Exposures to multiple pesticides and the risk of Hodgkin lymphoma in Canadian men

Interplay between Epstein-Barr virus infection and environmental xenobiotic exposure in cancer

Epstein-Barr virus (EBV) is a herpesvirus associated with lymphoid and epithelial malignancies. Both B cells and epithelial cells are susceptible and permissive to EBV infection. However, considering that 90% of the human population is persistently EBV-infected, with a minority of them developing cancer, additional factors are necessary for tumor development. Xenobiotics such as tobacco smoke (TS) components, pollutants, pesticides, and food chemicals have been suggested as cofactors involved in EBV-associated cancers. In this review, the suggested mechanisms by which xenobiotics cooperate with EBV for carcinogenesis are discussed. Additionally, a model is proposed in which xenobiotics, which promote oxidative stress (OS) and DNA damage, regulate EBV replication, promoting either the maintenance of viral genomes or lytic activation, ultimately leading to cancer. Interactions between EBV and xenobiotics represent an opportunity to identify mechanisms by which this virus is involved in carcinogenesis and may, in turn, suggest both prevention and control strategies for EBV-associated cancers.

Occupational exposure to organophosphate pesticides and hematologic neoplasms: a systematic review

OBJECTIVE

To update findings of observational analytical studies on the association between occupational exposure to organophosphates and hematologic malignancies.

METHODOLOGY

Systematic literature review, including cohort and case-control studies, without limitation of publication time, in Portuguese and English. The articles were traced from June 2017 to July 2019 in PubMed, MEDLINE, LILACS, Web of Science, and Scopus databases. The qualitative bias risk assessment was performed using the Newcastle-Ottawa Scale and the Downs and Black Checklist. Results were presented according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA).

RESULTS

Seventeen studies evaluated as good/high methodological quality were eligible. Exposure to diazinon (1 cohort), phonophos (1 cohort), dichlorvos, crotoxiphos and famphur (1 case control) was associated with leukemia, while exposure to organophosphate was associated to lymphomas (6 case control); the risk of non-Hodgkin's lymphoma was higher in those exposed to diazinon (1 control case) and malathion (3 control case) than non-exposed ones. Multiple myeloma occurred more commonly in organophosphate exposed than in non-exposed individuals (1 case-control).

CONCLUSION

Occupational exposure to organophosphates increases the risk of hematologic malignancies, especially among individuals with longer exposure periods. Worker monitoring and exposure control measures are recommended.

Pesticide use and risk of Hodgkin lymphoma: results from the North American Pooled Project (NAPP)

PURPOSE

The purpose of this study was to investigate associations between pesticide exposures and risk of Hodgkin lymphoma (HL) using data from the North American Pooled Project (NAPP).

METHODS

Three population-based studies conducted in Kansas, Nebraska, and six Canadian provinces (HL = 507, Controls = 3886) were pooled to estimate odds ratios and 95% confidence intervals for single (never/ever) and multiple (0, 1, 2-4, ≥ 5) pesticides used, duration (years) and, for select pesticides, frequency (days/year) using adjusted logistic regression models. An age-stratified analysis (≤ 40/ > 40 years) was conducted when numbers were sufficient.

RESULTS

In an analysis of 26 individual pesticides, ever use of terbufos was significantly associated with HL (OR: 2.53, 95% CI 1.04-6.17). In age-stratified analyses, associations were stronger among those ≤ 40 years of age. No significant associations were noted among those > 40 years old; however, HL cases ≤ 40 were three times more likely to report ever using dimethoate (OR: 3.76 95% CI 1.02-33.84) and almost twice as likely to have ever used malathion (OR: 1.86 95% CI 1.00-3.47). Those ≤ 40 years of age reporting use of 5 + organophosphate insecticides had triple the odds of HL (OR: 3.00 95% CI 1.28-7.03). Longer duration of use of 2,4-D, ≥ 6 vs. 0 years, was associated with elevated odds of HL (OR: 2.59 95% CI 1.34-4.97).

CONCLUSION

In the NAPP, insecticide use may increase the risk of HL, but results are based on small numbers.

Risk of lymphoma subtypes by occupational exposure in Southern Italy

Background

Occupational exposure is known to play a role in the aetiology of lymphomas. The aim of the present work was to explore the occupational risk of the major B-cell lymphoma subtypes using a case–control study design.

Methods

From 2009 to 2014, we recruited 158 lymphoma cases and 76 controls in the provinces of Bari and Taranto (Apulia, Southern Italy). A retrospective assessment of occupational exposure based on complete work histories and the Carcinogen Exposure (CAREX) job-exposure matrix was performed.

Results

After adjusting for major confounding factors, farmers showed an increased risk of diffuse large B-cell lymphoma (DLBCL) [odds ratio (OR) = 10.9 (2.3–51.6)] and multiple myeloma (MM) [OR = 16.5 (1.4–195.7)]; exposure to the fungicide Captafol was significantly associated with risk of non-Hodgkin lymphoma (NHL) [OR = 2.6 (1.1–8.2)], particularly with the risk of DLBCL [OR = 5.3 (1.6–17.3)].

Conclusions

Agricultural activity seems to be a risk factor for developing lymphoma subtypes, particularly DLBCL, in the provinces of Bari and Taranto (Apulia Region, Southern Italy). Exposure to the pesticides Captafol, Paraquat and Radon might be implicated.

Trial registration

Protocol number UNIBA 2207WEJLZB_004 registered 22/09/2008.

Occupational exposure to carcinogens: Benzene, pesticides and fibers (Review)

It is well known that the occupational exposure to contaminants and carcinogens leads to the development of cancer in exposed workers. In the 18th century, Percivall Pott was the first to hypothesize that chronic exposure to dust in the London chimney sweeps was associated with an increased risk of developing cancer. Subsequently a growing body of evidence indicated that other physical factors were also responsible for oncogenic mutations. Over the past decades, many carcinogens have been found in the occupational environment and their presence is often associated with an increased incidence of cancer. Occupational exposure involves several factors and the association between carcinogens, occupational exposure and cancer is still unclear. Only a fraction of factors is recognized as occupational carcinogens and for each factor, there is an increased risk of cancer development associated with a specific work activity. According to the International Agency for Research on Cancer (IARC), the majority of carcinogens are classified as 'probable' and 'possible' human carcinogens, while, direct evidence of carcinogenicity is provided in epidemiological and experimental studies. In the present review, exposures to benzene, pesticides and mineral fibers are discussed as the most important cancer risk factors during work activities.

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.

Cholinergic system and cell proliferation

The cholinergic system, comprising acetylcholine, the proteins responsible for acetylcholine synthesis and release, acetylcholine receptors and cholinesterases, is expressed by most human cell types. Acetylcholine is a neurotransmitter, but also a local signalling molecule which regulates basic cell functions, and cholinergic responses are involved in cell proliferation and apoptosis. So, activation of nicotinic and muscarinic receptors has a proliferative and anti-apoptotic effect in many cells. The content of choline acetyltransferase, acetylcholine receptors and cholinesterases is altered in many tumours, and cholinesterase content correlates with patient survival in some cancers. During apoptosis, acetylcholinesterase is induced and appears in the nuclei. Acetylcholinesterase participates in the regulation of cell proliferation and apoptosis through hydrolysis of acetylcholine and by other catalytic and non catalytic mechanisms, in a variant-specific manner. This review gathers information on the role of cholinergic system and specially acetylcholinesterase in cell proliferation and apoptosis.

Knowledge, attitude, and practice of Indonesian farmers regarding the use of personal protective equipment against pesticide exposure

The use of synthetic pesticides in tropical countries has increased over the years, following the intensification of agriculture. However, awareness among farmers of the importance of protecting themselves from hazards associated with pesticide application is still lacking, especially in Indonesia. This paper reports results of an inventory on knowledge and attitudes regarding pesticide use by melon farmers of a village in Central Java, Indonesia. The importance of using personal protective equipment such as hats, masks, goggles, boots, and gloves on agricultural land is known and well understood by the farmers. However, in practice, only 3.8 % were wearing glasses and 1.9 % were using boots. In fact, the masks used only consisted of a part of their shirt tied around the mouth. The farmers were not wearing long pants and shirts with long sleeves and used the same clothes for more than 1 day without washing. Almost no farmers used personal protective equipment that was standard, in good condition, and complete. Based on the results of statistical analysis, no significant relationship was found between knowledge and attitude on the required practices on the one hand and the use of personal protective equipment in practice on the other hand. This shows that improved knowledge and attitudes are not enough to change the behavior of farmers to work in a healthy and safe way. The gap between knowledge and practice needs to be bridged by a more interactive and participatory training model. It is therefore of paramount importance to develop a special toolkit for pesticide risk reduction which is developed in a participatory manner involving the farmers as the main actors through a series of focus group discussions and field simulations.