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

Exposure to pesticides and risk of Hodgkin lymphoma in an international consortium of agricultural cohorts (AGRICOH)

PURPOSE

Some pesticides may increase the risk of certain lymphoid malignancies, but few studies have examined Hodgkin lymphoma (HL). In this exploratory study, we examined associations between agricultural use of 22 individual active ingredients and 13 chemical groups and HL incidence.

METHODS

We used data from three agricultural cohorts participating in the AGRICOH consortium: the French Agriculture and Cancer Cohort (2005-2009), Cancer in the Norwegian Agricultural Population (1993-2011), and the US Agricultural Health Study (1993-2011). Lifetime pesticide use was estimated from crop-exposure matrices or self-report. Cohort-specific covariate-adjusted overall and age-specific (< 40 or ≥ 40 years) hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression and combined using random effects meta-analysis.

RESULTS

Among 316 270 farmers (75% male) accumulating 3 574 815 person-years at risk, 91 incident cases of HL occurred. We did not observe statistically significant associations for any of the active ingredients or chemical groups studied. The highest risks of HL overall were observed for the pyrethroids deltamethrin (meta-HR = 1.86, 95% CI 0.76-4.52) and esfenvalerate (1.86, 0.78-4.43), and inverse associations of similar magnitude were observed for parathion and glyphosate. Risk of HL at ≥ 40 years of age was highest for ever-use of dicamba (2.04, 0.93-4.50) and lowest for glyphosate (0.46, 0.20-1.07).

CONCLUSION

We report the largest prospective investigation of these associations. Nonetheless, low statistical power, a mixture of histological subtypes and a lack of information on tumour EBV status complicate the interpretability of the results. Most HL cases occurred at older ages, thus we could not explore associations with adolescent or young adult HL. Furthermore, estimates may be attenuated due to non-differential exposure misclassification. Future work should aim to extend follow-up and refine both exposure and outcome classification.

Exposures to pesticides and risk of cancer: Evaluation of recent epidemiological evidence in humans and paths forward

Knowledge of the role in cancer etiology of environmental exposures as pesticides is a prerequisite for primary prevention. We review 63 epidemiological studies on exposure to pesticides and cancer risk in humans published from 2017 to 2021, with emphasis on new findings, methodological approaches, and gaps in the existing literature. While much of the recent evidence suggests causal relationships between pesticide exposure and cancer, the strongest evidence exists for acute myeloid leukemia (AML) and colorectal cancer (CRC), diseases in which the observed associations were consistent across several studies, including high-quality prospective studies and those using biomarkers for exposure assessment, with some observing dose-response relationships. Though high-quality studies have been published since the IARC monograph on organophosphate insecticides in 2017, there are still gaps in the literature on carcinogenic evidence in humans for a large number of pesticides. To further knowledge, we suggest leveraging new techniques and methods to increase sensitivity and precision of exposure assessment, incorporate multi-omics data, and investigate more thoroughly exposure to chemical mixtures. There is also a strong need for better and larger population-based cohort studies that include younger and nonoccupationally exposed individuals, particularly during developmental periods of susceptibility. Though the existing evidence has limitations, as always in science, there is sufficient evidence to implement policies and regulatory action that limit pesticide exposure in humans and, hence, further prevent a significant burden of cancers.

Occupational exposure to pesticides in mothers and fathers and risk of cancer in the offspring: A register-based case-control study from Sweden (1960-2015)

Maternal and paternal occupational exposure to pesticides was linked to leukemia in the offspring in some previous studies. Risks for other cancers, particularly from maternal exposure, are largely unknown. We examined the association between maternal and paternal exposure to pesticides and childhood cancer in a Swedish register-based case-control study (1960-2015). Cancer cases <20 years old were identified from the Cancer Register (n = 17313) and matched to controls (1:25) on birth year and sex. Employment history of each biological parent around the child's birth was retrieved from six censuses and a nationwide register, and exposure to any of herbicides, insecticides, and fungicides was evaluated using the Swedish job-exposure matrix (SWEJEM) in 9653/172194 mothers and 12521/274434 fathers of cases/controls. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated from conditional logistic regression models for any cancer, leukemia, lymphoma, central nervous system [CNS], and other solid tumors. We found an OR of 1.42 (95% CI 0.78, 2.57; 12 exposed cases) for lymphoma and 1.30 (95% CI 0.88, 1.93; 27 exposed cases) for other solid tumors associated with maternal occupational exposure to pesticides. No associations were observed between maternal exposure and leukemia or CNS tumors, or paternal exposure and any of the cancers examined, except for a potential association between pesticides exposure and myeloid leukemia (OR 1.15 [95% CI 0.73, 1.79; 22 exposed cases]). Although these findings merit further investigation, they indicate that parental exposure to pesticides may lead to higher risks of childhood cancer even in settings of low exposure.

A Review and Update with Perspective of Evidence that the Herbicide Glyphosate (Roundup) is a Cause of Non-Hodgkin Lymphoma

Glyphosate-based formulations (GBFs), such as Roundup, are the most heavily used herbicides in the world. In 2015, the International Agency for Research on Cancer (IARC) concluded that glyphosate and GBFs are probably carcinogenic to humans (group 2A), mainly for non-Hodgkin lymphoma (NHL). However, this finding has been controversial, and most pesticide regulatory agencies have not followed their lead. The purpose of this review was to examine the scientific literature linking exposure to glyphosate and GBFs to the development of NHL, with emphasis on new findings since publication of the IARC report. The epidemiologic studies provide ample evidence for an association between exposure to GBFs and an increased risk of NHL. Animal studies have shown that glyphosate is carcinogenic in rodents and causes NHL in mice. Mechanistic studies have demonstrated that glyphosate and GBFs are genotoxic to human lymphocytes, the normal cell of origin of NHL, both in vitro and in vivo. Genotoxic and other biological effects have also been shown in various animal and cell models with these agents even at low doses. A novel mechanism underlying the specificity of glyphosate for NHL, that is upregulation of the B-cell genome mutator enzyme activation-induced cytidine deaminase, has recently been demonstrated. These findings were evaluated holistically using the guidelines for evaluation of general causation set forth by Bradford Hill. This evaluation provides coherent and compelling evidence that glyphosate and GBFs are a cause of NHL in humans exposed to these agents. These findings should prompt new reviews by pesticide regulatory agencies around the world.

Correlation between the prevalence of T-cell lymphomas and alcohol consumption

Background and aims

Alcohol is a psychoactive substance that causes dependence, with many thousands of years in the history of mankind, being widely used in different cultures. According to the International Agency for Research on Cancer, alcohol is involved in the development of cancer, being directly associated with it. Considering that alcohol is involved in the initiation and dissemination of gastrointestinal malignancies, the objective of the study was to assess its role in the pathogenesis of T-cell lymphomas, as well as its possible correlation with chronic consumption.

Methods

The patient cohort was compiled from the Sixth Medical Center of the People's Liberation Army Navy General Hospital in Beijing, China. A total of 30 patients matched the criteria and were enrolled in the study. Statistical analysis of the raw data was performed using R Statistics version R 3.5.1. released on the 29.08.2018.

Results

Our data demonstrate that the most common extranodal involvment of T-cell lymphoma patients is represented in decreasing order by bone marrow, peritoneum, rhino-oropharynx and the liver-biliary system. Nodal involvement is mainly represented in decreasing order by the laterocervical, axillary, mediastinal and inguinal regions.

Conclusions

These findings may be of value in further research and practical/clinical settings. Fever is the most common clinical feature and was present in most studied patients.

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.

Exposure to pesticides and oxidative stress in Brazilian agricultural communities

BACKGROUND

Oxidative stress may be an important mechanism linking pesticide exposure to several diseases. We evaluated the association between pesticide exposures and oxidative stress biomarkers in Brazilian agricultural workers.

METHODS

A cross-sectional study was conducted in healthy agricultural (N = 52) and non-agricultural workers (N = 68) in a rural community in Rio de Janeiro State, Brazil. Regular pesticide use, sociodemographic, and lifestyle information was obtained by questionnaire. Oxidative stress biomarkers (N = 7) were measured in serum and plasma. We calculated percent differences and 95% confidence intervals (CI) in oxidative stress biomarkers for use of pesticides adjusted for sex, age, education, smoking, and alcohol consumption, using multiple linear regression.

RESULTS

Living close to or in the fields was associated with glutathione peroxidase activity but not with any other markers. We observed significant positive associations between 8-isoprostane levels and activities of glutathione reductase, glutathione peroxidase, and glutathione-S-transferase with reported use of certain insecticides, fungicides, and herbicides. Our results also indicate a significant and negative association between glutathione-S-transferase activity and insecticide use.

CONCLUSIONS

These findings suggest that use of pesticides may be associated with differences in oxidative stress biomarkers.

Pesticides Hazardous Hotspots: Empirical Evidences from North India

The pesticide use in Indian agriculture showed a declining trend in the late 1990s and early 2000s. Since 2007, pesticide use gained an upward trend. To study the pesticide use pattern and identify pesticide hotspots, we collected data from a sample of 1201 apple, rice, vegetable, and cotton growers from the temperate Kashmir Valley, subtropical Jammu, and Punjab. Our study provided some interesting empirical results: prophylactic pesticide applications in apple crop making it a pesticide guzzler [25.2 kg of active ingredient (ai)/ha] with use of riskiest carcinogen pesticides (9 kg of a.i/ha) and field use environmental impact quotient (FEIQ) (620.4/ha) being the highest, the Kashmir Valley is the "pesticide hottest spot", followed by cotton and rice areas of Punjab and vegetable cultivation in Jammu subtropics. Pesticides banned for use in vegetables, such as monocrotophos were also applied by farmers in vegetable crops. However, rice areas in Kashmir and Jammu were only treated with herbicides. The protective measures taken by farmers while mixing and applying pesticides were primitive, resulting in localized mild/moderate pesticide poisoning besides loss of consciousness. We also found that the official data on the pesticide use are underreported and hence unreliable. Our study shows that neither the pesticide use by mass nor the pesticide use frequency, in combination or alone, is the robust indicator to measure the pesticide hazardous hotspots; besides these, FEIQ and less hazardous pesticides that are not probable or possible carcinogen should be rather used in conjunction.