The epidemiology of pesticide exposure and cancer: A review

Evaluating the use of unmanned aerial vehicles for spray applications in mountain Nanguo pear orchards

BACKGROUND

Nanguo pear is a distinctive pear variety in northeast China, grown mainly in mountainous areas. Due to terrain limitations, ground-based pesticide application equipment is difficult to use. This limitation could be overcome by using unmanned aerial vehicles (UAVs) for pesticide application in Nanguo pear orchards. This study evaluated the spraying performance of two UAVs in the Nanguo pear orchards and compared them with a manually used backpack electric sprayer (BES). The study also analyzed the effect of canopy size on droplet deposition and ground loss, and evaluated two sampling methods, leaf sampling and telescopic rod sampling.

RESULTS

Compared to BESs, droplet deposition is lower for UAVs, but the actual pesticide active ingredient deposition is not necessarily lower given the solution concentration. The droplet deposition varies among different UAVs due to structural differences. Under the same UAV operating parameters, droplet deposition on trees with smaller canopy sizes is typically greater than that on trees with larger canopy sizes, and the ground loss was also more severe. Although telescopic rod sampling is a quick and convenient method, it can only reflect the trend of droplet deposition, and the data error is greater compared with leaf sampling.

CONCLUSION

UAVs can achieve better droplet deposition in mountainous Nanguo pear orchards and does almost no harm to the operators compared with the BES. However, canopy size needs to be considered to adjust the application volume rate. Telescopic rods can be used for qualitative analyses, but are not recommended for quantitative analyses. © 2024 Society of Chemical Industry.

Pesticide exposure and risk of cholangiocarcinoma: A hospital-based matched case-control study

BACKGROUND

Cholangiocarcinoma (CCA) caused by Opisthorchis viverrini is a well-known and significant public health issue in northeastern Thailand; however, a link between pesticide exposure (PE) and CCA risk has not yet been established. Therefore, our research objective was to investigate the relationship between PE and CCA risk.

METHODS

A hospital-based matched case-control study was carried out. All cases (in-patients) and controls (out-patients) were volunteers at a tertiary hospital in northeast Thailand. Between 2015 and 2019, 178 incident cases of pathologically-confirmed CCA and 356 controls were selected from the check-up clinic from the Srinagarind Hospital outpatient database (two controls per case). The recruited controls were individually-matched to the CCA cases based on sex, age (±5 years) and admission date (±3 months). During face-to-face interviews, a standardised pre-tested questionnaire was used to collect data. Multivariable conditional logistic regression was used to analyse the data.

RESULTS

The respective frequency of PE between the 178 CCA cases and 356 controls was 77.0% versus 87.6% for never used, 14.6% versus 5.3% for have used but stopped and 8.4% versus 7.0% for currently using. After adjusting for the highest educational attainment, smoking behaviour, alcohol use and family history of cancer, PE was not significantly associated with CCA (p-value = 0.086). Using volunteers who have never used PE as the reference group, the respective odds of developing CCA for those who have ever used but have since stopped and are currently using was 2.04 (adjusted OR = 2.04; 95% CI: 1.03-4.04) versus 0.83 (adjusted OR = 0.83; 95% CI: 0.39-1.76) times more likely to develop CCA than those who had never used PE.

CONCLUSION

There is no association between PE and the risk of CCA. Notwithstanding the finding, future research should focus on enhancing PE assessment methods that consider complex chemical mixtures, chemicals of interest, historical exposure and exposure pathways. Moreover, there is need for more extensive and longer population-based cohort studies that include younger, non-occupationally exposed individuals during periods of developmental susceptibility.

Genotoxicity of Occupational Pesticide Exposures among Agricultural Workers in Arab Countries: A Systematic Review and Meta-Analysis

Exposure to pesticides in Arab countries is a significant public health concern due to extensive agricultural activity and pesticide use. This systematic review aimed to evaluate the genotoxic effects of agricultural pesticide exposure in the region, identify research gaps, and assess methodological limitations. Following the PRISMA guidelines, a comprehensive search yielded five relevant studies conducted in Egypt, Syria, and Jordan. Various genotoxicity assays were employed, revealing a higher level of DNA damage in exposed compared to non-exposed individuals. Farmers exposed to pesticides exhibited a significantly higher occurrence of chromosomal translocation (t(14;18)), micronuclei, and chromosomal aberrations. However, only two studies assessed cytotoxicity indirectly. The studies predominantly focused on male participants, with variations in sample size and pesticide types. The lack of detailed exposure data necessitates cautious interpretation. This review underscores the need for further research on the genotoxicity of occupational pesticide exposure in the Middle East. Future studies should adopt robust study designs, collect biological and environmental samples, conduct repeated sampling, analyze seasonal variations, and encompass diverse study sites associated with specific crop groups.

Elevated exposures to persistent endocrine disrupting compounds impact the sperm methylome in regions associated with autism spectrum disorder

Environmental exposures to endocrine disrupting compounds (EDCs) such as the organochlorines have been linked with various diseases including neurodevelopmental disorders. Autism spectrum disorder (ASD) is a highly complex neurodevelopmental disorder that is considered strongly genetic in origin due to its high heritability. However, the rapidly rising prevalence of ASD suggests that environmental factors may also influence risk for ASD. In the present study, whole genome bisulfite sequencing was used to identify genome-wide differentially methylated regions (DMRs) in a total of 52 sperm samples from a cohort of men from the Faroe Islands (Denmark) who were equally divided into high and low exposure groups based on their serum levels of the long-lived organochlorine 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), a primary breakdown product of the now banned insecticide dichlorodiphenyltrichloroethane (DDT). Aside from being considered a genetic isolate, inhabitants of the Faroe Islands have a native diet that potentially exposes them to a wide range of seafood neurotoxicants in the form of persistent organic pollutants (POPs). The DMRs were mapped to the human genome using Bismark, a 3-letter aligner used for methyl-seq analyses. Gene ontology, functional, and pathway analyses of the DMR-associated genes showed significant enrichment for genes involved in neurological functions and neurodevelopmental processes frequently impacted by ASD. Notably, these genes also significantly overlap with autism risk genes as well as those previously identified in sperm from fathers of children with ASD in comparison to that of fathers of neurotypical children. These results collectively suggest a possible mechanism involving altered methylation of a significant number of neurologically relevant ASD risk genes for introducing epigenetic changes associated with environmental exposures into the sperm methylome. Such changes may provide the potential for transgenerational inheritance of ASD as well as other disorders.

Exposure to neonicotinoid insecticides and their characteristic metabolites: Association with human liver cancer

Neonicotinoid insecticides (NEOs) are commonly applied for pest control in China and around the world. Previous studies reported that NEOs are hepatotoxic to mammals. However, limited studies have explored the associations between NEOs exposure and liver disease. In the present study, we detected six parent NEOs (p-NEOs), including acetamiprid, thiacloprid, dinotefuran, clothianidin, imidacloprid, and thiamethoxam, and five characteristic metabolites (m-NEOs), including 5-hydroxy-imidacloprid, olefin-imidacloprid, N-desmethyl-acetamiprid, 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine and 1-methyl-3-(tetrahydro-3-furyl methyl) urea, in blood samples collected from healthy donors (n = 100; females vs. males: 45 vs. 55; age: 22-91 years) and liver cancer patients (n = 274; females vs. males: 118 vs. 156; age: 11-88 years) in one hospital from Guangzhou city, South China. NEOs were frequently detected (61%-94%) in blood samples, with median concentrations ranging from 0.19 ng/mL to 1.28 ng/mL and 0.20 ng/mL to 2.03 ng/mL for healthy and liver cancer populations, respectively. olefin-imidacloprid was the most abundant NEOs in healthy and liver cancer populations, accounting for 23.4% and 20.7%, respectively. Significant positive correlations among most m-NEOs concentrations were found, and associations between m-NEOs and their corresponding p-NEOs were positively correlated. These findings indicated that the sources of m-NEOs were both endogenous and exogeneous. Females had higher median concentrations of NEOs and their metabolites than males. Moreover, the α-fetoprotein values and blood concentrations of target analytes (r = 0.428-0.601, p < 0.05) were positively correlated. Meanwhile, associations between the concentrations of p-NEOs and m-NEOs and liver cancer were found (odds ratio = 2.33-9.02, 95% confidence interval = 0.31-22.7, p < 0.05), indicating that human exposure to NEOs and their metabolites might increase the odds of liver cancer prevalence. Our work provided a new insight into the hepatotoxicity of NEOs and their metabolites, and human health risks of exposure to these pollutants warranted further studies.

High Doses of Pesticides Induce mtDNA Damage in Intact Mitochondria of Potato In Vitro and Do Not Impact on mtDNA Integrity of Mitochondria of Shoots and Tubers under In Vivo Exposure

It is well known that pesticides are toxic for mitochondria of animals. The effect of pesticides on plant mitochondria has not been widely studied. The goal of this research is to study the impact of metribuzin and imidacloprid on the amount of damage in the mtDNA of potato (Solanum tuberosum L.) in various conditions. We developed a set of primers to estimate mtDNA damage for the fragments in three chromosomes of potato mitogenome. We showed that both metribuzin and imidacloprid considerably damage mtDNA in vitro. Imidacloprid reduces the rate of seed germination, but does not impact the rate of the growth and number of mtDNA damage in the potato shoots. Field experiments show that pesticide exposure does not induce change in aconitate hydratase activity, and can cause a decrease in the rate of H₂O₂ production. We can assume that the mechanism of pesticide-induced mtDNA damage in vitro is not associated with H₂O₂ production, and pesticides as electrophilic substances directly interact with mtDNA. The effect of pesticides on the integrity of mtDNA in green parts of plants and in crop tubers is insignificant. In general, plant mtDNA is resistant to pesticide exposure in vivo, probably due to the presence of non-coupled respiratory systems in plant mitochondria.

Pesticide applicators and cancer: a systematic review

The objective of the study was to identify and analyse the research done on the occurrence of cancer among pesticide applicators by conducting a systematic review of the scientific literature. PRISMA Guidelines was followed to conduct the study. Search was done in Scopus, PubMed, Embase, MEDLINE and Google Scholar databases with search terms "PESTICIDE APPLICATORS", "CANCER" using Boolean operator "AND". Meta-analysis and review articles were excluded from the study. A total of 32 studies were identified among which the average sample size was found to be 60,521. Increased RRs/ORs and positive exposure-response relationships were observed for 31 pesticides. Organophosphate and organochlorine classes of pesticides were the most to be associated with cancer. Lung cancer was observed the most followed by prostate, multiple myeloma and colon cancers among pesticide applicators. It was concluded that there is an increased risk of cancer among the pesticide applicators, whereby which bringing into focus the need to educate and train the workers on following adequate safety measures and making them aware of the hazardous chemicals. Further evaluation on the carcinogenicity of pesticides is also required.

A Systematic Review of Studies on Genotoxicity and Related Biomarkers in Populations Exposed to Pesticides in Mexico

In agricultural activities, pest control is essential, and the most effective method is the use of chemical agents that also represent an important source of exposure to potentially toxic compounds. Pesticides constitute a heterogeneous group of compounds designed specifically to control different pests. Besides measuring their levels or that of their metabolites in air, plasma, serum, blood, urine, etc., some studies reported increased DNA damage levels after occupational or environmental pesticides exposure, evidenced by several cytogenetic biomarkers such as chromosomal aberrations (CA), sister chromatid exchanges (SCE), micronuclei frequency (MN) together with other nuclear abnormalities (NA), alkaline comet assay, but also changes in oxidative stress parameters and miRNA levels. Single or combined, these techniques have also been used in genotoxic biomonitoring studies of workers occupationally exposed to pesticides in Mexico. Despite being a country with great agricultural activity and reported excessive pesticide use, genotoxic studies have been relatively few and, in some cases, contradictory. A review was made of the studies available (published until the end of 2020 on PubMed, Web of Science, Redalyc and Scielo, both in English and Spanish) in the scientific literature that evaluated occupational exposure of human samples to pesticides assessed with DNA damage and related biomarkers in Mexico.

Structure-based Identification of Endocrine Disrupting Pesticides Targeting Breast Cancer Proteins

Endocrine disrupting pesticides (EDPs) are exogenous compounds that disrupt endocrine activity. Human exposure to EDPs can occur through occupational contact, and through the consumption of food, milk and water with trace amounts of these pollutants. Several EDPs are epidemiologically linked to breast cancer or are considered as possible carcinogens. However, current evidence is not fully conclusive and their mechanisms of action remain unknown. Thus, the potential interactions between 262 EDPs and 189 proteins associated with breast cancer were evaluated by using a virtual high-throughput screening approach, with AutoDock Vina 1.1.1. The molecular coordinates were previously downloaded from Protein Data Bank and EDCs DataBank, and used for preparation and optimization in Sybyl X-2.0. The best affinity score (-11.0 kcal/mol) was obtained for flucythrinate with the nuclear receptor for vitamin D (VDR). This synthetic pyrethroid, along with other EDPs, such as fluvalinate, bifenthrin, cyhalothrin and cypermethrin, are proposed as multi-target ligands of several proteins related to breast cancer. In addition, the validation of our protocol showed a good accuracy in terms of binding pose prediction and affinity estimation. This study provides a guide to prioritize EDPs for which further in vitro and in vivo analysis could be done to evaluate the risk and possible mechanisms of action of these contaminants and their potential association with breast cancer.

Occupational Risk Factors for Prostate Cancer: A Meta-analysis

Prostate cancer is the second most common cancer in men worldwide. There are many occupational factors that have been suggested to cause prostate cancer. Our aim was to evaluate the evidence for causality by a literature review of occupational factors. We searched literature in Medline and SCOPUS from 1966 to June 30, 2015 to identify occupational risk factors for prostate cancer. The following risk factors were selected: farmers/agricultural workers, pesticides - whole group, and separately organophosphate and organochlorine pesticides, carbamates and triazines, cadmium, chromium, cutting fluids, acrylonitrile, rubber manufacturing, whole body vibration, shift work, flight personnel, ionizing radiation, and occupational physical activity. For each factor a literature search was performed and presented as meta-analysis of relative risk and heterogeneity (Q and I2 index). A total of 168 original studies met the inclusion criteria with 90,688 prostate cancer cases. Significantly increased risks were observed for the following occupational exposures: pesticides (metaRR = 1.15, 95% confidence interval [CI] = 1.01-1.32; I2 = 84%), and specifically group of organochlorine pesticides (meta relative risk [metaRR] = 1.08, 95% CI = 1.03-1.14; I2 = 0%), chromium (metaRR = 1.19, 95% CI = 1.07-1.34; I2 = 31%), shift work (metaRR = 1.25, 95% CI = 1.05-1.49; I2 = 78%) and pilots (metaRR = 1.41, 95% CI = 1.02-1.94; I2 = 63%) and occupational physical activity in cohort studies (metaRR = 0.87, 95% CI = 0.81-0.94; I2 = 0%). The literature review supports a causal association for a few of the previously suggested factors.

Cancer time trend in a population following a socio-economic transition: results of age-period-cohort analysis

OBJECTIVES

To examine cancer trend using age-period-cohort analysis with a cohort of patients in Sardinia, Italy, where epidemiological transition occurred between 1950 and 1960.

METHODS

Poisson log-linear regression models were used to analyze time trend in patients undergoing upper endoscopy between 1995 and 2013.

RESULTS

A total of 10,546 clinical records (62.2% women) were retrieved. In 541 patients (5.1%), a diagnosis of cancer was reported, more often in men (5.5%) than in women (4.9%). Age and birth cohort were significantly associated with cancer rate according to age-period-cohort analysis (p < 0.0001), whereas the effect of time period was negligible (p = 0.875). An upward trend for all cancers was observed in the younger generations (7.15% before 1950, 8.85% between 1950 and 1960, and 10.7% after 1960).

CONCLUSIONS

Population aging and increased exposure to cancer risk factors after epidemiological transition were the major determinants associated with cancer in this Sardinian cohort, whereas time period had no effect, ruling out any variation in diagnostic accuracy. These results may facilitate the provision of preventive measures by the health care system, and improve population-tailored cancer screening strategies.

High pesticide exposure events and DNA methylation among pesticide applicators in the agricultural health study

Pesticide exposure has been associated with acute and chronic adverse health effects. DNA methylation (DNAm) may mediate these effects. We evaluated the association between experiencing unusually high pesticide exposure events (HPEEs) and DNAm among pesticide applicators in the Agricultural Health Study (AHS), a prospective study of applicators from Iowa and North Carolina. DNA was extracted from whole blood from male AHS pesticide applicators (n = 695). Questionnaire data were used to ascertain the occurrence of HPEEs over the participant's lifetime. Pyrosequencing was used to quantify DNAm in CDH1, GSTp1, and MGMT promoters, and in the repetitive element, LINE-1. Linear and robust regression analyses evaluated adjusted associations between HPEE and DNAm. Ever having an HPEE (n = 142; 24%) was associated with elevated DNAm in the GSTp1 promoter at CpG7 (chr11:67,351,134; P < 0.01) and for the mean across the CpGs measured in the GSTp1 promoter (P < 0.01). In stratified analyses, elevated GSTP1 promoter DNAm associated with HPEE was more pronounced among applicators >59 years and those with plasma folate levels ≤16.56 ng/mL (p-interaction <0.01); HPEE was associated with reduced MGMT promoter DNAm at CpG2 (chr10:131,265,803; P = 0.03), CpG3 (chr10:131,265,810; P = 0.05), and the mean across CpGs measured in the MGMT promoter (P = 0.03) among applicators >59 years and reduced LINE-1 DNAm (P = 0.05) among applicators with ≤16.56 ng/mL plasma folate. Non-specific HPEEs may contribute to increased DNAm in GSTp1, and in some groups, reduced DNAm in MGMT and LINE-1. The impacts of these alterations on disease development are unclear, but elevated GSTp1 promoter DNAm and subsequent gene inactivation has been consistently associated with prostate cancer. Environ. Mol. Mutagen. 58:19-29, 2017. © 2016 Wiley Periodicals, Inc.

The association of nuclear abnormalities in exfoliated buccal epithelial cells with the health status of different agricultural activities farmers in Peninsular Malaysia

BACKGROUND

Pesticide exposure possesses risk of genotoxicity to humans, particularly farmers. Despite accumulating evidences linking genotoxicity to pesticide exposure, epidemiological studies to address pesticide toxicity in occupationally exposed farmers in Malaysia remain underreported. Thus, this study was aimed to determine the presence of nuclear abnormalities through the assessment of micronucleus (MN) and binucleus (BNu) frequencies in exfoliated buccal epithelial cells from farmers who were exposed to pesticides. A cross-sectional study of farmers among different agricultural activities farmers in Bachok and Pasir Puteh, Kelantan, North East of Peninsular Malaysia was done to evaluate the presence of nuclear abnormalities and its correlation with their health status and farming activities.

RESULTS

Analysis of buccal cells revealed that the frequency of MN was significantly higher (p < 0.05) in farmers as compared to controls. In contrast, no significant difference (p > 0.05) was observed for BNu frequency in between groups. Correlation analysis showed that apart from a significant (p < 0.05) and positive correlation between the duration of fertilizers exposure and frequencies of MN (r = 0.42, P = 0.001) and BNu (r = 0.37, P = 0.02), no other correlation of various confounding factors on the formation of MN and BNu were observed.

CONCLUSION

In conclusion, pesticide and fertilizers exposure may contribute to the promotion of nuclear anomalies among Malaysian farmers who are engaged in mixed plantation activities. Further assessment of larger populations is important to address and overcome the potential risk of pesticide-induced genotoxicity.

Gene chip analysis of Arabidopsis thaliana genomic DNA methylation and gene expression in response to carbendazim

OBJECTIVES

To examine the effects of carbendazim on Arabidopsis genomic DNA methylation and gene expression.

RESULTS

Carbendazim caused widespread changes in gene loci methylation and gene expression. With 0.1 mM (D2) and 0.2 mM (D3) carbendazim, there were, respectively, 1522 and 2278 demethylated sites and 1541 and 2790 methylated sites. A total of 279 and 505 genes were up-regulated by more than 300 % and 175 and 609 genes were down-regulated by 67 % in D2 and D3 treatments, respectively, compared with the control. Conjoint analysis showed that 20 and 39 demethylated genes were up-regulated >300 % and 21 and 24 methylated genes were down-regulated <67 % in D2 and D3, respectively.

CONCLUSIONS

Carbendazim causes methylation or demethylation of certain genes and changes the expression of these genes. These findings provide a theoretical basis for novel epigenetics-based methods to detect organic food and a new interpretation for the degradation of crop varieties.

A comparison of health, health behavior, and access between farm and nonfarm populations in rural New York state

BACKGROUND

Recent technological and demographic changes in US agriculture raise questions about whether the previously observed benefits of the agricultural lifestyle persist.

METHODS

In 2009, researchers conducted a household survey of 9,612 adults (aged 20+) in a rural region of Upstate New York. Data on health status, health behaviors, and health care access among farmers and rural nonfarm residents were compared.

RESULTS

After adjustment for age, gender, education, and having a regular health care provider, male farmers had elevated prevalence of asthma (OR: 1.82, 95% CI: 1.05-3.16) and untreated chronic obstructive pulmonary disease (COPD) (OR: 3.17, 95% CI: 1.12-9.01). Farmers had significantly lower hypercholesterolemia (OR: 0.70, 95% CI: 0.50-0.99), but not lower prevalence of heart disease or stroke. Farmers had lower rates of smoking (OR: 0.60, 95% CI: 0.40-0.89) and higher rates of hard physical labor (OR: 2.61, 95% CI: 1.83-3.72) than nonfarmers, but they had notably worse health behavior prevalence relative to various types of screening, vaccinations, and having a regular medical care provider (OR: 0.53, 95% CI: 0.39-0.71).

CONCLUSIONS

The farm population is becoming more like the rural nonfarm population with regard to health outcomes and lifestyle, yet it remains notably poorer with regard to prevention. Targeted outreach is needed to increase prevention within the agricultural community.

Prevalence of diagnosed cancer according to duration of diagnosed diabetes and current insulin use among U.S. adults with diagnosed diabetes: findings from the 2009 Behavioral Risk Factor Surveillance System

OBJECTIVE

To estimate the prevalence of diagnosed cancer according to duration of diagnosed diabetes and current insulin use among U.S. adults with diagnosed diabetes.

RESEARCH DESIGN AND METHODS

We analyzed data from 25,964 adults aged ≥ 18 years with diagnosed diabetes who participated in the 2009 Behavioral Risk Factor Surveillance System.

RESULTS

After adjustment for potential confounders, we found that the greater the duration of diagnosed diabetes, the higher the prevalence of diagnosed cancers (P < 0.0001 for linear trend). Among adults with diagnosed type 2 diabetes, the prevalence estimate for cancers of all sites was significantly higher among men (adjusted prevalence ratio 1.6 [95% CI 1.3-1.9]) and women (1.8 [1.5-2.1]) who reported being diagnosed with diabetes ≥ 15 years ago than among those reporting diabetes diagnosis <15 years ago. The prevalence estimate for cancers of all sites was ~1.3 times higher among type 2 diabetic adults who currently used insulin than among those who did not use insulin among both men (1.3 [1.1-1.6]) and women (1.3 [1.1-1.5]).

CONCLUSIONS

Our results suggest that there is an increased burden of diagnosed cancer among adults with a longer duration of diagnosed diabetes and among type 2 diabetic adults who currently use insulin.

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.

Pesticide induced immunotoxicity in humans: a comprehensive review of the existing evidence

The immune system can be the target of many chemicals, with potentially severe adverse effects on the host's health. In Western countries pesticides, together with new and modified patterns of exposure to chemicals, have been implicated in the increasing prevalence of diseases associated with alterations of the immune response, such as hypersensitivity reactions, certain autoimmune diseases and cancers. Xenobiotics may initiate, facilitate or exacerbate pathological immune processes, resulting in immunotoxicity by induction of mutations in genes coding for immunoregulatory factors, modifying immune tolerance and activation pathways. The purpose of this article is to update the evidence of pesticide immunotoxicity. Even if experimental data as well as sporadic human studies indicate that some pesticides can affect the immune system, overall, existing epidemiological studies are inadequate to raise conclusions on the immunotoxic risk associated to pesticide exposure. The available studies on the effects of pesticides on human immune system have several limitations including poor indication on exposure levels, multiple chemical exposures, heterogeneity of the approach, and difficulty in giving a prognostic significance to the slight changes often observed. Further studies are necessary, and they should be preferably carried out through comparison of pre and post-exposure findings in the same group of subjects with a matched control group. Attempt should be made to define the prognostic significance of slight changes often observed. Animal and in vitro studies are also important and necessary to scientifically support epidemiological evidences on pesticide-induced immunotoxicity.

Lack of human tissue-specific correlations for rodent pancreatic and colorectal carcinogens

To better understand the relationships between chemical exposures and human cancer causation, incidence data for human cancer types were identified and pancreatic and colorectal cancers were studied in-depth to assess whether data supporting the causation of pancreatic or colorectal tumors by chemicals in rodents is predictive of causation by the same chemicals of the same tumors in humans. A search of the Carcinogenic Potency Database, the National Toxicology Program (NTP) technical report database, and the published literature identified 38 and 39 chemicals reported to cause pancreatic and colorectal tumors, respectively, in mice or rats. For each of these chemicals, searches were conducted of the International Agency for Research on Cancer monographs, the NTP Report on Carcinogens, and the published literature for evidence of induction of the same tumors in humans. Based on this evaluation, no conclusive evidence was identified to suggest that chemicals reported to cause pancreatic or colorectal tumors in rodents also cause these tumors in humans. These findings suggest that pancreatic tumor data from mouse and rat bioassays are of limited utility with regard to predicting similar tumor induction in humans. For colorectal cancer, a lack of correlation was noted for the vast majority of chemicals.

Human volunteer studies investigating the potential for toxicokinetic interactions between the pesticides deltamethrin; pirimicarb and chlorpyrifos-methyl following oral exposure at the acceptable daily intake

Human volunteer studies have been conducted by orally administering the pesticides deltamethrin (0.01 mg/kg/day) or pirimicarb (0.02 mg/kg/day) at the acceptable daily intake (ADI) together with chlorpyrifos-methyl (0.01 mg/kg/day), in order to investigate any potential interactions that may occur during dietary exposure. Deltamethrin and pirimicarb are metabolised in vivo by hydrolytic enzymes, which may be susceptible to inhibition by esterase-inhibiting compounds, such as chlorpyrifos-methyl. Urine samples were collected at time points up to at least 48 h post-exposure and metabolites were quantified. Urinary metabolite excretion data obtained from the mixed exposures were compared with data obtained from the same individuals given a dose of each individual pesticide on a separate occasion. Metabolite excretion profiles for both pesticides administered as a mixed dose with chlorpyrifos-methyl were qualitatively similar to those obtained for the individual doses. Peak excretion of deltamethrin and pirimicarb metabolites occurred at around 4h post-exposure for both the individual and the mixed exposure scenarios, and metabolite excretion was almost complete within 24h. No statistically significant differences were found between the individual and mixed doses for either metabolite excretion half-life or metabolite levels quantified in 24-h total urine collections. The data presented here indicate that no significant toxicokinetic interactions occur between either deltamethrin or pirimicarb and chlorpyrifos-methyl when orally administered together at the ADI.

Effect of N-metylcarbamate pesticide bendiocarb on cattle lymphocytes after in vitro exposure

Bendiocarb is a carbamate broad-spectrum insecticide used to control disease vectors such as mosquitoes and flies, as well as household and agricultural pests. Nowadays, only few papers reporting cytogenetic or possible genotoxic effect of this insecticide on mammalian cells are available. In the present study 24-hour exposure to bendiocarbamate at concentrations ranging from 20 to 160 μg/ml was used for investigation of unstable chromosomal aberrations (CA), sister chromatid exchanges (SCE) and stable chromosomal aberration induction in cultured bovine peripheral lymphocytes. The slight but no significant increase of chromatide breaks frequency was observed after the exposure of lymphocytes to 80 μg/ml of bendiocarb. At the highest concentration added to the cell cultures (160 μg/ml) mitotic index decrease was shown in both donors (p < 0.05; p < 0.01). Both statistically significant elevation of SCEs (p < 0.05) and a reduction of proliferative indices (PI) (p < 0.01) were shown at a dose of 80 μg/ml. By means of two fluorescent-labelled whole chromosome-painting probes, stable aberrations such as bovine chromosome 1 and 5 translocation as well as numerical aberrations (polyploidies, heteroploidies) were visualised under fluorescent microscope in some examined metaphases.

Effects of pesticide exposure on the human immune system

Epidemiological evidence from Western countries indicates that the prevalence of diseases associated with alterations in the immune response, such as asthma, certain autoimmune diseases and cancer, are increasing to such an extent that it cannot be attributed to improved diagnostics alone. There is some concern that this trend could be, at least, partially attributable to new or modified patterns of exposures to chemicals, including pesticides. The purpose of this article is to review the evidence on pesticide immunotoxicity in humans. Overall, the available data are inadequate to draw firm conclusions on the immunotoxic risk associated with pesticide exposure. The available studies on the effects of pesticides on the human immune system have several limitations, including limited data on exposure levels, heterogeneity of the applied methods, and difficulties in assessing the prognostic significance of observed slight changes and in the interpretation of the reported findings. Further studies are needed and preferably as prospective studies, comparing pre- and post-exposure data in the same group of subjects and including an appropriate non-exposed control group. More knowledge is required regarding the prognostic significance of the small changes observed.

Causal attributions to epidemiological risk factors and their associations to later psychological adjustment among Japanese breast cancer patients

GOALS

The objective of this study was to evaluate the causal attributions for breast cancer and their association with the subsequent psychological adjustment.

MATERIALS AND METHODS

Sixty-three Japanese patients newly diagnosed with breast cancer were asked by an interviewer about risk factors and explanations for the etiology of breast cancer using a four-point scale. The General Health Questionnaire (GHQ-28) and the Center for Epidemiologic Studies Depression Scale (CES-D) were administered about 2 months later to measure psychological adjustment to the illness. The relationship between each causal attribution and measure of psychological adjustment was assessed with the Spearman rank correlation after adjusting for potential confounders (age, marital status, cancer stage at diagnosis, time between the day of diagnosis and follow-up, and physical symptoms at the follow-up).

MAIN RESULTS

Attributions to several explanations, including "stress" and "personal characteristics," were positively associated with the GHQ-28 measures. Of the attributions to risk factors, "body size" was significantly inversely (r = -0.29) associated and "never having children" was insignificantly and highly inversely (r = -0.77) associated with the GHQ-28 measures, indicating better adjustment to the illness. On the other hand, the attribution to "tobacco" was significantly and positively associated with the GHQ-28 measures (r = 0.34), indicating that the attributions antagonized adjustment to the illness.

CONCLUSION

The current study indicates that forming causal attributions influences the adjustment to the illness in Japanese breast cancer patients and attributions to certain risk factors for breast cancer may contribute to better adjustment.

Endocrine disrupting pesticides: implications for risk assessment

Endocrine disrupting (ED) chemicals are compounds that alter the normal functioning of the endocrine system, potentially causing disease or deformity in organisms and their offspring. Pesticides are used widely to kill unwanted organisms in crops, public areas, homes and gardens and medicinally to kill parasites. Many are proven or suspected to be EDs. Ancient physiological similarities between different vertebrate groups suggest that disorders observed in wildlife may indicate risks to humans. This makes accurate risk assessment and effective legislation difficult. In this paper, the hazardous properties of pesticides which are known to have ED properties are reviewed in order to assess the implications for risk assessment. As well as data on sources of exposure in the United Kingdom (UK) an assessment of the evidence on the health effects of ED pesticides is also included. In total, 127 have been identified from the literature and their effects and modes of action are listed in this paper. Using the UK as a case study, the types and quantities of pesticides used, and their methods of application are assessed, along with their potential pathways to humans. In the UK reliable data are available only for agricultural use, so non-agricultural routes of pesticide exposure have been poorly quantified. The exposure of people resident in or visiting rural areas could also have been grossly under-estimated. Material links between ED pesticide use and specific illnesses or deformities are complicated by the multifactorial nature of disease, which can be affected by factors such as diet. Despite these difficulties, a large body of evidence has accumulated linking specific conditions to ED pesticides in wildlife and humans. A more precautionary approach to the use of ED pesticides, especially for non-essential purposes is proposed.

Occupational exposure to pesticides and risk of hematopoietic cancers: meta-analysis of case–control studies

OBJECTIVE

In this study we conducted a meta-analysis of 13 case-control studies that examined the occurrence of hematopoietic cancers in pesticide related occupations in order to undertake a qualitative and quantitative evaluation of a possible relationship.

METHODS

Pubmed databases were searched for case-control studies published between 1990 and 2005 investigating the relation between hematopoietic cancers and occupational exposure to pesticides. Fixed and random effect meta-analysis models were used depending on the presence of heterogeneity between studies.

RESULTS

The overall meta-odds ratio obtained after pooling 44 ORs from 13 studies was 1.3 (95% CI: 1.3-1.5). We realized stratified analysis on three different types of hematopoietic cancers (non-Hodgkin lymphoma (NHL), leukemia and multiple myeloma). A significant increased risk of NHL was found (OR = 1.35; 95% CI = 1.2-1.5). Moreover, increased risks of Leukemia (OR = 1.35; 95% CI = 0.9-2) and multiple myeloma (OR = 1.16; 95% CI = 0.99-1.36) were also detected but these results were not statistically significant. Significant heterogeneity existed among the different studies and a publication bias was detected. Therefore, a meta-regression was carried out. Our results showed that a long period of exposure (more than 10 years) provided an increase in the risk of all hematopoietic cancers and for NHL by fractions of 2.18 (95% CI = 1.43-3.35) and 1.65 (95% CI = 1.08-2.51), respectively.

CONCLUSIONS

The overall meta-odds ratio suggests that there is a significantly positive association between occupational exposure to pesticides and all hematopoietic cancers as well as NHL. A major limitation of our meta-analysis is the lack of sufficient data about exposure information and other risk factors for hematopoietic cancer (genetic predisposition, ethnic origin, immunodepression...). In addition, data concerning specific subtypes of hematopoietic cancers are often confusing. Thus, future epidemiological studies should undertake a major effort to assess the identity and the level of pesticides exposure and should control for the most likely potential confounders.

The interrelation between organophosphate toxicity and the epidemiology of depression and suicide

The literature on an association between organophosphate (OP) toxicity and depression or suicide is scarce. An interrelation exists among populations exposed to OPs, acute OP toxicity, neurobehavioral effects, depression, suicide, and fatality. Acute OP toxicity is characterized by the cholinergic syndrome with systemic and central nervous system effects. Organophosphate-induced neurobehavioral effects result in depression. A potential risk of depression and suicide exists in farm workers exposed to OPs. The sociodemographics of depression include age, gender, race, geographic region, social factors, economics, psychiatric disorders, medical conditions, and hereditary factors. Suicide is a major consequence of depression, with multiple sociodemographic risk factors. Developing countries have a higher incidence of OP toxicity, with limited information on the prevalence of depression. In these countries, the incidence of suicide is high, affecting more females. Suicide is more prevalent in rural areas, and in farming communities, commonly with ingestion of OPs. In industrialized countries, the incidence of OP toxicity is lower, but the prevalence of depression is higher. Suicide rates are lower in industrialized countries, affecting more males, the urban population, and farming communities. Other lethal methods of suicide, such as hanging, firearms, electrocution, and drug overdose are more common in industrialized countries. A potential risk of depression or suicide certainly exists from OP toxicity, largely depending on the epidemiology or sociodemographics of these disorders. Scientific evidence shows that the association between environmental toxicology and psychiatry has important public health implications.

Organochlorine levels in adipose tissue of women from a littoral region of Argentina

Organochlorine compounds (OCCs), such as pesticides and polychlorinated biphenyls (PCBs), are persistent lipophilic chemicals identified as endocrine disruptors, mainly with estrogen-like effects. Northeastern Argentina, near the Paraná River, is characterized by intensive farming and agricultural activities and industrial development, and is therefore prone to high incidences of environmental and dietary exposure to OCCs. Hence, we conducted a study to (1) estimate the organochlorine residues present in mammary fat tissue in a population of women from this littoral region and (2) identify potential sources of exposure to OCCs. Our subjects were 76 women (residing in and around Santa Fe city and not occupationally exposed to organochlorines) who underwent excision biopsy of a breast lesion or had plastic surgery. Both frequency of occurrence and levels of organochlorine residues were high in breast adipose tissue of all the participants. The organochlorine residues most frequently found were p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) in all the subjects analyzed, hexachlorobenzene (HCB) in 86.8%, and beta-hexachlorocyclohexane (beta-HCH) in 75.0%. The incidence of PCB congeners was very low. p,p'-DDE and beta-HCH residues reached the highest levels, 4794 and 1780 ppb, respectively. The diet was a relevant source of exposure, consumption of animal fat and freshwater fish playing a significant role. Bioaccumulation was evidenced by the significant positive association between organochlorine levels and body mass index (p = 0.0003) and the age of the patient (p = 0.0002). The frequency and levels of OCCs found in our study population raise concerns regarding Argentinean exposure to these endocrine disruptors.

Cancer and Pesticides: An Overview and Some Results of the Italian Multicenter Case-Control Study on Hematolymphopoietic Malignancies

Exposure to pesticides is recognized as an important environmental risk factor associated with development of cancer. Epidemiological studies, although sometimes contradictory, have linked phenoxy acid herbicides with non-Hodgkin's lymphoma (NHL) and Soft Tissue Sarcoma (STS); organochlorine insecticides with STS, NHL, and leukemia; organophosphorous compounds with NHL and leukemia; and triazine herbicides with ovarian cancer. Exposure assessment is a crucial point in studying the association between cancer and pesticides. In order to investigate the association between hematolymphopoietic malignancies and occupational exposures, including pesticides, a population-based case-control study was carried out in Italy in 11 areas, 9 of which are agricultural or mixed areas. All newly diagnosed cases of hematolymphopoietic malignancies were collected in a 3-year period (1991-1993). The control group consisted of a random sample of the population residing in each area. The approach to infer exposures in agriculture was based on: the use of an agricultural questionnaire with 24 crop-specific questionnaires; expert agronomists who reviewed the collected information for each subject and translated it into pesticides histories. In total, 1925 cases and 1232 controls were interviewed in the nine agricultural areas. Increased risk was observed for some specific classes of pesticides. Furthermore, a nonstatistically significant increased risk of NHL was observed for subjects who were exposed to phenoxy herbicides not using protective equipment and a significant increased risk for exposure to 2, 4-dichlorophenoxy acetic acid (2,4-D).