Design and fabrication of La-based perovskites incorporated with functionalized carbon nanofibers for the electrochemical detection of roxarsone in water and food samples.

The pentavalent arsenic compound roxarsone (RSN) is used as a feed additive in poultry for rapid growth, eventually ending up in poultry litter. Poultry litter contains chicken manure, which plays a vital role as an affordable fertilizer by providing rich nutrients to agricultural land. Consequently, the extensive use of poultry droppings serves as a conduit for the spread of toxic forms of arsenic in the soil and surface water. RSN can be easily oxidized to release highly carcinogenic As(III) and As(IV) species. Thus, investigations were conducted for the sensitive detection of RSN electrochemically by developing a sensor material based on lanthanum manganese oxide (LMO) and functionalized carbon nanofibers (f-CNFs). The successfully synthesised LMO/f-CNF composite was confirmed by chemical, compositional, and morphological studies. The electrochemical activity of the prepared composite material was examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The obtained results confirmed that LMO/f-CNF showed enhanced electrocatalytic activity and improved current response with a good linear range (0.01-0.78 µM and 2.08-497 µM, respectively), exhibiting a low limit of detection (LOD) of 0.004 µM with a high sensitivity of 13.24 µA µM-1 cm-2 towards the detection of RSN. The noteworthy features of LMO/f-CNF composite with its superior electrochemical performance enabled reliable reproducibility, exceptional stability and reliable practical application in the analysis of tap water and food sample, affording a recovery range of 86.1-98.87%.

Fabrication of Praseodymium Vanadate Nanoparticles on Disposable Strip for Rapid and Real-Time Amperometric Sensing of Arsenic Drug Roxarsone.

Nanomaterials have versatile properties owing to their high surface-to-volume ratio and can thus be used in a variety of applications. This work focused on applying a facile hydrothermal strategy to prepare praseodymium vanadate nanoparticles due to the importance of nanoparticles in today's society and the fact that their synthesis might be a challenging endeavor. The structural and morphological characterizations were carried out to confirm the influence of the optimizations on the reaction's outcomes, which revealed praseodymium vanadate (PrVO4) with a tetragonal crystal system. In this regard, the proposed development of electrochemical sensors based on the PrVO4 nanocatalyst for the real-time detection of arsenic drug roxarsone (RXS) is a primary concern. The detection was measured by amperometric (i-t) signals where PrVO4/SPCE, as a new electrochemical sensing medium for RXS detection, increased the sensitivity of the sensor to about ∼2.5 folds compared to the previously reported ones. In the concentration range of 0.001-551.78 µM, the suggested PrVO4/SPCE sensor has a high sensitivity for RXS, with a detection limit of 0.4 nM. Furthermore, the impact of several selected potential interferences, operational stability (2000 s), and reproducibility measurements have no discernible effect on RXS sensing, making it the ideal sensing device feasible for technical analysis. The real-time analysis reveals the excellent efficiency and reliability of the prosed sensor toward RXS detection with favorable recovery ranges between ±97.00-99.66% for chicken, egg, water, and urine samples.

Selective solid-phase extraction of four phenylarsonic compounds from feeds, edible chicken and pork with tailoring imprinted polymer.

The novel molecularly imprinted microspheres for four phenylarsonic compounds have been firstly prepared with the reversible addition-fragmentation chain transfer polymerization in a suspension system. The resulting polymeric microspheres were characterized by infrared spectrum, scanning electron microscope and differential scanning calorimetry. With serial adsorption experiments, the polymeric microspheres showed highly specific molecular recognition, fast mass transfer rate and robust adsorption of the substrates. Then, the imprinted polymer was used as the solid-phase extraction adsorbent to extract the phenylarsonic compounds from the feeds, edible chicken and pork. The cartridge was washed with 2 mL ethyl acetate and eluted with 3 mL of methanol- acetic acid (90:10, v/v). The recoveries of the molecularly imprinted solid-phase extraction (MISPE) column ranged from 83.4% to 95.1%. This work provided a versatile approach for the specific extraction of the organoarsenic compounds from complicated matrices and exhibited a bright future for the application of MISPE column.

Identification of an anaerobic bacterial consortium that degrades roxarsone.

The degradation of roxarsone, an extensively used organoarsenic feed additive, occurs quickly under anaerobic conditions with microorganisms playing an important role in its degradation. Here, an anaerobic bacterial consortium that effectively degraded roxarsone was isolated, and its degradation efficiency and community changes along a roxarsone concentration gradient under anaerobic conditions were assessed. We used batch experiments to determine the roxarsone degradation rates, as well as the bacterial community structure and diversity, at initial roxarsone concentrations of 50, 100, 200, and 400 mg/kg. The results showed that roxarsone was degraded completely within 28, 28, 36, and 44 hr at concentrations of 50, 100, 200, and 400 mg/kg, respectively. The anaerobic bacterial consortium displayed considerable potential to degrade roxarsone, as the degradation rate increased with increasing roxarsone concentrations. Roxarsone promoted microbial growth, and in turn, the microorganisms degraded the organoarsenic compound, with the functional bacterial community varying between different roxarsone concentrations. Lysinibacillus, Alkaliphilus, and Proteiniclasticum were the main genera composing the roxarsone-degrading bacterial community.

A screen-printed electrode modified with tungsten disulfide nanosheets for nanomolar detection of the arsenic drug roxarsone.

A sensitive electrochemical (voltammetric; DPV) sensor has been developed for the determination of coccidiostat drug (roxarsone) based on the use of an SPCE (screen-printed carbon electrode) modified with tungsten disulfide nanosheets (WS2 NSs). The electrochemical detection of roxarsone on the WS2-modified SPCE was examined by electrochemical strategies. XPS, XRD, Raman, SEM, TEM, EDS and EIS were used to characterize the nanosheets. The effects of scan rate, pH values (phosphate buffer) and buffer concentration were optimized. A selective roxarsone sensor was developed that works best at -0.64 V (vs. Ag/AgCl) and performs much better than the bare SPCE. Features include (a) a wider linear range (0.05 to 490 µM), (b) a nanomolar detection limit (0.03 µM) and (c) high sensitivity (29 µA·µM-1·cm-2). The modified SPCEs have been successfully applied to the determination of roxarsone in spiked meat samples where they gave high accuracy and good recoveries. Graphical abstract Synthesis of WS2 nanosheets and electrochemical detection of roxarsone.

Facile synthesis of mesoporous WS2 nanorods decorated N-doped RGO network modified electrode as portable electrochemical sensing platform for sensitive detection of toxic antibiotic in biological and pharmaceutical samples.

We report a facile and ultrasound assisted sonochemical synthesis of a Tungsten disulfide nanorods decorated nitrogen-doped reduced graphene oxide based nanocomposite. The WS2 NRs/N-rGOs nanocomposite was characterized by FESEM, HRTEM, XRD, XPS and electrochemical methods and its application towards the electrochemical detection of organo-arsenic drug (coccidiostat). The WS2 NRs/N-rGOs modified SPCE was used for the electrochemical reduction of roxarsone (ROX) and it showed superior electrocatalytic performance in terms of reduction peak current and shift in overpotential when compared to those of WS2 NRs/SPCE, N-rGOs/SPCE and based SPCE. The WS2 NRs/N-rGOs modified SPCE showed an excellent sensing ability towards ROX in nitrogen saturated phosphate buffer (PB) then the other controlled modified and unmodified electrodes. The WS2 NRs/N-rGOs/SPCE displays high sensitive response towards ROX and gives wide linearity in the range of 0.1-442.6 µM ROX in neutral phosphate buffer (pH 7.0) and the sensitivity of the sensor is calculated as 14.733 µA µM-1 cm-2. The WS2 NRs/N-rGOs nanocomposite modified sensor also exhibits valuable ability of anti-interference to electroactive analytes. Furthermore, the as-prepared WS2 NRs/N-rGOs/SPCE has been applied to the determination of ROX in biological and pharmaceutical samples.

Biotransformation of arsenic-containing roxarsone by an aerobic soil bacterium Enterobacter sp. CZ-1.

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, ROX) is an arsenic-containing compound widely used as a feed additive in poultry industries. ROX excreted in chicken manure can be transformed by microbes to different arsenic species in the environment. To date, most of the studies on microbial transformation of ROX have focused on anaerobic microorganisms. Here, we isolated a pure cultured aerobic ROX-transforming bacterial strain, CZ-1, from an arsenic-contaminated paddy soil. On the basis of 16S rRNA gene sequence, strain CZ-1 was classified as a member of the genus Enterobacter. During ROX biotransformation by strain CZ-1, five metabolites including arsenate (As[V]), arsenite (As[III]), N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA), 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) and a novel sulfur-containing arsenic species (AsC9H13N2O6S) were detected and identified based on high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS), HPLC-ICP-MS/electrospray ionization mass spectrometry (ESI-MS) and HPLC-electrospray ionization hybrid quadrupole time-of-flight mass spectrometry (ESI-qTOF-MS) analyses. N-AHPAA and 3-AHPAA were the main products, and 3-AHPAA could also be transformed to N-AHPAA. Based on the results, we propose a novel ROX biotransformation pathway by Enterobacter. sp CZ-1, in which the nitro group of ROX is first reduced to amino group (3-AHPAA) and then acetylated to N-AHPAA.

Effect of roxarsone metabolites in chicken manure on soil biological property.

Roxarsone (ROX), an organoarsenic feed additive, occurs as itself and its metabolites including As(V), As(III), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in animal manure. Animal manure improves soil biological property, whereas As compounds impact microorganisms. The integral influence of animal manure bearing ROX metabolites on soil biological quality is not clear yet. Herein, the effect of four chicken manures excreted by chickens fed with four diets containing 0, 40, 80 and 120 mg ROX kg-1, on soil biological attributes. ROX addition in chicken diets increased total As and ROX metabolites in manures, but decreased manure total N, ammonium and nitrate. The elevated ROX metabolites in manures increased soil total As, As species and total N, and increased first and then decreased soil nitrate and nitrite, but did not affect soil ammonium in manure-applied soils. The promoting role of both soil As(III) and ammonium on soil microbial biomass carbon and nitrogen, respiration and saccharase activity, were exceeded or balanced by the inhibiting effect of soil nitrate. The suppression of soil catalase activity by soil As(V) was surpassed by the enhancement caused by soil nitrate and nitrite. Soil urease, acid phosphatase and polyphenol oxidase activities were not suitable bioindicators in the four manure-amended soils. Soil DMA did not affect soil biological properties, and MMA was not detectable in all manure-amended soils. The above highlights the complexity of joint influence of soil As and N on biological attributes. Totally, when ROX is used at allowable dose in chicken diet, soil biological quality would be suppressed in manure-amended soil.

Transformation of roxarsone in the anoxic-oxic process when treating the livestock wastewater.

In order to evaluate the influence of roxarsone (ROX) on the livestock wastewater treatment, a lab-scale pilot employing an anoxic-oxic (A-O) process was investigated by adding different concentrations of ROX at different periods. The mass balance of arsenic (As) in the A-O system was established through the analysis of As speciation and As migration in the gas, liquid and solid phases. The results showed that around 80% of total ROX (initial concentration was 50mgROXL-1) was eliminated in the anoxic reactor (R1) in which at least about 11% of total ROX was transformed to inorganic Asv (iAsv) due to the direct breaking of the C-As bond of ROX. Inorganic AsIII (iAsIII) and arsine (AsH3) were produced in R1, while the generated iAsIII in the effluent of R1 was almost completely oxidized to iAsV in the aerobic reactor (R2). However, the concentration of ROX in the effluent of R2 was almost the same as that in the effluent of R1. After 85days operation, iAsV and residual ROX as the main forms of As were observed after the A-O process. Furthermore, the mass balance of As at steady state revealed that around 0.08%, 3.91% and 96.01% of total As was transformed into gas (biogas), solid (excess sludge) and liquid (effluent). Additionally, the 16S rRNA analysis demonstrated that the existence of ROX in livestock wastewater may play a crucial role in the diversity of bacterial community in the A-O system.

Phytotoxicity and uptake of roxarsone by wheat (Triticum aestivum L.) seedlings.

Roxarsone (ROX), the primary aromatic arsenical additive (AAA) used in animal feeding operations, is of increasing concern to environmental and human health due to land application of ROX-laden animal manure. Few studies have investigated the phytotoxicity, uptake mechanisms, and speciation of AAA in crop plants. In this study, wheat seedlings were employed to address these issues under hydroponic conditions. Compared to inorganic arsenic, ROX was less toxic to wheat root elongation. Wheat roots were more sensitive to ROX stress than shoots. For the first time, metabolized inorganic arsenic was detected in plants, although ROX was the predominant detected arsenic species in wheat seedlings. ROX uptake and toxicity to roots were inhibited by humic acid at concentrations higher than 50 mg/L due to interaction with ROX. Phosphate enhanced ROX uptake, but no trends were observed for ROX uptake in the presence of glycerol at concentrations lower than 250 mM. In addition, ROX uptake was significantly decreased by silicate (Si(IV), 0.5-10 mM) and the metabolic inhibitor, 2,4-dinitrophenol (0.5-2 mM), indicating that ROX transport into wheat roots was actively mediated by Si(IV)-sensitive transporters. These findings provide important insights into the fate and speciation of AAA in soil-water-plant systems relevant to human health.

Roxarsone binding to soil-derived dissolved organic matter: Insights from multi-spectroscopic techniques.

The fate and transport of roxarsone (ROX), a widely used organoarsenic feed additive, in soil is significantly influenced by the ubiquitous presence of soil-derived dissolved organic matter (DOM). In this study, fluorescence quenching titration and two-dimensional correlation spectroscopy (2D-COS) were employed to study ROX binding to DOM. Binding mechanisms were revealed by fluorescence lifetime measurement and Fourier transform infrared spectroscopy (FTIR). Humic- and protein-like fluorophores were identified in the excitation-emission matrix and synchronous fluorescence spectra of DOM. The conditional stability constant (log KC) for ROX binding to DOM was found to be 5.06, indicating that ROX was strongly bound to DOM. The binding order of ROX to DOM fluorophores revealed by 2D-COS followed the sequence of protein-like fluorophore ≈ the longer wavelength excited humic-like (L-humic-like) fluorophore > the shorter wavelength excited humic-like (S-humic-like) fluorophore. 2D-COS resolved issues with peak overlapping and allowed further exploration of the interaction between ROX and DOM. Results of fluorescence lifetime and FTIR spectra demonstrated that ROX interacted with DOM through the hydroxyl, amide II, carboxyl, aliphatic CH, and NO2 groups, yielding stable DOM-ROX complexes. The strong interaction between ROX and DOM implies that DOM plays an important role in the environmental fate of ROX in soil.

[Residue and Degradation of Roxarsone in the System of Soil-Vegetable].

The field experiment was developed for simulating the residues, transformation and degradation in soil-vegetable system of Roxarsone contained in organic fertilizer. Under the treatment, the yield of Brassica chinensis decreased in low Roxarsone concentration with a decline by 15% to 32% compared with the control group; there had an accumulating role of vegetables to arsenic, and the root was the main part; total content of arsenic in the soil was positively correlated with the dose of the applied Roxarsone; total arsenic in soil first increased and then decreased with the planting time prolonged and peaked at 12.94 mg x kg(-1), while the level of inorganic arsenic in the soil stabilized after 30 d, which accounting for 66.75% to 98.56% of the total arsenic; there existed a positively significant correlation of total arsenic content between the Brassica chinensis and the soil as well as the arsenic enrichment factor of vegetables; the degradation rate of Roxarsone in soil was slow, there was still some Roxarsone remained in soil after 45 d when added the organic fertilizer which containing Roxarsone with the dose higher than 5 000 kg x hm(-2); Roxarsone could significantly increase the number of bacteria in the soil, and low concentration showed an inhibited role in the growth of fungi and actinomyces, while high concentration of Roxarsone promoted the growth.

Optimization of microwave-assisted extraction for six inorganic and organic arsenic species in chicken tissues using response surface methodology.

Response surface methodology was applied to optimize the parameters for microwave-assisted extraction of six major inorganic and organic arsenic species (As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone) from chicken tissues, followed by detection using a high-performance liquid chromatography with inductively coupled mass spectrometry detection method, which allows the simultaneous analysis of both inorganic and organic arsenic species in the extract in a single run. Effects of extraction medium, solution pH, liquid-to-solid ratio, and the temperature and time of microwave-assisted extraction on the extraction of the targeted arsenic species were studied. The optimum microwave-assisted extraction conditions were: 100 mg of chicken tissue, extracted by 5 mL of 22% v/v methanol, 90 mmol/L (NH4 )2 HPO4 , and 0.07% v/v trifluoroacetic acid (with pH adjusted to 10.0 by ammonium hydroxide solution), ramping for 10 min to 71°C, and holding for 11 min. The method has good extraction performance for total arsenic in the spiked and nonspiked chicken tissues (104.0 ± 13.8% and 91.6 ± 7.8%, respectively), except for the ones with arsenic contents close to the quantitation limits. Limits of quantitation (S/N = 10) for As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone in chicken tissues using this method were 0.012, 0.058, 0.039, 0.061, 0.102, and 0.240 mg/kg (dry weight), respectively.

Phosphate enhances uptake of As species in garland chrysanthemum (C. coronarium) applied with chicken manure bearing roxarsone and its metabolites.

Roxarsone (ROX), a world widely used feed organoarsenic additive in animal production, can be excreted as itself and its metabolites in animal manure. Animal manure is commonly land applied with phosphorous (P) fertilizer to enhance the P phytoavailability in agriculture. We investigated the accumulation of As species in garland chrysanthemum (C. coronarium) plants fertilized with 1% (w/w, manure/soil) chicken manure bearing ROX and its metabolites, plus 0, 0.05, 0.1, 0.2, 0.4, and 0.8 g P2O5/kg, respectively. The results show that As(III) was the sole As compound in garland chrysanthemum shoots, and As(III) and As(V) were detectable in roots. Elevated phosphate level supplied more As(V) for garland chrysanthemum roots through competitive desorption in rhizosphere, leading to significantly enhanced accumulation of As species in plants. As(III) was the predominant As form in plants (85.0∼90.6%). Phosphate could not change the allocation of As species in plants. Hence, the traditional practice that animal manure is applied with P fertilizer may inadvertently increase the potential risk of As contamination in crop via the way ROX → animal → animal manure → soil → crop.

[Simultaneous determination of arsanilic, nitarsone and roxarsone residues in foods of animal origin by ASE-LC-AFS].

A method for simultaneous determination of arsanilic, nitarsone and roxarsone (ROX) residues in foods of animal origin was developed by accelerated solvent extraction-liquid chromatography-atomic fluorescence spectrometry (ASE-LC-AFS). The ultrasound centrifugation extraction and accelerated solvent extraction were compared, and the accelerated solvent extraction conditions, namely the proportion of the extraction solvent, the extraction temperature, extraction time and extraction times, were optimized. The operating conditions of LC-AFS and the mobile phase were optimized. Under the optimal conditions, the calibration curves for ASA , NIT and ROX were linear over the concentration range of 0-2.0 mg x L(-1) and their correlation coefficients were 0.999 2-0.999 8. The detection limits of ASA, NIT and ROX were 2.4, 7.4 and 4.1 microg x L(-1) respectively. The average recoveries of ASA, NIT and ROX from two samples spiked at three levels of 0.5, 2, 5 mg x kg(-1) were in the ranges of 87.1%-93.2%, 85.2%-93.9%, and 84.2%-93.7% with RSDs of 1.4%-4.6%, 1.2%-4.2%, and 1.1%-4.5%, respectively. This method possesses the merits of convenience and good repeatability, and is a feasible method for analysis of ASA, NIT and ROX in foods of animal origin.

Biosensor for organoarsenical herbicides and growth promoters.

The toxic metalloid arsenic is widely distributed in food, water, and soil. While inorganic arsenic enters the environment primarily from geochemical sources, methylarsenicals either result from microbial biotransformation of inorganic arsenic or are introduced anthropogenically. Methylarsenicals such as monosodium methylarsonic acid (MSMA) have been extensively utilized as herbicides, and aromatic arsenicals such as roxarsone (Rox) are used as growth promoters for poultry and swine. Organoarsenicals are degraded to inorganic arsenic. The toxicological effects of arsenicals depend on their oxidation state, chemical composition, and bioavailability. Here we report that the active forms are the trivalent arsenic-containing species. We constructed a whole-cell biosensor utilizing a modified ArsR repressor that is highly selective toward trivalent methyl and aromatic arsenicals, with essentially no response to inorganic arsenic. The biosensor was adapted for in vitro detection of organoarsenicals using fluorescence anisotropy of ArsR-DNA interactions. It detects bacterial biomethylation of inorganic arsenite both in vivo and in vitro with detection limits of 10(-7) M and linearity to 10(-6) M for phenylarsenite and 5 × 10(-6) M for methylarsenite. The biosensor detects reduced forms of MSMA and roxarsone and offers a practical, low cost method for detecting activate forms and breakdown products of organoarsenical herbicides and growth promoters.

Uptake of arsenic species by turnip (Brassica rapa L.) and lettuce (Lactuca sativa L.) treated with roxarsone and its metabolites in chicken manure.

Roxarsone is an organoarsenic feed additive that can be metabolised to other higher toxic arsenic (As) species in animal manure such as arsenate, arsenite, monomethylarsonic acid, dimethylarsinic acid, 3-amino-4-hydroxyphenylarsonic acid and other unknown As species. The accumulation, transport and distribution of As species in turnip (Brassica rapa L.) and lettuce (Lactuca sativa L.) amended with roxarsone and its metabolites in chicken manure were investigated. Results showed arsenite was the predominant As form, followed by arsenate in turnip and lettuce plants, and a low content of dimethylarsinic acid was detected only in lettuce roots. Compared with the control plants treated with chicken manure without roxarsone and its metabolites, the treatments containing roxarsone and its metabolites increased arsenite content by 2.0-3.2% in turnip shoots, by 6.6-6.7% in lettuce shoots, by 11-44% in turnip tubers and by 18-20% in lettuce roots at two growth stages. The enhanced proportion of arsenate content in turnip shoots, turnip tubers and lettuce roots was 4.3-14%, 20-35% and 70%, respectively, while dimethylarsinic acid content in lettuce roots increased 2.4 times. Results showed that the occurrence of dimethylarsinic acid in lettuce roots might be converted from the inorganic As species and the uptake of both inorganic and organic As compounds in turnip and lettuce plants would be enhanced by roxarsone and its metabolites in chicken manure. The pathway of roxarsone metabolites introduced into the human body via roxarsone → animal → manure → soil → crop was indicated.

Perspectives on communicating risks of chemicals.

The Agrochemicals Division symposium "Perfecting Communication of Chemical Risk", held at the 244th National Meeting and Exposition of the American Chemical Society in Philadelphia, PA, August 19-23, 2012, is summarized. The symposium, organized by James Seiber, Kevin Armbrust, John Johnston, Ivan Kennedy, Thomas Potter, and Keith Solomon, included discussion of better techniques for communicating risks, lessons from past experiences, and case studies, together with proposals to improve these techniques and their communication to the public as effective information. The case studies included risks of agricultural biotechnology, an organoarsenical (Roxarsone) in animal feed, petroleum spill-derived contamination of seafood, role of biomonitoring and other exposure assessment techniques, soil fumigants, implications of listing endosulfan as a persistant organic pollutant (POP), and diuron herbicide in runoff, including use of catchment basins to limit runoff to coastal ecozones and the Great Barrier Reef. The symposium attracted chemical risk managers including ecotoxicologists, environmental chemists, agrochemists, ecosystem managers, and regulators needing better techniques that could feed into better communication of chemical risks. Policy issues related to regulation of chemical safety as well as the role of international conventions were also presented. The symposium was broadcast via webinar to an audience outside the ACS Meeting venue.

[Investigation of As, Cu and Zn species and concentrations in animal feeds].

Seventy chicken and seventy-six pig feeds were collected from the feed stores in Guangdong province, and the species and concentrations of As, Cu and Zn were determined. We also examined the stability of roxarsone (ROX), one of the most widely used organoarsenical additives, either in the additive or in the feed at room temperature. The results showed that, averagely, the chicken and pig feeds contained 3.6 and 6.5 mg.kg-1 (As), 18.2 and 119.4 mg.kg-1 (Cu),and 124.6 and 486.2 mg.kg-1 (Zn), respectively. The excessive dosages of As, Cu and As in animal feeds will lead to higher residue of As, Cu and Zn in animal manures. Based on the national limit criteria for feed or feed additive, it was supposed that organoarsenicals had been used, only few feed samples exceeded the As limit, however, the excessive Cu and Zn in pig feeds were much more common. Organoarsenicals were found in 25.4% of the total feed samples, and As(Ill) and As(V) were the two most commonly detected As impurities in feeds bearing organoarsenicals. The mean detectable ROX and arsenilic acid were 7.0 and 21.2 mg.kg-1, respectively. Organoarsenicals were detectable in 24. 3% of the chicken feed samples and 26. 3% of the pig feed samples. Moreover, ROX was commonly used in chicken feeds, while p-ASA in pig feeds. ROX and the inorganic As impurities, either in the commercial additive or in the feed, remained stable for at least 30 days at room temperature, indicating the higher As impurities in feeds probably originated from the As impurities in organoarsenical additives. This is a new As exposure pathway for the producer and user of organoarsenicals and feeds amending organoarsenicals.

Roxarsone, inorganic arsenic, and other arsenic species in chicken: a U.S.-based market basket sample.

BACKGROUND: Inorganic arsenic (iAs) causes cancer and possibly other adverse health outcomes. Arsenic-based drugs are permitted in poultry production; however, the contribution of chicken consumption to iAs intake is unknown. OBJECTIVES: We sought to characterize the arsenic species profile in chicken meat and estimate bladder and lung cancer risk associated with consuming chicken produced with arsenic-based drugs. METHODS: Conventional, antibiotic-free, and organic chicken samples were collected from grocery stores in 10 U.S. metropolitan areas from December 2010 through June 2011. We tested 116 raw and 142 cooked chicken samples for total arsenic, and we determined arsenic species in 65 raw and 78 cooked samples that contained total arsenic at ≥ 10 µg/kg dry weight. RESULTS: The geometric mean (GM) of total arsenic in cooked chicken meat samples was 3.0 µg/kg (95% CI: 2.5, 3.6). Among the 78 cooked samples that were speciated, iAs concentrations were higher in conventional samples (GM = 1.8 µg/kg; 95% CI: 1.4, 2.3) than in antibiotic-free (GM = 0.7 µg/kg; 95% CI: 0.5, 1.0) or organic (GM = 0.6 µg/kg; 95% CI: 0.5, 0.8) samples. Roxarsone was detected in 20 of 40 conventional samples, 1 of 13 antibiotic-free samples, and none of the 25 organic samples. iAs concentrations in roxarsone-positive samples (GM = 2.3 µg/kg; 95% CI: 1.7, 3.1) were significantly higher than those in roxarsone-negative samples (GM = 0.8 µg/kg; 95% CI: 0.7, 1.0). Cooking increased iAs and decreased roxarsone concentrations. We estimated that consumers of conventional chicken would ingest an additional 0.11 µg/day iAs (in an 82-g serving) compared with consumers of organic chicken. Assuming lifetime exposure and a proposed cancer slope factor of 25.7 per milligram per kilogram of body weight per day, this increase in arsenic exposure could result in 3.7 additional lifetime bladder and lung cancer cases per 100,000 exposed persons. CONCLUSIONS: Conventional chicken meat had higher iAs concentrations than did conventional antibiotic-free and organic chicken meat samples. Cessation of arsenical drug use could reduce exposure and the burden of arsenic-related disease in chicken consumers.