Carry-over of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in dairy cows fed smoke contaminated maize silage or sugar beet pulp

Accumulation Rate, Depuration Kinetics, and Tissue Distribution of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans (PCDD/Fs) in Suckler Ewes (Ovis aries)

Understanding the transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in farm animals is essential for ensuring food safety, but such information for suckler ewes (Ovis aries) has been lacking. This work quantifies the accumulation, tissue distribution, and depuration kinetics of PCDD/Fs in these animals. Six suckler ewes (EXP group) were exposed to PCDD/Fs through contaminated hay (2.3-12.7 ng toxic-equivalent kg-1 dry matter) and then allowed to depurate by switching to noncontaminated hay from 29 days of lactation. Four control ewes were fed continuously with noncontaminated hay. At different time points covering depuration, weaning and slaughter, PCDD/F analysis of milk (three time points), blood and sternal adipose tissue (five time points), Longissimus thoracis muscle, liver, and empty body homogenate at slaughter (188 days of depuration) was performed. A relevant PCDD/F bioaccumulation was observed from oral intake in milk and adipose tissue (biotransfer factors of 1.24 and 1.06 day kg-1 lipids for the sum toxic-equivalent, respectively) in the EXP ewes, especially for penta- and hexa-chlorinated congeners. The EXP ewes' adipose tissue started at 10-fold the EU maximum level (ML) and showed depuration below the ML after 130 days. Specific PCDD/F accumulation in the ewe liver was observed, especially for dibenzofurans. These toxicokinetic data can inform recommendations to ensure the chemical safety of sheep food products.

Generic methodology to prevent food contamination by soil born legacy POPs in free range livestock

Government monitoring commonly includes regulating POPs in animal feed and products of animal origin, with many countries setting Maximum Residue Levels (MRLs) to ensure safe tolerable concentrations. However, these MRLs do not address the presence of most POP families in soil, where concentrations can be much higher due to the contaminants' strong affinity and persistence in comparison to other environmental matrices. Extensive damage to food and production systems during a pollution incident causing soil contamination by POPs lead to severe economic and social consequences for the affected area. To mitigate these effects, it is crucial to implement necessary measures for consumer protection while also focusing on rehabilitating conditions for food production, tailored to both commercial farms and private holders. In this context, the present work aims to develop and test a methodology for assessing the tolerable concentration of the most cancerogenic legacy POPs in soil for various livestock animals in diverse rearing systems ensuring the safety of food of animal origin. Therefore, we summarize existing knowledge about the risk of POP transfer in different livestock breeding systems via soil exposure, and modeling via a backward calculation from the MRLs the corresponding tolerable quantity of POPs that may be ingested by animals in the considered rearing system. Results of these simulations showed that soil ingestion is a predominant contamination pathway, which is a central factor in the risk assessment of POP exposure on livestock farms, especially in free-range systems. In field conditions of POP exposure, low productive animals may be more susceptible to uptake through soil than high-yielding animals, even if the feed respected MRLs. Results show that PCDD/Fs revealed the lowest security ratio for low productive dairy cows (1.5) compared to high productive ones (52). Laying hens with a productivity of 45% show also as a high sensitivity to POPs exposure via soil ingestion. Indeed, their security ratio for PCDD/Fs, lindane and DDT were 3, 2 and 1, respectively. In perspective, proposed methodology can be adapted for assessing the risk of industrial POPs newly listed in the Stockholm Convention. In practice, it could be useful for food producers to apprehend their own risk of chemical contamination.

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.

Transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) from oral exposure into cow's milk - Part I: state of knowledge and uncertainties

Polychlorinated dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) (collectively and colloquially referred to as 'dioxins') as well as polychlorinated biphenyls (PCBs) are persistent and ubiquitous environmental contaminants that may unintentionally enter and accumulate along the food chain. Owing to their chronic toxic effects in humans and bioaccumulative properties, their presence in feed and food requires particular attention. One important exposure pathway for consumers is consumption of milk and dairy products. Their transfer from feed to milk has been studied for the past 50 years to quantify the uptake and elimination kinetics. We extracted transfer parameters (transfer rate, transfer factor, biotransfer factor and elimination half-lives) in a machine-readable format from seventy-six primary and twenty-nine secondary literature items. Kinetic data for some toxicologically relevant dioxin congeners and the elimination half-lives of dioxin-like PCBs are still not available. A well-defined selection of transfer parameters from literature was statistically analysed and shown to display high variability. To understand this variability, we discuss the data with an emphasis on influencing factors, such as experimental conditions, cow performance parameters and metabolic state. While no universal interpretation could be derived, a tendency for increased transfer into milk is apparently connected to an increase in milk yield and milk fat yield as well as during times of body fat mobilisation, for example during the negative energy balance after calving. Over the past decades, milk yield has increased to over 40 kg/d during high lactation, so more research is needed on how this impacts feed to food transfer for PCDD/Fs and PCBs.

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.

Kinetics of PCDD/Fs from feed to cow milk and its implications for food safety

Guideline levels of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in feed and food have been separately recommended for the official food safety control around the world. However, less is considered about the transfer effect of PCDD/Fs from feed to food, and consequently possible human exposure risk. In this study, different controlled feeding experiments (E1 group: 4.92 pg TEQ/g in feed, E2 group: 0.61 pg TEQ/g in feed) were conducted on dairy cow (Chinese Holstein breed) to evaluate kinetics of PCDD/Fs from feed to milk and blood. Even though the PCDD/F level in feed in E2 was satisfied with the EU Regulation (No 277/2012), the TEQ levels in milk and tissues exceeded the European Union maximum level (EU ML) after approximately one-week exposure. The dynamic variation in milk during the initial 20-day exposure was successfully described by a first-order kinetic model. The levels at the plateau period showed a significant linear relationship (p < 0.01, R² = 0.98) against the intake amounts from feed. Based on modeling, a maximum content was obtained at approximately 0.33 pg TEQ/g in cow feed with 12 % moisture to ensure the milk and meat safety under the current regulatory requirements of EU for cow-origin food. After the cease of exposure, the PCDD/F levels in milk declined below the EU ML within 40 days, while those in meat were still higher than the EU ML over 160 days. In serum, PCDD/Fs detected in E1 showed a similar dynamic variation during the exposure period. Regarding congener profile, higher-chlorinated congeners tended to transfer from feed to feces, whereas lower ones were preferably transferred into milk, which required specific concern about the metabolic effect of PCDD/Fs in large mammals. This study revealed a necessity for re-evaluation of official regulation on pollutants in cow feed and cow-origin food in terms of biotransfer and bioaccumulation.

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.

Transgenerational mass balance and tissue distribution of PCBs and PCDD/Fs from grass silage and soil into cow-calf continuum

Grass-based suckling beef-derived foods occasionally exceed regulatory levels for polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). Ensuring chemical safety requires understanding the cow-calf transgenerational PCB and PCDD/F fate. The current focus was on dairy cows, omitting transgenerational fate and suckling beef-related physiological effects. This study aimed to investigate PCB and PCDD/F absorption, distribution, metabolism, and excretion within 12 Simmental cows (six primiparous/six multiparous) and 12 calves fed with the milk of their respective mothers for 109 days prepartum until 288 days in milk (DIM), i.e., slaughter time. Eight cows were exposed to a grass silage-soil mixture. Four were decontaminated after DIM164 by receiving uncontaminated grass silage, which four control cows received. An input-output balance during gestation and lactation was computed from PCB, PCDD/F, and lipid inputs (solid feed/milk intakes), outputs (fecal/milk excretions), and body storage (initial/final burdens). At slaughter, PCB and PCDD/F tissue distribution, and lipid allometry were linked. Apparent PCB and PCDD/F absorption rates and metabolized fractions decreased with increasing chlorination. In calves, PCB absorption showed no effect due to chlorination (steady range: 71-87%). High-chlorinated PCB and PCDD/F absorption rates decreased when provided through soil. Cows excreted PCBs and PCDD/Fs via feces (50% relative to input) and milk (9%) and accumulated only 5% in their body, whereas calves accumulated the largest fraction of the total input in their bodies (44%). Cow physiology affected accumulation and excretion, as in primiparous cows, net body burden and milk assimilation efficiencies were higher and lower, respectively, than in multiparous. Liver-specific enrichment was observed in cows and calves (7.0- and 3.2-fold iPCB and dlPCB + PCDD/F TEQ, compared to empty body-based lipid concentrations), whereas iPCBs were also enriched in kidneys (3.1-fold) and muscles (1.5-fold). Consequently, adipose concentrations did not perfectly represent most edible beef tissues. This highlights the essence of integrating the interplay between physicochemical pollutant properties and animal physiology in transgenerational transfer assessments of PCBs and PCDD/Fs.

Accumulation and decontamination kinetics of PCBs and PCDD/Fs from grass silage and soil in a transgenerational cow-calf setting

Polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) are bioaccumulative pollutants that endanger bovine food safety. Bioaccumulation depends, among others, on the physiological dynamics of the cow's reproductive cycle. However, recent studies have focused only on near steady-state situations. Thus, the effects of animal physiology on PCB + PCDD/F transfer from grass silage and soil to cows' blood, adipose tissue, and milk and subsequently to suckling calves during gestation and lactation were investigated. In the exposed group, nine cows ate a grass silage/contaminated soil mixture (6.6 ± 0.8 μg iPCBs and 2.6 ± 0.4 ng dlPCB + PCDD/F TEQ kg_DM^-1) for 109 days prepartum until 288 days in milk (DIM). Four of these cows underwent decontamination after DIM164, receiving the same clean grass silage as the four control cows during the experiment. Calves were fed the milk of their respective mothers. In the exposed group, transgenerational bioaccumulation occurred until DIM164, with calf blood and adipose tissue PCB + PCDD/F concentrations reaching levels twice as high as those in their respective mothers. Transfer rates from oral intake to milk ranged from 0.1 up to 42%, depending on pollutant congener, dietary treatment, and reproductive parity of the cow. Congener and parity also influenced the decontamination half-lives of milk. In decontaminated calves, declines in adipose tissue PCB + PCDD/F concentrations coincided with increases in body fat mass. Therefore, it is essential to know the physiological characteristics of cattle, exposure dose and duration, and physicochemical compound properties to perform reliable transfer assessments.

Deriving “potential target values” of PCDD/F in animal feed: the role of livestock at the interface between feed and food chain

Linking derivation of potential target values of PCDD/Fs in animal feed with risk assessment for consumer protection is a challenge when tolerable weekly intake (TWI) and transfer factors from feed to food are considered. Generally, maximum values for feed and food are set separately without considering the feed and the food producing animal as an important factor along the food chain from farm to fork. Levels of contaminants in feed can accumulate in animals and their products effect consumers at the end of the food chain. Hence, the process of setting legal maximum levels of contaminants should account for transfer from feed consumed by food producing animals into animal products for human consumption. Here, we calculated potential target values of PCDD/F in feed to ensure that animal products such as milk from dairy cows, eggs from laying hens and pork and pork products from fattening pigs are safe for human consumption. In our approach, we calculated potential target values of PCDD/Fs in animal feed using transfer factors for PCDD/F-TEQs from feed to milk fat, eggs fat, and fat in pork and pork products, taking into account the tolerable weekly intake derived by European Food Safety  Authority. We assumed equal proportions of WHO-PCDD/F-TEQ and WHO-PCB-TEQ in feed. Potential target values of PCDD/F in feed are expressed as the quantity of toxicologically evaluated PCDD/Fs, expressed in WHO toxic equivalents (WHO2005-PCDD/F-TEQ) per kg feed with 12% moisture. In the current approach, derived values would be 10–54 times lower than the current legal maximum level of 0.75 ng WHO2005-PCDD/F-TEQ per kg feed (12% moisture), according to Directive 2002/32/EC as amended.

Transfer of persistent organic pollutants in food of animal origin - Meta-analysis of published data

The transfer of POPs in food of animal origin has been studied by a meta-analysis of 28 peer-reviewed articles using transfer rate (TR) for milk and eggs and bioconcentration factors (BCF) for eligible tissues after establishing an adapted methodology. TRs of the most toxic PCDD/Fs into milk were generally elevated and even higher into eggs. BCFs in excreting adult animals varied widely between studies complicating to hierarchize tissues or congeners, even if liver and fat seemed to bioconcentrate more than lean tissues. Short time studies have clearly shown low BCFs contrarily to field studies showing the highest BCFs. The BCFs of PCDD/Fs in growing animals were higher in liver than in fat or muscle. In contrast to easily bioconcentrating hexachlorinated congeners, octa- and heptachlorinated congeners barely bioconcentrate. PCB transfer into milk and eggs was systematically high for very lipophilic congeners. Highly ortho-chlorinated PCBs were transferred >50% into milk and eggs and even >70% for congeners 123 and 167 into eggs. BCFs of the most toxic PCBs 126 and 169 were significantly higher than for less toxic congeners. BCFs seem generally low in PBDEs except congeners 47, 153 and 154. DDT and its metabolites showed high bioconcentration. Differences between tissues appeared but were masked by a study effect. In addition to some methodologic recommendations, this analysis showed the high transfer of POPs into eggs, milk and liver when animals were exposed justifying a strong monitoring in areas with POP exposure.

High levels of dioxins and PCBs in meat, fat and livers of free ranging pigs, goats, sheep and cows from the island of Curaçao

Samples of adipose tissue, meat and livers from pigs, cows, sheep and goats from Curaçao were analysed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and dioxin-like (dl-) and non-dioxin-like (ndl-) PCBs (polychlorinated biphenyls). Levels in many samples of adipose tissue were higher than the EU maximum levels (MLs) for PCDD/Fs and the sum of PCDD/Fs and dl-PCBs (sum-TEQ), indicating unusually high levels. Median sum-TEQ (Toxic Equivalents) levels for pigs, cows, sheep and goats were 0.9 (range 0.3-35), 3.0 (0.5-14), 5.7 (0.3-28) and 6.5 (0.5-134) pg TEQ g^-1 fat. For most samples, the congener pattern pointed to the burning of waste as the major source, in line with the fact that most animals forage outside. MLs for ndl-PCBs were also exceeded in some of the samples, indicating that some areas are additionally contaminated with PCBs. Meat levels showed similar lipid based levels as adipose tissue, contrary to liver levels, which were much higher in most animals. Pigs showed liver sequestration at lower levels in adipose tissue than the ruminants. The relatively high levels observed in this study are likely to result in high exposure of consumers and measures were taken to reduce the contamination of areas where animals forage.

Congener patterns of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls as a useful aid to source identification during a contamination incident in the food chain

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) are still considered among the most important groups of contaminants in the food chain. Self-control by food producers and official control by authorities are important activities that allow contaminant sources to be traced and promote further reduction in food and feed levels. Strict but feasible maximum levels were set by the EU Commission for food and feed to support this strategy, as well as action levels and thresholds. When products exceed these levels, it is important to trace the source of contamination and take measures to remove it. Congener patterns of PCDD/Fs and PCBs differ between sources and are important tools for source identification. Therefore, patterns associated with different sources and incidents relating to various feed matrices and certain agricultural chemicals were collated from published scientific papers, with additional ones available from some laboratories. The collection was evaluated for completeness by presentations at workshops and conferences. Primary sources appear to derive from 5 categories, i) by-products from production of organochlorine chemicals (e.g. PCBs, chlorophenols, chlorinated pesticides, polyvinyl chloride (PVC)), ii) the result of combustion of certain materials and accidental fires, iii) the use of inorganic chlorine, iv) recycling/production of certain minerals, and v) certain naturally occurring clays (ball clay, kaolinite). A decision tree was developed to assist in the identification of the source.

New approach for removing co-extracted lipids before mass spectrometry measurement of persistent of organic pollutants (POPs) in foods

Persistent organic pollutants (POPs) methods for foods and animal feeds require sufficient sample intake followed by an extensive removal of interfering matrix components and concentration before a gas chromatographic mass spectrometry (GC-MS) method can be applied. The extraction dissolves associated lipids in animal foods or feeds. Methods must eliminate all co-extracted lipids before determination by GC-MS. A new approach for removing lipids is presented using basic silica gel or metal ion immobilized silica gel (Ag+) in a single step. Absorbent order, adsorbent amounts, and flow rates were found to be essential for consistent results. KOH/silica gel or Ag⁺ ion (AgNO₃) silica gel were both shown to retain 75-85% of the co-extracted lipids without using sulfuric acid. KOH/silica gel method applied to butter fortified at 7.3 pg TEQ/g lipid with polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) produced accurate results for all fortified congeners with 20% of predicted (n = 6). Ag⁺ silica gel incorporated into the Miura GO-EHT automated system produced similar results fortified at 3 pg TEQ/g lipid. During PCDD/F fortifications of butter with PCDD/Fs (n = 6), labeled standard recoveries for PCDD/Fs and planar polychlorinated biphenyls (PCBs) were all acceptable (52-99%) averaging 77% using the Miura system. A reduction in the amounts of sulfuric acid silica gel needed was possible in the completion of co-extractant removal. PCDD/F spikes into butter and for a spiked sunflower oil (PCDD/Fs and coplanar PCBs) were within ± 20% of the predicted using the Miura system; suitable for current methods criteria for foods including criteria in EU legislation.

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.

Application of a High-Resolution Quadrupole/Orbital Trapping Mass Spectrometer Coupled to a Gas Chromatograph for the Determination of Persistent Organic Pollutants in Cow's and Human Milk

A quadrupole/orbital trapping mass spectrometer or Q-Exactive (QE) interfaced with a gas chromatograph (GC) was optimized for measuring polychlorinated dibenzo- p-dioxins, dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs) in foods. Figures of merit include (1) an instrument detection limit (IDL) for 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) of 9 femtograms (fg), (2) quantitative mass resolution from PCDD interferences (e.g., PCBs, methoxy-PCBs DDTs, polychlorodibenzylphenyl ethers, polychloroxanthenes, methyl-polychlorodibenzofuran, and polychlorodibenzothiophenes), and (3) mass accuracy <1 ppm at the IDL. The QE measured the concentrations of PCDD/Fs and PCBs in whole cow's milk with no known source of contamination (e.g., TCDD 33 fg/g fat). A National Institute of Standards and Technology (NIST) unfortified human milk standard reference material (SRM) 1953 was measured determining 27 PCDD/F and PCB congeners with an average difference of 7.6% from the certified results. The QE-GC is a benchtop instrument, easy to service, easy to operate, and requires no lock masses, mass preselection, or chemical ionization conditions. The QE-GC demonstrated that it can be an alternative to the double focusing magnetic sector instruments (sector) for the high-resolution measurement of PCDD/Fs and PCBs in dairy products.

Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.

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.

Polychlorinated biphenyl and polybrominated diphenyl ether profiles in serum from cattle, sheep, and goats across California

It has been previously been shown by our lab and others that persistent organic pollutants, such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), are contaminants in milk produced for human consumption. To further this research we determined the concentration of 21 PCB and 14 PBDE congeners in livestock serum, mainly bovine, across California. Congeners were extracted from serum using solid phase extraction (SPE), cleaned up by silica cartridge and quantified using gas chromatography-triple quadruple mass spectrometry. We detected significant differences among species and the production class of cattle (beef or dairy). The sum of all 21 PCB congeners (ΣPCBs) in caprine and ovine sera had a mean value of 9.26 and 9.13 ng/mL, respectively, compared to 3.98 ng/mL in bovine sera. The mean value for the sum of all 14 PBDE congeners (ΣPBDEs) in caprine and ovine sera was 2.82 and 2.39 ng/mL, respectively, compared to 0.91 ng/mL in bovine sera. Mean ΣPCBs in dairy cattle was 5.92 ng/mL compared to 2.70 ng/mL in beef cattle. Mean ΣPBDEs in dairy cattle was 1.33 ng/mL compared to 0.70 ng/mL in beef cattle. There were no regional differences in the ΣPCBs or ΣPBDEs in cattle distributed across California. These results highlight the fact that livestock are still being exposed to these pollutants yet little is known about where this exposure may be coming from.

Modelling scenarios on feed-to-fillet transfer of dioxins and dioxin-like PCBs in future feeds to farmed Atlantic salmon (Salmo salar)

The salmon feed composition has changed the last decade with a replacement of traditionally use of fish oil and fishmeal diets with vegetable ingredients and the use decontaminated fish oils, causing reduced concentrations of dioxins and dioxin-like PCBs in farmed Norwegian Atlantic salmon. The development of novel salmon feeds has prompted the need for prediction on dioxins and dl-PCB concentrations in future farmed salmon. Prediction on fillet dioxins and dl-PCB concentrations from different feed composition scenarios are made using a simple one-compartmental transfer model based on earlier established dioxin and dl-PCB congener specific uptake and elimination kinetics rates. The model is validated with two independent feeding trials, with a significant linear correlation (r(2) = 0.96, y = 1.0x, p < 0.0001, n = 116) between observed and predicted values. Model fillet predictions are made for the following four scenarios; (1) general feed composition of 1999, (2) feed composition of 2013, (3) future feed composition with high fish oil and meal replacement, (4) future feed composition with high fish oil and meal replacement and decontaminated fish oil. Model predictions of fillet dioxin and dl-PCB concentrations from 1999 (1.05 ng WHO2005-TEQs kg(-1)ww) and 2013 (0.57 ng WHO2005-TEQs kg(-1)ww) are in line with the data observed in national surveillance programs of those years (1.1 and 0.52 ng WHO2005-TEQs kg(-1)ww, respectively). Future use of high replacement and decontaminated oils feeds gave predicted fillet concentrations of 0.27 ng WHO2005-TEQs kg(-1)ww, which is near the limit of quantification.