Elimination of dioxins in milk by dairy cows after the long-term intake of contaminated sugar beet pellets

Occurrence and dietary intake of dioxins, furans (PCDD/Fs), PCBs, and flame retardants (PBDEs and HBCDDs) in baby food and infant formula

This study determines the levels of 49 persistent organic pollutants which were grouped into polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecanes (HBCDDs), in infant formula and varieties of baby food. The analyzed samples (n = 80) came from stores all over Poland. The presence of PCDD/F, PCDD/F/PCB and non dioxin-like (ndl)-PCB congeners above the maximum levels stipulated in Commission Regulation (EU) No 1259/2011 was not detected in any sample. The determined average content of PCDD/Fs/dl-PCBs in the tested baby foods was in the range of 4-10 % of the maximum level, and content of ndl-PCBs was in the range of 2-6 % of the maximum level. Despite these low levels of dioxins, furans, and PCBs, a risk analysis assuming weekly consumption of the recommended food intake showed exceedances of the tolerable weekly intake (TWI). The content of flame retardants was low in all examined categories of food for children and infant formula. The lower-bound concentration of the sum of HBCDD isomers (LB ∑HBCDDs) ranged from below the limit of quantification (LOQ) to 0.0313 ng/g w.w. and the concentration of ∑PBDEs was in a 0.001-1.014 ng/g w.w. range. Neither infant formula nor baby food contributed considerably to infant exposure to HBCDDs or PBDEs. Our research indicates that the safe exposure thresholds for dioxins and PCBs in foods for infants and young children may be too high and perhaps it may be necessary to amend the legislation setting acceptable limits for baby food. It seems reasonable to introduce a recommendation on the frequency of food consumption for children and the control of raw materials for food production, in particular fish and cow milk, should be a permanent control point in the food safety assurance system.

Experimental Study on the Transfer of Polychlorinated Biphenyls (PCBs) and Polychlorinated Dibenzo-p-dioxins and Dibenzofurans (PCDD/Fs) into Milk of High-Yielding Cows during Negative and Positive Energy Balance

Dioxin-like polychlorinated biphenyls (dl-PCBs) as well as polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are a major concern for food safety, especially in fat-containing foods of animal origin, such as milk. Due to the lipophilic character of PCDD/Fs and PCBs, it is of special interest to explore whether the metabolic state of high-yielding cows influences the transfer rates into milk. Five German Holstein cows were orally exposed to a mixture of 17 PCDD/Fs, 12 dl-PCBs, and 6 non-dioxin-like PCBs (ndl-PCBs) for two dosing periods of 28 days each. The first period covered the negative energy balance (NEB) after calving, while the second period addressed the positive energy balance (PEB) in late lactation. Each dosing period was followed by a depuration period of around 100 days. During the NEB phase, the transfer rates of 14 PCDD/Fs and 7 dl-PCBs quantified were significantly (p ≤ 0.1) higher compared to the PEB phase, indicating an influence of the metabolic state on the transfer. Furthermore, the congener-specific transfer rates (0.3-39%) were in the range of the results from former studies. This indicates that the milk yield of the exposed cows is not the only determining factor for the transfer of these congeners into milk.

Polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in bivalve molluscs. Risk to Polish consumers?

Introduction

Concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were investigated in six species of bivalve mollusc purchased on the Polish retail market. The risk to consumers was calculated as a percentage of the tolerable weekly intake (TWI) (2 pg World Health Organization toxic equivalent (WHO-TEQ) kg-1 body weight (b.w.)).

Material and Methods

Altogether 32 samples were analysed using an isotope dilution technique with high resolution gas chromatography coupled with high resolution mass spectrometry.

Results

Low levels of all analysed compounds were found. The range of PCDD/Fs was 0.08-0.37 pg WHO-TEQ g-1 of wet weight (w.w.) and 0.04-0.41 pg WHO-TEQ g-1 w.w. for DL-PCBs. The highest concentrations of all analysed compounds were found in Pacific oysters, at 0.30 pg WHO-TEQ g-1 w.w. for the sum of PCDD/Fs and 0.19 pg WHO-TEQ g-1 for the sum of DL-PCBs. These concentrations were 2-4 times higher than those detected in the other analysed mollusc species. Different species-dependent congener profiles were observed for PCDD/F concentrations, while PCB congener concentration profiles were species independent. The risk to consumers was assessed relating theoretical intakes of PCDD/Fs and DL-PCBs per 25, 50 and 100 g of consumption of molluscs per week to the TWI.

Conclusion

Taking into account the low consumption of molluscs in Poland and low concentrations of analysed compounds, neither adults nor children are likely to exceed the TWI by ingestion of food in this category.

Dioxin transfer simulation from feed to animal tissues and risk assessment

Dioxins might be introduced into the food chain through a direct or an indirect pathway. The main source of human exposure to dioxins is food of animal origin, whereas feeds are the main route of exposure of farmed animals to dioxins and polychlorinated biphenyls. The aim of the study was to simulate dioxin passage from feed to tissues on farm animals using transfer models, and, in addition, to assess the risk to consumers of food of animal origin. From over 700 feed samples analyzed over the course of 9 years (2013-2021), those exceeding the maximum permissible levels set down in Commission Regulation No 277/2012/EU were selected. These samples being derived from real cases of dioxin contamination made it possible to present the most realistic picture of the effects these feed materials could have had if they had entered the food chain. Three species of animals were selected (laying hens, dairy cattle and slaughter pigs), for which feed materials with dioxin contents exceeding the maximum permissible level were selected in accordance with the nutritional recommendations. The calculated PCDD/PCDF concentrations in chicken eggs, cow's milk and pork were above the maximum permissible level in most cases.

Feed as a source of dioxins and PCBs

Dioxins (PCDD/PCDF) and polychlorinated biphenyls (PCBs) are a group of undesirable chemicals classified as persistent organic pollutants (POPs). The main route of human exposure to these compounds is through the diet (about 80%), with food of animal origin being the predominant source. For this reason, animal feed can contribute significantly to the presence of these compounds in food. The aim of this study was to present the concentrations of dioxins and PCBs as well as congener profiles in feed exceeding the acceptable limits (277/2012/EU). In addition, an attempt was made to identify the source of contamination for the different types of contaminated feedstuffs. Among a total of 743 samples of feed materials from the Polish market tested between 2013 and 2021, exceedances of the maximum levels of dioxins and PCBs were found in 21 samples (2.8%). The largest group among the non-compliant feed samples were feed materials of plant origin (43%) followed in decreasing order by vegetable oils and fats of animal origin (24%), materials of mineral origin (9%), and fish oils and meals (5%). The exceedances of the dioxin limits in the category feed materials of plant origin were only caused by dried materials (pulp, dried alfalfa, dried apple). Furthermore, for 8 (1%) samples, the concentrations of test substances exceeding the Action Levels (AL) were recorded.

Transfer of Non-Dioxin-Like Polychlorinated Biphenyls (ndl-PCBs) from Feed and Soil into Hen Eggs

Understanding the transfer of non-dioxin-like polychlorinated biphenyls (ndl-PCBs) into foods of animal origin is crucial for human health risk assessment. In two experiments, we investigated the transfer of ndl-PCBs from contaminated feed and soil into eggs and meat of laying hens. The transfer from the feed was investigated with 30 laying hens. The treated hens were divided into two groups fed a contaminated diet (12.8 μg/kg sum of indicator ndl-PCBs; 88% dry matter (DM)) for 28 and 63 days, respectively, and then experienced a depuration period of 100 days with control feed. The transfer from soil was investigated with 72 laying hens kept in three separate outdoor pens (with three levels of ndl-PCB soil contamination) for 168 days. In both experiments, eggs were collected and analyzed for ndl-PCBs. In the second experiment, animals (n = 3 at the beginning, n = 6 per group after 42, 84, and 168 days) were slaughtered to determine ndl-PCBs in meat (breast muscle tissue) fat. The transfer of ndl-PCB from both feed and soil was clearly measurable and concentrations in eggs quickly exceeded maximum levels. Clear differences between individual congeners were observed. In particular, the low-chlorinated ndl-PCBs 52 and 101 are hardly found in eggs, despite their relatively high concentration in feed and soil. PCBs 138, 153, and 180, on the other hand, were found in large proportions in eggs and meat.

PCDD/Fs, DL-PCBs, and NDL-PCBs in Dairy Cows: Carryover in Milk from a Controlled Feeding Study

A feeding study was carried out to investigate the kinetics in cow milk of the 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), the 12 dioxin-like polychlorinated biphenyls (DL-PCBs), and the 6 non-dioxin-like PCBs (NDL-PCBs) regulated by the European (EU) legislation. A fortified ration (ΣPCDD/Fs and DL-PCBs: 24.68 ng TEQ/day/cow; ΣNDL-PCBs: 163.99 μg/day/cow) was given to the animals for 49 days, followed by 42 days on clean feed. EU maximum limit for TEQ_{PCDD/F+DL-PCB} was exceeded in milk after 1 week of exposure, while for ΣNDL-PCBs, after 5 weeks. Milk compliance was restored after 1 week on clean feed, but to return to the basal TEQ_{PCDD/F+DL-PCB} it took 42 days. At the end of the study, ΣNDL-PCBs had not yet reached the basal level. The carryover rate of ΣNDL-PCBs was 25.4%, while the carryover rate of TEQ_{PCDD/F+DL-PCB} was 36.9%. The latter was mainly affected by the 12 congeners contributing most to the toxic equivalent (TEQ) level, explaining the fast overcome of the maximum limit in milk.

Levels and trends of PCDD/Fs and DL-PCBs in Polish animal feeds, 2004-2017

Feed control is essential for the safety of animal-origin food. It is estimated that more than 80% of human exposure to dioxins and related compounds comes from the consumption of animal-origin food, and farm animals are exposed to dioxins mainly through the feed. A monitoring programme for dioxins (polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs)) and dioxin-like polychlorinated biphenyls (DL-PCBs) was conducted in the Polish feed market between 2004 and 2017. Using two complementary ISO 17025-accredited analytical methods (bioassay and high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS)), 2919 samples of plant, animal and minerals origin were analysed. The total number of samples exceeding the maximum limit (ML) was 52, which is 1.8% of all tested samples. They all contained PCDD/Fs in concentrations over the ML, and in 16 samples the limit for the sum of PCDD/F/DL-PCBs was also exceeded. The highest dioxins level was found in feedstuffs derived from Baltic fish; the fish oil was followed by fish meal. Low-chlorinated furans (2.3,7,8 TCDF, 2,3,4,7,8-PCDF and 1,2,3,7,8-PeCDF) were dominant and these congeners accounted for the toxicity expressed in WHO toxic equivalents (WHO-TEQ). In this category, 155 out of the 498 samples (32%) exceeded the action threshold (AT) for PCDD/Fs and in 10 samples (2.0%) for DL-PCBs. Non-compliant fish meals were found in 34 (5.6%) of the tested samples, in 0.7% of compound feeds, and in 1.5% of plant-origin materials. Seven dried plant-derived materials contained PCDD/F level above ML, including alfalfa, maize, apple, basil and beet pulp pellets containing molasses. The dry vegetable materials were mostly contaminated by the 2,3,7,8-furans, the congeners arising from a faulty drying process. No significant time trend can be seen. From the obtained results, it can be concluded that concentrations of PCDD/Fs and DL-PCBs in Polish feed materials were sufficiently low to ensure low concentrations in animal-derived products.

Application of the AhR Reporter Gene Assay for the Determination of PCDD/Fs and DL-PCBs in Feed Samples

Introduction

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) belong to a well-known group of pollutants. Present in feedstuffs, they bioaccumulate in tissues of food-producing animals. Food is the source of over 90% of human PCDD/Fs and DL-PCBs intake. Thus, feed control is one of the pillars of the EU strategy and a mean of reducing human exposure. The article presents AhR based reporter gene bioassay method for PCDD/Fs and DL-PCBs analysis in feed and its validation results.

Material and Methods

Analytes were extracted from samples with fat. Subsequently, fat and other interferences were removed from extract using sulphuric acid modified silica. Extract was further cleaned and PCDD/Fs separated from DL-PCBs using carbon column. Contaminants detection was performed using H1L6.1c3 cell line, which produces luciferase in response to AhR ligands present in extract.

Results

Performance characteristics (repeatability, reproducibility, and apparent recovery) fulfil the requirements of Regulation 2017/771/EU. The positive correlation between bioassay and reference HRGC-HRMS method was confirmed. Moreover, the role of screening method used in connection with the confirmatory HRGC-HRMS method in providing feed and food safety has been discussed.

Conclusion

Bioassay is a useful method for dioxin and DL-PCBs analysis, allowing cost reduction of monitoring programmes with minimal risk of false negative results.