Compositional profiles, persistency and toxicity of polychlorinated naphthalene (PCN) congeners in edible cod liver products from 1972 to 2017

Edible cod liver products including cod liver oil and canned cod liver, sampled over the last five decades from the North Atlantic region, including the Baltic Sea were analysed for a set of persistent and toxicologically significant polychlorinated naphthalene (PCN) congeners with some of the highest relative potencies (dioxin-like toxicity) among PCNs. The targeted congeners showed a near-universality of occurrence in all samples apart from the most recent sample of cod liver oil which was assumed to be highly purified, as cod livers from the same period and location showed appreciable amounts of PCNs. The majority of dominant congeners in legacy technical PCN mixtures were absent or occurred in low concentrations, raising the possibility that congeners arising from combustion related sources may be acquiring a greater significance following the decline and elimination of PCN production. The apparent appreciation in the relative amounts of PCN#70 in the last three to four decades may provide support for this view. The PCN contribution to dioxin-like toxic equivalence (TEQ) that was estimated for these samples (range 1.2–15.9 pg TEQ g −1) was significant in comparison to the EU regulated value of 1.75 pg TEQ g −1 for dioxins in fish oils. Most of the TEQ was associated with PCNs 66/67, 64/68, 69 and 73. Although metabolic processes are likely to influence this distribution, the profile is a little different to that observed in the tissues of higher order animals where PCNs #66/67 and #73 may contribute approximately 90% to the summed TEQ. The PCN contribution to dioxin-like toxic equivalence (TEQ) that was estimated for cod liver products (range 1.2–15.9 pg TEQ g −1) was significant in comparison to the EU regulated value of 1.75 pg TEQ g-1 for dioxins in fish oils. Most of the TEQ was associated with PCNs 66/67, 64/68, 69 and 73

Polybrominated dibenzo-p-dioxins and furans (PBDD/Fs): Contamination in food, humans and dietary exposure

Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) have been recognised as environmental pollutants for decades but their occurrence in food has only recently been reported. They elicit the same type of toxic response as analogous polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) with similar potencies and effects, and share similar origins - inadvertent production during combustion and occurrence as by-products in industrial chemicals. Surprisingly, PBDD/Fs have received considerably less attention than PCDD/Fs, perhaps because determination requires a higher degree of analytical competence, a result of the higher adsorptivity and lability associated with carbon-bromine bonding. For most populations, the principal exposure pathway is dietary intake. The PBDD/F toxicity arising from occurrence in foods has often been expressed as toxic equivalents (TEQs) using the same scheme developed for PCDD/Fs. This approach is convenient, but resulting TEQ estimates are more uncertain, given the known differences in response for some analogous congeners and also the different patterns of PBDD/F occurrence confirmed by the newer data. Further studies to consolidate potency factors would help to refine TEQ estimates. Characteristically, most foods and human tissues show more frequent and higher PBDF concentrations relative to PBDDs, reflecting major source patterns. Occurrence in food ranges from < 0.01 to several thousand pg/g (or up to 0.3 pg TEQ/g whole weight) which is comparable to PCDD/F occurrence (ΣPBDD/F TEQs are underestimated as not all relevant congeners are included). Plant based foods show higher PBDD/F: PCDD/F TEQ ratios. Reported PBDD/F dietary intakes suggest that some population groups, particularly young children, may exceed the revised tolerable weekly intake for dioxin-like contaminants (2 pg TEQ/kg bw/week), even for mean consumption estimated with lower bound data. It is evident that the omission of PBDD/Fs from the TEQ scheme results in a significant underestimation of the cumulative toxicity and associated risk arising from this mode of action

A retrospective investigation into the occurrence and human exposure to polychlorinated naphthalenes (PCNs), dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs through cod liver products (1972–2017)

A retrospective analysis of a number of historical medicinal grade cod-liver oil samples produced in Northern Europe revealed relatively high contamination levels of PCNs, PCDD/Fs and PCBs. The total toxic equivalence (TEQ) associated with PCDD/Fs, dl-PCBs and PCNs was in the range 95 to 427 pg g-1 for Baltic cod-liver oils and from 70 to 148 pg g-1 for oils sourced from the North Atlantic. The corresponding range for canned cod liver products (Baltic Sea) sampled in 2017 ranged from 52 to 104 pg g-1 fat (33 to 34 pg g-1 ww). The contribution from PCBs to the overall TEQ toxicity was around 3 to 6-fold higher than from PCDD/Fs and ranged from 24 to 318 pg TEQ g-1ww. The estimated summed TEQ intakes of PCDD/Fs, dl-PCBs and dl-PCNs resulting from the consumption of the daily recommended doses was highest for the Baltic cod-liver oils ranging from 16 to 293 pg kg-1 body mass (bm) day-1 for an adult, 20 to 183 pg kg-1 bm day-1 for a teenager and 15 to 131 pg kg-1 bm day-1 for a child. The contribution to daily adult TEQ intake from PCNs alone, although relatively small is estimated to contribute up to 5-fold above the recent EFSA proposed TWI of 2 pg kg-1 bm. The results indicate that although currently produced fish oils may undergo rigorous purification procedures and show low contaminant levels, cod livers sourced from the Baltic and consumed locally, continue to contribute substantially to the dietary intake of these contaminants

PBDEs in cod (Gadus morhua) liver products (1972 to 2017): Occurrence and human exposure

PBDEs occur in a range of commonly consumed foods but there is very little current information on occurrence in dietary supplements such as cod liver oil or cod livers used as food. This study retrospectively investigated a number of these products, sourced from the Baltic Sea and North Atlantic, historically dating from 1972 to 2017. For the sum of 17 measured PBDEs (ΣPBDE), the concentrations ranged from 9.9 to 415 ng g-1 for the oils and from 10.5 to 13 ng g-1 for canned liver products. Concentrations in the oils were highest during the period from 1993 to 2001. For all samples, BDE-47 was the dominant congener with a maximum detected concentration of 308 ng g-1 in a Baltic cod liver oil from 1993. Human exposure to PBDEs from recommended doses were estimated for adults, teenagers and children. Depending on the age group, BDE-47 intakes ranged from 1.3 to 211.5 ng kg-1 bm day-1 (Baltic Sea), 2.9 to 12.7 ng kg-1 bm day-1 (Atlantic, Norway) and 1.1 to 4.8 ng kg-1 bm day-1 (Atlantic, Iceland). Intakes for the other dominant congeners, BDE-49, BDE-99 and BDE-100, were relatively low. The intake estimates of ΣPBDE were highest for Baltic cod liver oils ranging from 2.2 to 284.8 ng kg-1 bm day-1 for adults, 2.8 to 178 ng kg-1 bm day-1 for teenagers and 2.0 to 127.8 ng kg-1 bm day-1 for a child. Estimated weekly intake of ΣPBDE from canned cod liver was highest for adults, ranging from 17.6 to 25.1 ng kg-1 bm

The effects of river flooding on dioxin and PCBs in beef

In 2008-2010, samples of meat from 40 beef cattle, along with grass, soil and commercial feed, taken from ten matched pairs of flood-prone and control farms, were analysed for PCDD/Fs and PCBs. Concentrations were higher in soil and grass from flood-prone farms. The beef samples from flood-prone farms had total TEQ levels about 20% higher than on control farms. A majority of flood-prone farms (7/10) had higher median levels in beef than on the corresponding control farm. This first controlled investigation into PCDD/F and PCB contamination in beef produced on flood-prone land, presents robust evidence that flooding is a contaminant transfer mechanism to cattle raised on river catchments with a history of urbanisation and industrialisation. PCDD/F and PCB sources in these river systems are likely to be a result of the legacy of contamination from previous industrialisation, as well as more recent combustion activity or pollution events. Crow

Dioxin-like polybrominated biphenyls (PBBs) and ortho-substituted PBBs in edible cod (Gadus morhua) liver oils and canned cod liverss

This study investigates the occurrence of polybrominated biphenyls (PBBs), a legacy flame retardant, in fishery products such as medicinal grade cod liver oils and canned liver products, sourced from the North Atlantic during 1972–2017. It also assesses the dietary and supplementary (the oils were commonly administered as dietary supplements to children and youth) intake of PBBs from these products. Summed ortho-PBB concentrations ranged from 770 to 1400 pg g−1 fat in the oils and from 99 to 240 pg g−1 whole weight in canned livers, with PBB-49, 52, 101 and 153 accounting for most of these levels. Among the more toxic non-ortho-PBBs, PBB-126 and PBB-169 were not detected, but PBB-77 concentrations ranged from 0.6 to 5.78 pg g−1 fat in the oils and 0.06–0.126 pg g−1 whole weight in canned livers. During 1972–1993, PBB contamination levels were similar for cod liver oils from the Baltic Sea and other North Atlantic regions, but over the timescale of the study, Baltic Sea products appear to show a decline in PBB concentrations. As PBB-77 was the only dioxin-like PBB detected in the samples, the corresponding supplementary (oils, 1972–2001) and dietary (cod liver from 2017) intakes were very low, at < 0.001 pg TEQ kg−1 bm d−1 (or < 0.01 pg TEQ kg−1 bm d−1 upper bound) for the sum of all the measured dioxin-like PBBs –four to six orders of magnitude lower than that arising from other dioxin-like contaminants that were shown to occur in these products, from earlier studies

Mercury and selenium in developing and mature fruiting bodies of Amanita muscaria

Both mercury (Hg) and selenium (Se) occur in many mushroom species, but the morphological distribution of these elements during different developmental stages of the fruiting bodies is not known. Although Amanita muscaria can be consumed after suitable processing, they are often ignored by mushroom foragers, leaving an abundance for investigative study. Multiple specimens in each of six developmental stages (button to fully mature) were collected in excellent condition during a single morning from the same forested location and composited. With an average of 30 specimens per composite, and low temporal, spatial, and measurement uncertainty, the data are likely to be representative of the typical concentrations of Hg and Se for each developmental stage. Hg (range 0.58–0.74 mg kg-1 dry weight cap; 0.33 to 0.44 mg kg-1 dw stipe) and Se (range 8.3–11 mg kg-1dw cap; 2.2 to 4.3 mg kg-1 dw stipe) levels were observed to vary during the developmental stages, and the variability may relate to the demands in growth. In common with some other species, the lower stipe concentrations may be consistent with nutrient/content transport and support functions. Both Hg and Se levels were lowest during periods of maximum sporocarp growth. Selenium occurs at almost an order of magnitude greater levels than Hg. Due to its role in mitigating the effects of Hg toxicity, this property is of significance to those who consume the species either for nutritional, medicinal, or recreational purposes, although the losses of both these elements during processing are not know

The effects of culinary processing on lithium from lithiated and reference button mushrooms (Agaricus bisporus)

Lithiated products such as button mushrooms that are cultivated in substrates fortified with lithium (Li) salts, have the potential to provide accessible and safe Li dosing as a treatment for some neurological disorders. However, Li losses sustained during culinary processing are not known. This study of commonly used culinary treatments including various combinations of drying, maceration, blanching (of fresh, deep-frozen and re-hydrated mushrooms) and pickling (of fresh and deep-frozen mushrooms) shows that Li is lost from the edible flesh at varying rates depending on the treatment. Blanching of fresh lithiated mushrooms resulted in a 40% loss, increasing to 77–87% when blanching was followed by pickling. Corresponding losses were similar (47–72%) for non-lithiated mushrooms. Higher losses through the combined treatment relative to just blanching appear to be due to chelating and acidifying effects of the vinegar used. This finding has important dose implications for potential future use of lithiated products

An evaluation of the occurrence and trends in 137Cs and 40K radioactivity in King Bolete Boletus edulis mushrooms in Poland during 1995–2019

B. edulis, collected from 33 forested or woodland sites across Poland over 25 years since 1995, were analysed for radiocaesium. The results ( 137Cs activity range: 25 to 10,000 Bq kg -1 dry weight) provide a good indication of artificial radioactivity in this food material. The relatively higher levels detected in the earlier years, mostly in easterly location, is consistent with depositions from the projected Chernobyl incident (1986) fallout plumes. Nevertheless, the 137Cs concentrations during 1995–2010 were, on average, higher than those reported by other studies for Polish B. edulis over the period 1986–1994. The data concurs with the general hypothesis and observations that deposited 137Cs permeates slowly over time to deeper soil horizons which host the mycelial networks. This delay in availability shows that (apart from hotspots) higher contamination of fruiting bodies occurred around 10 to 20 years after the incident. Local consumers and recreational mushroomers were undoubtedly exposed, although reported 137Cs concentrations suggest that serious breaches of regulated levels were uncommon