or industrial sector and solvents or pesticides, were highlighted with the highest publications number and the strongest association with NHL risk.

CONCLUSION

These results could be useful in both providing a ranked inventory of OCs associated with NHL risk and highlighting "hot" occupational activities and exposures. Am. J. Ind. Med. 59:561-574, 2016. © 2016 Wiley Periodicals, Inc.

Evaluation of Automatically Assigned Job-Specific Interview Modules

OBJECTIVE

In community-based epidemiological studies, job- and industry-specific 'modules' are often used to systematically obtain details about the subject's work tasks. The module assignment is often made by the interviewer, who may have insufficient occupational hygiene knowledge to assign the correct module. We evaluated, in the context of a case-control study of lymphoid neoplasms in Asia ('AsiaLymph'), the performance of an algorithm that provided automatic, real-time module assignment during a computer-assisted personal interview.

METHODS

AsiaLymph's occupational component began with a lifetime occupational history questionnaire with free-text responses and three solvent exposure screening questions. To assign each job to one of 23 study-specific modules, an algorithm automatically searched the free-text responses to the questions 'job title' and 'product made or services provided by employer' using a list of module-specific keywords, comprising over 5800 keywords in English, Traditional and Simplified Chinese. Hierarchical decision rules were used when the keyword match triggered multiple modules. If no keyword match was identified, a generic solvent module was assigned if the subject responded 'yes' to any of the three solvent screening questions. If these question responses were all 'no', a work location module was assigned, which redirected the subject to the farming, teaching, health professional, solvent, or industry solvent modules or ended the questions for that job, depending on the location response. We conducted a reliability assessment that compared the algorithm-assigned modules to consensus module assignments made by two industrial hygienists for a subset of 1251 (of 11409) jobs selected using a stratified random selection procedure using module-specific strata. Discordant assignments between the algorithm and consensus assignments (483 jobs) were qualitatively reviewed by the hygienists to evaluate the potential information lost from missed questions with using the algorithm-assigned module (none, low, medium, high).

RESULTS

The most frequently assigned modules were the work location (33%), solvent (20%), farming and food industry (19%), and dry cleaning and textile industry (6.4%) modules. In the reliability subset, the algorithm assignment had an exact match to the expert consensus-assigned module for 722 (57.7%) of the 1251 jobs. Overall, adjusted for the proportion of jobs in each stratum, we estimated that 86% of the algorithm-assigned modules would result in no information loss, 2% would have low information loss, and 12% would have medium to high information loss. Medium to high information loss occurred for <10% of the jobs assigned the generic solvent module and for 21, 32, and 31% of the jobs assigned the work location module with location responses of 'someplace else', 'factory', and 'don't know', respectively. Other work location responses had ≤8% with medium to high information loss because of redirections to other modules. Medium to high information loss occurred more frequently when a job description matched with multiple keywords pointing to different modules (29-69%, depending on the triggered assignment rule).

CONCLUSIONS

These evaluations demonstrated that automatically assigned modules can reliably reproduce an expert's module assignment without the direct involvement of an industrial hygienist or interviewer. The feasibility of adapting this framework to other studies will be language- and exposure-specific.

Occupation and Risk of Non-Hodgkin Lymphoma and Its Subtypes: A Pooled Analysis from the InterLymph Consortium

BACKGROUND

Various occupations have been associated with an elevated risk of non-Hodgkin lymphoma (NHL), but results have been inconsistent across studies.

OBJECTIVES

We investigated occupational risk of NHL and of four common NHL subtypes with particular focus on occupations of a priori interest.

METHODS

We conducted a pooled analysis of 10,046 cases and 12,025 controls from 10 NHL studies participating in the InterLymph Consortium. We harmonized the occupational coding using the 1968 International Standard Classification of Occupations (ISCO-1968) and grouped occupations previously associated with NHL into 25 a priori groups. Odds ratios (ORs) adjusted for center, age, and sex were determined for NHL overall and for the following four subtypes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and peripheral T-cell lymphoma (PTCL).

RESULTS

We confirmed previously reported positive associations between NHL and farming occupations [field crop/vegetable farm workers OR = 1.26; 95% confidence interval (CI): 1.05, 1.51; general farm workers OR = 1.19; 95% CI: 1.03, 1.37]; we also confirmed associations of NHL with specific occupations such as women's hairdressers (OR = 1.34; 95% CI: 1.02, 1.74), charworkers/cleaners (OR = 1.17; 95% CI: 1.01, 1.36), spray-painters (OR = 2.07; 95% CI: 1.30, 3.29), electrical wiremen (OR = 1.24; 95% CI: 1.00, 1.54), and carpenters (OR = 1.42; 95% CI: 1.04, 1.93). We observed subtype-specific associations for DLBCL and CLL/SLL in women's hairdressers and for DLBCL and PTCL in textile workers.

CONCLUSIONS

Our pooled analysis of 10 international studies adds to evidence suggesting that farming, hairdressing, and textile industry-related exposures may contribute to NHL risk. Associations with women's hairdresser and textile occupations may be specific for certain NHL subtypes.

CITATION

't Mannetje A, De Roos AJ, Boffetta P, Vermeulen R, Benke G, Fritschi L, Brennan P, Foretova L, Maynadié M, Becker N, Nieters A, Staines A, Campagna M, Chiu B, Clavel J, de Sanjose S, Hartge P, Holly EA, Bracci P, Linet MS, Monnereau A, Orsi L, Purdue MP, Rothman N, Lan Q, Kane E, Seniori Costantini A, Miligi L, Spinelli JJ, Zheng T, Cocco P, Kricker A. 2016. Occupation and risk of non-Hodgkin lymphoma and its subtypes: a pooled analysis from the InterLymph Consortium. Environ Health Perspect 124:396-405; http://dx.doi.org/10.1289/ehp.1409294.

Chronic TCDD exposure results in the dysregulation of gene expression in splenic B-lymphocytes and in the impairments in T-cell and B-cell differentiation in mouse model

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure in humans is associated with marked immune suppressions and increased incidence of lymphoblastic diseases. To elucidate mechanisms of impairments in humoral immune responses, we used a murine model. Following a 20-week administration of low doses of TCDD, we observed severely reduced antibody titers, dramatically decreased number of splenic Th1 and Th2 cells and an increase in CD19(+) B cells. Transcriptional profiling of CD19(+) B cells showed that markers of pre-B cells were significantly elevated, indicating delayed B cell maturation. These changes in B cells were accompanied by decreases of T helper cell numbers and reduced IgM and IgG titers. A transcriptome analysis of splenic B cells followed by Ingenuity Pathway Analysis (IPA) revealed a set of differentially expressed genes known to play roles in tumorigenesis, cell-proliferation and cell-migration. The most up-regulated transcript gene was Eph receptor A2 (EphA2), a known oncogene, and the most down-regulated transcript was ZBTB16 that codes for a negative transcriptional regulator important in epigenetic chromatin remodeling. IPA identified cAMP-responsive element modulator (CREM) and cAMP-responsive element binding protein 1 (CREB1) as top upstream regulators. Consistently, a MAPPER promoter database analysis showed that all top dysregulated genes had CREM and/or CREB1 binding sites in their promoter regions. In summary, our data showed that chronic TCDD exposure in mice caused suppressed humoral immunity accompanied with profound dysregulation of gene expression in splenic B-lymphocytes, likely through cAMP-dependent pathways. This dysregulation resulted in impairments in T-cell and B-cell differentiation and activation of the tumorigenic transcription program.

Association between Occupational Exposure to Wood Dust and Cancer: A Systematic Review and Meta-Analysis

Objective

To perform a systematic review to analyze the association between occupational exposure to wood dust and cancer.

Methods

A systematic literature search of entries made in the MEDLINE-PubMed database between 1957 and 2013 was conducted to identify studies that had assessed the relationship between occupational exposure to wood dust and different types of cancer. A meta-analysis of selected case-control and cohort studies was subsequently performed.

Results

A total of 114 studies were identified and 70 were selected for review. Of these, 42 studies focused on the relationship between wood dust and nasal cancer (n = 22), lung cancer (n = 11), and other types of cancer (n = 9). Low-to-moderate quality evidence that wood dust acts as a carcinogen was obtained, and a stronger association between wood dust and nasal adenocarcinoma was observed. A lesser association between wood dust exposure and lung cancer was also observed. Several studies suggested that there is a relationship between wood dust and the onset of other cancers, although there was no evidence to establish an association. A meta-analysis that included four case-controls studies showed that workers exposed to wood dust exhibited higher rates of nasal adenocarcinoma than other workers (odds ratio = 10.28; 95% confidence interval: 5.92 and 17.85; P<0,0001), although a large degree of heterogeneity was found.

Conclusions

Low-to-moderate quality evidence supports a causal association between cancer and occupational exposure to wood dust, and this association was stronger for nasal adenocarcinoma than for lung cancer. There was no evidence of an association between wood dust exposure and the other cancers examined.

Hospitalization due to cancer among German seafarers

OBJECTIVES

To evaluate the relative risk of cancer among male German seafarers employed on German vessels in respect of various shipboard ranks and types of vessel.

METHODS

The seafarers' cancer discharge diagnoses from hospital were compared with those discharge diagnoses from the German general population and expressed as a standardized hospitalization ratio (SHR).

RESULTS

The examined seafarers (on average 23,436 per year) showed a higher SHR for malignant neoplasms at all sites, in decreasing order for leukemia, non-Hodgkin lymphoma (NHL), respiratory cancer, and non-melanoma skin cancer. Seafarers employed on tankers showed a considerably elevated SHR for malignant neoplasms at all sites, which was mainly attributable to their high SHR for leukemia and respiratory cancer.

CONCLUSIONS

Seafaring occupations pose an elevated risk of certain cancers. Further studies are required to evaluate to what extent occupational exposure to carcinogenic substances and lifestyle-related unhealthy behaviours contribute to the increased risk of cancer in seafarers.

Polymorphisms in xenobiotic metabolizing genes (EPHX1, NQO1 and PON1) in lymphoma susceptibility: a case control study

Background

The interplay between genetic susceptibility and carcinogenic exposure is important in the development of haematopoietic malignancies. EPHX1, NQO1 and PON1 are three genes encoding proteins directly involved in the detoxification of potential carcinogens.

Methods

We have studied the prevalence of three functional polymorphisms affecting these genes rs1051740 EPHX1, rs1800566 NQO1 and rs662 PON1 in 215 patients with lymphoma and 214 healthy controls.

Results

Genotype frequencies for EPHX and NQO1 polymorphisms did not show any correlation with disease. In contrast, the GG genotype in the PON1 polymorphism was found to be strongly associated with the disease (15.3% vs. 4.7%; OR = 3.7 CI (95%): 1.8-7.7; p < 0.001). According to the pathological diagnosis this association was related to follicular (p = 0.004) and diffuse large B-cell (p = 0.016) lymphomas.

Conclusions

Despite the fact that further confirmation is needed, this study shows that the PON1 GG genotype in rs662 polymorphism could be a risk factor for B-cell lymphomas.

Occupational solvent exposure, genetic variation of DNA repair genes, and the risk of non-Hodgkin's lymphoma

The main objective of this study was to test the hypothesis that genetic variations in DNA repair genes may modify the association between occupational exposure to solvents and the risk of non-Hodgkin's lymphoma (NHL). A population-based case-control study was conducted on Connecticut women including 518 histologically confirmed incident NHL cases and 597 controls. Unconditional logistic regression models were used to estimate the odds ratios and effect modification from the 30 single nucleotide polymorphisms in 16 DNA repair genes of the association between solvent exposure and the risk of NHL overall and subtypes. Single nucleotide polymorphisms in MGMT (rs12917) and NBS1 (rs1805794) significantly modified the association between exposure to chlorinated solvents and the risk of NHL (Pfor interaction=0.0003 and 0.0048, respectively). After stratification by major NHL histological subtypes, MGMT (rs12917) modified the association between chlorinated solvents and the risk of diffuse large B-cell lymphoma (Pfor interaction=0.0027) and follicular lymphoma (Pfor interaction=0.0024). A significant interaction was also observed between occupational exposure to benzene and BRCA2 (rs144848) for NHL overall (Pfor interaction=0.0042). Our study results suggest that genetic variations in DNA repair genes modify the association between occupational exposure to solvents and the risk of NHL.

Current understanding of lifestyle and environmental factors and risk of non-hodgkin lymphoma: an epidemiological update

The incidence rates of non-Hodgkin lymphoma (NHL) have steadily increased over the last several decades in the United States, and the temporal trends in incidence can only be partially explained by the HIV epidemic. In 1992, an international workshop sponsored by the United States National Cancer Institute concluded that there was an “emerging epidemic” of NHL and emphasized the need to investigate the factors responsible for the increasing incidence of this disease. Over the past two decades, numerous epidemiological studies have examined the risk factors for NHL, particularly for putative environmental and lifestyle risk factors, and international consortia have been established in order to investigate rare exposures and NHL subtype-specific associations. While few consistent risk factors for NHL aside from immunosuppression and certain infectious agents have emerged, suggestive associations with several lifestyle and environmental factors have been reported in epidemiologic studies. Further, increasing evidence has suggested that the effects of these and other exposures may be limited to or stronger for particular NHL subtypes. This paper examines the progress that has been made over the last twenty years in elucidating the etiology of NHL, with a primary emphasis on lifestyle factors and environmental exposures.

Current status of the epidemiologic evidence linking polychlorinated biphenyls and non-hodgkin lymphoma, and the role of immune dysregulation

BACKGROUND

Although case-control studies conducted to date have largely affirmed the relationship between polychlorinated biphenyls (PCBs) and non-Hodgkin lymphoma (NHL), occupational cohort studies of PCB-exposed workers have been generally interpreted as negative, thereby raising doubts about a potential causal association. A common theme of immune dysregulation unifies many of NHL's strongest risk factors, and several authors have posited that subclinical immune dysregulation may increase NHL risk by decreasing host resistance, reducing control of cellular proliferation and differentiation, and diminishing tumor surveillance mechanisms.

OBJECTIVES

The goals of this review were a) to evaluate the epidemiological research examining the association between PCB exposure and NHL and discuss the contribution to the weight of evidence of case-control studies and occupational cohort studies; and b) to summarize the evidence for immune dysregulation as a means by which PCBs may cause NHL.

METHODS

We performed a literature search using PubMed and seven additional online biomedical and toxicological referencing libraries to identify literature published through August 2011.

DISCUSSION AND CONCLUSIONS

Overall, we conclude that the weight of evidence supports a causal role of PCBs in lymphomagenesis. The strongest epidemiological evidence for the relationship between PCBs and NHL comes from case-control studies conducted among the general population. Epidemiological and toxicological data demonstrating immunosuppressive and inflammatory effects of PCBs further contribute to the weight of evidence by providing a plausible explanation for how PCBs can cause NHL through immune dysregulation.

Risk Factors of Non-Hodgkin Lymphoma

INTRODUCTION: Despite decades of intensive research, Non-Hodgkin Lymphoma (NHL) remains poorly understood and is largely incurable. NHL is a heterogeneous group of malignancies with multiple subtypes, each of which has distinct morphologic, immunophenotypic, and clinical features. Identifying the risk factors for NHL may improve our understanding of the underlying biological mechanisms and have an impact on clinical practice. AREAS COVERED: This article provides a review of several aspects of NHL, including epidemiology and subtype classification, clinical, environmental, genetic, and genomic risk factors identified for etiology and prognosis, and available statistical and bioinformatics tools for identification of genetic and genomic risk factors from the analysis of high-throughput studies. EXPERT OPINION: Multiple clinical and environmental risk factors have been identified. However, they have failed to provide practically effective prediction. Genetic and genomic risk factors identified from high-throughput studies have suffered a lack of reproducibility. The identification of genetic/genomic risk factors demands innovative statistical and bioinformatics tools. Although multiple analysis methods have been developed, there is still room for improvement. There is a critical need for well-designed, prospective, large-scale pangenomic studies.

[Non dietetic environmental risk factors in prostate cancer]

INTRODUCTION

The aim is to update and disclose the main environmental risk factors, excluding dietary factors, involved in the etiopathology of prostate cancer.

MATERIALS AND METHOD

Bibliographic review of the last 25 years of non-dietary environmental risk factors associated with prostate cancer between 1985 and 2010, obtained from MedLine, CancerLit, Science Citation Index and Embase. The search profiles were Environmental Risk Factors/Tobacco/Infectious-Inflammatory Factors/Pesticides/Vasectomy/Occupational Exposures/Chemoprevention Agents/Radiation and Prostate Cancer.

RESULTS

While some non-dietary environmental risk factors increase the risk of acquiring the disease, others decrease it. Of the former, it is worth mentioning exposal to tobacco smoke, chronic infectious-inflammatory prostatic processes and occupational exposure to cadmium, herbicides and pesticides. The first factors that reduce the risk are the use of chemopreventive drugs (Finasterida, Dutasteride) and exposure to ultraviolet solar radiation. With the current data, a vasectomy does not influence the risk of developing the disease.

CONCLUSIONS

The slow process of prostate carcinogenesis is the final result of the interaction of constitutional risk and environmental factors. Non-dietary environmental factors play an important role in the etiopathology of this disease. To appropriately assess the risk factors, extensive case studies that include all the possible variables must be analysed.

Risk of Aplastic Anemia and Pesticide and Other Chemical Exposures

Risk of aplastic anemia (AA) from occupational exposures to pesticides and industrial chemicals was evaluated in a hospital-based case control study in Thailand (541 cases of AA and 2261 controls). Exposure data were obtained via participants’ self-reports and by experts’ assessments and the data from these 2 exposure assessment methods were compared. There was an increased risk of AA associated with several classes of pesticides measured by either self-report or expert assessment. The strongest associations were seen in those whose exposures were identified both by self-report and by expert assessment. Comparing very high/high to no exposure, odds ratios (95% confidence intervals) were as follows: for organophosphates 3.20 (1.87-5.46), carbamates 4.75 (1.92-11.75), organochlorines 6.04 (1.31-27.84), and paraquat 2.17 (1.11-4.25). There were correlations among the pesticides because many types were used in the same job, so it was not possible to determine whether these risks were independent or because of confounding of one by another.

Genetic variation in metabolic genes, occupational solvent exposure, and risk of non-hodgkin lymphoma

Using 1996-2000 data among Connecticut women, the authors evaluated whether genetic variation in 4 metabolic genes modifies organic solvent associations with non-Hodgkin lymphoma and 5 major histologic subtypes. P(interaction) values were determined from cross-product terms between dichotomous (ever/never) solvent variables and genotypes at examined loci in unconditional logistic regression models. The false discovery rate method was used to account for multiple comparisons. Overall associations between the chlorinated solvents dichloromethane (odds ratio (OR) = 1.69, 95% confidence interval (CI): 1.06, 2.69), carbon tetrachloride (OR = 2.33, 95% CI: 1.23, 4.40), and methyl chloride (OR = 1.44, 95% CI: 0.94, 2.20) and total non-Hodgkin lymphoma were increased among women TT for rs2070673 in the cytochrome P4502E1 gene, CYP2E1 (dichloromethane: OR = 4.42, 95% CI: 2.03, 9.62; P(interaction) < 0.01; carbon tetrachloride: OR = 5.08, 95% CI: 1.82, 14.15; P(interaction) = 0.04; and methyl chloride: OR = 2.37, 95% CI: 1.24, 4.51; P(interaction) = 0.03). In contrast, no effects of these solvents were observed among TA/AA women. Similar patterns were observed for diffuse large B-cell lymphoma and follicular lymphoma, as well as marginal zone lymphoma for dichloromethane. The weak, nonsignificant overall association between benzene and diffuse large B-cell lymphoma (OR = 1.29, 95% CI: 0.84, 1.98) was increased among women AA for rs2234922 in the microsomal epoxide hydrolase gene, EPHX1 (OR = 1.77, 95% CI: 1.06, 2.97; P(interaction) = 0.06). In contrast, no effect was observed among AG/GG women. Additional studies with larger sample size are needed to replicate these findings.

A case-control study of occupational exposure to trichloroethylene and non-Hodgkin lymphoma

BACKGROUND

Previous epidemiologic findings suggest an association between exposure to trichloroethylene (TCE), a chlorinated solvent primarily used for vapor degreasing of metal parts, and non-Hodgkin lymphoma (NHL).

OBJECTIVES

We investigated the association between occupational TCE exposure and NHL within a population-based case-control study using detailed exposure assessment methods.

METHODS

Cases (n = 1,189; 76% participation rate) and controls (n = 982; 52% participation rate) provided information on their occupational histories and, for selected occupations, on possible workplace exposure to TCE using job-specific interview modules. An industrial hygienist assessed potential TCE exposure based on this information and a review of the TCE industrial hygiene literature. We computed odds ratios (ORs) and 95% confidence intervals (CIs) relating NHL and different metrics of estimated TCE exposure, categorized using tertiles among exposed controls, with unexposed subjects as the reference group.

RESULTS

We observed associations with NHL for the highest tertiles of estimated average weekly exposure (23 exposed cases; OR = 2.5; 95% CI, 1.1–6.1) and cumulative exposure (24 exposed cases; OR = 2.3; 95% CI, 1.0-5.0) to TCE. Tests for trend with these metrics surpassed or approached statistical significance (p-value for trend = 0.02 and 0.08, respectively); however, we did not observe dose–response relationships across the exposure levels. Overall, neither duration nor intensity of exposure was associated with NHL, although we observed an association with the lowest tertile of exposure duration (OR = 2.1; 95% CI, 1.0-4.7).

CONCLUSIONS

Our findings offer additional support for an association between high levels of exposure to TCE and increased risk of NHL. However, we cannot rule out the possibility of confounding from other chlorinated solvents used for vapor degreasing and note that our exposure assessment methods have not been validated.

Cancer incidence among pesticide applicators exposed to butylate in the Agricultural Health Study (AHS)

Although limited, epidemiologic studies suggest possible associations between butylate use and cancer risk, specifically prostate cancer and non-Hodgkin lymphoma (NHL). We examined butylate use and cancer risk more broadly in the AHS, a cohort of licensed pesticide applicators in Iowa and North Carolina. Pesticide use information was collected using self-administered questionnaires. Poisson regression was used to calculate rate ratios (RR) and 95% confidence intervals (CI). Two exposure metrics were used: lifetime exposure days (LD) and intensity-weighted lifetime exposure days (IWLD). We used two referent groups: unexposed to butylate and the lowest butylate usage category. This analysis included 19,655 applicators with complete butylate use information; 5297 applicators were exposed to butylate, making this the largest study of butylate to date. The mean follow-up time since enrollment was 9 years. Prostate cancer risk was significantly elevated among applicators in the highest LD category in both referent groups (low-exposed referent: RR(LD)=2.09, 95% CI=1.27-3.44). We observed a significantly elevated joint effect of prostate cancer family history and high butylate usage across both exposure metrics and both referent groups (low-exposed referent: RR(LD)=2.00, 95% CI=1.07-3.74), and a non-significant, elevated interaction between butylate use and prostate cancer family history, similar to a previous AHS finding. Statistically significant increased risks and exposure-response trends were seen for all lymphohematopoietic cancers (AL) and NHL for both exposure metrics and referent groups (low-exposed referent: AL:RR(LD)=2.27, 95% CI=1.18-4.37; NHL: RR(LD)=3.44, 95% CI=1.29-9.21). Our analysis did not find meaningful associations for other cancers analyzed. Further study is warranted for AL, NHL and prostate cancers.

Clustering of cancer among families of cases with Hodgkin Lymphoma (HL), Multiple Myeloma (MM), Non-Hodgkin's Lymphoma (NHL), Soft Tissue Sarcoma (STS) and control subjects

Background

A positive family history of chronic diseases including cancer can be used as an index of genetic and shared environmental influences. The tumours studied have several putative risk factors in common including occupational exposure to certain pesticides and a positive family history of cancer.

Methods

We conducted population-based studies of Hodgkin lymphoma (HL), Multiple Myeloma (MM), non-Hodgkin's Lymphoma (NHL), and Soft Tissue Sarcoma (STS) among male incident case and control subjects in six Canadian provinces. The postal questionnaire was used to collect personal demographic data, a medical history, a lifetime occupational history, smoking pattern, and the information on family history of cancer. The family history of cancer was restricted to first degree relatives and included relationship to the index subjects and the types of tumours diagnosed among relatives. The information was collected on 1528 cases (HL (n = 316), MM (n = 342), NHL (n = 513), STS (n = 357)) and 1506 age ± 2 years and province of residence matched control subjects. Conditional logistic regression analyses adjusted for the matching variables were conducted.

Results

We found that most families were cancer free, and a minority included two or more affected relatives. HL [(OR_adj (95% CI) 1.79 (1.33, 2.42)], MM (1.38(1.07, 1.78)), NHL (1.43 (1.15, 1.77)), and STS cases (1.30(1.00, 1.68)) had higher incidence of cancer if any first degree relative was affected with cancer compared to control families. Constructing mutually exclusive categories combining "family history of cancer" (yes, no) and "pesticide exposure ≥10 hours per year" (yes, no) indicated that a positive family history was important for HL (2.25(1.61, 3.15)), and for the combination of the two exposures increased risk for MM (1.69(1.14,2.51)). Also, a positive family history of cancer both with (1.72 (1.21, 2.45)) and without pesticide exposure (1.43(1.12, 1.83)) increased risk of NHL.

Conclusion

HL, MM, NHL, and STS cases had higher incidence of cancer if any first degree relative affected with cancer compared to control families. A positive family history of cancer and/or shared environmental exposure to agricultural chemicals play an important role in the development of cancer.

Occupational exposure to solvents and risk of non-Hodgkin lymphoma in Connecticut women

A population-based case-control study involving 601 incident cases of non-Hodgkin lymphoma (NHL) and 717 controls was conducted in 1996-2000 among Connecticut women to examine associations with exposure to organic solvents. A job-exposure matrix was used to assess occupational exposures. Increased risk of NHL was associated with occupational exposure to chlorinated solvents (odds ratio (OR) = 1.4, 95% confidence interval (CI): 1.1, 1.8) and carbon tetrachloride (OR = 2.3, 95% CI: 1.3, 4.0). Those ever exposed to any organic solvent in work settings had a borderline increased risk of NHL (OR = 1.3, 95% CI: 1.0, 1.6); moreover, a significantly increased risk was observed for those with average probability of exposure to any organic solvent at medium-high level (OR = 1.5, 95% CI: 1.1, 1.9). A borderline increased risk was also found for ever exposure to formaldehyde (OR = 1.3, 95% CI: 1.0, 1.7) in work settings. Risk of NHL increased with increasing average intensity (P = 0.01), average probability (P < 0.01), cumulative intensity (P = 0.01), and cumulative probability (P < 0.01) level of organic solvent and with average probability level (P = 0.02) and cumulative intensity level of chlorinated solvent (P = 0.02). Analyses by NHL subtype showed a risk pattern for diffuse large B-cell lymphoma similar to that for overall NHL, with stronger evidence of an association with benzene exposure. Results suggest an increased risk of NHL associated with occupational exposure to organic solvents for women.

Meta-analysis of benzene exposure and non-Hodgkin lymphoma: biases could mask an important association

OBJECTIVES

Benzene is a widely recognised cause of leukaemia but its association with non-Hodgkin's lymphoma (NHL) is less well established. The goal of this project is to review the current published literature on this association.

METHODS

We performed a meta-analysis of cohort and case-control studies of benzene exposure and NHL and a meta-analysis of NHL and refinery work, a potential source of benzene exposure.

RESULTS

In 22 studies of benzene exposure, the summary relative risk for NHL was 1.22 (95% CI 1.02 to 1.47; one-sided p value = 0.01). When studies that likely included unexposed subjects in the "exposed" group were excluded, the summary relative risk increased to 1.49 (95% CI 1.12 to 1.97, n = 13), and when studies based solely on self-reported work history were excluded, the relative risk rose to 2.12 (95% CI 1.11 to 4.02, n = 6). In refinery workers, the summary relative risk for NHL in all 21 studies was 1.21 (95% CI 1.00 to 1.46; p = 0.02). When adjusted for the healthy worker effect, this relative risk estimate increased to 1.42 (95% CI 1.19 to 1.69).

CONCLUSIONS

The finding of elevated relative risks in studies of both benzene exposure and refinery work provides further evidence that benzene exposure causes NHL. In addition, the finding of increased relative risks after removing studies that included unexposed or lesser exposed workers in "exposed" cohorts, and increased relative risk estimates after adjusting for the healthy worker effect, suggest that effects of benzene on NHL might be missed in occupational studies if these biases are not accounted for.

Environmental and occupational causes of cancer: new evidence 2005-2007

What do we currently know about the occupational and environmental causes of cancer? As of 2007, the International Agency for Research on Cancer (IARC) identified 415 known or suspected carcinogens. Cancer arises through an extremely complicated web of multiple causes, and we will likely never know the full range of agents or combinations of agents. We do know that preventing exposure to individual carcinogens prevents the disease. Declines in cancer rates-such as the drop in male lung cancer cases from the reduction in tobacco smoking or the drop in bladder cancer among cohorts of dye workers from the elimination of exposure to specific aromatic amines-provides evidence that preventing cancer is possible when we act on what we know. Although the overall age-adjusted cancer incidence rates in the United States among both men and women have declined in the last decade, the rates of several types of cancers are on the rise; some of which are linked to environmental and occupational exposures. This report chronicles the most recent epidemiologic evidence linking occupational and environmental exposures with cancer. Peer-reviewed scientific studies published from January 2005 to June 2007 were reviewed, supplementing our state-of-the-evidence report published in September 2005. Despite weaknesses in certain individual studies, we consider the evidence linking the increased risk of several types of cancer with specific exposures somewhat strengthened by recent publications, among them brain cancer from exposure to non-ionizing radiation, particularly radiofrequency fields emitted by mobile telephones; breast cancer from exposure to the pesticide dichlorodiphenyltrichloroethane (DDT) before puberty; leukemia from exposure to 1,3-butadiene; lung cancer from exposure to air pollution; non-Hodgkin's lymphoma (NHL) from exposure to pesticides and solvents; and prostate cancer from exposure to pesticides, polyaromatic hydrocarbons (PAHs), and metal working fluids or mineral oils. In addition to NHL and prostate cancer, early findings from the National Institutes of Health Agricultural Health Study suggest that several additional cancers may be linked to a variety of pesticides. Our report also briefly describes the toxicological evidence related to the carcinogenic effect of specific chemicals and mechanisms that are difficult to study in humans, namely exposures to bis-phenol A and epigenetic, trans-generational effects. To underscore the multi-factorial, multi-stage nature of cancer, we also present a technical description of cancer causation summarizing current knowledge in molecular biology. We argue for a new cancer prevention paradigm, one based on an understanding that cancer is ultimately caused by multiple interacting factors rather than a paradigm based on dubious attributable fractions. This new cancer prevention paradigm demands that we limit exposure to avoidable environmental and occupational carcinogens, in combination with additional important risk factors like diet and lifestyle. The research literature related to environmental and occupational causes of cancer is constantly growing, and future updates will be carried out in light of new biological understanding of the mechanisms and new methods for studying exposures in human populations. The current state of knowledge is sufficient to compel us to act on what we know. We repeat the call of ecologist Sandra Steingraber: "From the right to know and the duty to inquire flows the obligation to act."

Aberrations in chromosomes associated with lymphoma and therapy-related leukemia in benzene-exposed workers

Epidemiological studies show that benzene exposure is associated with an increased incidence of leukemia and perhaps lymphoma. Chromosomal rearrangements are common in these hematopoietic diseases. Translocation t(14;18), the long-arm deletion of chromosome 6 [del(6q)], and trisomy 12 are frequently observed in lymphoma patients. Rearrangements of the MLL gene located on chromosome 11q23, such as t(4;11) and t(6;11), are common in therapy-related leukemias resulting from treatment with topoisomerase II inhibiting drugs. To examine numerical and structural changes in these chromosomes (2, 4, 6, 11, 12, 14, and 18), fluorescence in situ hybridization (FISH) was employed on metaphase spreads from workers exposed to benzene (n = 43) and matched controls (n = 44) from Shanghai, China. Aneuploidy (both monosomy and trisomy) of all seven chromosomes was increased by benzene exposure. Benzene also induced del(6q) in a dose-dependent manner (P(trend) = 0.0002). Interestingly, translocations between chromosomes 14 and 18, t(14;18), known to be associated with follicular non-Hodgkin lymphoma, were increased in the highly exposed workers (P < 0.001). On the other hand, translocations between chromosome 11 and other partner chromosomes that are found in therapy-induced leukemias were not increased. These data add weight to the notion that benzene can induce t(14;18) and del(6q) found in lymphoma, but do not support the idea that benzene induces t(4;11) or t(6;11). However, they do not rule out the possibility that other rearrangements of the MLL gene at chromosome 11q23 may be induced by benzene.

The non-Hodgkin lymphomas: a review of the epidemiologic literature

The non-Hodgkin lymphomas (NHL) are a heterogeneous group of B-cell and T-cell neoplasms that arise primarily in the lymph nodes. NHL incidence rates in the US doubled between about 1970 and 1990, and stabilized during the 1990s. NHL accounts for approximately 3.4% of cancer deaths in the US. Although some of the observed patterns in NHL have been related to HIV/AIDS, these conditions cannot fully explain the magnitude of the changes; neither do changes in classification systems nor improved diagnostic capabilities. Studies of occupational and environmental exposures (e.g., pesticides, solvents) have produced no consistent pattern of significant positive associations. Inverse associations with ultraviolet radiation exposure and alcohol and fish intake, and positive associations with meat and saturated fat intake have been reported in several studies; additional studies are needed to confirm or refute these associations. Family history of NHL or other hematolympho-proliferative cancers and personal history of several autoimmune disorders are associated with increased risk of NHL, but are not likely to account for a large proportion of cases. HIV and other infectious agents, such as human herpesvirus 8 and Epstein-Barr, appear to be associated with differing types of NHL, such as some B-cell lymphomas. Future epidemiologic studies should evaluate associations by NHL type, enhance exposure information collected, and elucidate factors that may identify susceptible (or resistant) subpopulations because of genetic, immunologic or other characteristics. The extent to which the etiology of NHL types may differ is important to resolve in ongoing and future studies.

Occupation and the risk of non-Hodgkin lymphoma

Although thus far no occupational agents have been classified as established causes of non-Hodgkin lymphoma (NHL), employment as a farmer, teacher, dry cleaner, meat worker, printer, or wood worker has been associated with elevated risk in the peer-reviewed literature. We conducted several meta-analyses to assess risk in these occupations and industries from articles published in MEDLINE up to August 1, 2006. The summary risk estimates suggest a homogeneous excess risk for NHL among workers in the printing industry [relative risk (RR), 1.86; 95% confidence interval (95% CI), 1.37-2.52] and wood workers (RR, 1.15; 95% CI, 1.00-1.31). Considerable heterogeneity but elevated risks were found for farmers (RR, 1.11; 95% CI, 1.05-1.17), especially in animal husbandry (RR, 1.31; 95% CI, 1.08-1.60), and teaching (RR, 1.47; 95% CI, 1.34-1.61). An increased risk was absent for employment in the meat processing industry (RR, 0.99; 95% CI, 0.77-1.29). These results suggest that although excess risk is found for employment in the printing industry, wood processing industry, teaching, and farming, it is unlikely that occupation represents a major risk factor for NHL in most populations. At present, no conclusive evidence of causal relations between occupations and increased NHL risk exists; this can be ascribed to methodologic problems in studying the link between NHL risk and occupation, including heterogeneity of disease and exposure circumstances and low statistical power. Implementing state-of-the-art exposure assessment technologies, including biomarker-based assessment, and aiming to identify susceptible subgroups can increase the statistical power enough to analyze etiologically relevant NHL subtypes and provide clues on possible causal agents in future studies. These goals can be best attained within the framework of large-scale, international collaborative projects.

Polychlorinated biphenyls and non-Hodgkin lymphoma

Several epidemiologic studies suggest that polychlorinated biphenyl (PCB) levels measured in peripheral blood or adipose tissue are related to increased risk of non-Hodgkin lymphoma (NHL) and, therefore, may be at least partially responsible for the rising incidence of NHL unrelated to HIV infection in recent decades. Case-control studies that measured PCBs in blood, adipose tissue, or household carpet dust, at the time of diagnosis, have observed elevated NHL risk associated with concentrations of either total PCBs or of specific congeners. Similar associations have been found in a number of prospective cohorts. These associations do not seem to be due to confounding by other organochlorines or by other known NHL risk factors. These results support evidence of PCB carcinogenicity from animal studies. However, interpretation of the epidemiologic evidence is limited by the wide range in measurement precision across congeners and by the moderate to high correlation among many congeners. Occupational cohort studies provide very limited support for a relationship between PCBs and NHL. In conclusion, there is mounting evidence of a relationship between certain PCBs and risk of NHL, but important questions remain, especially regarding the magnitude, timing, and causality of that relationship.

Hobbies with solvent exposure and risk of non-Hodgkin lymphoma

Occupational exposure to solvents has been reported to increase non-Hodgkin lymphoma (NHL) risk in some, but not all, studies. In a population-based case-control study, we examined whether participation in selected hobbies involving solvent exposure increases NHL risk. We identified NHL cases diagnosed at ages 20-74 years between 1998 and 2000 in Iowa or metropolitan Los Angeles, Detroit, and Seattle. Controls were selected using random digit dialing or Medicare files. Computer-assisted personal interviews (551 cases, 462 controls) elicited data on model building, painting/silkscreening/artwork, furniture refinishing, and woodworking/home carpentry. Hobby participation (68% of cases, 69% of controls) was not associated with NHL risk (OR = 0.9, 95% CI = 0.7-1.2). Compared to people with none of the hobbies evaluated, those who built models had significantly lower risk (OR = 0.7, CI = 0.5-1.0), but risk did not vary with the number of years or lifetime hours. Risk estimates for the other hobbies were generally less than one, but the associations were not significant and there were no notable patterns with duration of exposure. Use of oil-based, acrylic, or water-based paints; paint strippers; polyurethane; or varnishes was not associated with NHL risk. We conclude that participation in hobbies involving exposure to organic solvents is unlikely to increase NHL risk.

Family history of hematopoietic and non-hematopoietic malignancies and risk of non-Hodgkin lymphoma

BACKGROUND

Family history of hematopoietic malignancies has been linked to the risk of non-Hodgkin lymphoma (NHL). The relationship between family history of specific hematopoietic and non-hematopoietic malignancies and the risk of NHL and by NHL subtypes are unclear.

METHODS

We analyzed data from a population-based case-control study in Connecticut women. A total of 601 histologically confirmed NHL incident cases and 717 randomly selected controls were included in the study. Unconditional logistic regression was used to estimate the association between family cancer history and risk of NHL overall and by NHL subtypes.

RESULTS

Compared to women who reported to have no family history of any malignancies in first-degree relatives, those who reported to have a family history of lymphoma (OR = 2.2, 95%CI: 1.1-4.5) or leukemia (OR = 2.5, 95%CI: 1.2-5.2) had an increased risk of NHL. The risk was higher among women who had a sibling with lymphoma or leukemia than those who had parents with lymphoma or leukemia. Several non-hematopoietic malignancies in first-degree relatives, including cancer of the lung (OR = 1.7, 95%CI: 1.1-2.6) in first-degree relatives, stomach (OR = 2.2, 95%CI: 0.8-5.9) and pancreas (OR = 2.6, 95%CI: 0.9-7.1) in parents, as well as liver (OR = 5.0, 95%CI: 1.0-24.6), breast (OR = 2.2, 95%CI: 1.3-3.9), cervix (OR = 7.5, 95%CI: 0.9-64.9), and ovary (OR = 3.5, 95%CI: 1.1-11.5) in siblings were also associated with an increased risk of NHL.

CONCLUSIONS

The risk associated with a family history of malignancies in first degree-relatives appears to vary by type of first-degree relatives.

Specific infections, infection-related behavior, and risk of non-Hodgkin lymphoma in adults

Infections were examined as possible risk factors for non-Hodgkin lymphoma in a population-based case-control study in New South Wales and the Australian Capital Territory, Australia. Incident cases (n = 694) had no history of HIV infection or transplantation. Controls (n = 694) were randomly selected from electoral rolls and frequency matched to cases by age, sex, and area of residence. A postal questionnaire and telephone interview measured history of specific infections, occupational exposures, and behavioral and other risk factors for infection. Blood samples were tested for antibodies to human T-lymphotrophic virus type I and hepatitis C virus. Logistic regression models included the three matching variables and ethnicity. There was no association between risk of non-Hodgkin lymphoma and any of the variables analyzed, including sexually transmitted infections, sexual behavior, blood transfusions, influenza, acne, and either occupational or domestic exposure to zoonotic infections. Non-Hodgkin lymphoma risk was nonsignificantly elevated (odds ratio, 2.99; 95% confidence interval, 0.78-11.51) for those with a history of injecting drug use. Three cases and two controls (odds ratio, 1.32; 95% confidence interval, 0.22-7.98) tested positive to hepatitis C virus infection and none tested positive to human T-lymphotrophic virus type I/II infection. This study provides consistent evidence that sexually transmitted infections and zoonoses are not risk factors for non-Hodgkin lymphoma.

Occupational exposure to power frequency magnetic fields and risk of non-Hodgkin lymphoma

OBJECTIVES

To investigate the risk of non-Hodgkin lymphoma (NHL) using a job-exposure matrix (JEM) to assess exposure to occupational magnetic fields at the power frequencies of 50/60 Hz.

METHODS

The study population consisted of 694 cases of NHL, first diagnosed between 1 January 2000 and 31 August 2001, and 694 controls from two regions in Australia, matched by age, sex and region of residence. A detailed occupational history was given by each subject. Exposure to power frequency magnetic fields was estimated using a population-based JEM which was specifically developed in the United States to assess occupational magnetic field exposure. The cumulative exposure distribution was divided into quartiles and adjusted odds ratios were calculated using the lowest quartile as the referent group.

RESULTS

For the total work history, the odds ratio (OR) for workers in the upper quartile of exposure was 1.48 (95% CI 1.02 to 2.16) compared to the referent (p value for trend was 0.006). When the exposure was lagged by 5 years the OR was 1.59 (95% CI 1.07 to 2.36) (p value for trend was 0.003). Adjusting for other occupational exposures did not significantly alter the results.

CONCLUSIONS

These findings provide weak support for the hypothesis that occupational exposure to 50/60 Hz magnetic fields increases the risk of NHL.

The epidemiology of non-Hodgkin lymphoma

Non-Hodgkin lymphoma (NHL) includes a group of more than 20 different malignant lymphoproliferative diseases that originate from lymphocytes. Rates of NHL have increased dramatically over the past few decades, although the rate of increase has recently slowed. It is now the sixth most common cancer in Australia. Globally, it is somewhat more common in men than in women, and rates are highest in North America and Australia. The causes of the increase in NHL rates are largely unknown. The best described risk factor for NHL is immune deficiency; rates of NHL are greatly increased, with relative risks of 10-100 or more, in people with immune deficiency associated with immune suppressive therapy after transplantation, HIV/AIDS, and congenital conditions. In addition, some NHL subtypes are associated with specific infections. These include immune-deficiency-associated central nervous system NHL (Epstein-Barr virus); gastric mucosa-associated lymphoid tissue NHL (Helicobacter pylori); adult T-cell leukemia/lymphoma (human T-lymphotrophic virus type 1) and body cavity-based lymphoma (human herpesvirus 8). However, these specific infections account for a very small proportion of total NHL incidence. In addition to immune deficiency and infection, other immune-related conditions are increasingly being recognised as related to NHL risk. Specific autoimmune conditions, including rheumatoid arthritis, systemic lupus erythema, Sjogren's syndrome, psoriasis and coeliac disease are associated with moderately increased risk of NHL. On the other hand, allergic and atopic conditions and their correlates such as early birth order, appear to be associated with a decreased risk of NHL.A variety of other exposures are less strongly related to NHL risk. These include occupational exposures, including some pesticides, herbicides, and solvents. Recently, two studies have reported that sun exposure is associated with a decreased risk of NHL. Smoking appears to be weakly positively associated with risk of follicular NHL, and alcohol intake is associated with a decreased risk of NHL. The pooled analysis of several case-control studies of NHL risk that are currently in the field promises to help clarify which of these risk factors are real, and will contribute to the elucidation of the mechanisms of how disorders of the immune system, and other factors, are related to NHL risk.