Chlorate and perchlorate in tea leaves from major producing regions in China and related human exposure risk.

Chlorate and perchlorate are emerging pollutants that may interfere with thyroid function. Since they are highly water soluble, chlorate and perchlorate in tea leaves cause health concerns but have scarcely been studied. In this study, chlorate and perchlorate concentrations in 216 tea samples from different regions of China were determined. Perchlorate was detected in all the samples with a median concentration of 44.1 µg kg-1, while the chlorate detection frequency was 15.7%. We observed regional differences in perchlorate contents in tea leaves, with the highest quantity found in the central region of China. Except for dark tea, the concentration of perchlorate in tea infusions decreased with the increased number of times the tea leaves were brewed. The hazard quotients (HQs) of chlorate and perchlorate in all the samples were less than 1, suggesting negligible health risks caused by these pollutants from tea consumption. To the best of our knowledge, this is the first study to investigate chlorate and perchlorate contamination in tea infusions by simulating brewing behavior.

Quantification of Chlorate and Perchlorate in a Broad Range of Food Commodities, Including Baby Food, Nutritional Formulas, and Ingredients by LC-MS/MS: First Action AOAC 2022.06.

BACKGROUND: Chlorate is an effective herbicide, but also a byproduct of chlorinating agents used to disinfect water, which is one of the reasons why it is regularly found in food. Perchlorate is a ubiquitous contaminant, which is naturally occurring in the environment but also released from anthropogenic sources such as the industrial use of certain natural fertilizers. Chlorate affects the hematological system, and perchlorate the thyroid. OBJECTIVE: Implement and validate a simple and robust analytical method for the accurate determination of chlorate and perchlorate in baby food, infant and adult formulas, and ingredients thereof, which is suited for its application in routine environments where a broad variety of food commodities must be analyzed simultaneously. METHOD: Typically, analytes are extracted with a mixture of water, acidified methanol, and dichloromethane. Optionally, for dairy products and byproducts, extraction can be performed with water, acidified methanol, and EDTA, followed by two steps of cleanup (freezing out and dispersive solid-phase extraction with C18 in acetonitrile). Quantitative determination is carried out by isotopic dilution liquid chromatography tandem mass spectrometry (LC-MS/MS). RESULTS: The method was single-laboratory validated in five Nestlé Quality Assurance Centers (NQACs) in a comprehensive range of representative matrixes of different categories such as baby foods, infant/adult formulas, and ingredients, with results generally in agreement with the acceptance criteria of the Standard Method Performance Requirement (SMPR®) 2021.001 defined by AOAC INTERNATIONAL, in terms of representative matrixes validated, LOQs, trueness, and precision.The data generated during validation show that the method proposed is simple, accurate and robust enough to be implemented and applied in routine environments. CONCLUSION: The data generated during validation show that the method proposed is simple, accurate and robust enough to be implemented and applied in routine environments. HIGHLIGHTS: The AOAC Expert Review Panel approved the present method as AOAC Official First Action 2022.06.

Perchlorate and chlorate assessment in drinking water in northern Chilean cities.

Perchlorate and chlorate are endocrine disruptors considered emerging contaminants (ECs). Both oxyanions are commonly associated with anthropogenic contamination from fertilizers, pesticides, explosives, and disinfection byproducts. However, the soils of the Atacama Desert are the most extensive natural reservoirs of perchlorate in the world, compromising drinking water sources in northern Chile. Field campaigns were carried (2014-2018) to assess the presence of these ECs in the water supply networks of twelve Chilean cities. Additionally, the occurrence of perchlorate, chlorate and other anions typically observed in drinking water matrices of the Atacama Desert (i.e., nitrate, chloride, sulfate) was evaluated using a Spearman correlation analysis to determine predictors for perchlorate and chlorate. High concentrations of perchlorate (up to 114.48 µg L-1) and chlorate (up to 9650 µg L-1) were found in three northern cities. Spatial heterogeneities were observed in the physicochemical properties and anion concentrations of the water supply network. Spearman correlation analysis indicated that nitrate, chloride, and sulfate were not useful predictors for the presence of perchlorate and chlorate in drinking water in Chile. Hence, this study highlights the need to establish systematic monitoring, regulation, and treatment for these EC of drinking water sources in northern Chilean cities for public health protection.

Analysis of Chlorate in Chemical Leavening Agents Used for Bakery Products by Liquid Chromatography-Mass Spectrometry.

Chlorate is a food contaminant that is mainly attributed to the use of chlorinated water and disinfectants. The present study investigated if chlorate could also occur as a process contaminant in chemical leavening agents for baking products. Thus, a sensitive and rapid ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed and validated. Chlorate was quantified using an isotopically labeled internal standard after complete degassing of carbonate-based products. The limit of detection/limit of quantification was 0.02 and 0.1 mg/kg, respectively, with recovery rates between 97.0 and 101.2% (concentration levels: 0.3, 1.4, or 5.0 mg/kg). Samples of baking powder, sodium bicarbonate, ammonium bicarbonate, and potassium carbonate were analyzed. Chlorate was detected in all samples of baking powder in concentrations of 0.23-1.87 mg/kg. Potassium carbonate contained the highest chlorate levels, with a maximum of 60.9 mg/kg. These results indicate that baking powder and, particularly, potassium carbonate can be relevant sources of chlorate in food.

Chlorate induced false reduction in chemical oxygen demand (COD) based on standard dichromate method: Countermeasure and mechanism.

Deliberate addition of mildly oxidative chlorate (ClO3-), so-called "chemical oxygen demand (COD) remover", into wastewater in China or electrochemical production of ClO3- from Cl- induces the false COD reduction, which would bring about false appearance of effluents meeting the COD discharge standards. In this study, an easy sulfite-based reduction method was developed for the first time to remove ClO3- from the water samples before COD determination to eliminate this interference of ClO3-. In this reaction system, keeping the reaction temperature of sulfite reducing ClO3- at 60 °C was crucial for fast ClO3- removal rate, fixed molar [sulfite]ini/[chlorate]ini ratio value and the synchronous exhaustion of sulfite and ClO3-, which were of great significance for the real application of this improved COD determination method. The ClO3- interference on COD determination could be successfully eliminated after 20 min reduction of ClO3- by sulfite at pHini 4.0∼6.0 with the molar [sulfite]ini/[chlorate]ini ratio value in the range of 5∼6 when concentration of ClO3- was below 5 mM. Despite of the involvement of SO4·- in the sulfite reducing ClO3- system, the degradation of organic matters by SO4·- could be greatly impeded due to the lessened dissolved oxygen for SO4·- production at high reaction temperature and the scavenging of SO4·- by sulfite. In this reaction system, ClO2, ClO2- and ClO- were also generated and could be further reduced by sulfite stoichiometrically via oxygen transfer process with Cl- as the final product. In general, this study pioneered an effective, fast and convenient method for COD determination of the ClO3--laden wastewaters and evaluating the real electrochemical wastewater treatment performance in terms of COD removal.

Chlorate and perchlorate residues in food products on the Danish market.

Upon the European commission's request in 2013, Denmark initiated a survey of the levels of chlorate and perchlorate in agriculture products from the Danish market over a period of 4 years from 2014 to 2017. The results of the survey were used to guide decision making with a view to setting maximum levels for intra-Union trade in 2013 and reviewing and updating the levels from 2020. The results of the Danish survey and the employed analytical method are documented in this paper. In addition to the 89 domestic samples, 30 samples of foreign origin were analysed for chlorate and perchlorate, together with ten samples of baby food and seven samples of infant formula collected from the Danish market. Samples were extracted using the Quick Polar Pesticides extraction method (QuPPe) and analysed on a triple quadrupole LC-MS/MS system. The levels of both chlorate and perchlorate detected in samples originating from Denmark were lower than the current MRLs except for a single sample of lettuce. Moreover, the percentage of foreign samples that were positive for chlorate and perchlorate residues was higher than the percentage of domestic samples. The reason for the generally low levels and low frequency of chlorate and perchlorate in Danish products is most likely linked to the fact that the water supply in Denmark is 100% unchlorinated ground water. The present study shows that residues of perchlorate and chlorate are found in Danish food products at a relatively low frequency and that the levels found are below the EU's MRLs implemented in 2020.

The fate of sodium chlorite in simulated gastric and intestinal fluids and residues of chlorate in broiler chickens after oral administration of sodium chlorite.

The fate of sodium [36Cl]chlorite in simulated intestinal fluids and residues of chlorate in broiler chickens fed 0, 10, 100, or 1000 mg•kg-1 of dietary sodium chlorite for 7 days was determined. [36Cl]Chlorite was stable in water and simulated intestinal fluid during 6 h incubations but was rapidly degraded to chlorine dioxide, sodium chloride, and sodium chlorate in simulated gastric fluids. Addition of starch, citrate, or soybean shifted the relative proportions of chloroxyanions formed; addition of ferrous chloride caused quantitative formation of sodium chloride in gastric and intestinal fluids. [36Cl]Chlorite underwent reductive transformation when fortified into chicken serum. Residues of chlorate in broiler chickens ranged from 3.5 to 374 ng•g-1 in gizzard, were <6.8 to 126 ng•g-1 in liver and were <7.2 to 190 ng•g-1 in muscle when slaughtered with no withdrawal period. Data are presented suggesting that reductive processes govern the fate of chlorite when present in closed biological systems.

The contamination and estimation of dietary intake for perchlorate and chlorate in infant formulas in China.

The contents of perchlorate and chlorate were determined in a total of 278 samples of infant formulas marketed in China. The associated health risk via infant and young child formulas consumption for 0-36 month old children in China was also assessed. The contents of perchlorate and chlorate were measured by a validated method with LC-MS and the limit of detection (LOD) was 1.5 µg kg-1 and 3.0 µg kg-1 for perchlorate and chlorate, respectively. Perchlorate and chlorate were detected in about 85.8% (median 6.92 µg kg-1, maximum 74.20 µg kg-1) and 99.3% (median 52.80 µg kg-1, maximum 2780 µg/kg) of the samples. The exposures of infant and young children to perchlorate from formulas were lower than the provisional maximum tolerable daily intake (PMTDI, 0.7 µg/kg bw/day), which was established by U.S. Environmental Protection Agency (EPA). The European Food Safety Authority (EFSA) in 2015 also proposed a tolerable daily intake (TDI) of 3 µg/kg bw/day for chlorate based on the mean and average concentrations. Only for infants 0-6 month at the 95th percentile did exposures exceed the TDI of 3 µg/day for chlorate. Therefore, the safety of infant and young child formulas is excellent. To our knowledge, this is the first report to assess the exposure of infant and young child formulas in China to perchlorate and chlorate.

Hazardous inorganic disinfection by-products in Egypt's tap drinking water: Occurrence and human health risks assessment studies.

This study is the first that monitored the presence and levels of chlorite, chlorate and bromate in tap drinking water of Egypt. Three hundred and eight samples were collected from 22 governorates across Egypt and were analyzed using a standardized ion chromatography method. Forty-seven samples were contaminated by one or more of the inorganic disinfection by-products (DBPs) and only 12 samples exceeded the admissible maximum contamination levels (MCLs). The ratio of samples detected, and exceeding the MCLs were low relative to the global literature. Chlorate was the most prevalent inorganic DBPs (40 samples; concentration <12-4082 µg/L) followed by bromate (12 samples; concentration <3-626 µg/L) then chlorite (5 samples; concentration <12-123 µg/L). Chlorite was always below the MCL and had no human health risk even for the worst-case scenario. Bromate is a real challenge as it poses a significant cancer risk even for the median concentrations. None of the inorganic DBPs was detected in the tap drinking water of Beheira, Cairo, Gharbia, Giza, Kafr El Sheikh, Luxor, Monufia, and Suez governorates. This study manifested the importance of routine monitoring, and implementing counter measures to control the levels of the hazardous inorganic DBPs in tap drinking water.

Occurrence of perchlorate, chlorate and polar herbicides in different baby food commodities.

The incidence of endocrine disruptors, both possible (glyphosate and glufosinate), and demonstrated (perchlorate and chlorate), was estimated in baby food commodities (meat, fish, cheese, vegetable and fruit). Ion-chromatography coupled to high resolution mass spectrometry analysis of the 105 samples did not show traces of glyphosate, glufosinate or their metabolites, while in 10.5% of the samples a quantifiable amount of perchlorate was found. Some samples based on fruit and vegetables revealed a substantial amount of chlorate, especially the preparations that contained carrots and potatoes: five samples were in a concentration range of 40-120 µg kg-1, while one homogenized pear sample reached 372.2 µg kg-1. The pure meat samples revealed occasional chlorate appearance, with less than 10 µg kg-1. This is the first report of chlorate evaluated in various types of baby food and may serve as symptomatic data regarding its occurrence in infant/toddler diets. Therefore, effective monitoring programs and subsequent strict regulations are strongly required.

Short communication: Effects of electrochemically activated drinking water on bovine milk production and composition, including chlorate, perchlorate, and fatty acid profile.

The objective of this study was to assess the effects of electrochemically activated drinking water (ECW) on milk chlorate, milk perchlorate, milk iodine, milk composition, milk fatty acid profile, and overall performance of dairy cows. Ten Red Danish cows in mid-lactation (203 ± 31 d in milk; average ± SD) were chosen from these 2 groups for intensive sampling. The treated group drank water with 4 ppm of ECW (29 mg/L of chlorate of Neuthox, Danish Clean Water A/S, Sønderborg, Denmark). The treatment lasted 60 consecutive days, with milk and water sampling on d 0, 30, and 60. Additionally, milk samples from both the control group and treated group were taken on d 90 to assess if any carry-over effect was present. Interactions between period and milk yield and somatic cell for the full group and period and milk fat content and milk urea nitrogen in the selected animals occurred. Milk yield was not significantly affected by treatments. Milk fat, milk fatty acid profile, chlorate, perchlorate, and iodine contents were not significantly different between treatments. Milk urea increased, whereas ß-hydroxybutyrate and somatic cell count decreased significantly in the treated groups. Results showed that at a dosing of 4 ppm of ECW, both chlorate and perchlorate concentrations in milk (<0.002 mg/kg) were low, and no deleterious effects on milk production or milk chemical composition were observed. These data can be of use when assessing the effects of ECW on milk and milk powder chlorate and perchlorate levels and provide a context for assessing the potential for influencing human health under the conditions prevailing on a commercial dairy farm.

[Determination of chlorate and perchlorate in milk power by high-performance liquid chromatography-tandem mass spectrometry].

An analytical method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for detecting chlorate and perchlorate residues in milk power. Chlorate and perchlorate in milk power were extracted using a 0.1% (v/v) formic acid-acetonitrile solution. The extract was centrifuged at 10000 r/min for 10 min, and the supernatant was cleaned up on a PRiME HLB column. Separation of chlorate and perchlorate was performed on an ion-exchange column (Thermo Scientific Acclaim TRINITY P1, 50 mm×2.1 mm, 3 µm) by gradient elution using acetonitrile and 20 mmol/L ammonium acetate solution as the mobile phase. The analytes were identified by MS/MS. Quantification was achieved using internal standards. Chlorate and perchlorate demonstrated good linearity in the ranges of 2.0-40.0 and 1.0-20.0 µg/L, respectively, with correlation coefficients (r2) greater than 0.999. The limits of quantification (LOQs) of chlorate and perchlorate were found to be 15.0 and 7.5 µg/kg, respectively. The recoveries of chlorate and perchlorate ranged from 89.24% to 107.85% at the three spike levels of 30.0, 60.0, and 120.0, and 15.0, 30.0, and 60.0 µg/kg, respectively, with relative standard deviations (RSDs) ranging from 3.15% to 10.42% (n=6). This method is convenient, rapid, accurate, and efficient, thus demonstrating its suitability for use in the determination of chlorate and perchlorate in milk power.

Monitoring residue concentrations in milk from farm and throughout a milk powder manufacturing process.

The experiments reported in this research paper aimed to investigate differences in the levels of chlorate (CHLO), perchlorate (PCHLO), trichloromethane (TCM) and iodine residues in bulk tank (BT) milk produced at different milk production periods, and to monitor those levels throughout a skim milk powder (SMP) production chain (BTs, collection tankers [CTs], whole milk silo [WMS] and skim milk silo [SMS]). Chlorate, PCHLO and iodine were measured in SMP, while TCM was measured in the milk cream. The CHLO, TCM and iodine levels in the mid-lactation milk stored in the WMS were lower than legislative and industrial specifications (0.0100 mg/kg, 0.0015 mg/kg and 150 µg/l, respectively). However, in late-lactation, these levels were numerically higher than the mid-lactation levels and specifications. Trichloromethane accumulated in the cream portion after separation. Perchlorate was not detected in any of the samples. Regarding iodine, the levels in mid-lactation reconstituted SMP were higher than that required by manufacturers (100 µg/l), indicating that the levels in milk should be lower than 142 µg/l. The higher residue levels observed in late-lactation could be related to the low milk volume produced during that period and changes in sanitation practices, while changes in feed management could have affected iodine levels. This study could assist in controlling and setting limits for CHLO, TCM and iodine levels in milk, ensuring premium quality dairy products.

LC-ESI-MS/MS determination of oxyhalides (chlorate, perchlorate and bromate) in food and water samples, and chlorate on household water treatment devices along with perchlorate in plants.

The results of the validation study of the LC-ESI-MS/MS method for the determination of chlorate (ClO3-), perchlorate (ClO4-) and bromate (BrO3-) in water and food samples are summarized. Towards this, 284 samples of drinking water were analysed, out of which the 69% contained chlorate above the limit of quantitation (LOQ) of 0.01 mg/L, with maximum amount of 1.1 mg/L. Only 6 samples were found to be positive with perchlorate at levels <0.01 mg/L. Bromate was detected in 5 drinking water samples at levels above the LOQ, at concentrations up to 0.026 mg/L. For the validation of the method in food, 108 blank samples were spiked with chlorate and perchlorate for the LC-MS/MS analysis at two levels. In total 247 food samples from the market of 19 different commodities including fruits, vegetables, cereals and wine, were analysed. The maximum concentration of chlorate was found at 0.83 mg/kg in a sample of cultivated mushrooms. The number of samples contaminated with perchlorate was also small, with all the determined concentrations below the LOQ of 0.05 mg/kg. Experiments for the chlorate reduction in drinking water, showed that reverse osmosis treatment is effective in particular with newly installed cartridges. Finally, according to the results of the pilot study when chlorinated water is used for the plant irrigation, accumulation of chlorate is observed, especially in the green parts of the plant. Perchlorate was also detected in leafy samples, although it was not present in the irrigation water.

Mussel-inspired immobilization of silver nanoparticles toward sponge for rapid swabbing extraction and SERS detection of trace inorganic explosives.

It is fairly crucial to detect inorganic explosives through a sensitive and fast method in the field of public safety, nevertheless, the high non-volatility and stability characteristics severely confine their accurate on-site detection from a real-world surface. In this work, an efficient, simple and cost effective method was developed to fabricate uniform silver nanoparticles (AgNPs) immobilized on polyurethane (PU) sponge through the in-situ reduction of polydopamine (PDA) based on mussel-inspired surface chemistry, in virtue of a large quantities catechol and amine functional groups. The formed PU@PDA@Ag sponges exhibited high SERS sensitivity, uniformity and reproducibility to 4-Aminothiophenol (4-ATP) probe molecule, and the limit of detection was calculated to be about 0.02 nmol L-1. Moreover, these PU@PDA@Ag sponges could be served as excellent flexible SERS substrates to rapidly detect trace inorganic explosives with high collection efficiency via swabbing extraction. The detection limit for perchlorates (ClO4-), chlorates (ClO3-) and nitrates (NO3-) were approximately down to 0.13, 0.13 and 0.11 ng respectively. These flexible substrates not only could drastically increase the sample collection efficiency, but also enhance analytical sensitivity and reliability for inorganic explosive, and would have a great potential application in the future homeland security fields.

Formation, distribution, and speciation of DBPs (THMs, HAAs, ClO2-,andClO3-) during treatment of different source water with chlorine and chlorine dioxide.

Formation potential and speciation characteristics of two important groups of disinfection byproducts (DBPs), namely, trihalomethanes (THMs) and haloacetic acids (HAAS), during Cl2 and ClO2 treatment of water samples collected from three different sources, namely, sea, river, and reservoir, were investigated with reference to key controlling parameters. Formation of inorganic DBPs such as chlorate and chlorite was evaluated. Dissolved organic carbon (DOC) and UV absorbance (UV254) of the sea, river, and reservoir samples were 3.35 ±â€¯0.05, 3.12 ±â€¯0.05, and 3.23 ±â€¯0.05 mg/L and 0.062 ±â€¯0.01, 0.074 ±â€¯0.01, and 0.055 ±â€¯0.01 cm-1, respectively. For Cl2 and ClO2 treatments, the respective formation potential of THMs and HAAs from the three water sources studied exhibited unidentical trend suggesting that higher THM formation was not necessarily associated with higher HAA formation. On chlorination, the concentrations of total HAAs formed were 9.8 µg/L (sea), 12.8 µg/L (river), and 20.6 µg/L (reservoir) and total THM yields were 38.3 µg/L (sea), 18.8 µg/L (river), and 21.5 µg/L (reservoir) for a Cl2 dose of 1 mg/L and 30 min reaction time. The trend of formation of THMs and HAAs for Cl2 treatment was similar to that for ClO2 treatment. However, the amount of HAAs (3.5 µg/L (sea), 1.8 µg/L (river), and 1.9 µg/L (reservoir)) and THMs (not detected) formed was much lower than that formed during chlorination. Regardless of source water type, di-HAAs were the most favored HAAs, followed by tri-HAAs with a small amount of mono-HAAs formed for both Cl2 and ClO2 treatment. Chlorination yielded more THMs than HAAs, whereas it was reverse for chlorine dioxide treatment. Irrespective of treatment with ClO2 or Cl2, seawater samples showed the highest bromine incorporation percentage (BIP) in both THMs and HAAs followed by that for river and reservoir water samples. HAAs were found to be always associated with lower amount of BIP than THMs.

Kinetic assessment of simultaneous removal of arsenite, chlorate and nitrate under autotrophic and mixotrophic conditions.

In this work, a kinetic model was proposed to evaluate the simultaneous removal of arsenite (As (III)), chlorate (ClO3-) and nitrate (NO3-) in a granule-based mixotrophic As (III) oxidizing bioreactor for the first time. The autotrophic kinetics related to growth-linked As (III) oxidation and ClO3- reduction by As (III) oxidizing bacteria (AsOB) were calibrated and validated based on experimental data from batch test and long-term reactor operation under autotrophic conditions. The heterotrophic kinetics related to non-growth linked As (III) oxidation and ClO3- reduction by heterotrophic bacteria (HB) were evaluated based on the batch experimental data under heterotrophic conditions. The existing kinetics related to As (III) oxidation with NO3- as the electron acceptor together with heterotrophic denitrification were incorporated into the model framework to assess the bioreactor performance in treatment of the three co-occurring contaminants. The results revealed that under autotrophic conditions As (III) was completely oxidized by AsOB (over 99%), while ClO3- and NO3- were poorly removed. Under mixotrophic conditions, the simultaneous removal of the three contaminants was achieved with As (III) oxidized mostly by AsOB and ClO3- and NO3- removed mostly by HB. Both hydraulic retention time (HRT) and influent organic matter (COD) concentration significantly affected the removal efficiency. Above 90% of As (III), ClO3- and NO3- were removed in the mixotrophic bioreactor under optimal operational conditions of HRT and influent COD.

Disinfection by-products in baby lettuce irrigated with electrolysed water.

BACKGROUND: Irrigation water disinfection reduces the microbial load but it might lead to the formation and accumulation of disinfection by-products (DBPs) in the crop. If DBPs are present in the irrigation water, they can accumulate in the crop, particularly after the regrowth, and be affected by the postharvest handling such as washing and storage. To evaluate the potential accumulation of DBPs, baby lettuce was grown using irrigation water treated with electrolysed water (EW) in a commercial greenhouse over three consecutive harvests and regrowths. The impact of postharvest practices such as washing and storage on DBP content was also assessed. RESULTS: Use of EW caused the accumulation of chlorates in irrigation water (0.02-0.14 mg L-1 ), and in the fresh produce (0.05-0.10 mg kg-1 ). On the other hand, the disinfection treatment had minor impact regarding the presence of trihalomethanes (THMs) in water (0.3-8.7 µg L-1 max), and in baby lettuce (0.3-2.9 µg kg-1 max). CONCLUSIONS: Disinfection of irrigation water with EW caused the accumulation of chlorates in the crop reaching levels higher than the current maximum residual limit established in the EU legislation for leafy greens. © 2017 Society of Chemical Industry.

Chlorate origin and fate in shallow groundwater below agricultural landscapes.

In agricultural lowland landscapes, intensive agricultural is accompanied by a wide use of agrochemical application, like pesticides and fertilizers. The latter often causes serious environmental threats such as N compounds leaching and surface water eutrophication; additionally, since perchlorate can be present as impurities in many fertilizers, the potential presence of perchlorates and their by-products like chlorates and chlorites in shallow groundwater could be a reason of concern. In this light, the present manuscript reports the first temporal and spatial variation of chlorates, chlorites and major anions concentrations in the shallow unconfined aquifer belonging to Ferrara province (in the Po River plain). The study was made in 56 different locations to obtain insight on groundwater chemical composition and its sediment matrix interactions. During the monitoring period from 2010 to 2011, in June 2011 a nonpoint pollution of chlorates was found in the shallow unconfined aquifer belonging to Ferrara province. Detected chlorates concentrations ranged between 0.01 and 38 mg/l with an average value of 2.9 mg/l. Chlorates were found in 49 wells out of 56 and in all types of lithology constituting the shallow aquifer. Chlorates concentrations appeared to be linked to NO3-, volatile fatty acids (VFA) and oxygen reduction potential (ORP) variations. Chlorates behaviour was related to the biodegradation of perchlorates, since perchlorates are favourable electron acceptors for the oxidation of labile dissolved organic carbon (DOC) in groundwater. Further studies must take into consideration to monitor ClO4- in pore waters and groundwater to better elucidate the mass flux of ClO4- in shallow aquifers belonging to agricultural landscapes.

[How does a pesticide residue turn into a contaminant?] / Wie wird ein Pflanzenschutzmittelrückstand zur Kontaminante?

Over the last few years pesticide residues have been repeatedly detected during official food controls that would not be expected from authorized pesticide uses. These residues do not always pose a health risk for consumers. However, the legal and economic consequences of such findings are often far-reaching, especially if the admissible maximum residue limits have been fixed at the LOQ level only. For some example cases, we discuss the real entry pathways into the food chain and under which circumstances residues of such unintentionally added substances could be better regulated under the contaminant legal framework rather than the pesticide legal framework.