Assessing diet as a modifiable risk factor for pesticide exposure

Biomonitoring urinary pesticide metabolites in preschool children by supported liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry and their association with oxidative stress

Investigating pesticide exposure and oxidative stress in preschool children is essential for elucidating the determinants of environmental health in early life, with human biomonitoring of urinary pesticide metabolites serving as a critical strategy for achieving this objective. This study demonstrated biomonitoring of 2 phenoxyacetic acid herbicides, 2 organophosphorus pesticide metabolites, and 4 pyrethroid pesticide metabolites in 159 preschool children and evaluated their association with oxidative stress biomarker 8-hydroxydeoxyguanosine. An enzymatic deconjugation process was used to release urinary pesticide metabolites, which were then extracted and enriched by supported liquid extraction, and quantified by ultra-high performance liquid chromatography-tandem mass spectrometry with internal standard calibration. Dichloromethane: methyl tert‑butyl ether (1:1, v/v) was optimized as the solvent for supported liquid extraction, and we validated the method for linear range, recovery, matrix effect and method detection limit. Method detection limit of the pesticide metabolites ranged from 0.01 μg/L to 0.04 μg/L, with satisfactory recoveries ranging from 70.5 % to 95.5 %. 2,4,5-Trichlorophenoxyacetic acid was not detected, whereas the other seven pesticide metabolites were detected with frequencies ranging from 10.1 % to 100 %. The concentration of urinary pesticide metabolites did not significantly differ between boys and girls, with the median concentrations being 9.39 μg/L for boys and 4.90 μg/L for girls, respectively. Spearman correlation analysis indicated that significant positive correlations among urinary metabolites. Bayesian kernel machine regression revealed a significant positive association between urinary pesticide metabolites and 8-hydroxydeoxyguanosine. Para-nitrophenol was the pesticide metabolite that contributed significantly to the elevated level of oxidative stress.

Dietary Predictors of Urinary Biomarkers of Pyrethroids in the General Population - A Scoping Review

BACKGROUND

Pyrethroid pesticides are ubiquitous environmental contaminants, contributing to chronic and potentially harmful exposure among the general population. Although studies have measured pesticide residues on agricultural products, the link between food intake and concentrations of pyrethroid biomarkers in urine remains unclear.

OBJECTIVE

This scoping review aims to analyze peer-reviewed publications investigating dietary predictors of pyrethroid exposure through urinary biomarkers. We assess existing evidence, identify research gaps, and highlight current limitations.

METHODS

We conducted a comprehensive search using PubMed and Google Scholar. Eligible studies examined associations between diets, food items or dietary components, and measured urinary pyrethroid biomarkers. No geographical restriction was applied to our search. Results were summarized in themes referring to study characteristics, relevant outcomes, biomarker measurement, dietary assessment and statistical analyses.

RESULTS

We identified 20 relevant articles. Most studies presented evidence on associations between the consumption of organic diets or food items and reduced concentrations of 3-phenobenzoic acid metabolites in urine. There was less evidence for diet affecting other pyrethroid-specific biomarkers. Dietary assessment methodologies and recall periods varied, as did the number and timing of urine collections. Many studies did not control for potential alternative pyrethroid sources, exposure to other pesticides, or demographic and socioeconomic characteristics.

CONCLUSION

Researchers should consider standardized dietary assessment, chemical analyses of foods consumed, adequate recall time, and food preparation methods. Consistency in biomarker measurement, including urine collection time and corrections for specific gravity or creatinine, is needed. Ensuring the validity of such studies also requires larger samples and appropriate control for confounders.

Neurotoxicity induced by the pyrethroid lambda-cyhalothrin: Alterations in monoaminergic systems and dopaminergic and serotoninergic pathways in the rat brain

The effects of Type II pyrethroid lambda-cyhalothrin on dopamine (DA) and serotonin (5-HT) synthesis in rat brain regions (striatum, hippocampus, prefrontal cortex, hypothalamus and midbrain) were studied. Lambda-cyhalothrin (1, 4 and 8 mg/kg bw, oral gavage, 6 days) induced a decrease of DA, 5-HT and metabolites contents, in a brain regional- and dose-related manner. The major decreases in DA and 5-HT contents were observed in hippocampus and prefrontal cortex tissues. This research study also showed in hippocampus and prefrontal cortex, that lambda-cyhalothrin modified the mRNA levels of DA transporter gene (Dat1 up-regulation), 5-HT transporter gene (SERT down-regulation), DA receptor genes (Drd1and Drd2 down-regulation), 5-HT receptor genes (5-HT1A and 5-HT2A down-regulation/up-regulation), DA synthesis gene (TH down-regulation), 5-HT synthesis gene (TPH2 down-regulation), DA and 5-HT degradation genes (MAOA and MAOB up-regulation). These results reveal that lambda-cyhalothrin altered central nervous system (CNS) monoaminergic neurotransmitters. Lambda-cyhalothrin evoked a selective neurotoxic injury to dopaminergic and serotoninergic pathways. These findings may clarify on the pyrethroids-induced neurotoxicity mechanisms and could involve pyrethroids as environmental risk factors leading to the development of neurodegenerative diseases.

In vitro investigation of endocrine disrupting effects of pesticides on Ca2+-signaling in human sperm cells through actions on the sperm-specific and steroid-activated CatSper Ca2+-channel

BACKGROUND

Ca²⁺-signaling controls sperm cell functions necessary for successful fertilization. Multiple endocrine disrupting chemicals have been found to interfere with normal Ca²⁺-signaling in human sperm cells through an activation of the sperm-specific CatSper Ca²⁺-channel, which is vital for normal male fertility.

OBJECTIVES

We investigated 53 pesticides for their ability to interfere with CatSper mediated Ca²⁺-signaling and function in human sperm cells.

METHODS

Effects of the pesticides on Ca²⁺-signaling in human sperm cells were evaluated using a Ca²⁺-fluorometric assay. Effects via CatSper were assessed using the specific CatSper inhibitor RU1968. Effects on human sperm function and viability were assessed using an image cytometry-based acrosome reaction assay and the modified Kremer's sperm-mucus penetration assay.

RESULTS

28 of 53 pesticides were found to induce Ca²⁺-signals in human sperm cells at 10 µM. The majority of these 28 active pesticides induced Ca²⁺-signals through CatSper and interfered with subsequent Ca²⁺-signals induced by the two endogenous CatSper ligands progesterone and prostaglandin E₁. Multiple active pesticides were found to affect Ca²⁺-mediated sperm functions and viability at 10 µM. Low nM dose mixtures of the active pesticides alone or in combination with other environmental chemicals were found to significantly induce Ca²⁺-signals and inhibit Ca²⁺-signals induced subsequently by progesterone and prostaglandin E₁.

CONCLUSIONS

Our results show that pesticides, both alone and in low nM dose mixtures, interfere with normal Ca²⁺-signaling in human sperm cells in vitro in low nM concentrations. Biomonitoring of the active pesticides in relevant matrices such as blood and reproductive fluids is very limited and the effects of real time human pesticide exposure on human sperm cells and fertility thus remains largely unknown. To which extent human pesticide exposure affects the chances of a successful fertilization in humans in vivo needs further research.

OBOMod - Integrated modelling framework for residents' exposure to pesticides

BACKGROUND

Pesticides can be transported from the site of application to homes via different routes and lead to exposure of residents, raising concerns regarding health effects. We built a deterministic model framework (OBOmod) to assess exposure of residents living near fields where pesticides are applied.

METHODS

OBOmod connects five independent models operating on an hourly timescale and high spatial resolution (meters). Models include descriptions of spray drift, volatilization, atmospheric transport and dispersion, exchange between outdoor and indoor air and exchange between indoor air and dust. Fourteen bulb field applications under different weather conditions and comprising 12 pesticides were simulated. Each simulation included the first seven days after the application. The concentrations computed with OBOmod were compared with those measured in outdoor and indoor air and the amounts measured in indoor dust samples.

RESULTS

Model evaluation indicated suitability of the developed framework to estimate outdoor and indoor air concentrations. For most pesticides, model accuracy was good. The framework explained about 30% to 95% of the temporal and spatial variability of air concentrations. For 20% of the simulations, the framework explained more than 35% of spatial variability of concentrations in dust. In general, OBOmod estimates remained within one order of magnitude from measured levels. Calculations showed that in addition to spray drift during application, volatilization from the field after spraying and pesticides in house dust are important routes for residents' exposure to pesticides.

CONCLUSIONS

Our framework covers many processes needed to calculate exposure of residents to pesticides. The evaluation phase shows that, with the exception of the dust model, the framework can be used in support of health and epidemiological studies, and can serve as a tool to support development of regulations and policy making regarding pesticide use.

Phosphate-triggered ratiometric fluoroimmunoassay based on nanobody-alkaline phosphatase fusion for sensitive detection of 1-naphthol for the exposure assessment of pesticide carbaryl

The excessive use of carbaryl has resulted in the risk of its exposure. In this study, we isolated six nanobodies (Nbs) from a camelid phage display library against the biomarker of carbaryl, 1-naphthol (1-NAP). Owing to its characteristics of easy genetic modifications, we produced a nanobody-alkaline phosphatase (Nb-CC4-ALP) fusion protein with good stability. A dual-emission system based ratiometric fluoroimmunoassay (RFIA) for quick and highly sensitive determination of 1-NAP was developed. Silicon nanoparticles (SiNPs) was used as an internal reference and for aggregation-induced emission enhancement (AIEE) of gold nanoclusters (AuNCs), while AuNCs could be quenched by MnO2 via oxidation. In the presence of ALP, ascorbic acid phosphate (AAP) can be transformed into ascorbic acid (AA), the later can etch MnO2 to recover the fluorescence of the AuNCs. Based on optimal conditions, the proposed assay showed 220-fold sensitivity improvement in comparison with conventional monoclonal antibody-based ELISA. The recovery test of urine samples and the validation by standard HPLC-FLD demonstrated the proposed assay was an ideal tool for screening 1-NAP and provided technical support for the monitoring of carbaryl exposure.

Following the community development of SIHUMIx - a new intestinal in vitro model for bioreactor use

Diverse intestinal microbiota is frequently used in in vitro bioreactor models to study the effects of diet, chemical contaminations, or medication. However, the reproducible cultivation of fecal microbiota is challenging and the resultant communities behave highly dynamic. To approach the issue of reproducibility in in vitro models, we established an intestinal microbiota model community of reduced complexity, SIHUMIx, as a valuable model for in vitro use. The development of the SIHUMIx community was monitored over time with methods covering the cellular and the molecular level. We used microbial flow cytometry, intact protein profiling and terminal restriction fragment length polymorphism analysis to assess community structure. In parallel, we analyzed the functional level by targeted analysis of short-chain fatty acids and untargeted metabolomics. The stability properties constancy, resistance, and resilience were approached both on the structural and functional level of the community. We show that the SIHUMIx community is highly reproducible and constant since day 5 of cultivation. Furthermore, SIHUMIx has the ability to resist and recover from a pulsed perturbation, with changes in community structure recovered earlier than functional changes. Since community structure and function changed divergently, both levels need to be monitored at the same time to gain a full overview of the community development. All five methods are highly suitable to follow the community dynamics of SIHUMIx and indicated stability on day five. This makes SIHUMIx a suitable in vitro model to investigate the effects of e.g. medical, chemical, or dietary interventions.

Concentrations and temporal trends in pesticide biomarkers in urine of Swedish adolescents, 2000-2017

Agricultural pesticides are extensively used for weed- and pest control, resulting in residues of these compounds in food. The general population is mainly exposed through dietary intake. Exposure to certain pesticides has been associated with adverse human health outcomes. Our aim was to assess urinary concentrations and temporal trends in the biomarkers of commonly used pesticides. Samples were collected from adolescents (n = 1060) in Scania, Sweden, from 2000 to 2017. Concentrations of 14 pesticide biomarkers were analyzed in urine using LC-MS/MS. Temporal trends in biomarker concentrations (ln-transformed) were evaluated using linear regression. Biomarkers of pyrethroids (3-PBA and DCCA), chlorpyrifos (TCPy), chlormequat (CCC), thiabendazole (OH-TBZ), and mancozeb (ETU) were detected in >90% of the population all sampling years. The biomarkers CCC and TCPy had the highest median concentrations (>0.8 µg/L), whereas the biomarkers of cyfluthrin (4F-3-PBA) and two pyrethroids (CFCA) had the lowest median concentrations (<0.02 µg/L). Increasing temporal trends were found for the biomarkers 3-PBA (3.7%/year), TCPy (1.7%/year) and biomarkers of pyrimethanil (11.9%/year) and tebuconazole (12.2%/year). Decreasing trends were found for CCC (-5.5%/year), OH-TBZ (-5.5%/year), and ETU (-3.9%/year). Our results suggest that Swedish adolescents are commonly exposed to pesticides in low concentrations (median concentrations <3.88 µg/L).

Effect of a 24-week randomized trial of an organic produce intervention on pyrethroid and organophosphate pesticide exposure among pregnant women

BACKGROUND

Introduction of an organic diet can significantly reduce exposure to some classes of pesticides in children and adults, but no long-term trials have been conducted.

OBJECTIVES

To assess the effect of a long-term (24-week) organic produce intervention on pesticide exposure among pregnant women.

METHODS

We recruited 20 women from the Idaho Women, Infants, and Children (WIC) program during their first trimester of pregnancy. Eligible women were nonsmokers aged 18-35 years who reported eating exclusively conventionally grown food. We randomly assigned participants to receive weekly deliveries of either organic or conventional fruits and vegetables throughout their second or third trimesters and collected weekly spot urine samples. Urine samples, which were pooled to represent monthly exposures, were analyzed for biomarkers of organophosphate (OP) and pyrethroid insecticides.

RESULTS

Food diary data demonstrated that 66% of all servings of fruits and vegetables consumed by participants in the "organic produce" group were organic, compared to <3% in the "conventional produce" group. We collected an average of 23 spot samples per participant (461 samples total), which were combined to yield 116 monthly composites. 3-Phenoxybenzoic acid (3-PBA, a non-specific biomarker of several pyrethroids) was detected in 75% of the composite samples, and 3-PBA concentrations were significantly higher in samples collected from women in the conventional produce group compared to the organic produce group (0.95 vs 0.27 μg/L, p = 0.03). Another pyrethroid biomarker, trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid, was detected more frequently in women in the conventional compared to the organic produce groups (16% vs 4%, p = 0.05). In contrast, we observed no statistically significant differences in detection frequency or concentrations for any of the four biomarkers of OP exposure quantified in this trial.

DISCUSSION

To our knowledge, this is the first long-term organic diet intervention study, and the first to include pregnant women. These results suggest that addition of organic produce to an individual's diet, as compared to conventional produce, significantly reduces exposure to pyrethroid insecticides.

Organic diet intervention significantly reduces urinary pesticide levels in U.S. children and adults

BACKGROUND

Previous diet intervention studies indicate that an organic diet can reduce urinary pesticide metabolite excretion; however, they have largely focused on organophosphate (OP) pesticides. Knowledge gaps exist regarding the impact of an organic diet on exposure to other pesticides, including pyrethroids and neonicotinoids, which are increasing in use in the United States and globally.

OBJECTIVE

To investigate the impact of an organic diet intervention on levels of insecticides, herbicides, and fungicides or their metabolites in urine collected from adults and children.

METHODS

We collected urine samples from four racially and geographically diverse families in the United States before and after an organic diet intervention (n = 16 participants and a total of 158 urine samples).

RESULTS

We observed significant reductions in urinary levels of thirteen pesticide metabolites and parent compounds representing OP, neonicotinoid, and pyrethroid insecticides and the herbicide 2,4-D following the introduction of an organic diet. The greatest reductions were observed for clothianidin (- 82.7%; 95% confidence interval [95% CI]: - 86.6%, - 77.6%; p < 0.01), malathion dicarboxylic acid (MDA), a metabolite of malathion (- 95.0%; 95% CI: - 97.0%, - 91.8%; p < 0.01), and 3,5,6-trichlor-2-pyridinol (TCPy), a metabolite of chlorpyrifos (- 60.7%; 95% CI: - 69.6%, - 49.2%; p < 0.01). Metabolites or parent compounds of the fungicides boscalid, iprodione, and thiabendazole and the neonicotinoid insecticide imidacloprid were not detected among participants in our study.

CONCLUSION

An organic diet was associated with significant reductions in urinary excretion of several pesticide metabolites and parent compounds. This study adds to a growing body of literature indicating that an organic diet may reduce exposure to a range of pesticides in children and adults. Additional research is needed to evaluate dietary exposure to neonicotinoids, which are now the most widely used class of insecticides in the world.

Review of take-home pesticide exposure pathway in children living in agricultural areas

BACKGROUND

Children of farmworkers may be chronically exposed to pesticides via the take-home exposure pathway.

OBJECTIVE

The goal of this review was to analyze scientific literature evaluating the role of the take-home pesticide exposure pathway in children of agricultural workers.

METHODS

A systematic review was undertaken and inclusion criteria were applied to identify original articles of interest. Of the 30 articles included in this review, some belonged to the same studies, resulting in a total of 23 studies. Eight studies assessed environmental samples, nine collected biological samples, and the remaining six analyzed both. Eleven studies compared pesticide levels between farm and non-farm families.

RESULTS

There is convincing evidence that children of farmworkers are exposed to pesticides at higher levels than "non-agricultural" children, even when residing in the same agricultural communities. These levels were shown to depend on the season, occupation, number of farmworkers per home, and type of crops. Other factors such as age, gender and, sex seem to also influence this pathway. Some studies have shown that pesticides used solely in agriculture are found only in households of farmworkers spraying these pesticides. Moreover, intervention studies have shown that behaviors among farmworkers can significantly lower exposure of people living in the same households as farmworkers.

DISCUSSION AND CONCLUSION

The evidence presented here raises concerns regarding health effects associated with exposure to pesticides in children living in agricultural communities, and indicates that strategies should be developed to reduce exposures in these populations.

Organic Food in the Diet: Exposure and Health Implications

The market for organic food products is growing rapidly worldwide. Such foods meet certified organic standards for production, handling, processing, and marketing. Most notably, the use of synthetic fertilizers, pesticides, and genetic modification is not allowed. One major reason for the increased demand is the perception that organic food is more environmentally friendly and healthier than conventionally produced food. This review provides an update on market data and consumer preferences for organic food and summarizes the scientific evidence for compositional differences and health benefits of organic compared with conventionally produced food. Studies indicate some differences in favor of organic food, including indications of beneficial health effects. Organic foods convey lower pesticide residue exposure than do conventionally produced foods, but the impact of this on human health is not clear. Comparisons are complicated by organic food consumption being strongly correlated with several indicators of a healthy lifestyle and by conventional agriculture “best practices” often being quite close to those of organic.

Consumption of organic meat does not diminish the carcinogenic potential associated with the intake of persistent organic pollutants (POPs)

Numerous studies have shown an epidemiological link between meat consumption and the incidence of cancer, and it has been suggested that this relationship may be motivated by the presence of carcinogenic contaminants on it. Among the most frequently detected contaminants in meat are several types of persistent organic pollutants (POPs), and it is well known that many of them are carcinogenic. On the other hand, an increasing number of consumers choose to feed on what are perceived as healthier foods. Thus, the number of consumers of organic food is growing. However, environmental contamination by POPs is ubiquitous, and it is therefore unlikely that the practices of organic food production are able to prevent this contamination. To test this hypothesis, we acquired 76 samples of meat (beef, chicken, and lamb) of two modes of production (organic and conventional) and quantified their levels of 33 carcinogenic POPs. On this basis, we determined the human meat-related daily dietary exposure to these carcinogens using as a model a population with a high consumption of meat, such as the Spanish population. The maximum allowable meat consumption for this population and the carcinogenic risk quotients associated with the current pattern of consumption were calculated. As expected, no sample was completely free of carcinogenic contaminants, and the differences between organically and conventionally produced meats were minimal. According to these results, the current pattern of meat consumption exceeded the maximum limits, which are set according to the levels of contaminations, and this is associated with a relevant carcinogenic risk. Strikingly, the consumption of organically produced meat does not diminish this carcinogenic risk, but on the contrary, it seems to be even higher, especially that associated with lamb consumption.

Pyrethroid Pesticide Metabolite in Urine and Microelements in Hair of Children Affected by Autism Spectrum Disorders: A Preliminary Investigation

The number of children affected by Autism Spectrum Disorders (ASD) is dramatically increasing as well as the studies aimed at understanding the risk factors associated with the development of ASD. Since the etiology of ASD is partly genetic and partly environmental, factors (i.e., heavy metals, pesticides) as well as lifestyle seem to have a key role in the development of the disease. ASD and Control (CTR) children, aged 5–12 years, were compared. Gas chromatography coupled with trap mass detector was used to measure the level of 3-PBA, the main pyrethroid metabolite in urine in a group of ASD patients, while optical emission spectrometry analysis was employed to estimate the level of metals and microelements in hair in a different group of ASD children. The presence of 3-PBA in urine seems to be independent of age in ASD children, while a positive correlation between 3-PBA and age was observed in the control group of the same age range. Urine concentration of 3-BPA in ASD children had higher values than in the control group, which were marginally significant (p = 0.054). Mg results were significantly decreased in ASD with respect to controls, while V, S, Zn, and Ca/Mg were marginally increased, without reaching statistical significance. Results of Principal Component (PC) analysis of metals and microelements in hair were not associated with either age or health status. In conclusion, 3-PBA in urine and Mg in hair were changed in ASD children relative to control ones.

Behaviour of mesotrione in maize and soil system and its influence on soil dehydrogenase activity

The aim of this study was to investigate the dissipation of mesotrione and effect on dehydrogenase activity (DHA) in maize and soil system. The paper for the first time describes behaviour of this herbicide applied at various doses (separately or in mixture with other herbicide) in acidic and alkaline environment. The experiments were conducted using the method randomized blocks in four repetition cycles. Chemical application in seven variants at recommended doses of herbicide were performed. The sample preparation was performed by a modified QuEChERS method and the concentrations of mesotrione in maize and soil were determined by the liquid chromatography with tandem mass spectrometry (LC-MS/MS). The limit of detection was 0.0005mgkg(-1) and quantification 0.001mgkg(-1). The dissipation of mesotrione were described according to first-order (FO) kinetics equation with R(2) were between 0.8794 and 0.9934. The initial deposit of herbicide in soil and maize was higher in an acidic environment (0.06-0.18mgkg(-1)). A positive correlation between an alkaline pH and the rate of dissipation in soil was observed. The results showed that the time after which 50% (DT50) of substance has been degraded was different for both plant and soil. DT50 for soil was within the range 3.2-6.0days and 2.9-4.4days, for the maize 3.9-4.8days and 3.4-4.5days in an alkaline and an acidic environment, respectively. Concentration of mesotrione at applicable MRL level of 0.05mgkg(-1) in maize was achieved at 0.5-5.9days and at proposed MRL of 0.01mgkg(-1) at 8.8-15.8days. The results indicate that the application of mesotrione affected on DHA in the soil. One day after application this herbicide, concentration of DHA in soil was lower than in control plots, but after 21days was observed trend of increasing DHA.

Reaching Nutritional Adequacy Does Not Necessarily Increase Exposure to Food Contaminants: Evidence from a Whole-Diet Modeling Approach

BACKGROUND

Dietary guidelines are designed to help meet nutritional requirements, but they do not explicitly or quantitatively account for food contaminant exposures.

OBJECTIVE

In this study, we aimed to test whether dietary changes needed to achieve nutritional adequacy were compatible with acceptable exposure to food contaminants.

METHODS

Data from the French national dietary survey were linked with food contaminant data from the French Total Diet Study to estimate the mean intake of 204 representative food items and mean exposure to 27 contaminants, including pesticides, heavy metals, mycotoxins, nondioxin-like polychlorinated biphenyls (NDL-PCBs) and dioxin-like compounds. For each sex, 2 modeled diets that departed the least from the observed diet were designed: 1) a diet respecting only nutritional recommendations (NUT model), and 2) a diet that met nutritional recommendations without exceeding Toxicological Reference Values (TRVs) and observed contaminant exposures (NUTOX model). Food, nutrient, and contaminant contents in observed diets and NUT and NUTOX diets were compared with the use of paired t tests.

RESULTS

Mean observed diets did not meet all nutritional recommendations, but no contaminant was over 48% of its TRV. Achieving all the nutrient recommendations through the NUT model mainly required increases in fruit, vegetable, and fish intake and decreases in meat, cheese, and animal fat intake. These changes were associated with significantly increased dietary exposure to some contaminants, but without exceeding 57% of TRVs. The highest increases were found for NDL-PCBs (from 26% to 57% of TRV for women). Reaching nutritional adequacy without exceeding observed contaminant exposure (NUTOX model) was possible but required further departure from observed food quantities.

CONCLUSIONS

Based on a broad range of nutrients and contaminants, this first assessment of compatibility between nutritional adequacy and toxicological exposure showed that reaching nutritional adequacy might increase exposure to food contaminants, but within tolerable levels. However, there are some food combinations that can meet nutritional recommendations without exceeding observed exposures.

Gamma Radiation Reduced Toxicity of Azoxystrobin Tested on Artemia franciscana

Fungicide azoxystrobin toxicity was monitored by means of a 96-h biotest with Artemia franciscana nauplius stages after exposure to solutions with concentrations of 0.2, 0.4, 0.6 and 0.8 mg L(-1) irradiated with (60)Co gamma radiation with doses of 1, 2.5, 5 and 10 kGy. The effects of ionization radiation on azoxystrobin toxicity were mainly manifested by a statistically significant reduction of lethality after 72- and 96-h exposure. A maximum reduction of lethality of 72 % was achieved using doses of 1-5 kGy for an azoxystrobin initial concentration of 0.4 mg L(-1) and after 72 h of exposure. At a 96-h exposure, a difference of lethal effects reached up to 70 % for a dose of 10 kGy. The observed effect of gamma ionizing radiation on azoxystrobin toxicity suggest that this approach can be applied as an alternative for a reduction of azoxystrobin residua in food.

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.

Azole fungicides disturb intracellular Ca2+ in an additive manner in dopaminergic PC12 cells

Humans are exposed to complex mixtures of pesticides and other compounds, mainly via food. Azole fungicides are broad spectrum antifungal compounds used in agriculture and in human and veterinary medicine. The mechanism of antifungal action relies on inhibition of CYP51, resulting in inhibition of fungal cell growth. Known adverse health effects of azole fungicides are mainly linked to CYP inhibition. Additionally, azole fungicide-induced neurotoxicity has been reported, though the underlying mechanism(s) are largely unknown. We therefore investigated the effects of a group of six azole fungicides (imazalil, flusilazole, fluconazole, tebuconazole, triadimefon, and cyproconazole) on cell viability using a combined alamar Blue/CFDA-AM assay and on oxidative stress using a H2-DCFDA fluorescent assay. As calcium plays a pivotal role in neuronal survival and functioning, effects of these six azole fungicides and binary and quaternary mixtures of azole fungicides on the intracellular calcium concentration ([Ca(2+)]i) were investigated using single-cell fluorescence microscopy in dopaminergic PC12 cells loaded with the calcium-sensitive fluorescent dye Fura-2. Only modest changes in cell viability and ROS production were observed. However, five out of six azole fungicides induced a nonspecific inhibition of voltage-gated calcium channels (VGCCs), though with varying potency. Experiments using binary IC20 and quaternary IC10 mixtures indicated that the inhibitory effects on VGCCs are additive. The combined findings demonstrate modulation of intracellular Ca(2+) via inhibition of VGCCs as a novel mode of action of azole fungicides. Furthermore, mixtures of azole fungicides display additivity, illustrating the need to take mixture effects into account in human risk assessment.