Chromosomal aberrations in human lymphocytes exposed to the anticholinesterase pesticide isofenphos with mechanisms of leukemogenesis

Maternal and Paternal Household Pesticide Exposure During Pregnancy and Risk of Childhood Acute Lymphoblastic Leukemia

OBJECTIVE

The aim of this study was to investigate whether risk estimates for childhood acute lymphoblastic leukemia change when restricting model comparison groups to "nonpesticide exposure" (NPE10) households.

METHODS

Cases ( n = 1810) 15 years or younger were identified through Children's Cancer Group institutions between 1989 and 1993 and age-/sex-matched to controls ( n = 1951). Household pesticide use during pregnancy/month prior was collected via telephone. NPE10 comparison group reporting no parental exposure to 10 pesticide classes was identified.

RESULTS

Adjusted odds ratios increased from 15% to 49% when limiting the comparison to NPE10. Maternal termite insecticide exposure was associated with greatest risk (adjusted odds ratio, 4.21; 95% confidence interval, 2.00-8.88). There was minimal evidence of interaction by child sex or occupational pesticide exposure, and no monotonic dose-response pattern with frequency of use (times per year).

CONCLUSIONS

Elevated risks are consistent with published pooled-/meta-analyses and DNA damage. The consistency and magnitude of these associations warrant product labeling, exposure reduction interventions, or both.

Organophosphate pesticide-induced toxicity through DNA damage and DNA repair mechanisms

Organophosphate pesticides (OPs) are widely used in agriculture, healthcare, and other industries due to their ability to kill pests. However, OPs can also have genotoxic effects on humans who are exposed to them. This review summarizes the research on DNA damage caused by OPs, the mechanisms behind this damage, and the resulting cellular effects. Even at low doses, OPs have been shown to damage DNA and cause cellular dysfunction. Common phenomena seen in cells that are exposed to OPs include the formation of DNA adducts and lesions, single-strand and double-strand DNA breaks, and DNA and protein inter and intra-cross-links. The present review will aid in comprehending the extent of genetic damage and the impact on DNA repair pathways caused by acute or chronic exposure to OPs. Additionally, understanding the mechanisms of the effects of OPs will aid in correlating them with various diseases, including cancer, Alzheimer's, and Parkinson's disease. Overall, knowledge of the potential adverse effects of different OPs will help in monitoring the health complications they may cause.

Environmental Risk Factors for Childhood Acute Lymphoblastic Leukemia: An Umbrella Review

Leukemia is the most common type of cancer among children and adolescents worldwide. The aim of this umbrella review was (1) to provide a synthesis of the environmental risk factors for the onset of childhood acute lymphoblastic leukemia (ALL) by exposure window, (2) evaluate their strength of evidence and magnitude of risk, and as an example (3) estimate the prevalence in the German population, which determines the relevance at the population level. Relevant systematic reviews and pooled analyses were identified and retrieved through PubMed, Web of Science databases and lists of references. Only two risk factors (low doses of ionizing radiation in early childhood and general pesticide exposure during maternal preconception/pregnancy) were convincingly associated with childhood ALL. Other risk factors including extremely low frequency electromagnetic field (ELF-MF), living in proximity to nuclear facilities, petroleum, benzene, solvent, and domestic paint exposure during early childhood, all showed some level of evidence of association. Maternal consumption of coffee (high consumption/>2 cups/day) and cola (high consumption) during pregnancy, paternal smoking during the pregnancy of the index child, maternal intake of fertility treatment, high birth weight (≥4000 g) and caesarean delivery were also found to have some level of evidence of association. Maternal folic acid and vitamins intake, breastfeeding (≥6 months) and day-care attendance, were inversely associated with childhood ALL with some evidence. The results of this umbrella review should be interpreted with caution; as the evidence stems almost exclusively from case-control studies, where selection and recall bias are potential concerns, and whether the empirically observed association reflect causal relationships remains an open question. Hence, improved exposure assessment methods including accurate and reliable measurement, probing questions and better interview techniques are required to establish causative risk factors of childhood leukemia, which is needed for the ultimate goal of primary prevention.

Acute myeloid leukaemia at an early age: Reviewing the interaction between pesticide exposure and KMT2A-rearrangement

Acute myeloid leukaemia (AML) in early childhood is characterised by a high frequency of recurrent genomic aberrations associated with distinct myeloid subtypes, clinical outcomes and pathogenesis. Genomic instability is the first step of pathogenic mechanism in early childhood AML. A sum of adverse events is necessary to the development of infant AML (i-AML), which includes latency of biochemical-molecular and cellular effects. Inherited genetic susceptibility associated with exposures to biotransformation substances can modulate the risk of DNA damage and it is a very important piece in the pathogenic puzzle. In this review, we have aimed to explore the chain of events in the time-points of the natural history of i-AML, which includes maternal exposures during pregnancy, the speculations about the formation of somatic mutations during foetal life and the secondary genomic aberrations associated with i-AML. The modulation of risk conferred by xenobiotic metabolism´s genes variants is the bottom line of the pathogenic process. Since we have conducted observational and molecular investigations in early childhood leukaemia, the data focused here is based on Brazilian findings with summarised results of our experience with epidemiological and molecular studies in early-age leukaemia.

Cholinesterase-like organocatalysis by imidazole and imidazole-bearing molecules

Organocatalysis, which is mostly explored for its new potential industrial applications, also represents a chemical event involved in endogenous processes. In the present study, we provide the first evidence that imidazole and imidazole derivatives have cholinesterase-like properties since they can accelerate the hydrolysis of acetylthiocholine and propionylthiocholine in a concentration-dependent manner. The natural imidazole-containing molecules as L-histidine and histamine show a catalytic activity, comparable to that of imidazole itself, whereas synthetic molecules, as cimetidine and clonidine, were less active. In the experimental conditions used, the reaction progress curves were sigmoidal and the rational of such unexpected behavior as well as the mechanism of catalysis is discussed. Although indirectly, findings of the present study suggests that imidazolic compounds may interfere with the homeostasis of the cholinergic system in vivo.

Investigation into experimental toxicological properties of plant protection products having a potential link to Parkinson's disease and childhood leukaemia

In 2013, EFSA published a literature review on epidemiological studies linking exposure to pesticides and human health outcome. As a follow up, the EFSA Panel on Plant Protection Products and their residues (PPR Panel) was requested to investigate the plausible involvement of pesticide exposure as a risk factor for Parkinson's disease (PD) and childhood leukaemia (CHL). A systematic literature review on PD and CHL and mode of actions for pesticides was published by EFSA in 2016 and used as background documentation. The Panel used the Adverse Outcome Pathway (AOP) conceptual framework to define the biological plausibility in relation to epidemiological studies by means of identification of specific symptoms of the diseases as AO. The AOP combines multiple information and provides knowledge of biological pathways, highlights species differences and similarities, identifies research needs and supports regulatory decisions. In this context, the AOP approach could help in organising the available experimental knowledge to assess biological plausibility by describing the link between a molecular initiating event (MIE) and the AO through a series of biologically plausible and essential key events (KEs). As the AOP is chemically agnostic, tool chemical compounds were selected to empirically support the response and temporal concordance of the key event relationships (KERs). Three qualitative and one putative AOP were developed by the Panel using the results obtained. The Panel supports the use of the AOP framework to scientifically and transparently explore the biological plausibility of the association between pesticide exposure and human health outcomes, identify data gaps, define a tailored testing strategy and suggests an AOP's informed Integrated Approach for Testing and Assessment (IATA).

Passive exposure to agricultural pesticides and risk of childhood leukemia in an Italian community

BACKGROUND

Exposure to pesticides has been suggested as a risk factor for childhood leukemia, but definitive evidence on this relation and the specific pesticides involved is still not clear.

OBJECTIVE

We carried out a population-based case-control study in a Northern Italy community to assess the possible relation between passive exposure to agricultural pesticides and risk of acute childhood leukemia.

METHODS

We assessed passive pesticide exposure of 111 childhood leukemia cases and 444 matched controls by determining density and type of agricultural land use within a 100-m radius buffer around children's homes. We focused on four common crop types, arable, orchard, vineyard and vegetable, characterized by the use of specific pesticides that are potentially involved in childhood induced leukemia. The use of these pesticides was validated within the present study. We computed the odds ratios (OR) of the disease and their 95% confidence intervals (CI) according to type and density of crops around the children's homes, also taking into account traffic pollution and high-voltage power line magnetic field exposure.

RESULTS

Childhood leukemia risk did not increase in relation with any of the crop types with the exception of arable crops, characterized by the use of 2.4-D, MCPA, glyphosate, dicamba, triazine and cypermethrin. The very few children (n=11) residing close to arable crops had an OR for childhood leukemia of 2.04 (95% CI 0.50-8.35), and such excess risk was further enhanced among children aged <5 years.

CONCLUSIONS

Despite the null association with most crop types and the statistical imprecision of the estimates, the increased leukemia risk among children residing close to arable crops indicates the need to further investigate the involvement in disease etiology of passive exposure to herbicides and pyrethroids, though such exposure is unlikely to play a role in the vast majority of cases.

Cholinesterase-inhibiting and genotoxic effects of acute carbofuran intoxication in man: a case report

Carbofuran belongs to the group of N-methylcarbamate insecticides used for the control of soil-dwelling and foliar-feeding insects in various crops; its consumption totals approximately 20,000 tonnes per year. Although the neurological effects on human beings have been well documented, little is known on its impact on the genome. A 38-year-old, healthy male worker employed in a carbofuran production facility accidentally inhaled the dust of the active ingredient carbofuran. Thirty minutes later, he experienced weakness, fatigue, perspiration, breathing difficulties, cephalalgia, disorientation, abdominal pain and vomiting. Blood samples were taken to measure cholinesterase activity, and to perform the alkaline comet assay and micronucleus assay combined with pancentromeric probes. Analyses were repeated 72 hr after intoxication and compared with the results obtained from regular monitoring conducted 10 days prior to the accident. Cholinesterase activity showed the highest correlation with the number of apoptotic cells, comet assay tail length, and number of long-tailed nuclei, suggesting that these are the genomic end-points primarily affected by carbofuran intake. Only a weak correlation was detected for the total number of micronuclei, centromere-containing micronuclei and nuclear buds. Since those end-points increased significantly 72 hr after the accident, they could be considered as late biomarkers of the effects of carbofuran intoxication. The results of this report suggest that, in the interests of higher standards in risk assessment and health hazard protection, periodical medical examination of carbamate-exposed populations should include genotoxicity testing in addition to the assessment of cholinesterase activity.

Linking Pesticide Exposure with Pediatric Leukemia: Potential Underlying Mechanisms

Leukemia is the most common cancer in children, representing 30% of all childhood cancers. The disease arises from recurrent genetic insults that block differentiation of hematopoietic stem and/or progenitor cells (HSPCs) and drives uncontrolled proliferation and survival of the differentiation-blocked clone. Pediatric leukemia is phenotypically and genetically heterogeneous with an obscure etiology. The interaction between genetic factors and environmental agents represents a potential etiological driver. Although information is limited, the principal toxic mechanisms of potential leukemogenic agents (e.g., etoposide, benzene metabolites, bioflavonoids and some pesticides) include topoisomerase II inhibition and/or excessive generation of free radicals, which may induce DNA single- and double-strand breaks (DNA-DSBs) in early HSPCs. Chromosomal rearrangements (duplications, deletions and translocations) may occur if these lesions are not properly repaired. The initiating hit usually occurs in utero and commonly leads to the expression of oncogenic fusion proteins. Subsequent cooperating hits define the disease latency and occur after birth and may be of a genetic, epigenetic or immune nature (i.e., delayed infection-mediated immune deregulation). Here, we review the available experimental and epidemiological evidence linking pesticide exposure to infant and childhood leukemia and provide a mechanistic basis to support the association, focusing on early initiating molecular events.

Alteration of in vitro and acute in vivo toxicity of textile dyeing wastewater after chemical and biological remediation

INTRODUCTION

Textile industry is one of the most common and essential sectors in Tunisia. However, the treatment of textile effluents becomes a university because of their toxic impacts on waters, soils, flora, and fauna.

MATERIALS AND METHODS

The aim of this work was to evaluate the ability of Pseudomonas putida mt-2 to decolorize a textile wastewater and to compare the biologic decolorization process to the chemical one currently used by the textile industry.

RESULTS

P. putida exhibited a high decolorizing capacity of the studied effluent, compared to the coagulation-flocculation method with decolorization percentage of 86% and 34.5%, respectively. Genotoxicity of the studied effluent, before and after decolorization by P. putida mt-2, was evaluated in vitro, using the SOS chromotest, and in vivo, in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations compared to not treated mice. In addition, textile effluent statistically significant influenced acetylcholinesterase and butyrylcholinesterase activities and lipid peroxidation (p < 0.01) when compared to not-treated mice. Coagulation-flocculation treatment process used by industry was revealed to be ineffective. Indeed toxicities persisted after treatment and the effluent did not show any statistically significant decrease in toxicities compared to non-treated effluent. Our results indicate that P. putida is a promising and improved alternative to treating industrial scale effluent compared to current chemical decolorization procedures used by the Tunisian textile industry.

Acid violet 7 and its biodegradation products induce chromosome aberrations, lipid peroxidation, and cholinesterase inhibition in mouse bone marrow

INTRODUCTION

Acid violet 7 (AV7), mostly used in food, paper, cosmetic, and especially in textile industries, was degraded by Pseudomonas putida mt-2 at concentrations up to 200 mg/l.

MATERIALS AND METHODS

In this study, toxicity of AV7, before and after biodegradation, was evaluated in vivo, in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations, membrane lipid peroxidation, and acetylcholinesterasic activity inhibition. The studies included same conditions for animal treatment, corresponding to increasing doses by intraperitoneal (ip) injection.

RESULTS

Results indicated that AV7 showed a significant ability to induce chromosome aberrations, lipid peroxidation, and acetylcholinesterase inhibitory effect. The toxicity of AV7 increased significantly after static biodegradation with P. putida mt-2 and totally disappeared after shaken incubation. In addition, the toxicity generated by the pure azo dye and the corresponding azoreduction metabolites (4'-aminoacetanilide (4'-AA) and 5-acetamido-2-amino-1-hydroxy-3,6-naphtalene disulfonic acid (5-ANDS)) were compared. 4'-AA and 5-ANDS would be responsible of static biodegradation medium toxicity. The present study demonstrates that P. putida mt-2, incubated under aerobic condition, has a catabolism which enables it to degrade AV7, and especially to completely detoxify the dye mixture.

Fenamiphos and related organophosphorus pesticides: environmental fate and toxicology

In this review, we emphasize recent research on the fate, transport, and metabolism of tree selected organophosphorus pesticides (fenamiphos, isofenphos, and coumaphos) in soil an water environments. This review is also concerned with the side effects of these pesticides on nontarget organisms. Despite the fact that fenamiphos is not very mobile, its oxides have been detected in the groundwaters of Western Australia. Most organophosphorus pesticides generally are chemically unstable and underfo microbial degradation in soil and water environments. Enhanced biodegradation of many organophosphorus pesticides upon their repeted applications to soil and water is well established. Myriads of soil microorganisms, bacteria in particular, exhibit an exceptional capacity to transform many organophosphorus pesticides. Fenamiphos can undergo rapid microbially mediated degradation via oxidation to its oxides (sulfoxide and sulfone) and eventually to CO2 and water in soils, or via hydrolysis, in cultures of the soil bacterium, Brevinbacterium sp. There is evidence for enhanced biodegradation of (i) isofenphos in soils with a long history of use and (ii) coumaphos in cattle dip by bacterial cultures to chlorferon and diethylthiophosphoric acid.

Residential proximity to agricultural pesticide applications and childhood acute lymphoblastic leukemia

Ambient exposure from residential proximity to applications of agricultural pesticides may contribute to the risk of childhood acute lymphoblastic leukemia (ALL). Using residential histories collected from the families of 213 ALL cases and 268 matched controls enrolled in the Northern California Childhood Leukemia Study, the authors assessed residential proximity within a half-mile (804.5m) of pesticide applications by linking address histories with reports of agricultural pesticide use. Proximity was ascertained during different time windows of exposure, including the first year of life and the child's lifetime through the date of diagnosis for cases or reference for controls. Agricultural pesticides were categorized a priori into groups based on similarities in toxicological effects, physicochemical properties, and target pests or uses. The effects of moderate and high exposure for each group of pesticides were estimated using conditional logistic regression. Elevated ALL risk was associated with lifetime moderate exposure, but not high exposure, to certain physicochemical categories of pesticides, including organophosphates, chlorinated phenols, and triazines, and with pesticides classified as insecticides or fumigants. A similar pattern was also observed for several toxicological groups of pesticides. These findings suggest future directions for the identification of specific pesticides that may play a role in the etiology of childhood leukemia.

Detection of excision repaired DNA damage in the comet assay by using Ara-C and hydroxyurea in three different cell types

Because of its characteristics, the comet assay has been used to evaluate the ability of virtually any type of eukaryotic cell to repair different kinds of DNA damage, including double and single strand breaks and base damage. The ability to detect excision repair sites using the alkaline version can be enhanced by the inclusion of repair inhibitors, DNA synthesis inhibitors, or chain terminators. In this sense, we evaluated the ability of hydroxyurea (HU) and cytosine arabinoside (Ara-C), for detecting lesions produced by the alkylating agents ethyl methanesulfonate (EMS) and methyl methanesulfonate (MMS) in three different cell systems. Two hundred cells for experimental point were analyzed in the alkaline version of the comet assay, and the results are evidences of the utility of the assay to detect alkylation of bases in the cells lines MRC-5 and TK-6, as the treatment with HU +Ara-C significantly increases both the basal and induced frequency of DNA damage. The use of whole blood, although it detected the effects of MMS, with and without repair inhibitors, failed to detect the effect of the selected dose of EMS and does not permit detection increases in the background level.

Rationale for diagnosing deficiency of ChEs and for applying exogenous HuChEs to the treatment of diseases

Recent evidence strongly demonstrates that acetylcholine (ACh) is not only involved in the function of the central and peripheral nervous systems, including the parasympathetic and somatic systems, but also acts as a ubiquitous cell signaling molecule or cytotransmitter, and as a hormone with paracrine, juxtacrine and autocrine properties. This active molecule exerts versatile and potent functions primarily through its specific nicotinic and muscarinic receptors (nAChRs and mAChRs, respectively). These functions modulate numerous biomechanisms, including cell growth, survival, proliferation and differentiation, cell-cell contact, cell cycle, locomotion, electrical activity, immune function, apoptosis, organization of the cytoskeleton, trophic functions, secretion, adhesion, resorption, and stress-response-regulation. By nature, the precise ACh levels and responses from receptors must be controlled and regulated by its degrading enzymes, the cholinesterases (ChEs), namely, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Once ChEs become critically deficient in quality and quantity, ACh signaling will be uncontrollably aberrant and persistent. An in-depth account of the fundamental roles of ChEs, comprising their diverse soluble and membrane-bound forms, in maintaining the functional equilibrium of ACh in the macro and microenvironment has been undertaken. This work also covers ACh receptors, signaling pathways, other interdependent and interrelated substances, functional processes, role of ChEs as first-line gatekeepers and defenses for the architecture of cells, tissues and organisms, physically, chemically, and structurally. The mechanisms of many diseases ranging from the acute cholinergic crisis to the chronic degenerative and hypergenerative disorders such as Alzheimer's disease, cancers, atopic dermatitis, may involve a deficiency of ChEs or imbalance between ACh and ChEs, initially or consequentially. It is therefore essential to ascertain a ChE deficiency, or an imbalance between ACh and ChEs, in tissues and body fluids in order for conducting clinical diagnosis, prevention and treatment. An argument is put forward on the rationale of applying exogenous human ChEs to reverse enzymatic deficiency and correct the imbalance between ACh and ChEs, to repair the affected receptors and protect against their further loss in the body, and consequently to alleviate the signs and symptoms of diseases. Evidence is adduced for the safety and efficacy of ChEs treatment.