Validation of the exposure assessment for veterinary medicinal products

Enhanced properties of a positive-charged nanofiltration membrane containing quaternarized chitosan through second interfacial polymerization for the removal of salts and pharmaceuticals

Nanofiltration (NF) membrane technology has been widely used in the removal of salts and trace organic pollutants, such as pharmaceuticals and personal care products (PPCPs), due to its superiority. A positive-charged composite NF membrane with an active skin layer was prepared by polyethyleneimine (PEI), trimethyl benzene chloride, and quaternate chitosan (HTCC) through second interfacial polymerization on the polyethersulfone ultrafiltration membrane. The physicochemical properties of the nanocomposite membrane were investigated using surface morphology, hydrophilicity, surface charge, and molecular weight cut-off (MWCO). The influence of the concentration and reaction time of PEI and HTCC was documented. The optimized membrane had a MWCO of about 481 Da and possessed a pure water permeability of 25.37 L·m-2·h-1·MPa-1. The results also exhibited salt rejection ability as MgCl2 > CaCl2 > MgSO4 > Na2SO4 > NaCl > KCl, showing a positive charge on the fabricated membrane. In addition, the membrane had higher rejection to atenolol, carbamazepine, amlodipine, and ibuprofen at 89.46, 86.02, 90.12, and 77.21%, respectively. Moreover, the anti-fouling performance and stability of the NF membrane were also improved.

Do biotransformation data from laboratory experiments reflect micropollutant degradation in a large river basin?

Identifying a chemical's potential for biotransformation in the aquatic environment is crucial to predict its fate and manage its potential hazards. Due to the complexity of natural water bodies, especially river networks, biotransformation is often studied in laboratory experiments, assuming that study outcomes can be extrapolated to compound behavior in the field. Here, we investigated to what extent outcomes of laboratory simulation studies indeed reflect biotransformation kinetics observed in riverine systems. To determine in-field biotransformation, we measured loads of 27 wastewater treatment plant effluent-borne compounds along the Rhine and its major tributaries during two seasons. Up to 21 compounds were detected at each sampling location. Measured compound loads were used in an inverse model framework of the Rhine river basin to derive k'_bio,field values - a compound-specific parameter describing the compounds' average biotransformation potential during the field studies. To support model calibration, we performed phototransformation and sorption experiments with all the study compounds, identifying 5 compounds that are susceptible towards direct phototransformation and determining K_oc values covering four orders of magnitude. On the laboratory side, we used a similar inverse model framework to derive k'_bio,lab values from water-sediment experiments run according to a modified OECD 308-type protocol. The comparison of k'_bio,lab and k'_bio,field revealed that their absolute values differed, pointing towards faster transformation in the Rhine river basin. Yet, we could demonstrate that relative rankings of biotransformation potential and groups of compounds with low, moderate and high persistence agree reasonably well between laboratory and field outcomes. Overall, our results provide evidence that laboratory-based biotransformation studies using the modified OECD 308 protocol and k'_bio values derived thereof bear considerable potential to reflect biotransformation of micropollutants in one of the largest European river basins.

Interactions of microplastics and soil pollutants in soil-plant systems

In recent years, increasing studies have been reported on characterization and detection of microplastics (MPs), and their interactions with organic pollutants (OPs) and heavy metals (HMs) in soils. However, a comprehensive review on the characteristics and factors that influence MPs distribution in soils, the sorption characteristics and mechanisms of soil contaminants by MPs, especially the interactions of MPs and their complexes with pollutants in the soil-plant systems remains rarely available at present. This review focuses on the sorption features and mechanisms of pollutants by MPs in soil and discussed the effects of MPs and their complexing with pollutants on soil properties, microbe and plants. The polarity of MPs significantly influenced the sorption of OPs, and different sorption mechanisms are involved for the hydrophobic and hydrophilic OPs. The sorption of OPs on MPs in soils is different from that in water. Aging of MPs can promote the sorption and migration of contaminants. The enhanced effects of biofilm in microplastisphere on the sorption of pollutants by MPs are critical, and interactions of soil environment-MPs-microbe-HMs-antibiotics increase the potential pathogens and larger release of resistance genes. The coexistence of HMs and MPs affected the growth of plants and the uptake of HMs and MPs by the plants. Moreover, the type, dose, shape and particle size of MPs have important influences on their interactions with pollutants and subsequent effects on soil properties, microbial activities and plant growth. This review also pointed out some knowledge gaps and constructive countermeasures to promote future research in this field.

Emission estimation and prioritization of veterinary pharmaceuticals in manure slurries applied to soil

Veterinary pharmaceuticals (VPs) are emitted into the environment and transfer to groundwater and surface water is diffuse and complex, whereas actual information on the fate is frequently limited. For 17 VPs of potential concern in the Netherlands, we assessed sources and emission due to animal slurry applications to soil. Hence, we examined the use of VPs in four livestock sectors in the Netherlands for 2015-2018, and quantified animal excretion rates and dissipation during slurry storage. For almost all VPs, administrated quantities to the animals during the period 2015-2018 decreased. VP concentrations during a storage period of six months could decrease between 10 and 98% depending on the compound. Predicted concentrations of VPs in slurries after storage compared well with measured concentrations in the literature. Based on the storage model outcomes, we developed a residue indicator, that quantifies the potential for residues in applied slurry. This indicator agrees well with the most frequently detected VPs in the Dutch slurries, and is therefore useful to prioritize measures aiming at reducing VP emissions into the environment.

Sales data as a measure of antibiotics usage: Concepts, examples and discussion of influencing factors

Monitoring and surveillance of antimicrobial usage in animals is a public health concern and different methods are currently discussed widely in public, science and politics. The objective of the paper is to present the available methods of monitoring and to discuss possible differences in the assessment of the antibiotics treatment. Sales data are expressed as the average amount of substance per animal or kg live weight (e.g. population‐corrected unit, PCU). The number of Defined Daily Doses (nDDDvet) is calculated by extrapolating sales data with average animal weights and defined drug doses to a number of treatments theoretically applied to animals. In contrast, the number of Used Daily Doses (nUDDvet) displays the actual number of treatments which have been applied. As sales data are relatively easily obtained, they are frequently used. However, their results are influenced by the composition of the population and by the dose of the substances. As both may vary strongly between countries, direct comparison of sales data between countries may be misleading. The concept of analysing sales data is shown by exemplarily using the methods in the ESVAC report 2015. The presentation of usage data in terms of nDDDvet or of nUDDvet increases the comparability of the data from different countries or time periods. Furthermore, fluoroquinolones and third‐/fourth‐generation cephalosporins which, among other substances, bare a potential risk for human health, are used at low doses. Hence, their use contributes to a sales reduction while contrasting the guidelines of prudent use. nDDDvet or nUDDvet have the ability to better reflect the treatment frequency and thus to better link antibiotics use to public health concerns. Quantification of antibiotics should assist to focus on prudent use of antimicrobials to reduce the burden of resistant bacteria and, thus, enhance public health, animal health and animal welfare.

Data-driven approach to using individual cattle weights to estimate mean adult dairy cattle weight

BACKGROUND

Knowledge of accurate weights of cattle is crucial for effective dosing of individual animals and for reporting antimicrobial usage. For the first time, we provide an evidence-based estimate of the average weight of UK dairy cattle to better inform farmers, veterinarians and the scientific community.

METHODS

Data were collected for 2747 lactating dairy cattle from 20 farms in the UK. Data were used to calculate a mean weight for lactating dairy cattle by breed and a UK-specific mean weight. Trends in weight by lactation number and production level were also explored.

RESULTS

Mean weight for adult dairy cattle in this study was 617 kg (sd=85.6 kg). Mean weight varied across breeds, with a range of 466 kg (sd=56.0 kg, Jersey) to 636 kg (sd=84.1, Holsteins). When scaled to UK breed proportions, the estimated UK-specific mean weight was 620 kg.

CONCLUSION

This study is the first to calculate a mean weight of adult dairy cattle in the UK based on on-farm data. Overall mean weight was higher than that most often proposed in the literature (600 kg). Evidence-informed weights are crucial as the UK works to better monitor and report metrics to measure antimicrobial use and are useful to farmers and veterinarians to inform dosing decisions.

Extrapolating Antibiotic Sales to Number of Treated Animals: Treatments in Pigs and Calves in Switzerland, 2011-2015

To evaluate the contribution of antimicrobial use in human and veterinary medicine to the emergence and spread of resistant bacteria, the use of these substances has to be accurately monitored in each setting. Currently, various initiatives collect sales data of veterinary antimicrobials, thereby providing an overview of quantities on the market. However, sales data collected at the level of wholesalers or marketing authorization holders are of limited use to associate with the prevalence of bacterial resistances at species level. We converted sales data to the number of potential treatments of calves and pigs in Switzerland for the years 2011 to 2015 using animal course doses (ACD). For each authorized product, the number of potential therapies was derived from the sales at wholesaler's level and the ACD in mg per kg. For products registered for use in multiple species, a percentage of the sales was attributed to each authorized species according to their biomass distribution. We estimated a total of 5,914,349 therapies for pigs and 1,407,450 for calves in 2015. Using the number of slaughtered animals for that year as denominator, we calculated a treatment intensity of 2.15 therapies per pig and 5.96 per calf. Between 2011 and 2015, sales of veterinary antimicrobials decreased by 30%. The calculated number of potential therapies decreased by 30% for pigs and 15% for calves. An analysis of treatment intensity at antimicrobial class level showed a decrease of 64% for colistin used in pigs, and of 7% for macrolides used in both pigs and calves. Whereas the use of 3rd and 4th generation cephalosporins in calves decreased by 15.8%, usage of fluoroquinolones increased by 10.8% in the same period. Corresponding values for pigs were −16.4 and +0.7%. This is the first extrapolation of antimicrobial usage at product level for pigs and calves in Switzerland. It shows that calves were more frequently treated than pigs with a decreasing trend for both number of therapies and use of colistin, macrolides and cephalosporins 3rd and 4th generations. Nonetheless, we calculated an increase in the usage of fluoroquinolones. Altogether, this study's outcomes allow for trend analysis and can be used to assess the relationship between antimicrobial use and resistance at the national level.

Three methods for integration of environmental risk into the benefit-risk assessment of veterinary medicinal products

Veterinary medicinal products (VMPs) require, as part of the European Union (EU) authorization process, consideration of both risks and benefits. Uses of VMPs have multiple risks (e.g., risks to the animal being treated, to the person administering the VMP) including risks to the environment. Environmental risks are not directly comparable to therapeutic benefits; there is no standardized approach to compare both environmental risks and therapeutic benefits. We have developed three methods for communicating and comparing therapeutic benefits and environmental risks for the benefit-risk assessment that supports the EU authorization process. Two of these methods support independent product evaluation (i.e., a summative classification and a visual scoring matrix classification); the other supports a comparative evaluation between alternative products (i.e., a comparative classification). The methods and the challenges to implementing a benefit-risk assessment including environmental risk are presented herein; how these concepts would work in current policy is discussed. Adaptability to scientific and policy development is considered. This work is an initial step in the development of a standardized methodology for integrated decision-making for VMPs.

Quantitative modelling to estimate the transfer of pharmaceuticals through the food production system

Use of pharmaceuticals in animal production may cause an indirect route of contamination of food products of animal origin. This study aimed to assess, through mathematical modelling, the transfer of pharmaceuticals from contaminated soil, through plant uptake, into the dairy food production chain. The scenarios, model parameters, and values refer to contaminants in emission slurry production, storage time, immission into soil, plant uptake, bioaccumulation in the animal's body, and transfer to meat and milk. Modelling results confirm the possibility of contamination of dairy cow's meat and milk due the ingestion of contaminated feed by the cattle. The estimated concentration of pharmaceutical residues obtained for meat ranged from 0 to 6 ng kg(-1) for oxytetracycline, from 0.011 to 0.181 μg kg(-1) for sulfamethoxazole, and from 4.70 to 11.86 μg kg(-1) for ketoconazole. The estimated concentrations for milk were: zero for oxytetracycline, lower than 40 ng L(-1) for sulfamethoxazole, and from 0.98 to 2.48 μg L(-1) for ketoconazole. Results obtained for the three selected pharmaceuticals indicate a minor risk for human health. This study showed that supply chain modelling could be an effective tool in assessing the indirect contamination of feedstuff and animal products by residues of pharmaceuticals. The model can easily be adjusted to other contaminants and supply chain and, in this way, present a valuable tool to underpin decision making.

Uptake of oxytetracycline, sulfamethoxazole and ketoconazole from fertilised soils by plants

This study was performed to investigate the potential for a set of two antibiotics and one antifungal compound to be taken up from the soil by plants. Plants are used for animal or human consumption, and so the measured concentrations in the plant material will be used to model potential human exposure to these compounds. The uptake by two types of plants (grass and watercress) from two types of soil was studied. The compounds used for these experiments were sulfamethoxazole, oxytetracycline and ketoconazole at concentrations of 5 and 10 mg kg(-1) in the soil. The compounds of interest were extracted out of the plant matrix by applying accelerated solvent extraction. Analyses were carried out by a LC-MS/MS. From the results, it was concluded that the plant materials used for this study were able to take up sulfamethoxazole and ketoconazole when the soil was contaminated with these compounds at a concentration ranging from 5 to 10 mg kg(-1). Sulfamethoxazole was detected in all samples, at levels ranging from 7 to 21 µ kg(-1) for grass and 4 to 7.5 µ kg(-1) for watercress. For ketoconazole, the results showed low absorption. Oxytetracycline was not detected in any sample. A partition-limited model approach was applied for the comparison of experimental and estimated data, and the relationship between physicochemical properties of the compounds and plant uptake was highlighted.

Serão os carrapaticidas agrotóxicos? Implicações na saúde e na percepção de riscos de trabalhadores da pecuária leiteira

O presente artigo tem por objetivo caracterizar os riscos relacionados ao uso de agrotóxicos na pecuária leiteira, no que tange a questões de legislação, de saúde e da percepção de riscos de trabalhadores dessa atividade. Para tanto, baseia-se em articulação metodológica que incluiu: a) revisão sistemática da literatura de referência sobre o objeto da pesquisa; b) análise da legislação correlata (produtos veterinários e agrotóxicos); c) identificação de perigos relacionados a produtos veterinários formulados à base de princípios ativos regulados como agrotóxicos; d) e análise da percepção de riscos de um grupo de trabalhadores da pecuária leiteira. A análise dos resultados do estudo apontou uma situação de especial interesse para o campo da Saúde Coletiva. No que diz respeito aos trabalhadores da pecuária leiteira, a invisibilidade de riscos associados ao manejo de agrotóxicos de uso veterinário aumenta sua exposição e está relacionada a diversos problemas de saúde, em especial nas mulheres. Esta mesma invisibilidade leva a um negligenciamento do respeito ao período de carência. Parte dos problemas pode estar associada à não classificação dos inseticidas de uso veterinários como agrotóxicos, o que torna necessária e urgente a discussão do tema.

Eco-toxic effects of sulfadiazine sodium, sulfamonomethoxine sodium and enrofloxacin on wheat, Chinese cabbage and tomato

Investigation of the toxic effects of three veterinary drugs [sulfadiazine sodium (SDS), sulfamonomethoxine sodium (SMMS), and enrofloxacin (EFLX)] on seed germination, root elongation and shoot elongation of wheat (Triticum aestivum L.), Chinese cabbage (Brassica campestris L.) and tomato (Cyphomandra betacea) was carried out. Significant linear relationships between the root and shoot elongation and the concentration of veterinary drugs addition were observed. The effects of the three veterinary drugs on seed germination of wheat, Chinese cabbages and tomato were not significant (P > 0.05), but on shoot and root elongation they were markedly significant (P < 0.05). The inhibitory rates of veterinary drugs on root and shoot elongation of crops were significantly stronger than that on seed germination. Based on IC(50) (drugs concentration when 50% plants show inhibition) of root elongation, wheat was the most sensitive plant to the toxicity of SDS with a IC(50) value as high as 28.1 mg/kg; Chinese cabbage was the most sensitive plant to the toxicity of SMMS with a IC(50) value as high as 27.1 mg/kg; tomato was the most sensitive plant to the toxicity of EFLX with a IC(50) value as high as 125.7 mg/kg. The toxic effects of sulfadiazine sodium and sulfamonometh-oxine sodium on the three crops were much higher than that of enrofloxacin.

Simulating sulfadimidine transport in surface runoff and soil at the microplot and field scale

To prevent residues of veterinary medicinal products (VMPs) from contaminating surface waters and ground water, an environmental impact assessment is required before a new product is allowed on the market. Physically based simulation models are advocated for the calculation of predicted environmental concentrations at higher tiers of the assessment process. However, the validation status of potentially useful models is poor for VMP transport. The objective of this study was to evaluate the dual-permeability model MACRO for simulation of transport of sulfonamide antibiotics in surface runoff and soil. Special focus was on effects of solute application in liquid manure, which may alter the hydraulic properties at the soil surface. To this end we used data from a microplot runoff experiment and a field experiment, both conducted on the same clay loam soil prone to preferential flow. Results showed that the model could accurately simulate concentrations of sulfadimidine and the nonreactive tracer bromide in runoff and in soil from the microplot experiments. The use of posterior parameter distributions from calibrations using the microplot data resulted in poor simulations for the field data of total sulfadimidine losses. The poor results may be due to surface runoff being instantly transferred off the field in the model, whereas in reality re-infiltration may occur. The effects of the manure application were reflected in smaller total and micropore hydraulic conductivities compared with the application in aqueous solution. These effects could easily be accounted for in regulatory modeling.