Potential impact on food safety and food security from persistent organic pollutants in top soil improvers on Mediterranean pasture

Foraging animal origin food samples as passive indicators of dioxin-like POPs contamination in industry sites: Method development, characterisation and risk assessment

Titanium dioxide (TiO2) is an important industrial chemical, and studies suggest its major production route - the chloride process could lead to the generation of unintentional dl-POPs. However, no relevant studies assessed the occurrence of dl-POPs associated with TiO2 production in the industrial zones, which is mostly due to the ultra-trace level distribution of these compounds in environmental compartments. The present study explored the novel possibility of utilising foraging animal-origin foods as sensitive indicators for addressing this challenge and generated a globally beneficial dataset by assessing the background levels of dl-POPs in the vicinity of a TiO2 production house in Southern India. Systematic sampling of foraging cow's milk and free-ranging hen's eggs was carried out from the study site, and the dl-POPs assessments were conducted utilising an in-house developed cost-effective GC-MS/MS-based analytical methodology. The median dl-POPs levels in milk and egg samples were about 3 times higher than the control samples collected from farm-fed animals and retail markets. The contaminant loads in the foraging animal-origin food samples were further traced to their presence in environmental compartments of soil and sediment and admissible degree of correlations were observed in congener fingerprints. Elevated health risks were inferred for the population in the industrial zones with weekly intakes weighing about 0.15-17 times the European Food Safety Authority-assigned levels. The consumption of foraging cow's milk was observed to have a higher contribution towards the hazard indices and cancer risk estimates and were significantly higher (p < 0.05) for children. The study also presents a critical validation of the GC-MS/MS-based method for the purpose of regulatory monitoring of dl-POPs, which could be of practical significance in economies in transition.

Factors influencing the fate of chemical food safety hazards in the terrestrial circular primary food production system-A comprehensive review

Food safety is recognized as a major hurdle in the transition toward circular food production systems due to the potential reintroduction and accumulation of chemical contaminants in these food systems. Effectively managing these hazardous contaminants in a risk-based manner requires quantitative insights into the factors influencing the presence and fate of contaminants in the entire circular food chain. A systematic literature review was performed to gain an up-to-date overview of the known factors and their influence on the transfer and accumulation of contaminants. This review focused on the terrestrial circular primary food production system, including the pathways between waste- or byproduct-based fertilizers, soil, crops, animal feed, and farmed animals. This review revealed an imbalance in research regarding the different pathways: studies on the soil-to-crop pathway were most abundant. The factors identified can be categorized as compound-related (intrinsic) factors, such as hydrophobicity, molecular weight, and chain length, and extrinsic factors, such as soil organic matter and carbon, pH, milk yield of cows, crop age, and biomass. Quantitative data on the influence of the identified factors were limited. Most studies quantified the influence of individual factors, whereas only a few studies quantified the combined effect of multiple factors. By providing a holistic insight into the influential factors and the quantification of their influence on the fate of contaminants, this review contributes to the improvement of food safety management for chemical hazards when transitioning to a circular food system.

Contamination characteristics and potential health risk of brominated flame retardants in paddy soils and rice plants around a typical e-waste recycling site in south China

Brominated flame retardants (BFRs) are widely used in various productions. As typical BFRs, polybrominated diphenyl ethers (PBDEs) are prohibited because of their toxicity and persistence. Some of the alternatives to PBDEs, new brominated flame retardants (NBFRs), have also been found in the environment and some have assigned hazardous properties and were categorized as persistent. In this study, a typical e-waste dismantling area was chosen as the study area, and the soil and rice samples were collected from the paddy fields around the circular economy park in Guiyu, China. The contaminations of PBDEs and NBFRs in soils and rice plants were detected, and the health risks associated with consumption and exposure to the environment were calculated as well. The concentrations of ∑PBDEs and ∑NBFRs in soil ranged from 283 to 928 μg/kg and 54.7-437 μg/kg, respectively. In rice plants, the majority of BFRs were concentrated in the following order: root > leaf > stem > grain. Additionally, only the PBT exhibited a stronger bioaccumulation ability in rice with the bioconcentration factors more than 1.00. The results of the health quotient calculation shown that BDE-47 might have an impact on people's health that only the HQ of BDE-47 in the soil was higher than 1.00, while there had no significant health risk in grain of BFRs. We believe that our work could assist researchers in investigating and revealing the human health effects of BFRs in soil and rice.

Organic ligands activate the dark formation of hydroxyl radicals (HO•) in surface soil/sediment: Yields, mechanisms, and applications

Soil is an important sink for various pollutants. Recent findings suggest that soil and sediment would spontaneously form HO^• through Fenton or Fenton-like reactions under natural conditions. In this study, the effects and mechanisms of organic ligands (OLs) on the occurrence of HO^• in surface soil/sediment were experimentally and computationally examined. Results confirmed that HO^• generation was ND-12.92 nmol/g in surface soil/sediment, and the addition of EDTA-2Na would significantly enhance the yields of HO^• by 1.4-352 times. Moisture was the decisive factor of soil HO^• generation. The release of Fe(II) from solid into the aqueous phase was essential for the stimulation of HO^• in EDTA-2Na suspensions. Furthermore, complexation reactions between Fe(II) and OLs would enhance single electron transfer (SET) reactions and the formation of O₂^•-. Interestingly, for specific OLs, their stimulations on SET and formation of O₂^•- would depress HO^• generation. Provoking HO^• generation by OLs could be efficiently used to degrade sulfamethoxazole in rice field sediment. The study provided new knowledge on how commonly synthetic OLs affect the HO^• generation in surface soil/sediment, and it additionally shed light on the engineered stimulation of in-situ Fenton reactions in natural soil/sediment.

Ammonia recovery from anaerobic digester centrate using onsite pilot scale bipolar membrane electrodialysis coupled to membrane stripping

Ammonia recovery from centrate of an anaerobic digester was investigated using an onsite bipolar-electrodialysis (BP-ED) pilot scale plant coupled to two liquid/liquid membrane contactor (LLMC) modules. To investigate the process performance and robustness, the pilot plant was operated at varying current densities, load ratio (current to nitrogen loading), and in continuous and intermittent current (Donnan) mode. A higher load ratio led to higher total ammonium nitrogen (TAN, sum of ammonia and ammonium) removal efficiency, whereas the increase in the applied current did not have a significant impact the TAN removal efficiency. Continuous current application resulted in the higher TAN removal compared with the Donnan dialysis mode. The lowest specific energy consumption of 6.3 kWh kg_N^-1 was recorded in the Donnan mode, with the load ratio of 1.4, at 200 L h^-1 flowrate and current density of 75 A m^-2. Lower energy demand observed in the Donnan mode was likely due to the lower scaling and fouling of the ion exchange membranes. Nevertheless, scaling and fouling limited the operation of the BP-ED stack in all operational modes, which had to be interrupted by the daily cleaning procedures. The LLMC module enabled a highly selective recovery of ammonia as ammonium sulfate ((NH₄)₂SO₄), with the concentration of ammonia ranging from 19 to 33 g_N L^-1. However, the analysis of per- and polyfluoroalkyl substances (PFASs) in the obtained (NH₄)₂SO₄ product revealed the presence of 212-253 ng L^-1 of 6:2 fluorotelomer sulfonate (FTS), a common substitute of legacy PFAS. Given the very low concentrations of 6:2 FTS (i.e., < 2 ng L^-1) encountered in the concentrated stream, 6:2 FTS was likely released from the Teflon-based components in the sulfuric acid dosage line. Thus, careful selection of the pilot plant tubing, pumps and other components is required to avoid any risks associated with the PFAS presence and ensure safe use of the final product as fertilizer.

A sensitive method for the detection of legacy and emerging per- and polyfluorinated alkyl substances (PFAS) in dairy milk

There is widespread contamination by per- and polyfluoroalkyl substances (PFAS) across the globe, with adverse effects on human and environmental health. For human exposure, drinking water and dietary exposure have been recognized as important PFAS exposure pathway for the general population. Several documented cases of dairy milk contamination by PFAS have raised concerns over this exposure pathway in general. A sensitive method for determination of 27 PFAS in milk was hence modified and applied on raw and processed milk samples from 13 farms across the United States (U.S.). A combination of acid and basic extraction method and ENVI-Carb clean-up achieved recoveries of targeted PFAS between 70 and 141%. The method detection limits (MDL) ranged from 0.8 to 22 ng/L (for 26 PFAS) and 144 ng/L for perfluorobutanoic acid (PFBA). The uniqueness of this method is considered in the targeted screening of a broad range of legacy PFAS, as well as perfluorinated sulfonamide species and fluorotelomer sulfonates. No legacy PFAS were detected in 13 milk samples from regions of concern given local use of biosolids or proximity to fire training areas. Overall, then, the uptake of perfluoroalkyl acids (PFAA) from dairy milk in the U.S. is considered low.

Per- and polyfluoroalkyl substances (PFAS) in livestock and game species: A review

Per- and polyfluoroalkyl substances (PFAS) are synthetic, organic chemicals that resist environmental breakdown. The properties that made PFAS into an industrial success also led to their persistence and bioaccumulation. As PFAS were widely used for many decades their presence is evident globally, and their persistence and potential for toxicity create concern for human, animal and environmental health. Following the precautionary principle, a reduction in human exposure is generally recommended. The most significant source of human exposure to PFAS is dietary intake (food and water) with additional exposure via dust. As PFAS concentrations have been more frequently studied in aquatic food sources, there is less understanding of exposure via terrestrial animals. To further define human exposure via animal products, it is necessary to determine PFAS concentrations and persistence in terrestrial livestock and game species. Studies assessing ambient concentrations of PFAS have noted that, aside from point sources of contamination, there is generally low input of PFAS into terrestrial agricultural food chains. However, livestock and game species may be exposed to PFAS via contaminated water, soil, substrate, air or food, and the contribution of these exposures to PFAS concentrations in food products is less well studied. This review focuses on perfluoroalkyl substances (PFAAs) and compiles information from terrestrial livestock and game species as a source of dietary exposure in humans, and discusses toxicokinetics and health effects in animals, while identifying future focus areas. Publications describing the transfer of PFAAs to farmed and hunted animals are scarce, and demonstrate large variability in distribution and elimination. We outline several relatively small, short-term studies in cattle, sheep, pigs and poultry. While negative effects have not been noted, the poultry investigations were the only studies to explicitly assess health effects. Comparative information is presented on PFAA concentrations in livestock products and edible tissues of game animals.

Concentrations of organic contaminants in industrial and municipal bioresources recycled in agriculture in the UK

Many types of bioresource materials are beneficially recycled in agriculture for soil improvement and as alternative bedding materials for livestock, but they also potentially transfer contaminants into plant and animal foods. Representative types of industrial and municipal bioresources were selected to assess the extent of organic chemical contamination, including: (i) land applied materials: treated sewage sludge (biosolids), meat and bone meal ash (MBMA), poultry litter ash (PLA), paper sludge ash (PSA) and compost-like-output (CLO), and (ii) bedding materials: recycled waste wood (RWW), dried paper sludge (DPS), paper sludge ash (PSA) and shredded cardboard. The materials generally contained lower concentrations of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) relative to earlier reports, indicating the decline in environmental emissions of these established contaminants. However, concentrations of polycyclic aromatic hydrocarbons (PAHs) remain elevated in biosolids samples from urban catchments. Polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) were present in larger amounts in biosolids and CLO compared to their chlorinated counterparts and hence are of potentially greater significance in contemporary materials. The presence of non-ortho-polychlorinated biphenyls (PCBs) in DPS was probably due to non-legacy sources of PCBs in paper production. Flame retardent chemicals were one of the most significant and extensive groups of contaminants found in the bioresource materials. Decabromodiphenylether (deca-BDE) was the most abundant polybrominated diphenyl ether (PBDE) and may explain the formation and high concentrations of PBDD/Fs detected. Emerging flame retardant compounds, including: decabromodiphenylethane (DBDPE) and organophosphate flame retardants (OPFRs), were also detected in several of the materials. The profile of perfluoroalkyl substances (PFAS) depended on the type of waste category; perfluoroundecanoic acid (PFUnDA) was the most significant PFAS for DPS, whereas perfluorooctane sulfonate (PFOS) was dominant in biosolids and CLO. The concentrations of polychlorinated alkanes (PCAs) and di-2-ethylhexyl phthalate (DEHP) were generally much larger than the other contaminants measured, indicating that there are major anthropogenic sources of these potentially hazardous chemicals entering the environment. The study results suggest that continued vigilance is required to control emissions and sources of these contaminants to support the beneficial use of secondary bioresource materials.

Waste Management through Composting: Challenges and Potentials

Composting is the controlled conversion of degradable organic products and wastes into stable products with the aid of microorganisms. Composting is a long-used technology, though it has some shortcomings that have reduced its extensive usage and efficiency. The shortcomings include pathogen detection, low nutrient status, long duration of composting, long mineralization duration, and odor production. These challenges have publicized the use of chemical fertilizers produced through the Haber–Bosch process as an alternative to compost over time. Chemical fertilizers make nutrients readily available to plants, but their disadvantages outweigh their advantages. For example, chemical fertilizers contribute to greenhouse effects, environmental pollution, death of soil organisms and marine inhabitants, ozone layer depletion, and human diseases. These have resulted in farmers reverting to the application of composts as a means of restoring soil fertility. Composting is a fundamental process in agriculture and helps in the recycling of farm wastes. The long duration of composting is a challenge; this is due to the presence of materials that take a longer time to compost, especially during co-composting. This review discusses the proper management of wastes through composting, different composting methods, the factors affecting composting, long-duration composting, the mechanism behind it, the present trends in composting and prospects. The extraction of mono-fertilizers from compost, development of strips to test for the availability of heavy metals and pathogens as well as an odor-trapping technique can go a long way in enhancing composting techniques. The addition of activators to raw materials can help to improve the nutritional quality of compost. This review further recommends that degradable organic material in which composts slowly should be assessed for their ability to mineralize slowly, which could make them advantageous to perennial or biennial crops. Viricides, fungicides, anti-nematodes, and anti-bacterial of plant or organic sources could as well be added to improve compost quality. The enhancement of composting duration will also be useful.

Assessment of pops contaminated sites and the need for stringent soil standards for food safety for the protection of human health

Persistent organic pollutants (POPs) including PCDD/Fs, PCBs and organochlorine pesticides (OCPs) are among the most important and hazardous pollutants of soil. Food producing animals such as chicken, beef, sheep and goats can take up soil while grazing or living outdoors (free-range) and this can result in contamination. In recent decades, large quantities of brominated flame retardants such as polybrominated diphenyl ethers (PBDEs), short-chain chlorinated paraffins (SCCPs) and per- and polyfluorinated alkylated substances (PFAS) have been produced and released into the environment and this has resulted in widespread contamination of soils and other environmental matrices. These POPs also bioaccumulate and can contaminate food of animal origin resulting in indirect exposure of humans. Recent assessments of chicken and beef have shown that surprisingly low concentrations of PCBs and PCDD/Fs in soil can result in exceedances of regulatory limits in food. Soil contamination limits have been established in a number of countries for PCDD/Fs but it has been shown that the contamination levels which result in regulatory limits in food (the maximum levels in the European Union) being exceeded, are below all the existing soil regulatory limits. 'Safe' soil levels are exceeded in many areas around emission sources of PCDD/Fs and PCBs. On the other hand, PCDD/F and dioxin-like PCB levels in soil in rural areas, without a contamination source, are normally safe for food producing animals housed outdoors resulting in healthy food (e.g. meat, eggs, milk). For the majority of POPs (e.g. PBDEs, PFOS, PFOA, SCCP) no regulatory limits in soils exist. There is, therefore, an urgent need to develop appropriate and protective soil standards minimising human exposure from food producing animals housed outdoors. Furthermore, there is an urgent need to eliminate POPs pollution sources for soils and to control, secure and remediate contaminated sites and reservoirs, in order to reduce exposure and guarantee food safety.

Intake estimates of dioxins and dioxin-like polychlorobiphenyls in the Italian general population from the 2013-2016 results of official monitoring plans in food

The implementation of the European Union strategy for polychlorodibenzo-dioxins and -furans (PCDD/Fs), and dioxin-like polychlorobiphenyls (DL-PCBs) is determining a general reduction of their presence in the environment and in the food chain. The most important route for human exposure to these substances is food consumption and, as a consequence, a progressive decrease of their dietary intake has been observed in the last decades. In this context, it seemed worth updating the PCDD/F and DL-PCB intake estimation for the Italian population. A total of 2659 samples of food of animal and vegetable origin analyzed for PCDD/Fs and DL-PCBs in the period 2013-2016 by accredited official laboratories and the national food consumption database were considered for the dietary intake assessment in different age groups of the Italian general population The median cumulative intake estimates expressed as pg WHO-TEQ/kg body weight per day and computed with a deterministic and a probabilistic approach were 1.40-1.52 for children, 0.82-0.85 for adolescents, and 0.64-0.61 for adults, respectively. Such results confirm the decreasing trend of PCDD/F and DL-PCB dietary intake even though the Tolerable Daily Intake (TDI) value of 2 WHO-TEQ/kg body weight per day is exceeded at the 95th percentile for all age groups, with children as sensitive group. Most contributing food categories to the intake resulted fish, food of vegetable origin, and cheese. A sensitivity analysis was also performed to calculate the target contamination levels able to keep the dietary exposure below the TDI. Computed target levels fall between P50 and P97 of the occurrence distribution of the main food groups, meaning that most of the Italian food production can be considered safe.

Reviewing the relevance of dioxin and PCB sources for food from animal origin and the need for their inventory, control and management

BACKGROUND

In the past, cases of PCDD/F and PCB contamination exceeding limits in food from animal origin (eggs, meat or milk) were mainly caused by industrially produced feed. But in the last decade, exceedances of EU limit values were discovered more frequently for PCDD/Fs or dioxin-like(dl)-PCBs from free range chicken, sheep, and beef, often in the absence of any known contamination source.

RESULTS

The German Environment Agency initiated a project to elucidate the entry of PCBs and PCDD/Fs in food related to environmental contamination. This paper summarizes the most important findings. Food products from farm animals sensitive to dioxin/PCB exposure-suckling calves and laying hens housed outdoor-can exceed EU maximum levels at soil concentrations that have previously been considered as safe. Maximum permitted levels can already be exceeded in beef/veal when soil is contaminated around 5 ng PCB-TEQ/kg dry matter (dm). For eggs/broiler, this can occur at a concentration of PCDD/Fs in soil below 5 ng PCDD/F-PCB-TEQ/kg dm. Egg consumers-especially young children-can easily exceed health-based guidance values (TDI). The soil-chicken egg exposure pathway is probably the most sensitive route for human exposure to both dl-PCBs and PCDD/Fs from soil and needs to be considered for soil guidelines. The study also found that calves from suckler cow herds are most prone to the impacts of dl-PCB contamination due to the excretion/accumulation via milk. PCB (and PCDD/F) intake for free-range cattle stems from feed and soil. Daily dl-PCB intake for suckler cow herds must in average be less than 2 ng PCB-TEQ/day. This translates to a maximum concentration in grass of 0.2 ng PCB-TEQ/kg dm which is less than 1/6 of the current EU maximum permitted level. This review compiles sources for PCDD/Fs and PCBs relevant to environmental contamination in respect to food safety. It also includes considerations on assessment of emerging POPs.

CONCLUSIONS

The major sources of PCDD/F and dl-PCB contamination of food of animal origin in Germany are (1) soils contaminated from past PCB and PCDD/F releases; (2) PCBs emitted from buildings and constructions; (3) PCBs present at farms. Impacted areas need to be assessed with respect to potential contamination of food-producing animals. Livestock management techniques can reduce exposure to PCDD/Fs and PCBs. Further research and regulatory action are needed to overcome gaps. Control and reduction measures are recommended for emission sources and new listed and emerging POPs to ensure food safety.

Comparative analysis of metagenomes of Italian top soil improvers

Biosolids originating from Municipal Waste Water Treatment Plants are proposed as top soil improvers (TSI) for their beneficial input of organic carbon on agriculture lands. Their use to amend soil is controversial, as it may lead to the presence of emerging hazards of anthropogenic or animal origin in the environment devoted to food production. In this study, we used a shotgun metagenomics sequencing as a tool to perform a characterization of the hazards related with the TSIs. The samples showed the presence of many virulence genes associated to different diarrheagenic E. coli pathotypes as well as of different antimicrobial resistance-associated genes. The genes conferring resistance to Fluoroquinolones was the most relevant class of antimicrobial resistance genes observed in all the samples tested. To a lesser extent traits associated with the resistance to Methicillin in Staphylococci and genes conferring resistance to Streptothricin, Fosfomycin and Vancomycin were also identified. The most represented metal resistance genes were cobalt-zinc-cadmium related, accounting for 15-50% of the sequence reads in the different metagenomes out of the total number of those mapping on the class of resistance to compounds determinants. Moreover the taxonomic analysis performed by comparing compost-based samples and biosolids derived from municipal sewage-sludges treatments divided the samples into separate populations, based on the microbiota composition. The results confirm that the metagenomics is efficient to detect genomic traits associated with pathogens and antimicrobial resistance in complex matrices and this approach can be efficiently used for the traceability of TSI samples using the microorganisms' profiles as indicators of their origin.