Pendimethalin exposure and cancer incidence among pesticide applicators

Exposure to pesticides and risk of colorectal cancer: A systematic review and meta-analysis

Colorectal cancer (CRC) is a widespread malignancy worldwide, and its relationship with pesticide exposure remains inconclusive. This study aims to elucidate the relationship between pesticide exposure and the risk of colon, rectal, or CRC, focusing on specific pesticide groups. We conducted an extensive literature search for peer-reviewed studies published up to March 31, 2023. Summary risk ratios (RR) and their corresponding 95% confidence intervals (CI) were calculated using stratified random-effects meta-analyses, taking into account different types of exposure and outcomes, and various exposed populations and pesticide subgroups. This approach aimed to address the substantial heterogeneity observed across the literature. We also assessed heterogeneity and potential small-study effects to ensure the robustness of our findings. From the 50 studies included in this review, 33 contributed to the meta-analysis. Our results indicate a significant association between herbicide exposure and colon cancer in both lifetime-days (LDs) (RR = 1.20; 95% CI = 1.01-1.42) and intensity-weighted lifetime-days (IWLDs) (RR = 1.29, 95% CI = 1.12-1.49) exposure. Similarly, insecticide exposure was associated with an increased risk of colon cancer in IWLDs (RR = 1.32; 95% CI = 1.02-1.70) exposure, and rectal cancer in any versus never exposure (RR = 1.21; 95% CI = 1.07-1.36), IDs (RR = 1.86; 95% CI = 1.30-2.67) and IWLDs (RR = 1.70; 95% CI = 1.03-2.83) exposure. While these findings suggest significant associations of herbicide and insecticide exposure with colon and rectal cancer, respectively, further research is needed to explore the impact of other pesticide groups and deepen our understanding of pesticide exposure. These results have important implications for policymakers and regulators, underscoring the need for stricter supervision and regulation of pesticide use to mitigate CRC risk.

Pesticide exposure and lung cancer risk: A case-control study in Nakhon Sawan, Thailand

Background

Pesticide exposure might increase risk of lung cancer. The purpose of this study was to investigate the association between the historical use of pesticides and lung cancer using a case-control design.

Methods

This case-control study compared a lifetime pesticide exposure of 233 lung cancer cases, and 447 healthy neighbours matched for gender, and age (±5 years). Data on demographic, pesticide exposure and other related factors were collected using a face-to-face interview questionnaire. Associations between lung cancer and types of pesticides as well as individual pesticides were analysed using logistic regression adjusted for gender, age, cigarette smoking, occupation, cooking fumes exposure, and exposure to air pollution.

Results

It was found that lung cancer was positively associated with the lifetime use of herbicides and insecticides. Compared to people in the non-exposed groups, those in Q3-Q4 days of using herbicides and insecticides had an elevated risk of lung cancer, with odds ratio (OR) between 2.20 (95% confidence interval (CI) 1.24-3.89), and 3.99 (95% CI 1.62-7.11) (p < 0.001). For individual pesticides, those presenting a significant association with lung cancer were dieldrin (OR = 2.56; 95% CI 1.36-4.81), chlorpyrifos (OR = 3.29; 95 % CI 1.93-5.61), and carbofuran (OR = 2.10; 95% CI 1.28-3.42). It was also found, for the first time, carbofuran, glyphosate, and paraquat to be significantly associated with lung cancer.

Conclusions

The study confirmed dieldrin, and chlorpyrifos as risk factors and suggested carbofuran, glyphosate, and paraquat as potential risk factors for the disease. The paper stands as a noteworthy contribution to literature, particularly because the majority of publications on the topic originate from developed Western countries. However, further studies are imperative to validate the results and pinpoint additional individual pesticides that may be associated with lung cancer.

Development of competitive and noncompetitive lateral flow immunoassays for pendimethalin using synthetic peptides

Peptidomimetic and anti-immunocomplex peptides can be easily isolated from phage display libraries, and can be used as alternatives to chemical competing haptens to improve the sensitivity of small molecule immunoassay. In this work, 16 peptidomimetics and 7 anti-immunocomplex peptides of pendimethalin (PND) were obtained from cyclic 7-, 8-, 9-, and 10-residue peptide phage libraries. Peptidomimetic EJ-2 (CMFTGTDFPC) with the highest sensitivity in competitive phage enzyme-linked immunosorbent assay (ELISA) and immunocomplex peptide EF-30 (CNPGWPPIPC) with the highest sensitivity in noncompetitive phage ELISA were selected to prepare phage-free peptides with GGGSSK-biotin at the C-terminus. Competitive and noncompetitive lateral flow immunoassays (CLFIA and NLFIA) were developed by using the phage-free peptides. After optimization, the CLFIA and NLFIA showed visual limit of detections (vLODs) of 5 ng/mL and 2.5 ng/mL, respectively, which were improved two- and fourfold compared with a LFIA based on chemical hapten. The NLFIA showed better sensitivity than CLFIA in the detection of spiked samples, and can meet the detection requirements for agro-products regulated by EU and China. The detection results of CLFIA and NLFIA for blind samples were consistent with that of ultra performance liquid chromatography/tandem mass spectrometry.

Investigation of the Relationship between Spontaneous Abortion, Serum Pesticides, and Polychlorinated Biphenyl Levels

Occupational and environmental chemical exposure have been associated with adverse reproductive consequences. This study investigates the relationship between spontaneous abortion and blood pesticide and polychlorinated biphenyl (PCB) levels. A survey was conducted, and blood samples were collected from 200 patients, consisting of 100 cases with spontaneous abortion and 100 cases with normal deliveries. A total of 150 different pesticides, including organophosphates, organochlorines, carbamates, and pyrethroids, were screened in the collected blood samples and analyzed quantitatively using Tandem mass spectrometry-specifically in combination with liquid chromatography and gas chromatography-tandem mass spectrometry methods. Eight types of PCBs were analyzed with the gas chromatography-tandem mass spectrometry method. The groups were compared based on these analyses. The mean age of the participants was 28.09 ± 4.94 years. In 59% of the spontaneous abortion group, 5.05 ± 1.97 chemicals were detected in different amounts. (p < 0.05). Analysis of the samples identified the presence of β-Hexachlorocyclohexane (β-HCH), delta-hexachlorocyclohexane (δ HCH), Hexachlorobenzene (HCB), Pentachlorobiphenyl-28 (PCB-28), Pentachlorobiphenyl-52 (PCB-52), o,p'-Dichlorodiphenyldichloroethylene (o,p'-DDE), p,p'-Dichlorodiphenyldichloroethylene (p,p'DDE), o,p'-Dichlorodiphenyldichloroethane (o,p'-DDD), p,p'-Dichlorodiphenyldichloroethane (p,p'-DDD), Pentachlorobiphenyl-118 (PCB-118), Pentachlorobiphenyl-101 (PCB-101), Pentachlorobiphenyl-153 (PCB-153), Pentachlorobiphenyl-138 (PCB-138), Pentachlorobiphenyl-202 (PCB-202), Pentachlorobiphenyl-180 (PCB-180) as well as Fibronil, Buprimate, Acetoclor, Acemiprid, Pentimanthalin, and Triflokystrobin. The spontaneous abortion group had significantly higher exposure to PCB-101, PCB-52, PCB-138, and δ-HCH (p < 0.05). Women included in the study had high pesticide and PCB exposure rates. Many of the blood samples contained multiple pesticides with endocrine-disrupting effects. Higher exposure to organochlorine compounds in the serum was identified in the group with spontaneous abortions.

Determinants of Pesticide Exposure in Occupational Studies: A Meta-Analysis

Few epidemiological studies use exposure determinants specifically tailored to assess pesticide or plant protection product (PPP) exposures when assessing presumed association between occupational exposure and health outcomes among agricultural workers. This lack of exposure specificity could lead to results that fail to detect an association. It could be related to the lack of consensus on exposure assessment methods and the choice of exposure determinants. We conducted a meta-analysis following the PRISMA checklist to identify PPP exposure determinants used in occupational studies and identified exposure determinants that best characterized agricultural exposures to PPPs. Out of 1436 studies identified, 71 were included. The exposure determinants identified were active ingredients, chemical classes, types of PPP, crops, tasks, frequencies, duration, lifetime exposure days, and intensity-weighted exposure days. Only six over 17 associations between exposure determinants and health outcomes were found with moderate quality of evidence. Overall, epidemiological studies had difficulty defining relevant determinants to characterize PPP exposures for agricultural workers. We recommend that a standardized list of determinants for PPP exposures in occupational exposure studies should include information on formulations, intensity, duration, and frequency of PPP exposure. Harmonized data collection on exposure and health outcomes are required as well as standard units for each exposure determinant.

Pesticides and Bladder Cancer: Mechanisms Leading to Anti-Cancer Drug Chemoresistance and New Chemosensitization Strategies

Multiple risk factors have been associated with bladder cancer. This review focuses on pesticide exposure, as it is not currently known whether agricultural products have a direct or indirect effect on bladder cancer, despite recent reports demonstrating a strong correlation. While it is known that pesticide exposure is associated with an increased risk of bladder cancer in humans and dogs, the mechanism(s) by which specific pesticides cause bladder cancer initiation or progression is unknown. In this narrative review, we discuss what is currently known about pesticide exposure and the link to bladder cancer. This review highlights multiple pathways modulated by pesticide exposure with direct links to bladder cancer oncogenesis/metastasis (MMP-2, TGF-β, STAT3) and chemoresistance (drug efflux, DNA repair, and apoptosis resistance) and potential therapeutic tactics to counter these pesticide-induced affects.

The occurrence of bone and joint cancers and their association with rural living and radon exposure in Iowa

Primary bone and joint cancers are rare and understudied, yet these neoplasms are difficult to treat and impact all age groups. To explore the long-term changes in the occurrence of bone and joint cancers, patients diagnosed with these neoplasms between 1975 and 2016 were identified in the Surveillance Epidemiology and End Results of the National Cancer Institute of the USA. The age-adjusted incidence (AAIR) and mortality (AAMR) rates were calculated for three decades and compared to AAIR and AAMR in years 1975-1984. By using the population-based cancer registries of the USA, Iowa was identified as a state with increased cases of bone and joint malignancies. The bone and joint cancer cases in Iowa were correlated with the percentage of rural population, the average farmland size, or the residential radon levels. Results demonstrated that the mean AAIR of bone and joint cancers for US female and male patients (< 50 years of age) increased from 0.57 (95% C.I. 0.55-0.63) and 0.76 (95% C.I. 0.69-0.82) for years 1975-1984 to 0.71 (95% C.I. 0.66-0.76) and 0.94 (95% C.I. 0.87-1.07) for years 2005-2014, respectively. The increase in bone and joint cancer cases in Iowa positively correlated with the percentage rural population (R = 0.222, P < 0.02), and the average farmland size (R = 0.236, P < 0.02) but not the radon levels (R = - 0.038, P < 0.7). The findings revealed that patients younger than 50 years of age and those who resided in rural areas and engaged in farming were more likely to be diagnosed with primary bone and joint cancers.

Pendimethalin exposure induces bovine mammary epithelial cell death through excessive ROS production and alterations in the PI3K and MAPK signaling pathways

Herbicides are chemicals that have been established to have adverse impacts. However, they are still widely used in agriculture. Pendimethalin (PDM) is an herbicide that is widely used in many countries to control annual grasses. The possibility of livestock being exposed to PDM is relatively high, considering the half-life of PDM and its residues in water, soil and crops. However, the toxicity of PDM in cattle, especially in the mammary glands, has not been reported. Therefore, we investigated whether PDM has toxic effects in the mammary epithelial cells (MAC-T) of cattle. MAC-T cells were treated with various doses (0, 2.5, 5 and 10 μM) of PDM. We found that PDM affected cell viability and cell proliferation and causes cell cycle arrest. Furthermore, PDM triggered cell apoptosis, induced excessive ROS production and mitochondrial membrane potential (MMP) loss, and disrupted calcium homeostasis. In addition, PDM altered the activation of proteins associated with the endoplasmic reticulum (ER) stress response and modified PI3K and MAPK signaling cascades. In conclusion, our current study unveiled the mechanism of PDM in MAC-T cells and we suggest that PDM might be harmful to the mammary gland system of cattle, possibly affecting milk production.

Dinitroaniline herbicides: a comprehensive review of toxicity and side effects on animal non-target organisms

The widespread use of herbicides has increased concern about the hazards and risks to animals living in terrestrial and aquatic ecosystems. A comprehensive understanding of their effective action at different levels of biological organization is critical for establishing guidelines to protect ecosystems and human health. Dinitroanilines are broad-spectrum pre-emergence herbicides currently used for weed control in the conventional agriculture. They are considered extremely safe agrochemicals because they act specifically on tubulin proteins and inhibit shoot and root growth of plants. However, there is a lack of toxicity information regarding the potential risk of exposure to non-target organisms. The aim of the present review is to focus on side effects of the most commonly used active ingredients, e.g. pendimethalin, oryzalin, trifluralin and benfluralin, on animal non-target cells of invertebrates and vertebrates. Acute toxicity varies from slightly to high in terrestrial and aquatic species (i.e. nematodes, earthworms, snails, insects, crustaceans, fish and mammals) depending on the species-specific ability of tested organisms to adsorb and discharge toxicants. Cytotoxicity, genotoxicity and activation of oxidative stress pathways as well as alterations of physiological, metabolic, morphological, developmental and behavioural traits, reviewed here, indicate that exposure to sublethal concentrations of active ingredients poses a clear hazard to animals and humans. Further research is required to evaluate the molecular mechanisms of action of these herbicides in the animal cell and on biological functions at multiple levels, from organisms to communities, including the effects of commercial formulations.

Pendimethalin induces apoptotic cell death through activating ER stress-mediated mitochondrial dysfunction in human umbilical vein endothelial cells

Pendimethalin is globally registered for control of a wide range of weeds in agriculture and home landscaping. Human exposure to pendimethalin can occur by the oral route through food and other sources. Endothelial function is vital to numerous biological processes, and endothelial dysfunction and poor vascular health is associated with increased atherosclerotic events; however, no study has yet investigated the potential effect of pendimethalin on endothelial function and vasculature formation. The objective of the current study is to investigate if pendimethalin may affect the viability and function of vascular endothelial cells. We observed that pendimethalin significantly repressed viability of human endothelial cells, inducing G1 cell cycle arrest and apoptotic/necrotic cell death. Pendimethalin treatment also activated ER stress and autophagy, leading to loss of mitochondrial membrane potential. In addition, pendimethalin impaired the tube forming and migratory abilities of endothelial cells. This study provides previously unrecognized adverse effects of pendimethalin in vascular endothelial cells, mediated by ER stress-induced mitochondrial dysfunction.

The effects of the "Stomp" herbicide application on the microbial prevalence in the soil

Agricultural production has benefited a lot from herbicides; however, the use of herbicides caused many environmental problems. Herbicide application can affect the biodiversity of an ecosystem by killing non-target organisms. Microorganisms in the soil are important factors for plant growth; they represent the biological factor of soil fertility. Herbicides can have a beneficial effect on the development of some microorganisms and a negative on others, leading to depletion of microbial diversity in soil. The objective of this work is to determine microbial activity in the soil and to isolate herbicide-resistant bacteria after the use of the "Stomp" herbicide. Agar plate method was used for the determination of microbial prevalence in the soil. The results showed an increase in the total number of bacteria, ammonifiers, fungi, and actinomycetes. Nine isolates, mostly Gram-positive spore-forming rods, showed an ability to grow in the mineral salt medium with different concentrations of "Stomp" herbicide. Isolates G1/1 and G1/2, showed high level of tolerance at the initial pendimethalin concentration of 25 mg/l. Those isolates have the potential to be used to decontaminate herbicide affected ecosystems.

Pendimethalin biodegradation by soil strains of Burkholderia sp. and Methylobacterium radiotolerans

Pendimethalin herbicide is widely used and persists in the environment as a contaminant causing negative impacts, including for human health. Microorganisms have the capacity to remove many contaminants from the environment. Thus, the aim of this work was to evaluate the efficiency of soil bacterial species prospected by molecular modelling of cytochrome P450 in to degrade pendimethalin. Strains of Burkholderia sp. and Methylobacterium radiotolerans were cultivated in a mineral saline medium enriched with 281 mg/L pendimethalin (MSPEN) and another containing glucose 1.0 g/L as extra carbon source (MSPENGLI). Both strains were able to degrade pendimethalin under the two conditions experienced. Burkholderia sp. F7G4PR33-4 was more efficient in degrading 65% of the herbicide in MSPEN medium, with 49.3% in MSPENGLI; while Methylobacterium radiotolerans A6A1PR46-4 degraded 55.4% in MSPEN and 29.8% in MSPENGLI mediums. These findings contribute to the expansion of knowledge on the competence of isolates of these two bacterial genera in degrading herbicidal xenobiotics and biotechnological potential for pendimethalin degradation and bioremediation.

Benchmark dose and the adverse effects of exposure to pendimethalin at low dose in female rats

Pendimethalin (PND) is a dinitroaniline herbicide widely used to control broadleaf and annual grasses. Although the acute oral toxicity of PND is >5 g/kg b.wt. in humans (LD₅₀ for rats >5000 g/kg b.wt.), it has been classified as a possible human carcinogen. It is still used in agriculture so, agricultural workers and their families, as well as consumers, can be exposed to this herbicide. The present study is the first report investigating the dose-response effect using the benchmark dose (BMD) and the adverse effects of exposure to PND at low dose via apoptosis responses linked to the expression of tumor necrosis factor-α (TNF-α), FAS, and BAX proteins; oxidative stress; and DNA and liver damage in female rats. The rats were exposed to PND via drinking water at doses equivalent to no-observed-adverse-effect level (NOAEL = 100 mg/kg b.wt.), 200, and 400 mg/kg b.wt. for 28 days. PND caused the overexpression of Tnf-α, Fas, and Bax; increased the levels of serum liver biomarkers; and increased oxidative stress in the liver and erythrocytes. Furthermore, it induced DNA and liver damage in a dose-dependent manner. The BMD showed that serum alkaline phosphatase (ALP) and total antioxidant capacity (78.4 and 30.1 mg/kg b.wt./day, respectively), lipid peroxidation in liver tissue (30.9 mg/kg b.wt./day), catalase in erythrocytes (14.0 mg/kg b.wt./day), and FAS expression in liver tissue (6.89 mg/kg b.wt./day) were highly sensitive biomarkers of PND toxicity. Our findings suggest the generation of reactive oxygen species as a possible mechanism of PND-induced gene overexpression of tumor necrosis factor-α (TNF-α), FAS, and BAX proteins, oxidative stress, and DNA and liver damage in female rats.

Association between pesticide exposure and colorectal cancer risk and incidence: A systematic review

BACKGROUND

Studies investigating the association between pesticide exposure and colorectal cancer (CRC) risk have been inconclusive.

OBJECTIVES

Investigate the association between pesticide exposure and CRC risk through a systematic literature review.

METHODS

CRC has the fourth-highest rate of cancer-caused death in the US after lung cancer, breast cancer in women, and prostate cancer in men. Here we have conducted a systematic literature search on studies examining the association between any pesticide exposure and CRC risk using PubMed, MEDLINE via EBSCO host, and Embase according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist.

RESULTS

Following the review, 139 articles were included for qualitative evaluation. Study participants were farmers, pesticide applicators, pesticide manufacturers, spouses of pesticide applicators, farm residents, Korean veterans of the Vietnam War, rural communities, and those who consumed food with pesticide residues. The studies' results were split between those with significant positive (39 significant results) and inverse (41 significant results) associations when comparing pesticide exposure and CRC risk.

DISCUSSION

From our literature review, we have identified a similar number of significant positive and inverse associations of pesticide exposure with CRC risk and therefore cannot conclude whether pesticide exposure has a positive or inverse association with CRC risk overall. However, certain pesticides such as terbufos, dicamba, trifluralin, S-ethyl dipropylthiocarbamate (EPTC), imazethapyr, chlorpyrifos, carbaryl, pendimethalin, and acetochlor are of great concern not only for their associated elevated risk of CRC, but also for the current legal usage in the United States (US). Aldicarb and dieldrin are of moderate concern for the positive associations with CRC risk, and also for the illegal usage or the detection on imported food products even though they have been banned in the US. Pesticides can linger in the soil, water, and air for weeks to years and, therefore, can lead to exposure to farmers, manufacturing workers, and those living in rural communities near these farms and factories. Approximately 60 million people in the US live in rural areas and all of the CRC mortality hotspots are within the rural communities. The CRC mortality rate is still increasing in the rural regions despite the overall decreasing of incidence and mortality of CRC elsewhere. Therefore, the results from this study on the relationship between pesticide exposure and CRC risk will help us to understand CRC health disparities.

A Rare Case of Suicide by Ingestion of Phorate: A Case Report and a Review of the Literature

Phorate is a systemic organophosphorus pesticide (OP) that acts by inhibiting cholinesterases. Recent studies have reported that long-term low/moderate exposure to OP could be correlated with impaired cardiovascular and pulmonary function and other neurological effects. A 70-year-old farmer died after an intention ingestion of a granular powder mixed with water. He was employed on a farm for over 50 years producing fruit and vegetables, and for about 20 years, he had also applied pesticides. In the last 15 years, he used phorate predominantly. The Phorate concentration detected in gastric contents was 3.29 µg/mL. Chronic exposure to phorate is experimentally studied by histopathological changes observed in the kidney. In the light of current literature, our case confirms that there is an association between renal damage and chronic exposure to phorate in a subject exposed for years to the pesticide. Autopsies and toxicological analyses play a key role in the reconstruction of the dynamics, including the cause of the death.

Cytotoxicity and genotoxicity of methomyl, carbaryl, metalaxyl, and pendimethalin in human umbilical vein endothelial cells

Pesticides have adverse effects on the cellular functionality, which may trigger myriad of health consequences. However, pesticides-mediated toxicity in the endothelial cells (ECs) is still elusive. Hence, in this study, we have used human umbilical vein endothelial cells (HUVECs) as a model to quantify the cytotoxicity and genotoxicity of four pesticides (methomyl, carbaryl, metalaxyl, and pendimethalin). In the MTT assay, HUVECs exposed to methomyl, carbaryl, metalaxyl, and pendimethalin demonstrated significant proliferation inhibition only at higher concentrations (500 and 1000 μM). Likewise, neutral red uptake (NRU) assay also showed proliferation inhibition of HUVECs at 500 and 1000 μM by the four pesticides, confirming lysosomal fragility. HUVECs exposed to the four pesticides significantly increased the level of intracellular reactive oxygen species (ROS). Comet assay and flow cytometric data exhibited DNA damage and apoptotic cell death in HUVECs after 24 h of exposure with methomyl, metalaxyl, carbaryl, and pendimethalin. This is a first study on HUVECs signifying the cytotoxic-genotoxic and apoptotic potential of carbamate insecticides (methomyl and carbaryl), fungicide (metalaxyl), and herbicide (pendimethalin). Overall, these pesticides may affect ECs functions and angiogenesis; nonetheless, mechanistic studies are warranted from the perspective of vascular biology using in vivo test models.

Residue measurement of pendimethalin in tobacco by using heart-cutting two dimensional liquid chromatography coupled with tandem mass spectrometry

A novel heart-cutting two-dimensional liquid chromatography coupled with tandem mass spectrometry method was developed for quantitative analysis of pendimethalin residue in tobacco. The strategy of reversed phase liquid chromatography coupled with another reversed-phase liquid chromatography was employed for high column efficiency and excellent compatibility of mobile phase. In the first dimensional chromatography, a cyano column with methanol/water as the eluent was applied to separate pendimethalin from thousands of interference components in tobacco. By heart-cutting technique, which effectively removed interference components, the target compound was cut to the second dimensional C18 column for further separation. The pendimethalin residue was finally determined by the tandem mass spectrometry under multiple reaction monitoring reversed-phase liquid chromatography mode. Sample pretreatment of the new method was simplified, involving only extraction and filtration. Compared with traditional methodologies, the new method showed fairly high selectivity and sensitivity with almost no matrix interference. The limit of quantitation for pendimethalin was 1.21 ng/mL, whereas the overall recoveries ranged from 95.7 to 103.3%. The new method has been successfully applied to non-stop measure of 200 real samples, without contamination of ion source. Detection results of the samples agreed well with standard method.

Does pendimethalin develop in pancreatic cancer induced inflammation?

Pendimethalin, one of the dinitroaniline group herbicides, is applied for controlling weeds in cereals, legumes and vegetable crops, and has been classified as possible human carcinogen. It is indicated that pendimethalin should arise risks of developing some cancer types; however, there is no data on the effects of pendimethalin on pancreatic cancer-induced inflammation. Injuries resulting from by acute pancreatitis attacks and inflammation are significant factors in the development of pancreatic cancer. Therefore, we investigated whether pendimethalin triggers inflammation as a mechanism of pancreatic cancer development. Parameters related to pancreatic activation, oxidative stress, and inflammation were measured in the human pancreatic (PANC-1) cell line. In the range of 0-100 μM, the levels of chymotrypsin decreased. It should be indicated that the reason for the decrease in chymotrypsin may be the high rates of cell death (20%) observed in the high concentration levels. We observed that pendimethalin significantly induced oxidative damage, while levels of interleukin-6 (IL-6) and interleukin-8 (IL-8) did not change. The obtained results may draw attention to the usage and possible toxic effect of pendimethalin due to oxidative damage induction; however, detailed inflammation mechanisms and other cancer pathways should be investigated.

The association between pesticide use and cutaneous melanoma: a systematic review and meta-analysis

BACKGROUND

The incidence of cutaneous melanoma (CM), the deadliest form of skin cancer, has gradually increased in the last decades among populations of European origin. Epidemiological studies suggested that farmers and agricultural workers are at an increased risk of CM because they were exposed to pesticides. However, little is known about the relationship between pesticides and CM.

OBJECTIVES

To investigate the association between exposure to pesticides and CM by systematically reviewing the literature. Secondary aim was to determine the categories of pesticides mainly involved in CM development.

METHODS

A systematic review of the literature was performed up to September 2018 using MEDLINE, Embase and Web of Science. Studies assessing CM risk in licensed pesticide applicators were considered. Strict criteria were established to select independent studies and risk estimates; random effect models, taking into account heterogeneity, were applied. A pooled risk estimate for CM was calculated for the use of each type of pesticide and type of exposure. Between-study and estimate heterogeneity was assessed and publication bias investigated.

RESULTS

A total of nine studies (two case-controls and seven cohorts) comprising 184 389 unique subjects were included. The summary relative risks for the categories 'herbicides - ever exposure', 'insecticides - ever exposure', 'any pesticide - ever exposure' and 'any pesticide - high exposure' resulted 1.85 [95% confidence interval (CI): 1.01, 3.36], 1.57 (95% CI: 0.58, 4.25), 1.31 (95% CI: 0.85, 2.04) and 2.17 (95% CI: 0.45, 10.36), respectively. Herbicides and insecticides had no between-study heterogeneity (I2  = 0%), while a significant heterogeneity (I2  > 50%) was detected for the high exposure to any pesticide. No indication for publication bias was found.

CONCLUSIONS

Individuals exposed to herbicides are at an increased risk of CM. Future properly designed observational studies are required to confirm this finding.

Studies on conformational changes induced by binding of pendimethalin with human serum albumin

Pendimethalin (PND) is a widely used herbicide in modern means of agricultural practices. So, its toxic residues exist extensively in the environment and can enter human body. Therefore, the in vitro interaction of PND with human serum albumin (HSA) has been explored by employing various biophysical, molecular docking and dynamics simulation studies as well as enzyme kinetics to unravel its binding mechanism. The binding constant of the PND-HSA complex was about 10⁴ M^-1 using Fluorescence quenching spectra. The negative value of Gibbs free energy change (ΔG⁰ = -32.0 kJ mol^-1) indicates this interaction is a spontaneous process. A large negative ΔH⁰ and positive ΔS⁰ suggests that hydrophobic interactions and H-bonding are involved in the binding process of PND with HSA. The binding of PND can cause conformational and micro-environmental changes in HSA molecule, as shown by various biophysical and molecular dynamics simulation studies. The site marker competition and molecular docking and simulation experiments affirmed that the binding of PND to HSA occurs at or near site I. Esterase-like activity of HSA exhibited decline in the presence of PND revealed the direct involvement of Lys199 of subdomain IIA (Sudlow's site I) in the binding process.

Pendimethalin-induced oxidative stress, DNA damage and activation of anti-inflammatory and apoptotic markers in male rats

Male Wistar rats were exposed to herbicide, pendimethalin (PND) at varying oral doses of 62.5, 125 and 250 mg/kg b.w. for 14 days. Toxiological effects were assessed in terms of oxidative stress, DNA damage, histopathological alterations and induction of anti-inflammatory and apoptotic responses linked Bax, Bcl-2, IFN-γ, TNF-α and caspase-3 gene expression. In comparison with respective untreated controls, all exposure groups of PND exhibited significant changes in the oxidative stress markers (protein carbonylation and lipid peroxidation) and antioxidant defenses (GSH, SOD, CAT and GST) in liver and kidney tissues. The histopathological changes including leucocyte infiltration, pyknotic nuclei, necrosis, large bowman’s space, shrinked renal cortex, were observed in the liver and kidney tissues of PND exposed rats. Significant DNA damage was recorded through comet assay in liver and kidney cells of treated animals as compared to control. Alteration in anti-inflammatory and apoptotic genes expression determined by RT-PCR, revealed the activation of intrinsic apoptotic pathway(s) under the PND induced cellular stress. A pronounced increase in Bax expression, caspase-3 activities and decreased Bcl-2 expressions were also associated with PND-induced apoptosis. Data from this study suggests that PND induces cellular toxicity and genetic perturbations which can alter the normal cellular and physiological functioning in rats.

Pendimethalin induces oxidative stress, DNA damage, and mitochondrial dysfunction to trigger apoptosis in human lymphocytes and rat bone-marrow cells

Pendimethalin (PM) is a dinitroaniline herbicide extensively applied against the annual grasses and broad-leaved weeds. There is no report available on PM-induced low-dose genotoxicity in human primary cells and in vivo test models. Such data gap has prompted us to evaluate the genotoxic potential of PM in human lymphocytes and rats. PM selectively binds in the minor groove of DNA by forming covalent bonds with G and C nitrogenous bases, as well as with the ribose sugar. PM induces micronucleus formation (MN) in human lymphocytes, indicating its clastogenic potential. Comet assay data showed 35.6-fold greater DNA damage in PM (200 μM)-treated human lymphocytes. Rat bone-marrow cells, at the highest dose of 50 mg/kg b w/day of PM also exhibited 10.5-fold greater DNA damage. PM at 200 μM and 50 mg/kg b w/day induces 193.4 and 229% higher reactive oxygen species generation in human lymphocytes and rat bone-marrow cells. PM-treated human lymphocytes and rat bone-marrow cells both showed dysfunction of mitochondrial membrane potential (ΔΨ _m). PM exposure results in the appearance of 72.2 and 35.2% sub-G₁ apoptotic peaks in human lymphocytes and rat bone-marrow cells when treated with 200 μM and 50 mg/kg b w/day of PM. Rats exposed to PM also showed imbalance in antioxidant enzymes and histological pathology. Overall, our data demonstrated the genotoxic and apoptotic potentials of PM in human and animal test models.

Assessment of Genotoxic Effects of Pendimethalin in Chinese Hamster Over Cells by the Single Cell Gel Electrophoresis (Comet) Assay

OBJECTIVES

Pendimethalin (N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzeneamine) is a dinitroaniline herbicide compound which selectively controls weeds. It is a cell division and growth inhibitor. It descends plants in a short time after seedling. It is a soil and water pollutant due to the widespread use of formulations in Turkey and around the world. Pendimethalin is manufactured in and imported by Turkey. Pendimethalin is a slightly toxic compound that is classified in toxicity class 3 by the United States Environmental Protection Agency (USEPA). Even though it is classified as group C (human possible carcinogen) compound by the USEPA, there are limited number of studies about its genotoxic effects. The aim of this study was to evaluate in vitro genotoxic effects of different concentrations of pendimethalin in Chinese hamster over (CHO) cells by the single cell gel electrophoresis (comet) assay.

MATERIALS AND METHODS

The cells are incubated with 1, 10, 100, 1000 and 10000 µM concentrations of pendimethalin for 30 min at 37°C and DNA damage was compared with CHO cells untreated with pendimethalin. 50 µM hydrogen peroxide was used as positive control.

RESULTS

No significant cytotoxic effects were observed within the concentration ranges studied. The DNA damage in CHO cells was significantly increased in the pendimethalin concentrations of 1, 100, 1000 and 10000 µM, however, a significant decrease was observed in 10 µM pendimethalin concentration.

CONCLUSION

Our results show that 1-10000 µM concentrations of pendimethalin induce DNA damage in CHO cells, which was assessed by comet assay.

Occupational Exposure to Pesticides and the Incidence of Lung Cancer in the Agricultural Health Study

BACKGROUND

Occupational pesticide use is associated with lung cancer in some, but not all, epidemiologic studies. In the Agricultural Health Study (AHS), we previously reported positive associations between several pesticides and lung cancer incidence.

OBJECTIVE

We evaluated use of 43 pesticides and 654 lung cancer cases after 10 years of additional follow-up in the AHS, a prospective cohort study comprising 57,310 pesticide applicators from Iowa and North Carolina.

METHODS

Information about lifetime pesticide use and other factors was ascertained at enrollment (1993-1997) and updated with a follow-up questionnaire (1999-2005). Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for smoking (smoking status and pack-years), sex, and lifetime days of use of any pesticides.

RESULTS

Hazard ratios were elevated in the highest exposure category of lifetime days of use for pendimethalin (1.50; 95% CI: 0.98, 2.31), dieldrin (1.93; 95% CI: 0.70, 5.30), and chlorimuron ethyl (1.74; 95% CI: 1.02, 2.96), although monotonic exposure-response gradients were not evident. The HRs for intensity-weighted lifetime days of use of these pesticides were similar. For parathion, the trend was statistically significant for intensity-weighted lifetime days (p = 0.049) and borderline for lifetime days (p = 0.073). None of the remaining pesticides evaluated was associated with lung cancer incidence.

CONCLUSIONS

These analyses provide additional evidence for an association between pendimethalin, dieldrin, and parathion use and lung cancer risk. We found an association between chlorimuron ethyl, a herbicide introduced in 1986, and lung cancer that has not been previously reported. Continued follow-up is warranted.

Pesticide exposures and respiratory health in general populations

Human exposures to pesticides can occur in the workplace, in the household and through the ambient environment. While several articles have reviewed the impact of pesticide exposures on human respiratory health in occupational settings, to the best of our knowledge, this article is the first one to review published studies on the association between pesticide exposures and human respiratory health in the general populations. In this article, we critically reviewed evidences up to date studying the associations between non-occupational pesticide exposures and respiratory health in general populations. This article also highlighted questions arising from these studies, including our recent analyses using the data from the Canadian Health Measures Survey (CHMS), for future research. We found few studies have addressed the impact of environmental pesticide exposures on respiratory health, especially on lung function, in general populations. In the studies using the data from CHMS Cycle 1, exposures to OP insecticides, pyrethroid insecticides, and the organochlorine pesticide DDT were associated with impaired lung function in the Canadian general population, but no significant associations were observed for the herbicide 2,4-D. Future research should focus on the potential age-specific and pesticide-specific effect on respiratory health in the general population, and repeated longitudinal study design is critical for assessing the temporal variations in pesticide exposures. Research findings from current studies of non-occupational pesticide exposures and their health impact in general population will help to improve the role of regulatory policies in mitigating pesticide-related public health problems, and thereafter providing greater benefit to the general population.

Fresh water fish, Channa punctatus, as a model for pendimethalin genotoxicity testing: A new approach toward aquatic environmental contaminants

Pendimethalin (PND) is one of the common herbicides used worldwide. Fresh water fish, Channa punctatus, was exposed to PND in aquaria wherein its LC50 value was recorded to be 3.6 mg/L. Three sublethal (SL) concentrations, namely, 0.9, 1.8, and 2.7 mg/L were selected for the evaluation of genotoxicity and oxidative stress generated in the fish. In vivo comet assay was carried out in the blood, liver, and gill cells after exposing the fish to aforesaid SL concentrations of PND for 24, 48, 72, and 96 h. The results of the comet assay demonstrated the genotoxicity of PND in all the three tissues. Induction of oxidative stress in the gill cells was affirmed by the increased lipid peroxidation (LPO) and decreased levels of reduced glutathione, superoxide dismutase, and catalase. Frequencies of erythrocytic nuclear abnormalities (ENA) and micronuclei (MN) were also used to assess the genotoxic potential of PND on C. punctatus. MN frequency did not show any enhancement after PND exposure, but the frequency of ENA such as kidney-shaped nuclei, segmented nuclei and lobed nuclei, showed a significant increase after 24-96 h. Thus, ENA seems to be a better biomarker than MN for PND induced genotoxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1520-1529, 2016.

Exposure to pesticides and prostate cancer: systematic review of the literature

INTRODUCTION

Investigations about the association between prostate cancer and environmental and/or occupational pesticide exposure have evidenced a possible role of these chemical substances on tumor etiology, related to their action as endocrine disruptors.

OBJECTIVE

To assess the association between pesticide exposure and prostate cancer by conducting a systematic review of the scientific literature.

MATERIALS AND METHODS

Articles published until August 18, 2015 were searched in the databases MEDLINE/Pubmed, Scielo, and Lilacs using the keywords "pesticides" and "prostate cancer". Only the analytical observational studies whose methodological quality met the criteria established by the New Castle-Ottawa scale were included in this review.

RESULTS

The review included 49 studies published between 1993 and 2015. All studies were in English and analyzed exposure to pesticides and/or agricultural activities. Most studies (32 articles) found a positive association between prostate cancer and pesticides or agricultural occupations, with estimates ranging from 1.01 to 14.10.

CONCLUSION

The evidence provided by the reviewed studies indicates a possible association between the development of prostate cancer and pesticide exposure and/or agricultural occupations.

A comprehensive review of pesticides and the immune dysregulation: mechanisms, evidence and consequences

Nowadays, in many communities, there is a growing concern about possible adverse effects of pesticides on human health. Reports indicate that during environmental or occupational exposure, pesticides can exert some intense adverse effects on human health through transient or permanent alteration of the immune system. There is evidence on the relation between pesticide-induced immune alteration and prevalence of diseases associated with alterations of the immune response. In the present study, direct immunotoxicity, endocrine disruption and antigenicity have been introduced as the main mechanisms working with pesticides-induced immune dysregulation. Moreover, the evidence on the relationship between pesticide exposure, dysregulation of the immune system and predisposition to different types of psychiatric disorders, cancers, allergies, autoimmune and infectious diseases are criticized.

Binding properties of pendimethalin herbicide to DNA: multispectroscopic and molecular docking approaches

Pendimethalin (PND) is a systemic herbicide widely used on rice, cotton, peas, wheat, potatoes, fruits, nuts and other residential and non-residential crops; however, it concurrently exerts toxic effects on beneficial organisms like earthworms, aquatic invertebrates and other non-targeted animals including humans. Most likely, the genotoxicity of agrochemicals/drugs is modulated through cellular distribution of bound DNA. Therefore, the in vitro interaction of PND with calf thymus DNA (ctDNA) has been investigated using various sensitive biophysical techniques to ascertain its binding mechanism. UV-visible absorption and fluorescence spectra suggested the formation of a complex between PND and ctDNA. The binding constant of the PND-ctDNA complex was found to be around 10(4) M(-1) using steady state fluorescence titration. The calculated positive values of enthalpy and entropy changes suggested that the binding reaction was predominantly driven by hydrophobic interactions. Competitive displacement studies using acridine orange (AO), ethidium bromide (EB) and Hoechst dye suggested intercalation of PND molecules into the double helix of ctDNA by replacing the bound AO and EB probes. An increase in the viscosity and melting temperature of ctDNA and a decrease in iodine-quenching also support the intercalative binding of PND with ctDNA. Molecular docking analysis further confirmed the specific binding mode of PND between adjacent 'G-C' base pairs of ctDNA.

Occupational exposure to pesticides and prostate cancer: a systematic review and meta-analysis

Epidemiological studies on exposure to pesticides and risk of prostate cancer (PC) provide inconsistent results. We aimed to explore various potential sources of heterogeneity not previously assessed and to derive updated risk estimates from homogenous studies. We searched PubMed, Web of Science and Scopus databases for case-control and cohort studies published from 1985 to April 2014. We assessed the quality of the articles using the Newcastle-Ottawa Scale. Pooled estimates were calculated using random-effects models. Heterogeneity was explored using subset analyses and metaregression. Fifty-two studies were included in the review and 25 in the meta-analysis. No association was found between low exposure to pesticides and PC, but association was significant for high exposure, pooled OR 1.33 (1.02 to 1.63), I(2)=44.8%, p=0.024. Heterogeneity was explained by a number of variables including method used to assess exposure. Pooled OR was weak and non-significant for studies measuring serum pesticide level, 1.12 (0.74 to 1.50), I(2)=0.00%, p=0.966. For studies applying self-reporting of exposure, pooled estimate was 1.34 (0.91 to 1.77), I(2)=0.00%, p=0.493, while a high significant association was detected for grouped exposure assessment, 2.24 (1.36 to 3.11), I(2)=0.00%, p=0.955. In spite of a weak significant association detected when pooling ORs for high occupational exposure to pesticides, the magnitude of the association was related to the method of exposure assessment used by the original studies. A family history-pesticide exposure interaction was also observed for a number of pesticides.

Investing in prospective cohorts for etiologic study of occupational exposures

Prospective cohorts have played a major role in understanding the contribution of diet, physical activity, medical conditions, and genes to the development of many diseases, but have not been widely used for occupational exposures. Studies in agriculture are an exception. We draw upon our experience using this design to study agricultural workers to identify conditions that might foster use of prospective cohorts to study other occupational settings. Prospective cohort studies are perceived by many as the strongest epidemiologic design. It allows updating of information on exposure and other factors, collection of biologic samples before disease diagnosis for biomarker studies, assessment of effect modification by genes, lifestyle, and other occupational exposures, and evaluation of a wide range of health outcomes. Increased use of prospective cohorts would be beneficial in identifying hazardous exposures in the workplace. Occupational epidemiologists should seek opportunities to initiate prospective cohorts to investigate high priority, occupational exposures.

Occupational pesticide exposures and respiratory health

Pesticides have been widely used to control pest and pest-related diseases in agriculture, fishery, forestry and the food industry. In this review, we identify a number of respiratory symptoms and diseases that have been associated with occupational pesticide exposures. Impaired lung function has also been observed among people occupationally exposed to pesticides. There was strong evidence for an association between occupational pesticide exposure and asthma, especially in agricultural occupations. In addition, we found suggestive evidence for a link between occupational pesticide exposure and chronic bronchitis or COPD. There was inconclusive evidence for the association between occupational pesticide exposure and lung cancer. Better control of pesticide uses and enforcement of safety behaviors, such as using personal protection equipment (PPE) in the workplace, are critical for reducing the risk of developing pesticide-related symptoms and diseases. Educational training programs focusing on basic safety precautions and proper uses of personal protection equipment (PPE) are possible interventions that could be used to control the respiratory diseases associated with pesticide exposure in occupational setting.

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.

Occupational pesticide exposures and cancer risk: a review

A review of the epidemiological literature linking pesticides to cancers in occupational studies worldwide was conducted, with particular focus on those articles published after the release of IARC Monograph 53 (1991): Occupational Exposures in Insecticide Applications and Some Pesticides. Important new data are now available. Chemicals in every major functional class of pesticides including insecticides, herbicide, fungicides, and fumigants have been observed to have significant associations with an array of cancer sites. Moreover, associations were observed with specific chemicals in many chemical classes of pesticides such as chlorinated, organophosphate, and carbamate insecticides and phenoxy acid and triazine herbicides. However, not every chemical in these classes was found to be carcinogenic in humans. Twenty-one pesticides identified subsequent to the last IARC review showed significant exposure-response associations in studies of specific cancers while controlling for major potential confounders. This list is not an exhaustive review and many of these observations need to be evaluated in other epidemiological studies and in conjunction with data from toxicology and cancer biology. Nonetheless, it is reasonable and timely for the scientific community to provide a multidisciplinary expert review and evaluation of these pesticides and their potential to produce cancer in occupational settings.

A weight-of-evidence review of colorectal cancer in pesticide applicators: the agricultural health study and other epidemiologic studies

OBJECTIVE

To systematically evaluate epidemiologic studies on pesticides and colon cancer and rectal cancer in agricultural pesticide applicator populations using a transparent "weight-of-evidence" (WOE) methodological approach.

METHODS

Twenty-nine (29) publications from the Agricultural Health Study (AHS) and 13 additional epidemiologic studies were identified that reported data for pesticide applicators and/or specific pesticide compounds and colorectal, colon, or rectal cancer. The AHS evaluated pesticide applicators as well as dose-response associations for specific pesticide compounds, whereas the large majority of non-AHS evaluated applicators but did not analyze specific compounds or dose-response trends. This WOE assessment of 153 different pesticide-outcome pairs emphasized several key evidentiary features: existence of statistically significant relative risks, magnitude of observed associations, results from the most reliable exposure assessments, and evidence of convincing dose-response relationships (i.e., those monotonically increasing, with statistically significant trend tests).

RESULTS

Occupation as a pesticide applicator or pesticide application as a farming-related function was not associated with increasing the risk of colon or rectal cancer. Deficits of colon or rectal cancer were observed across most studies of pesticide applicators. After applying the WOE methodology to the epidemiologic studies of specific pesticide compounds and colon or rectal cancer, a number of pesticide-outcome pairs were identified and evaluated further based on positive statistical associations. Of these, only two-aldicarb and colon cancer and imazethapyr and proximal colon cancer-appears to warrant further discussion regarding a possible causal relationship, although the epidemiologic data are limited. For the remainder, a lack of a clear dose-response trend, inconsistencies in associations between exposure metrics and comparison groups, imprecise associations, variable participation rates for analyses of specific compounds, and the reliance upon data from one study (the AHS) limit interpretation regarding risk.

CONCLUSION

The available epidemiologic evidence does not support a causal relationship between occupation as a pesticide applicator or specific pesticide exposures and colon or rectal cancer.

Assessing environmental and occupational risk factors for lung cancer in Mexican-Americans

BACKGROUND

We investigated environmental and occupational exposures and smoking history (while controlling for demographics) in a population of Mexican-American lung cancer cases and controls from the Houston metropolitan area.

METHODS

Data were collected between 1991 and 2005 as part of an on-going multi-racial/ethnic, lung cancer case-control study. Cases included 212 Mexican-American lung cancer cases from UT MD Anderson Cancer Center. Controls (n = 328) were recruited from Houston's largest multispecialty group practice and frequency matched to the cases by age (± 5 years), sex, and ethnicity. Environmental and occupational factors were analyzed and odds ratios and 95% confidence intervals were calculated using logistic regression.

RESULTS

We detected elevated risks of lung cancer associated with pesticide exposure and found conventional and antimicrobial (e.g., sterilizers, disinfectants, antiseptics) pesticides were associated with an increased risk of lung cancer in Mexican-Americans (conventional pesticides and antimicrobial pesticides combined: OR = 1.80, 95% CI 1.13-2.86; conventional pesticides: OR = 2.05, 95% CI 1.23-2.39; antimicrobial pesticides: OR = 2.48, 95% CI 1.46-4.21).

CONCLUSIONS

Although we found over a two-fold increased risk of lung cancer among Mexican-Americans for pesticides, we could not identify individual pesticides. Our findings are an important preliminary step in identifying factors that are specifically associated with lung cancer risk among Mexican Americans.

A review of pesticide exposure and cancer incidence in the Agricultural Health Study cohort

OBJECTIVE

We reviewed epidemiologic evidence related to occupational pesticide exposures and cancer incidence in the Agricultural Health Study (AHS) cohort.

DATA SOURCES

Studies were identified from the AHS publication list available at http://aghealth.nci.nih.gov as well as through a Medline/PubMed database search in March 2009. We also examined citation lists. Findings related to lifetime-days and/or intensity-weighted lifetime-days of pesticide use are the primary focus of this review, because these measures allow for the evaluation of potential exposure-response relationships.

DATA SYNTHESIS

We reviewed 28 studies; most of the 32 pesticides examined were not strongly associated with cancer incidence in pesticide applicators. Increased rate ratios (or odds ratios) and positive exposure-response patterns were reported for 12 pesticides currently registered in Canada and/or the United States (alachlor, aldicarb, carbaryl, chlorpyrifos, diazinon, dicamba, S-ethyl-N,N-dipropylthiocarbamate, imazethapyr, metolachlor, pendimethalin, permethrin, trifluralin). However, estimates of association for specific cancers were often imprecise because of small numbers of exposed cases, and clear monotonic exposure-response patterns were not always apparent. Exposure misclassification is also a concern in the AHS and may limit the analysis of exposure-response patterns. Epidemiologic evidence outside the AHS remains limited with respect to most of the observed associations, but animal toxicity data support the biological plausibility of relationships observed for alachlor, carbaryl, metolachlor, pendimethalin, permethrin, and trifluralin.

CONCLUSIONS

Continued follow-up is needed to clarify associations reported to date. In particular, further evaluation of registered pesticides is warranted.

Risk of urinary bladder cancer: a case-control analysis of industry and occupation

Background

Uncertainty remains about urinary bladder cancer (UBC) risk for many occupations. Here, we investigate the association between occupation, industry and UBC.

Methods

Lifetime occupational history was collected by in-person interview for 604 newly diagnosed UBC patients and 604 cancer-free controls. Each job title was assigned a two-digit industry code and a three-digit occupation code. Odds ratios (ORs) for UBC associated with ever being employed in an industry or occupation were calculated by unconditional logistic regression adjusting for age, gender and smoking status. We also examined UBC risk by duration of employment (>0 to <10, ≥10 years) in industry or occupation.

Results

Significantly increased risk of UBC was observed among waiters and bartenders (OR 2.87; 95% CI 1.05 to 7.72) and occupations related to medicine and health (OR 2.17; 95% CI 1.21 to 3.92), agricultural production, livestock and animal specialties (OR 1.90; 95% CI 1.03 to 3.49), electrical assembly, installation and repair (OR 1.69; 95% CI 1.07 to 2.65), communications (OR 1.74; 95% CI 1.00 to 3.01), and health services (OR 1.58; 95% CI 1.02 to 2.44). For these occupations we also observed a significant excess risk of UBC for long-term work (i.e. ≥10 years), with the exception of waiters and bartenders. Employment for 10 years or more was associated with increased risk of UBC in general farmers (OR 9.58; 95% CI 2.18 to 42.05), agricultural production of crops (OR 3.36; 95% CI 1.10 to 10.27), occupations related to bench working (OR 4.76; 95% CI 1.74 to 13.01), agricultural, fishery, forestry & related (OR 4.58; 95% CI 1.97 to 10.65), transportation equipment (OR 2.68; 95% CI 1.03 to 6.97), and structural work (OR 1.85; 95% CI 1.16 to 2.95).

Conclusions

This study provides evidence of increased risk of UBC for occupations that were previously reported as at-risk. Workers in several occupation and industry groups have a significantly higher risk of UBC, particularly when duration of employment is 10 years or more.

Agricultural pesticide use and pancreatic cancer risk in the Agricultural Health Study Cohort

Pancreatic cancer is a rapidly fatal disease that has been linked with pesticide use. Previous studies have reported excess risks of pancreatic cancer with organochlorines such as DDT, however, many other commonly used pesticides have not been examined. To further examine the potential associations between the use of a number of pesticides and pancreatic cancer, we conducted a case-control analysis in the Agricultural Health Study, one of the largest prospective cohorts with over 89,000 participants including pesticide applicators and their spouses in Iowa and North Carolina. This analysis included 93 incident pancreatic cancer cases (64 applicators, 29 spouses) and 82,503 cancer-free controls who completed an enrollment questionnaire providing detailed pesticide use, demographic and lifestyle information. Ever use of 24 pesticides and intensity-weighted lifetime days [(lifetime exposure days) x (exposure intensity score)] of 13 pesticides was assessed. Risk estimates were calculated using unconditional logistic regression controlling for age, smoking, and diabetes. Among pesticide applicators, 2 herbicides (EPTC and pendimethalin) of the 13 pesticides examined for intensity-weighted lifetime use showed a statistically significant exposure-response association with pancreatic cancer. Applicators in the top half of lifetime pendimethalin use had a 3.0-fold (95% CI 1.3-7.2, p-trend = 0.01) risk compared with never users, and those in the top half of lifetime EPTC use had a 2.56-fold (95% CI = 1.1-5.4, p-trend = 0.01) risk compared with never users. Organochlorines were not associated with an excess risk of pancreatic cancer in this study. These findings suggest that herbicides, particularly pendimethalin and EPTC, may be associated with pancreatic cancer.

[Environmental pollutants and prostate cancer: epidemiological data]

Prostate cancer is the most frequent cancer affecting men in most Western countries. Certain risk factors have been identified (age, family history, ethnic origin), but the aetiology of this cancer remains largely unknown. However, a role for environmental factors is strongly suspected. Questions have been raised concerning the role of the chemical substances generated by human activities in the occurrence of this disease. Diverse studies have consistently demonstrated a higher risk of prostate cancer in agricultural populations than in the general population. The hypothesis that this higher risk is linked to the use of pesticides has been tested in a number of studies, mostly in North America and Europe. However, to date, with a few possible exceptions, it has been impossible to demonstrate a significant association between exposure to pesticides or a chemical family of pesticides and prostate cancer. Studies have also been carried out on the role of exposure to trace metals, such as cadmium, or to pollutants from industry, such as polychlorobiphenyls. However, no firm conclusions have been drawn. Finally, the effect of chemical substances with endocrine disruptor activity on the occurrence of prostate cancer remains largely unexplored in epidemiological studies. In the face of these uncertainties, rigorous studies are required, with objective measurements of exposure, taking into account confounding factors and individual risk factors, making it possible to assess gene-environment interactions.

Pesticides and prostate cancer: a review of epidemiologic studies with specific agricultural exposure information

Prostate cancer is the most commonly diagnosed cancer in US men, and the second most commonly diagnosed cancer among men worldwide. Although pesticides have been implicated in studies of prostate cancer among farmers, meta-analyses have found heterogeneity across studies, and a number of exposures and lifestyle factors may be unique to farmers. The purpose of this paper is to review the epidemiologic literature to evaluate the hypothesis that agricultural exposure to pesticides is causally associated with prostate cancer risk. We analyzed the eight cohort studies and five case-control studies that quantified and/or evaluated agricultural exposure to particular pesticide classes or chemicals. Despite sporadic positive findings, these studies did not show consistently increased risks to support a causal association between agricultural pesticide use and prostate cancer. Studies using an 'external' comparison group must be interpreted in the context of confounding by differences in prostate-specific antigen screening intensity. Furthermore, most studies did not adjust for potential confounders other than age and time period. It is clearly not possible to exonerate any particular pesticide as a putative cause of prostate cancer - to do so would require an inverse empirical association with an upper confidence limit below the null value. Existing evidence does not point to any pesticide as satisfying widely used guidelines for establishing causation: a strong, exposure-dependent and demonstrably unconfounded, unbiased association, documented in several studies.

Pesticide use and colorectal cancer risk in the Agricultural Health Study

We investigated the relationship between agricultural pesticides and colorectal cancer incidence in the Agricultural Health Study. A total of 56,813 pesticide applicators with no prior history of colorectal cancer were included in this analysis. Detailed pesticide exposure and other information were obtained from self-administered questionnaires completed at the time of enrollment (1993-1997). Cancer incidence was determined through population-based cancer registries from enrollment through December 31, 2002. A total of 305 incident colorectal cancers (212 colon, 93 rectum) were diagnosed during the study period, 1993-2002. Although most of the 50 pesticides studied were not associated with colorectal cancer risk, chlorpyrifos use showed significant exposure response trend (p for trend = 0.008) for rectal cancer, rising to a 2.7-fold (95% confidence interval: 1.2-6.4) increased risk in the highest exposure category. Aldicarb was associated with a significantly increased risk of colon cancer (p for trend = 0.001), based on a small number of exposed cases, with the highest exposure category resulting in a 4.1-fold increased risk (95% confidence interval: 1.3-12.8). In contrast, dichlorophenoxyacetic acid showed a significant inverse association with colon cancer but the association was not monotonic. Our findings should be interpreted cautiously since the literature suggesting that pesticides are related to colorectal cancer is limited. Nonetheless the possibility of an association between exposure to certain pesticides and incidence of colorectal cancer among pesticide applicators deserves further evaluation.

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.