Maternal and cord blood levels of aldrin and dieldrin in Delhi population

Origin, dietary exposure, and toxicity of endocrine-disrupting food chemical contaminants: A comprehensive review

Endocrine-disrupting chemicals (EDCs) are a growing public health concern worldwide. Consumption of foodstuffs is currently thought to be one of the principal exposure routes to EDCs. However, alternative ways of human exposure are through inhalation of chemicals and dermal contact. These compounds in food products such as canned food, bottled water, dairy products, fish, meat, egg, and vegetables are a ubiquitous concern to the general population. Therefore, understanding EDCs' properties, such as origin, exposure, toxicological impact, and legal aspects are vital to control their release to the environment and food. The present paper provides an overview of the EDCs and their possible disrupting impact on the endocrine system and other organs.

Pesticides at brain borders: Impact on the blood-brain barrier, neuroinflammation, and neurological risk trajectories

Pesticides are omnipresent, and they pose significant environmental and health risks. Translational studies indicate that acute exposure to high pesticide levels is detrimental, and prolonged contact with low concentrations of pesticides, as single and cocktail, could represent a risk factor for multi-organ pathophysiology, including the brain. Within this research template, we focus on pesticides' impact on the blood-brain barrier (BBB) and neuroinflammation, physical and immunological borders for the homeostatic control of the central nervous system (CNS) neuronal networks. We examine the evidence supporting a link between pre- and postnatal pesticide exposure, neuroinflammatory responses, and time-depend vulnerability footprints in the brain. Because of the pathological influence of BBB damage and inflammation on neuronal transmission from early development, varying exposures to pesticides could represent a danger, perhaps accelerating adverse neurological trajectories during aging. Refining our understanding of how pesticides influence brain barriers and borders could enable the implementation of pesticide-specific regulatory measures directly relevant to environmental neuroethics, the exposome, and one-health frameworks.

Xeno-Estrogenic Pesticides and the Risk of Related Human Cancers

In recent decades, "environmental xenobiotic-mediated endocrine disruption", especially by xeno-estrogens, has gained a lot of interest from toxicologists and environmental researchers. These estrogen-mimicking chemicals are known to cause various human disorders. Pesticides are the most heavily used harmful xenobiotic chemicals around the world. The estrogen-mimicking potential of the most widely used organochlorine pesticides is well established. However, their effect is not as clearly understood among the plethora of effects these persistent xenobiotics are known to pose on our physiological system. Estrogens are one of the principal risk modifiers of various disorders, including cancer, not only in women but in men as well. Despite the ban on these xenobiotics in some parts of the world, humans are still at apparent risk of exposure to these harmful chemicals as they are still widely persistent and likely to stay in our environment for a long time owing to their high chemical stability. The present work intends to understand how these harmful chemicals may affect the risk of the development of estrogen-mediated human cancer.

Assessment of genotoxicity and oxidative stress in pregnant women contaminated to organochlorine pesticides and its correlation with pregnancy outcome

The present study was aimed to assess the correlation between transplacental transfer of xenobiotics and resulting biochemical alterations (including genotoxicity and oxidative stress) in non-occupational pregnant women of North India along with the effect on pregnancy outcomes. Maternal and cord blood samples were collected from 221 healthy mother-infant couples and divided according to their gestational age and birth weight. Genotoxic effects in mother and cord blood were examined using comet assay. The quantitative determination of Organo-chlorine pesticides in blood serum of study population was carried out using gas chromatography-mass spectrometry (GC-MS). Notably higher Organo-chlorine pesticides levels were observed in maternal blood of preterm than term subjects for almost all of the compounds detected, with the maximum concentration found for aldrin (3.26 mg/l) in maternal blood and dieldrin (2.69 mg/l) in cord blood. The results showed a significant increment in olive tail moment, tail full length, catalase, super-oxide dismutase, and malondialdehyde levels whereas lower glutathione reductase and peroxidase were found in preterm babies when compared with term group and it varied in the order: maternal blood > cord blood. A clear trend was observed for preterm babies with their lower birth weight and cesarean mode of delivery. Therefore, reduction in birth weight in newborns may be the consequence of increased oxidative damage and genotoxicity brought about by pesticides and these markers could be employed for early detection of pesticides related ailments and toxicities. To the best of our knowledge, this was a pioneering study and it may help to increase our knowledge with regard to xenobiotic exposure in biological system and the need for stringent guidelines for agricultural use of pesticides.

Level of Organochlorine Pesticide in Prediabetic and Newly Diagnosed Diabetes Mellitus Patients with Varying Degree of Glucose Intolerance and Insulin Resistance among North Indian Population

BACKGROUND

Organochlorine pesticides (OCPs) exposure may induce an endocrine disruption which may lead to the risk of developing diabetes through alteration and disturbance of glucose metabolism, insulin resistance, and destruction of β-cells. The present study determines the recent trend of OCPs residue in blood samples and their association with the known risk factors responsible for developing the risk of diabetes among the North Indian population.

METHODS

Blood sample of 300 patients (100 each of normal glucose tolerance [NGT], prediabetes and newly detected diabetes mellitus [DM]) between the age group of 30 to 70 years were collected. OCPs residue in whole blood samples was analyzed by using gas chromatography equipped with a 63Ni selective electron capture detector.

RESULTS

Significantly higher levels of β-hexachlorocyclohexane (HCH), dieldrin, and p,p'-dichloro-diphenyl-dichloroethylene (DDE) were found in the prediabetes and newly detected DM groups as compared to NGT group. Insulin resistance showed to be significantly positive correlation with β-HCH and dieldrin. Also, fasting and postprandial glucose levels were significantly positively correlated with levels of β-HCH, dieldrin, and p,p'-DDE. Further, when OCPs level was adjusted for age and body mass index (BMI), it was found that β-HCH, dieldrin, and p,p'-DDE levels in blood increases the risk of diabetes by 2.70, 2.83, and 2.55 times respectively. Moreover, when we adjust OCPs level based on BMI categories (BMI <23, ≥23, and ≤25, and >25 kg/m2); β-HCH and p,p'-DDE showed a significant risk of developing newly detected DM with BMI >25 and ≥23 and ≤25 kg/m2.

CONCLUSION

The OCPs level present in the environment may be responsible for biological, metabolic, and endocrine disruptions within the human body which may increase the risk of developing newly detected DM. Hence, OCPs exposure can play a crucial role in the etiology of diabetes.

Why We Will Continue to Lose Our Battle with Cancers If We Do Not Stop Their Triggers from Environmental Pollution

Besides our current health concerns due to COVID-19, cancer is a longer-lasting and even more dramatic pandemic that affects almost a third of the human population worldwide. Most of the emphasis on its causes has been posed on genetic predisposition, chance, and wrong lifestyles (mainly, obesity and smoking). Moreover, our medical weapons against cancers have not improved too much during the last century, although research is in progress. Once diagnosed with a malignant tumour, we still rely on surgery, radiotherapy, and chemotherapy. The main problem is that we have focused on fighting a difficult battle instead of preventing it by controlling its triggers. Quite the opposite, our knowledge of the links between environmental pollution and cancer has surged from the 1980s. Carcinogens in water, air, and soil have continued to accumulate disproportionally and grow in number and dose, bringing us to today's carnage. Here, a synthesis and critical review of the state of the knowledge of the links between cancer and environmental pollution in the three environmental compartments is provided, research gaps are briefly discussed, and some future directions are indicated. New evidence suggests that it is relevant to take into account not only the dose but also the time when we are exposed to carcinogens. The review ends by stressing that more dedication should be put into studying the environmental causes of cancers to prevent and avoid curing them, that the precautionary approach towards environmental pollutants must be much more reactionary, and that there is an urgent need to leave behind the outdated petrochemical-based industry and goods production.

High levels of organochlorine pesticides in drinking water as a risk factor for type 2 diabetes: A study in north India

Organochlorine pesticides (OCPs) are well known synthetic pesticides widely used in agricultural practices and public health program. Higher toxicity, slow degradation, and bioaccumulation are the significant challenges of OCPs. Due to its uses in agricultural and public health, contamination of drinking water and water table also increases day by day. Contaminated drinking water has become a significant issue and alarming signal for public health globally. The purpose of this study was to assess the recent trend of organochlorine pesticides (OCPs) level in drinking water and blood samples of the North Indian population and also to find out its association with glucose intolerance, lipid metabolism, and insulin resistance, which are known risk factors of type 2 diabetes mellitus (T2DM). A case-control study was conducted on 130 Non-Glucose intolerance (NGT), 130 pre-diabetes and 130 recently diagnosed T2DM subjects of the age group of 30-70 years. Patients consuming drinking water from the same source for at least ten years were included in this study for blood and water samples collection. Significantly higher levels of α-HCH, β-HCH, γ-HCH, p,p'-DDE, and o,p'-DDT were found in groundwater samples. However, in tap water samples, the level of α-HCH was found to be slightly higher than the permissible limit of 0.001. Among all recruited subjects consuming contaminated groundwater, 42% had T2DM, 38% pre-diabetes, and the remaining 20% were found normal. We also observed that OCP contamination in groundwater is higher than tap and filter water. The levels of β-HCH, p,p'-DDE, and o,p'-DDT were higher in the pre-diabetes and T2DM group than the NGT group. With an increase of OCPs level in groundwater, the blood OCPs level tends to increase T2DM risk. It depicts that the elevated OCPs level in consumed groundwater may contribute to increased risk for the development of T2DM after a certain period of exposure.

Toxicological profile of organochlorines aldrin and dieldrin: an Indian perspective

Several epidemiological studies have suggested various environmental factors as a possible cause for increased incidence of various abnormalities. Of the various environmental contaminants, the most prevalent and the most discussed are the endocrine disrupting chemicals. Contact of such disruptors with humans has become inevitable today. They are cosmopolitan and present from agriculture to industrial sectors, even in day-to-day consumer products. Aldrin and dieldrin belong to one such class of substances which are known to have a toxic effect on various physiological systems of the human body. Despite an imposed ban on their manufacture and commercial use, these pesticides could still be detected in probable areas of consumption like agriculture. The present review discusses the known possible toxic effects of aldrin and dieldrin and their current existence in the ecosystem across India.

Concentrations of organochlorine pesticides in umbilical cord blood and related lifestyle and dietary intake factors among pregnant women of the Huaihe River Basin in China

Organochlorine pesticides (OCPs), one of the persistent organic pollutants (POPs) with highly lipophilic properties, long half-lives, and persistence in the environment, are prevalent in the environment even though they have been banned for >30years. We aimed to investigate the current OCP exposure levels in cord blood from healthy pregnant women residing in the Huaihe River Basin, China, and examined the association between OCP levels and dietary habits and lifestyle factors. In this study, we measured the exposure levels of 17 OCPs in the umbilical cord blood from 999 healthy pregnant women; we also administered 1000 self-reported questionnaires regarding the general characteristics and dietary habits of those women. Our results showed that ρ,ρ'-DDE, ρ,ρ'-DDT, aldrin, dieldrin, and methoxychlor, which had higher measured concentrations (2.01±1.89, 4.31±5.68, 7.29±8.74, 5.27±7.65, and 0.98±1.42ng/mL, respectively) and detection frequencies (99.69%, 100.00%, 81.79%, 75.00%, and 74.49%, respectively), were the predominant OCPs in cord blood, and the higher levels of DDTs, aldrin, dieldrin, and methoxychlor were mainly due to recent use. In addition, most of the HCHs in cord blood were derived not only from historical use of technical HCH, but also from the additional use of lindane. In addition, we found that the education level of the pregnant women and monthly household income were positively correlated with OCP levels, particularly ρ,ρ'-DDE, aldrin, and dieldrin. Furthermore, the consumption of red meat (pork, beef, and lamb), fish, and bean products may be an important contributing factor to the increased concentrations of OCPs in cord blood, while the intake of poultry and pickles was negatively correlated with aldrin level. This study is the first to provide adequate data on current OCP exposure levels in cord blood from pregnant women in the Huaihe River Basin.

In vitro dopaminergic neurotoxicity of pesticides: a link with neurodegeneration?

Around the globe, chemical compounds are used to treat or repel pests and plagues that pose a threat to food and feed production. From epidemiological studies, it is known that there is a link between exposure to certain chemical classes of these so-called pesticides and the prevalence of neurodegenerative disorders such as Parkinson's disease in humans. However, which particular compound(s) account for this link or what underlying mechanisms are involved is still largely unresolved. The degenerative process in Parkinson's disease is largely limited to the dopaminergic neurons in the basal ganglia. Cellular mechanisms that are implicated in parkinsonian neurodegeneration include mitochondrial dysfunction, oxidative stress, disturbance of intracellular calcium homeostasis and endoplasmic reticulum (ER) stress. A major characteristic that distinguishes the dopaminergic neurons in the basal ganglia from other dopaminergic neurons is a particular reliance on intracellular calcium for spontaneous activity. Considering the energy consuming nature of maintenance of the intracellular calcium homeostasis and its involvement in life and death of a neuron, this may explain the specific vulnerability of this neuronal population. Despite a large variation in primary mechanism of action it has been demonstrated that pesticides from different classes disturb intracellular calcium homeostasis, thus interfering with intracellular calcium signalling. This relates to altered dopaminergic signalling, disturbed protein homeostasis and increased oxidative stress. Therefore, effects of (mixtures of) pesticides on the intracellular calcium homeostasis may play a role in the development of Parkinson's disease in humans. Although human exposure to pesticides via e.g. food often occurs in complex mixtures, (human) risk assessment is largely based on the assessment of single compounds. The discovery of common modes of action across different classes of pesticides therefore underpins the urgency of development of new models and approaches in risk assessment.

The adverse effects of aldrin and dieldrin on both myometrial contractions and the secretory functions of bovine ovaries and uterus in vitro

Aldrin and dieldrin are chloroorganic insecticides which are recognised as endocrine disruptors. The aim of the study was to investigate their effect on the secretory functions of the uterus and ovary and on myometrial contractions. Myometrial strips and uterine and ovarian cells from nonpregnant cows were incubated with the xenobiotics (0.1, 1 or 10 ng/ml) for 24 or 72 h. Next, their effect on viability of myometrial, endometrial, granulosa and luteal cells, myometrial strip contractions, the synthesis and secretion of prostaglandins (PGs: PGF2α and PGE2) from uterine cells, the secretion of oestradiol (E2), testosterone (T) and oxytocin (OT) from granulosa cells and the secretion of progesterone (P4) and OT from luteal cells were determined. Neither of the xenobiotics (10 ng/ml) affected (P>0.05) the viability of the ovarian and uterine cells, while both (0.1-10 ng/ml) decreased (P<0.05) the basal and OT-stimulated myometrial contractions. In spite of these effects, neither of the insecticides affected (P>0.05) the synthesis and the secretion of PGs from the myometrial cells. Although they also did not impair the secretion of the PGs from the endometrial cells, they abolished (P<0.05) the stimulatory effect of OT (P<0.05) on the secretion of the PGs and stimulated (P<0.05) the secretion of OT from the granulosa and luteal cells. Moreover, aldrin and dieldrin stimulated secretion of E2 and T from the granulosa cells, while only dieldrin increased (P<0.05) the secretion of P4 from luteal cells. The data show that aldrin and dieldrin stimulated the secretory function of the cultured granulosa and luteal cells and inhibited the myometrial contractions of cows in vitro, which may affect on natural parturition.

Occurrence of specific environmental risk factors in brain tissues of sudden infant death and sudden intrauterine unexpected death victims assessed with gas chromatography-tandem mass spectrometry

Sudden infant death syndrome (SIDS) and sudden intrauterine unexpected death syndrome (SIUDS) are an unresolved teaser in the social-medical and health setting of modern medicine and are the result of multifactorial interactions. Recently, prenatal exposure to environmental contaminants has been associated with negative pregnancy outcomes, and verification of their presence in fetal and newborn tissues is of crucial importance. A gas chromatography-tandem mass spectrometry (MS/MS) method, using a triple quadrupole analyzer, is proposed to assess the presence of 20 organochlorine pesticides, two organophosphate pesticides, one carbamate (boscalid), and a phenol (bisphenol A) in human brain tissues. Samples were collected during autopsies of infants and fetuses that died suddenly without any evident cause. The method involves a liquid-solid extraction using n-hexane as the extraction solvent. The extracts were purified with Florisil cartridges prior to the final determination. Recovery experiments using lamb brain spiked at three different concentrations in the range of 1-50 ng g(-1) were performed, with recoveries ranging from 79 to 106%. Intraday and interday repeatability were evaluated, and relative standard deviations lower than 10% and 18%, respectively, were obtained. The selectivity and sensitivity achieved in multiple reaction monitoring mode allowed us to achieve quantification and confirmation in a real matrix at levels as low as 0.2-0.6 ng g(-1). Two MS/MS transitions were acquired for each analyte, using the Q/q ratio as the confirmatory parameter. This method was applied to the analysis of 14 cerebral cortex samples (ten SIUDS and four SIDS cases), and confirmed the presence of several selected compounds.

Polymorphism in Cytochrome P450 2D6, Glutathione S-Transferases Pi 1 Genes, and Organochlorine Pesticides in Alzheimer Disease: A Case-Control Study in North Indian Population

OBJECTIVES

It has been assumed that the association between Alzheimer disease (AD) and pesticides may be stronger among genetically susceptible individuals. The aim of the study was to examine the genetic polymorphism in cytochrome P450 2D6 (CYP2D6) and glutathione S-transferases pi 1 (GSTP1) with respect to organochlorine pesticides (OCPs) and metals in AD.

METHODS

This study included 100 patients with AD and 100 age-matched controls. The genetic polymorphisms were analyzed by restriction fragment length polymorphism. The OCPs and serum metal levels were determined using gas chromatography and an autoanalyzer, respectively.

RESULTS

We found a statistically significant association between AD and high levels of β-hexachlorocyclohexane (β-HCH; odds ratio [OR] = 2.064, 95% confidence intervals [95% CIs] = 1.373-3.102, dieldrin [OR = 2.086, 95% CI = 1.224-3.555], and copper [OR = 1.038, 95% CI = 1.012-1.064). The significant low level of magnesium (OR = 0.151, 95% CI = 0.047-0.489) even appears to have a protective role against AD. The GSTP1*B (P = .009) and GSTP1*C (P = .011) allelic variants were associated with increase in AD risk.

CONCLUSION

This study demonstrates that the GSTP1*B and *C allelic variants may be considered a candidate gene for AD. It can be suggested that although CYP2D6*4 polymorphism is not a risk of AD, the CYP2D6*4 and GSTP1 polymorphism may interact with β-HCH, dieldrin, and copper to influence the risk of AD.

Increased level of organochlorine pesticides in chronic kidney disease patients of unknown etiology: role of GSTM1/GSTT1 polymorphism

Chronic kidney disease (CKD) of unknown etiology represents about 16% of CKD patients in Indian subcontinents and 10% worldwide. The aetiology of CKD of unknown etiology remains unclear though epidemiological studies indicate the involvement of the environmental toxins. Organochlorine pesticides (OCPs) have been detected in general population in India. It is possible that polymorphism of xenobiotic metabolizing enzymes (XMEs) may play an important role in this process. In this we intend to find out blood levels of OCPs in CKD patients of unknown etiology and to evaluate the consequence of glutathione S-transferase (GST) gene polymorphism on the same. We have assessed 270 CKD patients and 270 age-sex-matched healthy controls for this study. The blood OCP levels were analyzed by gas chromatograph. GSTM1, GSTT1 genotyping were carried out by multiplex PCR. Blood levels of HCH, endosulfan and total pesticides were significantly higher in CKD patients and negatively correlated with eGFR. The combined frequency of GSTM1(-)/GSTT1(-) genotype increased the risk of CKD by 1.8-fold as compared to healthy controls. To find out the dependence of blood OCPs level on genotype, we carried out logistic regression analysis and results revealed that GSTM1(-)/GSTT1(-) genotype associated significantly with a number of OCPs namely γ-HCH, p,p'-DDT and total pesticides. Polymorphism of XMEs not only increased accumulation of pesticides but also aggravates kidney dysfunction as evident from significant decrease in eGFR.

Relationships of chemical concentrations in maternal and cord blood: a review of available data

The developing fetus is likely to be exposed to the same environmental chemicals as the mother during critical periods of growth and development. The degree of maternal-fetal transfer of chemical compounds will be affected by chemical and physical properties such as lipophilicity, protein binding, and active transport mechanisms that influence absorption and distribution in maternal tissues. However, these transfer processes are not fully understood for most environmental chemicals. This review summarizes reported data from more than 100 studies on the ratios of cord:maternal blood concentrations for a range of chemicals including brominated flame-retardant compounds, polychlorinated biphenyls (PCB), polychlorinated dibenzodioxins and dibenzofurans, organochlorine pesticides, perfluorinated compounds, polyaromatic hydrocarbons, metals, and tobacco smoke components. The studies for the chemical classes represented suggest that chemicals frequently detected in maternal blood will also be detectable in cord blood. For most chemical classes, cord blood concentrations were found to be similar to or lower than those in maternal blood, with reported cord:maternal ratios generally between 0.1 and 1. Exceptions were observed for selected brominated flame-retardant compounds, polyaromatic hydrocarbons, and some metals, for which reported ratios were consistently greater than 1. Careful interpretation of the data in a risk assessment context is required because measured concentrations of environmental chemicals in cord blood (and thus the fetus) do not necessarily imply adverse effects or risk. Guidelines and recommendations for future cord:maternal blood biomonitoring studies are discussed.

Chlorobenzenes, lindane and dieldrin induce apoptotic alterations in human peripheral blood lymphocytes (in vitro study)

In this study, we have assessed apoptotic effect of 1,2,4-trichlorobenzene, hexachlorobenzene, lindane and dieldrin on human peripheral blood lymphocytes. We observed an increase in ROS formation and a decrease in mitochondrial transmembrane potential in the cells incubated with low concentrations of all compounds studied, in particular lindane and dieldrin. ROS formation and changes in mitochondrial transmembrane potential may have influenced caspase-3 activation, a crucial enzyme in the apoptotic process. Moreover, chlorobenzenes, and in particular lindane and dieldrin changed cells' membrane permeability and induced phosphatidylserine translocation, which confirmed that they are capable of inducing apoptosis in human lymphocytes. Apoptotic changes in human lymphocytes provoked by biologically relevant concentrations of these substances suggest that they may disturb function of immunological system especially among people occupationally exposed to their action.

Synergistic increase in cell lethality by dieldrin and H2O2 in rat thymocytes: effect of dieldrin on the cells exposed to oxidative stress

Dieldrin, one of persistent pesticides, is highly resistant to biotic and abiotic degradation. It is accumulated in organisms. Recent studies suggest that dieldrin exerts a potent cytotoxic action on cells exposed to oxidative stress. In this study, the effect of dieldrin on rat thymocytes exposed to hydrogen peroxide (H2O2)-induced oxidative stress was examined. Dieldrin at 5μM and H2O2 at 300μM slightly increased cell lethality from a control value of 5.4±0.5% (mean±standard deviation of four experiments) to 7.8±1.3% and 9.0±0.3%, respectively. Simultaneous application of dieldrin and H2O2 significantly increased cell lethality to 46.2±1.8%. The synergistic increase in cell lethality was dependent on dieldrin concentration (0.3-5μM) but not on H2O2 concentration (30-300μM). Dieldrin accelerated H2O2-induced cell death, which was estimated with the help of annexin V-FITC and propidium iodide. Presence of either dieldrin or H2O2 decreased the cellular content of nonprotein thiol and increased intracellular Zn(2+) concentration. The combination of dieldrin and H2O2 further pronounced these effects. TPEN, a chelator of intracellular Zn(2+), significantly attenuated the synergistic increase in cell lethality induced by dieldrin and H2O2. It is, therefore, suggested that dieldrin augments the cytotoxicity of H2O2 in a Zn(2+)-dependent manner.

Organochlorine insecticides lindane and dieldrin and their binary mixture disturb calcium homeostasis in dopaminergic PC12 cells

Current hypotheses link long-term environmental exposure of humans to persistent organochlorine (OC) insecticides lindane (HCH) and dieldrin (HEOD) to the development of neurodegenerative disorders, such as Parkinson's disease. Primary adverse neurological effects of these insecticides are directed at inhibition of GABA(A) and glycine receptors, although GABA-independent effects have also been reported. In this paper we describe the effect of dieldrin and a binary mixture of dieldrin and lindane on a critical parameter of neuronal function and survival, i.e., intracellular calcium homeostasis. The intracellular calcium concentration ([Ca(2+)](i)) has been monitored using real-time single-cell fluorescence microscopy in dopaminergic PC12 cells loaded with the calcium-sensitive dye Fura-2. The results demonstrate that nanomolar concentrations of dieldrin time- and concentration-dependently inhibit depolarization-evoked influx of Ca(2+). Co-exposure of PC12 cells to a mixture of dieldrin and lindane revealed an additive inhibition of the depolarization-evoked increase in [Ca(2+)](i), whereas the lindane-induced increase in basal [Ca(2+)](i) is inhibited by dieldrin. The combined findings indicate that dieldrin and binary mixtures of organochlorines affect [Ca(2+)](i) already at concentrations below commonly accepted effect concentrations and close to human internal dose levels. Consequently, current findings illustrate the need to take mixtures of OC insecticides into account in human risk assessment.

Environmental neurotoxic pesticide dieldrin activates a non receptor tyrosine kinase to promote PKCδ-mediated dopaminergic apoptosis in a dopaminergic neuronal cell model

Oxidative stress and apoptosis are two key pathophysiological mechanisms underlying dopaminergic degeneration in Parkinson's disease (PD). Recently, we identified that proteolytic activation of protein kinase C-delta (PKCδ), a member of the novel PKC family, contributes to oxidative stress-induced dopaminergic degeneration and that phosphorylation of tyrosine residue 311 (tyr311) on PKCδ is a key event preceding the PKCδ proteolytic activation during oxidative damage. Herein, we report that a non-receptor tyrosine kinase Fyn is significantly expressed in a dopaminergic neuronal N27 cell model. Exposure of N27 cells to the dopaminergic toxicant dieldrin (60 μM) rapidly activated Fyn kinase, PKCδ-tyr311 phosphorylation and proteolytic cleavage. Fyn kinase activation precedes the caspase-3-mediated proteolytic activation of PKCδ. Pre-treatment with p60-tyrosine-specific kinase inhibitor (TSKI) almost completely attenuated dieldrin-induced phosphorylation of PKCδ-tyr311 and its proteolytic activation. Additionally, TSKI almost completely blocked dieldrin-induced apoptotic cell death. To further confirm Fyn's role in the pro-apoptotic function of PKCδ, we adopted the RNAi approach. siRNA-mediated knockdown of Fyn kinase also effectively attenuated dieldrin-induced phosphorylation of PKCδ-tyr311, caspase-3-mediated PKCδ proteolytic cleavage, and DNA fragmentation, suggesting that Fyn kinase regulates the pro-apoptotic function of PKCδ. Collectively, these results demonstrate for the first time that Fyn kinase is a pro-apoptotic kinase that regulates upstream signaling of the PKCδ-mediated apoptotic cell death pathway in neurotoxicity models of pesticide exposure.

Organochlorine pesticide gradient levels among maternal adipose tissue, maternal blood serum and umbilical blood serum

The objective of the present study was to determine levels and calculate ratios of copartition coefficients among organochlorine pesticides β-HCH, pp'DDE, op'DDT and pp'DDT in maternal adipose tissue, maternal blood serum and umbilical blood serum of mother-infant pairs from Veracruz, Mexico. Organochlorine pesticides were analyzed in 70 binomials: maternal adipose tissue, maternal serum and umbilical cord serum samples, using gas chromatography with electron capture detection (GC-ECD). The results were expressed as mg/kg on fat basis. p,p'-DDE was the major organochlorine component, detected in every maternal adipose tissue (0.770 mg/kg), maternal serum sample (5.8 mg/kg on fat basis) and umbilical cord blood sample (6.9 mg/kg on fat basis). p,p'-DDT was detected at 0.101 mg/kg, 2.2 mg/kg and 5.9 mg/kg respectively, according to the order given above. β-HCH was detected at 0.027 mg/kg, 4.2 mg/kg and 28.0 mg/kg respectively. op'DDT was detected only in maternal adipose tissue at 0.011 mg/kg. The copartition coefficients among samples identify significant increases in concentrations from adipose tissue to maternal blood serum and to umbilical blood serum. The increase indicated that maternal adipose tissue released organochlorine pesticides to blood serum and that they are carried over to umbilical cord blood.