Occupational exposures, animal exposure and smoking as risk factors for hairy cell leukaemia evaluated in a case-control study

Epidemiologic studies of glyphosate and non-Hodgkin's lymphoma: A review with consideration of exposure frequency, systemic dose, and study quality

I reviewed the epidemiologic literature for glyphosate and non-Hodgkin's lymphoma (NHL) in the context of the frequency of exposure in each epidemiologic study, systemic dose from biomonitoring studies of applicators, and aspects of study quality. Nine studies were identified, 7 case control and 2 cohort, by a literature search and a review of reference lists from published studies and recent regulatory evaluations. All but one study involved exposure scenarios that were so infrequent that they are not credible for cancer causation. Most studies failed to address potential confounding from other pesticides. Only one study - the US Agricultural Health Study (AHS) - included individuals with relatively frequent exposure to glyphosate and involved comprehensive statistical analyses to address potential confounding by personal factors and other pesticide exposures. The AHS did not find an association between glyphosate and NHL, even among the most frequently exposed participants (≥ 109 days of use) (RR = 0.80, 95% CI 0.60, 1.06). These findings are consistent with observations that glyphosate systemic doses from agricultural applications are many orders of magnitude less than daily lifetime doses considered by regulatory agencies to impart no excess risk of deleterious health effects, even for sensitive subpopulations.

Exposure to phenoxyacetic acids and glyphosate as risk factors for non-Hodgkin lymphoma- pooled analysis of three Swedish case-control studies including the sub-type hairy cell leukemia

The association between pesticide exposure and non-Hodgkin lymphoma (NHL) including hairy cell leukemia (HCL) was analyzed in a pooled study of three case-control studies. Results on exposure to pesticides were based on 1,425 cases and 2,157 controls participating in the studies. Exposures were assessed by self-administered questionnaires completed as needed by phone. In the pooled univariate analyses adjusted by age, gender and year of diagnosis, exposure to herbicides of the phenoxyacetic acid type yielded statistically significant increased risk with odds ratio (OR) = 1.9, 95% confidence interval CI) = 1.4-2.5. The herbicide glyphosate gave OR = 2.2, 95% CI = 1.3-3.8. Impregnating agents increased the risk. No clear dose-response effect was seen. OR was highest in the >10-20 years latency group for herbicides and impregnating agents. In the multivariate analysis including main pesticide groups, statistically significant increased risk was found for herbicides, OR = 1.6, 95% CI = 1.2-2.1 and impregnating agents with OR = 1.4, 95% CI = 1.1-1.8. This analysis confirmed an association between NHL including HCL and exposure to certain herbicides.

Lost opportunities for cancer prevention: historical evidence on early warnings with emphasis on radiofrequency radiation

Some historical aspects on late lessons from early warnings on cancer risks with lost time for prevention are discussed. One current example is the cancer-causing effect from radiofrequency (RF) radiation. Studies since decades have shown increased human cancer risk. The fifth generation, 5G, for wireless communication is about to be implemented world-wide despite no comprehensive investigations of potential risks to human health and the environment. This has created debate on this technology among concerned people in many countries. In an appeal to EU in September 2017, currently endorsed by more than 400 scientists and medical doctors, a moratorium on the 5G deployment was required until proper scientific evaluation of negative consequences has been made (www.5Gappeal.eu). That request has not been taken seriously by EU. Lack of proper unbiased risk evaluation of the 5G technology makes adverse effects impossible to be foreseen. This disregard is exemplified by the recent report from the International Commission on non-ionizing radiation protection (ICNIRP) whereby only thermal (heating) effects from RF radiation are acknowledged despite a large number of reported non-thermal effects. Thus, no health effects are acknowledged by ICNIRP for non-thermal RF electromagnetic fields in the range of 100 kHz-300 GHz. Based on results in three case-control studies on use of wireless phones we present preventable fraction for brain tumors. Numbers of brain tumors of not defined type were found to increase in Sweden, especially in the age group 20-39 years in both genders, based on the Swedish Inpatient Register. This may be caused by the high prevalence of wireless phone use among children and in adolescence taking a reasonable latency period and the higher vulnerability to RF radiation among young persons.

Occupational exposure to glyphosate and risk of lymphoma:results of an Italian multicenter case-control study

BACKGROUND

The International Agency for Research on Cancer (IARC) recently classified glyphosate, the most used herbicide worldwide, as a probable human carcinogen. We inquired into the association between occupational exposure to glyphosate and risk of lymphoma subtypes in a multicenter case-control study conducted in Italy.

METHODS

The Italian Gene-Environment Interactions in Lymphoma Etiology (ItGxE) study took place in 2011-17 in six Italian centres. Overall, 867 incident lymphoma cases and 774 controls participated in the study. Based on detailed questionnaire information, occupational experts classified duration, confidence, frequency, and intensity of exposure to glyphosate for each study subject. Using unconditional regression analysis, we modelled risk of major lymphoma subtypes associated with exposure to glyphosate adjusted by age, gender, education, and study centre.

RESULTS

Very few study subjects (2.2%) were classified as ever exposed to glyphosate. Risk of follicular lymphoma (FL) was elevated 7-fold in subjects classified as ever exposed to glyphosate with medium-high confidence, 4.5-fold in association with medium-high cumulative exposure level, 12-fold with medium-high exposure intensity, and 6-fold with exposure for 10 days or more per year. Significant upward trends were detected with all the exposure metrics, but duration. The overall p-value for an upward trend with four independent metrics was 1.88 × 10- 4. There was no association with risk of lymphoma (any subtype), Non Hodgkin Lymphoma, B-cell lymphoma, or the major lymphoma subtypes other than FL.

CONCLUSIONS

Our findings provide limited support to the IARC decision to classify glyphosate as Group 2A human carcinogen.

Cancer and occupational exposure to pesticides: an umbrella review

Purpose

The aim was to identify the scope of the epidemiology literature reviewed regarding the risk of cancer as related to occupational exposure to pesticides and to compare regulatory toxicity results where feasible.

Methods

Review studies of breast, lung, prostate, non-Hodgkin lymphoma, and colorectal cancer were identified from the published literature from 2010 to 2020 using a priori inclusion and exclusion criteria. Epidemiology observations were first assessed and then compared against carcinogenicity profiles derived from regulatory toxicology studies.

Results

Several active ingredients were associated with specific cancer but overall, there was neither strong nor consistent epidemiologic data supportive of a positive association between pesticide exposure in occupational settings and cancer. Authors noted common themes related to the heterogeneity of exposure, study design, control for confounders, and the challenge to collect these data reliably and validly with an adequate sample size. Toxicology studies in laboratory animals that assessed carcinogenic potential did not reveal cancer outcomes that were concordant with reported epidemiologic findings.

Conclusions

Farming and pesticides represent diverse exposures that are difficult to quantify in epidemiologic studies. Going forward, investigators will need creative and novel approaches for exposure assessment. Integration of epidemiologic and toxicological studies with attention to biological plausibility, mode of toxicological action and relevance to humans will increase the ability to better assess associations between pesticides and cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-020-01638-y.

Effects of glyphosate exposure on human health: Insights from epidemiological and in vitro studies

Glyphosate (GLY) is a broad-spectrum, post-emergent, non-selective and synthetic universal herbicide, whose commercial formulations are referred to as glyphosate-based-herbicides (GBHs). These chemicals and their metabolites can be found in soil, air, water, as well as groundwater and food products. This review summarizes to summarize current in vitro and epidemiological studies investigating the effects of GLY exposure on human health. Recent human cell studies have reported several GLY and GBH toxicological effects and have contributed to a better understanding of the deleterious consequences associated with their exposure. However, these detrimental effects are dependent on the cell type, chemical composition, as well as magnitude and time of exposure, among other factors. Moreover, the deleterious effects of GLY exposure on human health were observed in epidemiological studies; however, most of these studies have not determined the GLY dosage to confirm a direct effect. While GLY toxicity is clear in human cells, epidemiological studies investigating individuals exposed to different levels of GLY have reported contradictory data. Therefore, based on currently available in vitro and epidemiological data, it is not possible to confirm the complete safety of GLY use, which will require additional comprehensive studies in animal models and humans.

Exposure to glyphosate and risk of non-Hodgkin lymphoma and multiple myeloma: an updated meta-analysis

OBJECTIVE

We carried out a systematic review and meta-analysis of epidemiologic studies on the association between occupational exposure to glyphosate and risk of non-Hodgkin lymphoma (NHL) and multiple myeloma (MM).

METHODS

We conducted a systematic search of the literature, and identified 18 relevant publications, from which we extracted results from seven non-overlapping studies of NHL and three of MM. We performed random-effects meta-analyses for ever-exposure to glyphosate, dose-response, and risk of specific NHL subtypes.

RESULTS

The meta-relative risk (RR) of NHL was 1.03 (95% confidence interval [CI] 0.86-1.21), that of MM was 1.04 (95% CI 0.67-1.41). The meta-RR of NHL for highest category of exposure was 1.49 (95% CI 0.37-2.61; 3 studies). The meta-RR for diffuse large B-cell lymphoma (DLBCL) was 1.31 (95% CI 0.93-1.75); that for follicular lymphoma was 0.82 (95% CI 0.93-1.70), and that for chronic lymphocytic leukemia was 0.85 (95% CI 0.20-1.49). There was indication of publication bias for studies on NHL.

CONCLUSIONS

Our meta-analysis provided no overall evidence of an increased risk for both NHL and MM in subjects occupationally exposed to glyphosate. In secondary analyses we detected a small increase in risk for the category with highest level of exposure as well as for DLBCL. The evidence of publication bias suggests caution in the interpretation of the results.

Deciphering the genotype and phenotype of hairy cell leukemia: clues for diagnosis and treatment

Introduction: Hairy cell leukemia (HCL) is a rare, indolent B-cell neoplasm. The classical variant of the disease is characterized by the BRAF V600E mutation, which is present in virtually all cases. How this mutation leads to the signs and symptoms of the disease is currently not known. Areas covered: This review explores the genetic background of HCL, especially the BRAF V600E driver mutation, but passenger mutations and their effects are also included. The clinical significance of BRAF mutations in other cancer types is discussed, as well as BRAF- induced senescence. An overview of the major forms of treatment of HCL (cytostatic drugs, specific BRAF inhibitors, B cell-specific antibodies) is given. Finally, possible mechanisms of the monocytopenia and hairy morphology so typical of this disease are discussed. Expert opinion: Although being a rare disease, HCL and its pathogenesis can yield important information about BRAF-related cancer metabolism. Many aspects of the disease are still unclear, but with the right resources, this could change. This can lead to a more efficient and specific treatment, thus leading to decreased morbidity.

Exposure to glyphosate-based herbicides and risk for non-Hodgkin lymphoma: A meta-analysis and supporting evidence

Glyphosate is the most widely used broad-spectrum systemic herbicide in the world. Recent evaluations of the carcinogenic potential of glyphosate-based herbicides (GBHs) by various regional, national, and international agencies have engendered controversy. We investigated whether there was an association between high cumulative exposures to GBHs and increased risk of non-Hodgkin lymphoma (NHL) in humans. We conducted a new meta-analysis that includes the most recent update of the Agricultural Health Study (AHS) cohort published in 2018 along with five case-control studies. Using the highest exposure groups when available in each study, we report the overall meta-relative risk (meta-RR) of NHL in GBH-exposed individuals was increased by 41% (meta-RR = 1.41, 95% confidence interval, CI: 1.13-1.75). For comparison, we also performed a secondary meta-analysis using high-exposure groups with the earlier AHS (2005), and we calculated a meta-RR for NHL of 1.45 (95% CI: 1.11-1.91), which was higher than the meta-RRs reported previously. Multiple sensitivity tests conducted to assess the validity of our findings did not reveal meaningful differences from our primary estimated meta-RR. To contextualize our findings of an increased NHL risk in individuals with high GBH exposure, we reviewed publicly available animal and mechanistic studies related to lymphoma. We documented further support from studies of malignant lymphoma incidence in mice treated with pure glyphosate, as well as potential links between glyphosate / GBH exposure and immunosuppression, endocrine disruption, and genetic alterations that are commonly associated with NHL or lymphomagenesis. Overall, in accordance with findings from experimental animal and mechanistic studies, our current meta-analysis of human epidemiological studies suggests a compelling link between exposures to GBHs and increased risk for NHL.

2,4-dichlorophenoxyacetic acid (2,4-D) and risk of non-Hodgkin lymphoma: a meta-analysis accounting for exposure levels

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most commonly used selective herbicides in the world. A number of epidemiology studies have found an association between 2,4-D exposure and non-Hodgkin lymphoma (NHL) but these results are inconsistent and controversial. A previous meta-analysis found no clear association overall but did not specifically examine high-exposure groups. We conducted a systematic review and meta-analysis of the peer-reviewed epidemiologic studies of the associations between 2,4-D and NHL, with a particular focus on high-exposure groups, and evaluations of heterogeneity, dose-response, and bias. A total of 12 observational studies, 11 case-control studies, and one cohort study, were included. The summary relative risk for NHL using study results comparing subjects who were ever versus never exposed to 2,4-D was 1.38 (95% confidence interval (CI), 1.07-1.77). However, in analyses focusing on results from highly exposed groups, the summary relative risk for NHL was 1.73 (95% CI, 1.10-2.72). No clear bias based on study design, exposure assessment methodology, or outcome misclassification was seen. Overall, these findings provide new evidence for an association between NHL and exposure to the herbicide 2,4-D.

Pesticides: an update of human exposure and toxicity

Pesticides are a family of compounds which have brought many benefits to mankind in the agricultural, industrial, and health areas, but their toxicities in both humans and animals have always been a concern. Regardless of acute poisonings which are common for some classes of pesticides like organophosphoruses, the association of chronic and sub-lethal exposure to pesticides with a prevalence of some persistent diseases is going to be a phenomenon to which global attention has been attracted. In this review, incidence of various malignant, neurodegenerative, respiratory, reproductive, developmental, and metabolic diseases in relation to different routes of human exposure to pesticides such as occupational, environmental, residential, parental, maternal, and paternal has been systematically criticized in different categories of pesticide toxicities like carcinogenicity, neurotoxicity, pulmonotoxicity, reproductive toxicity, developmental toxicity, and metabolic toxicity. A huge body of evidence exists on the possible role of pesticide exposures in the elevated incidence of human diseases such as cancers, Alzheimer, Parkinson, amyotrophic lateral sclerosis, asthma, bronchitis, infertility, birth defects, attention deficit hyperactivity disorder, autism, diabetes, and obesity. Most of the disorders are induced by insecticides and herbicides most notably organophosphorus, organochlorines, phenoxyacetic acids, and triazine compounds.

Systematic review and meta-analysis of glyphosate exposure and risk of lymphohematopoietic cancers

This systematic review and meta-analysis rigorously examines the relationship between glyphosate exposure and risk of lymphohematopoietic cancer (LHC) including NHL, Hodgkin lymphoma (HL), multiple myeloma (MM), and leukemia. Meta-relative risks (meta-RRs) were positive and marginally statistically significant for the association between any versus no use of glyphosate and risk of NHL (meta-RR = 1.3, 95% confidence interval (CI) = 1.0-1.6, based on six studies) and MM (meta-RR = 1.4, 95% CI = 1.0-1.9; four studies). Associations were statistically null for HL (meta-RR = 1.1, 95% CI = 0.7-1.6; two studies), leukemia (meta-RR = 1.0, 95% CI = 0.6-1.5; three studies), and NHL subtypes except B-cell lymphoma (two studies each). Bias and confounding may account for observed associations. Meta-analysis is constrained by few studies and a crude exposure metric, while the overall body of literature is methodologically limited and findings are not strong or consistent. Thus, a causal relationship has not been established between glyphosate exposure and risk of any type of LHC.

Epidemiology and environmental risk in hairy cell leukemia

Hairy cell leukaemia (HCL) is an orphan subtype of leukaemia which constitutes less than 2% of all leukaemia's, with an incidence of less than 1 per 100,000 persons per annum. Median age at presentation is 55 years and it is 3-4 times more frequent in males. It is also more frequently encountered in whites and less in Asians, Africans and Arabs. The epidemiologic data are multi-factorial and influenced by ethnicity and geographical factors. Other reported associations relate to some environmental exposures and possible occupational factors. Smoking appears to have an inverse correlation with the development of hairy cell leukaemia, while farming and exposure to pesticides, petroleum products, diesel and ionizing radiation have also been reported to be associated with an increased risk. National and international collaborative efforts are needed in order to undertake more extensive studies involving larger patient cohorts, aiming to determine the role of occupational and environmental risk factors in the development of this rare form of chronic leukaemia.

Potential toxic effects of glyphosate and its commercial formulations below regulatory limits

Glyphosate-based herbicides (GlyBH), including Roundup, are the most widely used pesticides worldwide. Their uses have increased exponentially since their introduction on the market. Residue levels in food or water, as well as human exposures, are escalating. We have reviewed the toxic effects of GlyBH measured below regulatory limits by evaluating the published literature and regulatory reports. We reveal a coherent body of evidence indicating that GlyBH could be toxic below the regulatory lowest observed adverse effect level for chronic toxic effects. It includes teratogenic, tumorigenic and hepatorenal effects. They could be explained by endocrine disruption and oxidative stress, causing metabolic alterations, depending on dose and exposure time. Some effects were detected in the range of the recommended acceptable daily intake. Toxic effects of commercial formulations can also be explained by GlyBH adjuvants, which have their own toxicity, but also enhance glyphosate toxicity. These challenge the assumption of safety of GlyBH at the levels at which they contaminate food and the environment, albeit these levels may fall below regulatory thresholds. Neurodevelopmental, reproductive, and transgenerational effects of GlyBH must be revisited, since a growing body of knowledge suggests the predominance of endocrine disrupting mechanisms caused by environmentally relevant levels of exposure.

Medical history, lifestyle, and occupational risk factors for hairy cell leukemia: the InterLymph Non-Hodgkin Lymphoma Subtypes Project

BACKGROUND

Little is known about the etiology of hairy cell leukemia (HCL), a rare B-cell lymphoproliferative disorder with marked male predominance. Our aim was to identify key risk factors for HCL.

METHODS

A pooled analysis of individual-level data for 154 histologically confirmed HCL cases and 8834 controls from five case-control studies, conducted in Europe and Australia, was undertaken. Age-, race and/or ethnicity-, sex-, and study-adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression.

RESULTS

The usual patterns for age and sex in HCL were observed, with a median age of 55 years and sex ratio of 3.7 males to females. Cigarette smoking was inversely associated with HCL (OR = 0.51, 95% CI = 0.37 to 0.71) with dose-response relationships observed for duration, frequency, and lifetime cigarette smoking (P(trend) < .001). In contrast, occupation as a farmer was positively associated with HCL (OR = 2.34, 95% CI = 1.36 to 4.01), with a dose-response relationship observed for duration (OR = 1.82, 95% CI = 0.85 to 3.88 for ≤ 10 years vs never; and OR = 2.98, 95% CI = 1.50 to 5.93 for >10 years vs never; P(trend) = .025). Adult height was also positively associated with HCL (OR = 2.69, 95% CI = 1.39 to 5.29 for upper vs lower quartile of height). The observed associations remained consistent in multivariate analysis.

CONCLUSIONS

Our observations of an increased risk of HCL from farming exposures and decreased risk from smoking exposures, independent of one another, support a multifactorial origin and an etiological specificity of HCL compared with other non-Hodgkin lymphoma subtypes. The positive association with height is a novel finding that needs replication.

Human health effects of trichloroethylene: key findings and scientific issues

BACKGROUND

In support of the Integrated Risk Information System (IRIS), the U.S. Environmental Protection Agency (EPA) completed a toxicological review of trichloroethylene (TCE) in September 2011, which was the result of an effort spanning > 20 years.

OBJECTIVES

We summarized the key findings and scientific issues regarding the human health effects of TCE in the U.S. EPA's toxicological review.

METHODS

In this assessment we synthesized and characterized thousands of epidemiologic, experimental animal, and mechanistic studies, and addressed several key scientific issues through modeling of TCE toxicokinetics, meta-analyses of epidemiologic studies, and analyses of mechanistic data.

DISCUSSION

Toxicokinetic modeling aided in characterizing the toxicological role of the complex metabolism and multiple metabolites of TCE. Meta-analyses of the epidemiologic data strongly supported the conclusions that TCE causes kidney cancer in humans and that TCE may also cause liver cancer and non-Hodgkin lymphoma. Mechanistic analyses support a key role for mutagenicity in TCE-induced kidney carcinogenicity. Recent evidence from studies in both humans and experimental animals point to the involvement of TCE exposure in autoimmune disease and hypersensitivity. Recent avian and in vitro mechanistic studies provided biological plausibility that TCE plays a role in developmental cardiac toxicity, the subject of substantial debate due to mixed results from epidemiologic and rodent studies.

CONCLUSIONS

TCE is carcinogenic to humans by all routes of exposure and poses a potential human health hazard for noncancer toxicity to the central nervous system, kidney, liver, immune system, male reproductive system, and the developing embryo/fetus.

Pesticides and human chronic diseases: evidences, mechanisms, and perspectives

Along with the wide use of pesticides in the world, the concerns over their health impacts are rapidly growing. There is a huge body of evidence on the relation between exposure to pesticides and elevated rate of chronic diseases such as different types of cancers, diabetes, neurodegenerative disorders like Parkinson, Alzheimer, and amyotrophic lateral sclerosis (ALS), birth defects, and reproductive disorders. There is also circumstantial evidence on the association of exposure to pesticides with some other chronic diseases like respiratory problems, particularly asthma and chronic obstructive pulmonary disease (COPD), cardiovascular disease such as atherosclerosis and coronary artery disease, chronic nephropathies, autoimmune diseases like systemic lupus erythematous and rheumatoid arthritis, chronic fatigue syndrome, and aging. The common feature of chronic disorders is a disturbance in cellular homeostasis, which can be induced via pesticides' primary action like perturbation of ion channels, enzymes, receptors, etc., or can as well be mediated via pathways other than the main mechanism. In this review, we present the highlighted evidence on the association of pesticide's exposure with the incidence of chronic diseases and introduce genetic damages, epigenetic modifications, endocrine disruption, mitochondrial dysfunction, oxidative stress, endoplasmic reticulum stress and unfolded protein response (UPR), impairment of ubiquitin proteasome system, and defective autophagy as the effective mechanisms of action.

Epidemiologic studies of glyphosate and cancer: a review

The United States Environmental Protection Agency and other regulatory agencies around the world have registered glyphosate as a broad-spectrum herbicide for use on multiple food and non-food use crops. Glyphosate is widely considered by regulatory authorities and scientific bodies to have no carcinogenic potential, based primarily on results of carcinogenicity studies of rats and mice. To examine potential cancer risks in humans, we reviewed the epidemiologic literature to evaluate whether exposure to glyphosate is associated causally with cancer risk in humans. We also reviewed relevant methodological and biomonitoring studies of glyphosate. Seven cohort studies and fourteen case-control studies examined the association between glyphosate and one or more cancer outcomes. Our review found no consistent pattern of positive associations indicating a causal relationship between total cancer (in adults or children) or any site-specific cancer and exposure to glyphosate. Data from biomonitoring studies underscore the importance of exposure assessment in epidemiologic studies, and indicate that studies should incorporate not only duration and frequency of pesticide use, but also type of pesticide formulation. Because generic exposure assessments likely lead to exposure misclassification, it is recommended that exposure algorithms be validated with biomonitoring data.

Trichloroethylene and cancer: systematic and quantitative review of epidemiologic evidence for identifying hazards

We conducted a meta-analysis focusing on studies with high potential for trichloroethylene (TCE) exposure to provide quantitative evaluations of the evidence for associations between TCE exposure and kidney, liver, and non-Hodgkin lymphoma (NHL) cancers. A systematic review documenting essential design features, exposure assessment approaches, statistical analyses, and potential sources of confounding and bias identified twenty-four cohort and case-control studies on TCE and the three cancers of interest with high potential for exposure, including five recently published case-control studies of kidney cancer or NHL. Fixed- and random-effects models were fitted to the data on overall exposure and on the highest exposure group. Sensitivity analyses examined the influence of individual studies and of alternative risk estimate selections. For overall TCE exposure and kidney cancer, the summary relative risk (RRm) estimate from the random effects model was 1.27 (95% CI: 1.13, 1.43), with a higher RRm for the highest exposure groups (1.58, 95% CI: 1.28, 1.96). The RRm estimates were not overly sensitive to alternative risk estimate selections or to removal of an individual study. There was no apparent heterogeneity or publication bias. For NHL, RRm estimates for overall exposure and for the highest exposure group, respectively, were 1.23 (95% CI: 1.07, 1.42) and 1.43 (95% CI: 1.13, 1.82) and, for liver cancer, 1.29 (95% CI: 1.07, 1.56) and 1.28 (95% CI: 0.93, 1.77). Our findings provide strong support for a causal association between TCE exposure and kidney cancer. The support is strong but less robust for NHL, where issues of study heterogeneity, potential publication bias, and weaker exposure-response results contribute uncertainty, and more limited for liver cancer, where only cohort studies with small numbers of cases were available.

Pesticides, soft-tissue sarcoma and non-Hodgkin lymphoma--historical aspects on the precautionary principle in cancer prevention

BACKGROUND

After the 2(nd) World War a long range of chemical agents have been introduced on the market, both in Sweden and most other countries. From the 1950's several pesticides gained increasing use in agriculture and forestry. In the 1970's public concern increased in Sweden especially regarding use of phenoxy herbicides to combat deciduous wood, although statements from different authorities were reassuring of the safety.

MATERIALS AND METHODS

At the end of the 1970's the author and his colleagues published the first scientific evidence of an association between exposure to phenoxyacetic acids, chlorophenols and certain malignant tumours, i.e., soft-tissue sarcoma and malignant lymphoma. The study subjects were also exposed to contaminating dioxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Later studies showed also an association between certain persistent organic pollutants such as polychlorinated biphenyls and non-Hodgkin lymphoma (NHL) with an interaction with titers of antibodies to Epstein-Barr virus early antigen. These results have been corroborated in other studies.

DISCUSSION

Over the years industry and its allied experts have attacked our studies, but in 1997 IARC classified TCDD as a human carcinogen, Group I. The increasing incidence of NHL in Sweden levelled off about 1990. The author postulated that the regulation or ban of the use of chlorophenols, certain phenoxy herbicides and some persistent organic pollutants in Sweden back in the 1970s has contributed to the now decreasing incidence of NHL. Unfounded criticism from industry experts may prohibit the precautionary principle and early warnings of cancer risk can be ignored. Cancer risks by certain chlorinated phenols may serve as a model of how the precautionary principle should be used by taking early warnings seriously.

Two new cases of familial hairy cell leukemia associated with HLA haplotypes A2, B7, Bw4, Bw6

Hairy cell leukemia (HCL) is a rare hematological disorder of unknown origin. Thirteen familial cases of HCL have been reported, with 28 relatives affected. Here we report 2 cases of HCL in a family associated with HLA haplotypes A2, B7 and Bw4/6.

Hairy cell leukemia and bladder cancer in a patient: relation with dye exposure and review of the literaure

Chemical exposure is important in the etiology of some cancers. Dye or solvent exposures are important both in bladder cancer (BC) and hairy cell leukemia (HCL). Here a case with BC and HCL has been presented and literature has been reviewed.

Occupational exposure to pesticides and lymphoid neoplasms among men: results of a French case-control study

OBJECTIVES

Investigating the relationship between occupational exposure to pesticides and the risk of lymphoid neoplasms (LNs) in men.

METHODS

A hospital-based case-control study was conducted in six centres in France between 2000 and 2004. The cases were incident cases with a diagnosis of LN aged 18-75 years. During the same period, controls of the same age and sex as the cases were recruited in the same hospital, mainly in the orthopaedic and rheumatological departments. Exposures to pesticides were evaluated through specific interviews and case-by-case expert reviews. Four hundred and ninety-one cases (244 cases of non-Hodgkin's lymphoma (NHL), 87 of Hodgkin's lymphoma (HL), 104 of lymphoproliferative syndromes (LPSs) and 56 of multiple myeloma (MM) cases) and 456 controls were included in the analyses. The odds ratios (ORs) and 95% CI were estimated using unconditional logistic regressions.

RESULTS

Positive associations between HL and occupational exposure to triazole fungicides and urea herbicides were observed (OR = 8.4 (2.2 to 32.4), 10.8 (2.4 to 48.1), respectively). Exposure to insecticides, fungicides and herbicides were linked to a threefold increase in MM risk (OR = 2.8 (1.2 to 6.5), 3.2 (1.4 to 7.2), 2.9 (1.3 to 6.5)). For LPS subtypes, associations restricted to hairy-cell leukaemia (HCL) were evidenced for exposure to organochlorine insecticides, phenoxy herbicides and triazine herbicides (OR = 4.9 (1.1 to 21.2), 4.1 (1.1 to 15.5), 5.1 (1.4 to 19.3)), although based on small numbers. Lastly, despite the increased ORs for organochlorine and organophosphate insecticides, carbamate fungicides and triazine herbicides, no significant associations were evidenced for NHL.

CONCLUSIONS

The results, based on case-by-case expert review of occupation-specific questionnaires, support the hypothesis that occupational pesticide exposures may be involved in HL, MM and HCL and do not rule out a role in NHL. The analyses identified specific pesticides that deserve further investigation and the findings were consistent with those of previous studies.

Hairy cell leukaemia: a heterogeneous disease?

The US National Cancer Institute's Surveillance, Epidemiology and End Results program was used to develop aetiological clues for hairy cell leukaemia (HCL). Descriptive techniques (age-adjusted incidence trends, age-specific incidence rates (IR), and age distributions-at-diagnosis) were supplemented with mathematical models (two-component mixture, generalized linear regression, and age-period-cohort). There were 2856 cases of HCL diagnosed during 1978-2004 (IR 0.32/100,000 person-years). IRs were nearly 4-fold greater among men than women and more than 3-fold higher for Whites than Blacks. Temporal trends were stable over time. Age-specific IRs increased rapidly until approximately 40 years then rose at a slower pace. The age-specific IR curves reflected bimodal early- and late-onset age distributions-at-diagnosis (or density plots), with some variation by gender. Among both men and women, a two-component mixture model fitted the data better than a single density or cancer population. Age-period-cohort models confirmed statistically significant age-related effects after full adjustment for temporal trends (calendar-period and birth-cohort effects). In summary, age incidence patterns (rates and bimodal densities) suggested that HCL is a heterogeneous disease, consisting of at least two underlying subgroups and/or cancer populations by age-at-onset. Distinct early- and late-onset HCL populations may reflect different age-related causal pathways, risk factor profiles, and/or stem cells of origin.

Risk of leukaemia among pesticide manufacturing workers: a review and meta-analysis of cohort studies

PURPOSE

The purpose of this paper is to review available cohort studies and to estimate quantitatively the association between occupational exposure in plants manufacturing pesticides and leukaemia.

METHODS

Following a systematic literature search, relative risks were extracted from 14 studies published between 1984 and 2004. Fixed effect analyses were carried out as heterogeneity between studies was not detected. Meta-analyses were performed on the whole set of data and separate analyses were conducted for specific chemical classes of pesticides as well as type of leukaemia.

RESULTS

The meta-rate ratio estimate for all studies was 1.43 (95% confidence interval [CI] 1.05-1.94). After stratification by chemical class, consistent increases in the risk of leukaemia were found in all groups but statistical significance was found only for phenoxy herbicides unlikely to have been contaminated with dioxins and furans. This last finding appears equivocal in view of the existing literature. The separate analysis conducted on leukaemias from the myeloid lineage showed the highest relative risk (6.99; 95% CI 1.96-24.90). There was no obvious indication of publication bias.

CONCLUSION

The overall meta-analysis among pesticide manufacturing workers provides quantitative evidence to consider occupational exposure to pesticides as a possible risk factor for leukaemia but available data are too scarce for causality ascertainment. Epidemiological evidence did not allow identifying a specific pesticide or chemical class that would be responsible for the increased risk. Exposure to pesticides may be a significant risk factor for specifically developing myeloid leukaemia and there is a need for additional large well-conducted studies with clear definition of exposure and of leukaemia type(s).

A population-based study of hairy cell leukemia in Israel

OBJECTIVES

Few population-based data exist on the incidence and prognosis of hairy cell leukemia (HCL). Our objectives were to study the effect of socio-demographic factors on this rare disease and the risk of second malignancies occurring in HCL patients.

METHODS

We measured crude and age-adjusted incidence rates of HCL based on reporting to the Israel Cancer Registry (ICR) 1991-2001. Using Kaplan-Meier and multivariate analysis, we assessed survival by gender, ethnicity and geographic region. We ascertained additional primary tumors reported in this population and calculated standardized incidence ratios (SIRs) for tumors reported after the diagnosis of HCL.

RESULTS

The ICR registered 147 cases of HCL among males and 34 in females between 1991 and 2001. Age-adjusted incidence rates were 1.62/10(6)/yr for women and 7.97/10(6)/yr for men, with rates 1.5 times higher in Jewish than in non-Jewish (mainly Arab) men. Mean overall survival also differed by ethnicity. In a multivariate model, increasing age at diagnosis (P < 0.001), as well as Arab origin (P = 0.008) were associated with poorer survival but gender did not significantly affect the survival after controlling for age and ethnicity. Other primary malignancies were reported in 20 (11%) individuals, with a predominance of genito-urinary tumors (65%) among males. Secondary genito-urinary tumors were significantly increased above the expected population rates (SIR 3.23, 95% confidence interval: 1.39-6.36, P = 0.008).

CONCLUSIONS

In the Israeli population, age and ethnicity were associated with prognosis of HCL. Variations in disease characteristics, stage of disease at diagnosis or differential access to treatment may contribute to these findings. Patients with HCL appear to be at increased risk for genito-urinary malignancies.

Causal Relationship between Non-Hodgkin's Lymphoma and Exposure to Benzene and Benzene-Containing Solvents

Non-Hodgkin's lymphoma (NHL) is a malignant neoplasm of the lymphatic system made up of mainly B cell lymphocytes. A large number of studies have shown significant associations between NHL and benzene or benzene-containing solvents and products. This article summarizes studies detailing these associations and indicates those that are significant. Based on an analysis of the literature and the weight of evidence from numerous studies, it is reasonable to conclude that exposure to benzene or to solvents or products containing benzene is causally related to NHL.

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.

Lifestyle factors and the risk of adult leukemia in Canada

OBJECTIVES

To evaluate the impact of active smoking, obesity, and dietary intakes on the risk of adult leukemia.

METHODS

We analysed data obtained from a population-based case-control study conducted in eight Canadian provinces. Risk estimates were generated by applying multivariate logistic regression methods to 1068 incident histologically confirmed leukemia cases and 5039 controls aged 20-74.

RESULTS

We found a statistically significant increased risk for acute myeloid leukemia (AML) associated with active smoking, with a clear dose-response relationship and an adjusted odds ratio (OR) of 1.5 (95% confidence interval [CI]=1.1-2.0) for heavy smokers reporting more than 20 pack-years of cigarette smoking. We also observed positive associations with the highest body mass index (BMI) for AML, chronic myeloid leukemia, and chronic lymphoid leukemia with a significant dose-response relationship. No association with leukemia was observed for the intake of fruits and vegetables, and the effect of active smoking on adult leukemia risk was not modified by fruits and/or vegetables consumption or obesity. However, the positive risk for AML associated with active smoking disappeared among subjects with high BMI (> or =30 kg/m2).

CONCLUSIONS

Our study contributes to the accumulating evidence linking AML and active smoking, and provides some evidence that obesity increases the risk of most of the adult leukemia subtypes.

Non-Hodgkin's Lymphoma and Type of Tobacco Smoke

Background: In recent decades, the incidence of non-Hodgkin's lymphoma (NHL) has increased in all industrialized countries. Tobacco smoke contains several recognized or putative carcinogenic compounds that differ in concentration depending on which of the two main types, blond or black, is consumed. This investigation sought to evaluate the association between NHL and type of tobacco smoked (blond, black, or mixed), focusing on the Working Formulation (WF) subgroups. Methods: Reanalysis of Italian data from a recent multicenter population-based case-control study. The 1450 cases of NHL and 1779 healthy controls from 11 Italian areas with different demographic and productive characteristics were included in the study, corresponding to ∼7 million residents. Odds ratios (ORs) adjusted for age, gender, residence area, educational level, and type of interview were estimated by unconditional logistic regression model. Results: A statistically significant association [OR = 1.4, 95% confidence interval (CI) 1.1–1.7] was found for blond tobacco exposure and NHL risk. A dose-response relationship was limited to men younger than 52 years (χ2 for trend = 9.95, P &lt; 0.001). Subjects starting smoking at an early age showed a higher risk in men younger than 65 years, whereas no clear trend was evident for the other age and gender subgroups. The analysis by WF categories showed the highest risks for follicular lymphoma in blond (OR = 2.1, 95% CI 1.4–3.2) and mixed (OR = 1.8, 95% CI 1.1–3.0) tobacco smokers and for large cell within the other WF group (OR = 1.6, 95% CI 1.1–2.4) only for blond tobacco. Conclusion: Smoking blond tobacco could be a risk factor for NHL, especially follicular lymphoma.

Contacts with animals and humans as risk factors for adult brain tumours. An international case-control study

While numerous studies have addressed the possible role of farming and related exposures as risk factors for brain tumours in adults, few of them have examined the potential effect of exposure to farm animals or pets. In an international multicentre case-control study, we investigated whether residence on a farm, contact with animals, or working in occupations with a high degree of potential contact with animals or humans were associated with brain tumours. Using a common questionnaire, 1177 cases of glioma, 330 with meningioma and 2478 controls from eight centres were interviewed about the exposures and, in particular, about their contacts with nine species of animals: dairy cattle, beef cattle, pigs, horses, sheep, goats, poultry, dogs and cats. Living or working on a farm was not a risk factor, for either glioma or meningioma. Except in some centres, there was no relationship between having contacts with farm animals or pets and the risk of brain tumour, for either type of tumour or either sex. In relation to seven industrial groups involving frequent human and/or animal contacts, no association was apparent for either glioma or meningioma. In relation to 25 occupational groups with potential frequent contact with humans and/or animals, for glioma there was a reduced risk for biological technicians (Odds Ratio (OR)/=0, P=0.01), and general farm workers (OR=0.66, 95% Confidence Interval (CI): 0.5-0.9). For meningioma, there was an increased risk for cooks (OR=2.0; CI: 1.2-3.4). With some exceptions, these results indicate no association between either the type of brain tumour and contacts with animals, or with occupations that include a high level of contact with animals or a high level of contact with humans.

Hairy cell leukemia in first cousins and review of the literature

Familial hairy cell leukemia (HCL) occurs rarely. So far, 26 familial instances of HCL (in 12 families) have been reported in the literature. The consistent human leukocyte antigen (HLA) linkage could not be established in most cases of familial HCL. History of exposure to organic chemicals or employment in woodworking or farming was noted in only two out of 11 affected families. We present two familial cases of HCL as well as a thorough literature review. An influence of HLA or farming themselves on a predisposition to HCL remains unproven but does not rule out an HLA-linked and as yet unidentified gene responsible for increased disease susceptibility. HCL in families is unlikely to be due to random patterning, but there are insufficient data so far to decisively incriminate either HLA-related or environmental causative factors.

Epidemiology of lymphomas

Non-Hodgkin lymphoma (NHL) is the fifth most common cancer in the US, with about 55,000 new cases estimated for the year 2000. According to the new Surveillance, Epidemiology, and End Results (SEER) data from 1973 to 1997, the age-adjusted incidence rates rose by about 80%, with an annual percentage increase of nearly 3%, which is faster than for the majority of cancers. The increasing incidence of NHL is largely unexplained. AIDS-related NHL accounts for some but not all of the increase. The American Cancer Society predicts about 7,400 new cases of Hodgkin Disease (HD) in the year 2000 in the US. The incidence of HD is consistently lower than that of NHL, and has decreased about 16% since the 1970s. Only a small portion of the decrease in HD incidence can be explained by misdiagnosis of HD as NHL. Further research is needed on the cofactors that predispose AIDS cases to lymphoma, as well as other possible causes of NHL such as immunosuppression, genetics, viruses, medical conditions, pesticides, solvents, hair dyes, and diet. Further evaluation of the role of viruses, occupational exposures, and genetics in the etiology of HD should prove valuable.

Concentrations of organochlorines related to titers to Epstein-Barr virus early antigen IgG as risk factors for hairy cell leukemia

Hairy cell leukemia (HCL) is a rare chronic B-cell malignancy that, according to modern classifications, is a subgroup of non-Hodgkin lymphomas (NHLs). A rapid increase in incidence of NHL has been reported in many countries. The reasons for this increase are largely unknown, but exposure to organochlorines has been suggested as a risk factor. Epstein-Barr virus is a human herpesvirus that has been associated with certain subgroups of NHL. In this study, we measured lipid adjusted blood concentrations (in nanogram per gram) of 36 congeners of polychlorinated biphenyls (PCBs), p, p'-dichlorodiphenyldichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), and four subgroups of chlordanes (trans-nonachlor, cis-nonachlor, MC6, and oxychlordane) in incident cases of HCL and controls from the general population. We obtained results on organochlorines and antibodies for 54 cases and 54 controls. Titers of antibodies to the Epstein-Barr early antigen and Epstein-Barr nuclear antigen, measured as P107, were correlated to concentrations of organochlorines to evaluate the possibility of an interaction between these factors in the pathogenesis of HCL. We found no significant difference in lipid-adjusted blood concentrations of total PCBs, p,p'-DDE, HCB, or the sum of the chlordanes between cases and controls. Titers of antibodies to Epstein-Barr early antigen IgG [Greater and equal to] 40 were correlated to an increased risk for HCL. This risk was further increased in those with a level above the median value of p,p'-DDE, HCB, or the sum of the chlordanes, suggesting an interaction between Epstein-Barr virus and a higher concentration of these chemicals. We also found increased risk for the sum of immunotoxic PCB group.

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

BACKGROUND

The incidence of non-Hodgkin lymphoma (NHL) has increased in most Western countries during the last few decades. Immunodefective conditions are established risk factors. In 1981, the authors reported an increased risk for NHL following exposure to certain pesticides. The current study was designed to further elucidate the importance of phenoxyacetic acids and other pesticides in the etiology of NHL.

METHODS

A population-based case-control study in northern and middle Sweden encompassing 442 cases and twice as many controls was performed. Exposure data were ascertained by comprehensive questionnaires, and the questionnaires were supplemented by telephone interviews. In total, 404 cases and 741 controls answered the questionnaire. Univariate and multivariate analyses were performed with the SAS statistical data program.

RESULTS

Increased risk for NHL was found for subjects exposed to herbicides (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.0-2.5) and fungicides (OR, 3.7; 95% CI, 1.1-13.0). Among herbicides, the phenoxyacetic acids dominated (OR, 1.5; 95% CI, 0.9-2.4); and, when subclassified, one of these, 4-chloro-2-methyl phenoxyacetic acid (MCPA), turned out to be significantly associated with NHL (OR, 2.7; 95% CI, 1.0-6.9). For several categories of herbicides, it was noted that only exposure during the most recent decades before diagnosis of NHL was associated with an increased risk of NHL. Exposure to impregnating agents and insecticides was, at most, only weakly related to NHL.

CONCLUSIONS

Exposure to herbicides in total, including phenoxyacetic acids, during the decades before NHL diagnosis resulted in increased risk for NHL. Thus, the risk following exposure was related to the latency period. Fungicides also increased the risk for NHL when combined, but this group consisted of several different agents, and few subjects were exposed to each type of fungicide.