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

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          Abstract

          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.

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          The 2005 World Health Organization reevaluation of human and Mammalian toxic equivalency factors for dioxins and dioxin-like compounds.

          In June 2005, a World Health Organization (WHO)-International Programme on Chemical Safety expert meeting was held in Geneva during which the toxic equivalency factors (TEFs) for dioxin-like compounds, including some polychlorinated biphenyls (PCBs), were reevaluated. For this reevaluation process, the refined TEF database recently published by Haws et al. (2006, Toxicol. Sci. 89, 4-30) was used as a starting point. Decisions about a TEF value were made based on a combination of unweighted relative effect potency (REP) distributions from this database, expert judgment, and point estimates. Previous TEFs were assigned in increments of 0.01, 0.05, 0.1, etc., but for this reevaluation, it was decided to use half order of magnitude increments on a logarithmic scale of 0.03, 0.1, 0.3, etc. Changes were decided by the expert panel for 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) (TEF = 0.3), 1,2,3,7,8-pentachlorodibenzofuran (PeCDF) (TEF = 0.03), octachlorodibenzo-p-dioxin and octachlorodibenzofuran (TEFs = 0.0003), 3,4,4',5-tetrachlorbiphenyl (PCB 81) (TEF = 0.0003), 3,3',4,4',5,5'-hexachlorobiphenyl (PCB 169) (TEF = 0.03), and a single TEF value (0.00003) for all relevant mono-ortho-substituted PCBs. Additivity, an important prerequisite of the TEF concept was again confirmed by results from recent in vivo mixture studies. Some experimental evidence shows that non-dioxin-like aryl hydrocarbon receptor agonists/antagonists are able to impact the overall toxic potency of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds, and this needs to be investigated further. Certain individual and groups of compounds were identified for possible future inclusion in the TEF concept, including 3,4,4'-TCB (PCB 37), polybrominated dibenzo-p-dioxins and dibenzofurans, mixed polyhalogenated dibenzo-p-dioxins and dibenzofurans, polyhalogenated naphthalenes, and polybrominated biphenyls. Concern was expressed about direct application of the TEF/total toxic equivalency (TEQ) approach to abiotic matrices, such as soil, sediment, etc., for direct application in human risk assessment. This is problematic as the present TEF scheme and TEQ methodology are primarily intended for estimating exposure and risks via oral ingestion (e.g., by dietary intake). A number of future approaches to determine alternative or additional TEFs were also identified. These included the use of a probabilistic methodology to determine TEFs that better describe the associated levels of uncertainty and "systemic" TEFs for blood and adipose tissue and TEQ for body burden.
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            Risk for animal and human health related to the presence of dioxins and dioxin‐like PCBs in feed and food

            Abstract 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.
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              Dioxins and PCBs in feed and food--review from European perspective.

              During the 1990s, a number of adverse contamination incidents focussed the attention of the media and the general public on food safety. This led to the evaluation of safety measures with regard to dioxin intake from food. Important aspects regarding dioxins and PCBs in the food chain are reviewed here, allowing a contextual understanding of the present situation through its chronological developments. About 90-98% of the average exposure of humans to dioxins and PCBs results from dietary intake, with food of animal origin being the predominant source. Therefore, animal feed contributes considerably to the presence of these compounds in food. The detection of the "real" source of a contamination event in the food chain is a complex scientific problem and requires specific knowledge on production processes and changes of patterns during bioaccumulation. This is demonstrated by complex investigations performed in three studies on two continents to identify the source (e.g. from contamination of cow's milk in Germany, to citrus pulp pellets from Brazil as an ingredient in feed, then to contaminated lime for neutralization and finally to a landfill with residues of vinyl chloride monomer production). This example shows also the substantial economic losses resulting from incidents in the food chain and the consequences to global trade. In 2001, the EU Scientific Committee on Food established a group tolerable weekly intake (TWI) of 14 pg WHO-TEQ/kg body weight and concluded that a considerable proportion of the European population would exceed this TWI. On the global level, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) provides scientific advice to the Codex Alimentarius Commission and therefore contributes to harmonized international food standards. In its evaluation of 2001, JECFA derived a provisional tolerable monthly intake (PTMI) of 70 pg TEQ/kg body weight. The sum of the median intake of PCDD/F-TEQ and PCB-TEQ exceeded the PTMI in Western European countries, was in the PTMI range in North America, but lower in Japan and New Zealand. The 90th percentile of PCDD/F-TEQ exceeded the PTMI in Western European countries and North America, the 90th percentile of coplanar PCBs in Western European countries. Therefore, in 2001 the EU Commission developed a strategy to reduce the presence of dioxins and PCBs in the environment and in the food chain. The legislative measures comprised maximum levels and action levels for feed and food, and a Rapid Alert System for detected incidents was introduced. The network of the EU Reference Laboratory and National Reference Laboratories contributes to harmonization within the EU Member States and developed analytical criteria for screening and confirmatory methods for control of feed and food. After all these efforts it is of general interest to see whether these measures had an effect. The 2012 evaluation of the European Food Safety Authority (EFSA) based on comprehensive monitoring data of 26 European countries shows a general decrease in dietary exposure of dioxins and DL-PCBs between 2002-2004 and 2008-2010, estimated to be between 16.6% and 79.3% for the different population groups. A smaller decrease was observed for NDL-PCBs. The percentage of individuals exposed above the TWI of 14 pg TEQ/kg b.w. was estimated to be between 1.0 and 52.9%. Toddlers and other children were the most exposed groups (being at the upper end of these ranges). Fish, meat and dairy products appeared to be the highest contributing food groups to dietary exposure.
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                Author and article information

                Journal
                J Agric Food Chem
                J Agric Food Chem
                jf
                jafcau
                Journal of Agricultural and Food Chemistry
                American Chemical Society
                0021-8561
                1520-5118
                05 February 2020
                19 February 2020
                : 68
                : 7
                : 2201-2213
                Affiliations
                []Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna “Bruno Ubertini” , Via Antonio Bianchi 9, 25124 Brescia, Italy
                []Research Centre for Animal Production and Aquaculture, CREA , Via Antonio Lombardo 11, 26900 Lodi, Italy
                [§ ]Department of Food Science, Parma University , Via del Taglio 10, 43126 Parma, Italy
                Author notes
                [* ]E-mail: sergio.ghidini@ 123456unipr.it . Tel.: 0521902761. Fax: 0521902752.
                Article
                10.1021/acs.jafc.9b08180
                7997377
                32023042
                9b64dacd-568e-42ff-9265-e87845f2db43

                Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained ( https://creativecommons.org/licenses/by/4.0/).

                History
                : 24 December 2019
                : 23 January 2020
                : 18 January 2020
                Categories
                Article
                Custom metadata
                jf9b08180
                jf9b08180

                Food science & Technology
                non-ortho dl-pcbs,mono-ortho dl-pcbs,ndl-pcb indicators,feed,cow milk
                Food science & Technology
                non-ortho dl-pcbs, mono-ortho dl-pcbs, ndl-pcb indicators, feed, cow milk

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