Peter Pantazopoulos

Risks and benefits of consumption of great lakes fish

Background: Beneficial effects of fish consumption on early cognitive development and cardiovascular health have been attributed to the omega-3 fatty acids in fish and fish oils, but toxic chemicals in fish may adversely affect these health outcomes. Risk–benefit assessments of fish consumption have frequently focused on methylmercury and omega-3 fatty acids, not persistent pollutants such as polychlorinated biphenyls, and none have evaluated Great Lakes fish consumption. Objectives: The risks and benefits of fish consumption have been established primarily for marine fish. Here, we examine whether sufficient data are available to evaluate the risks and benefits of eating freshwater fish from the Great Lakes. Methods: We used a scoping review to integrate information from multiple state, provincial, and federal agency sources regarding the contaminants and omega-3 fatty acids in Great Lakes fish and fish consumers, consumption rates and fish consumption advisories, and health effects of contaminants and omega-3 fatty acids. Data synthesis: Great Lakes fish contain persistent contaminants—many of which have documented adverse health effects —that accumulate in humans consuming them. In contrast, data are sparse on omega-3 fatty acids in the fish and their consumers. Moreover, few studies have documented the social and cultural benefits of Great Lakes fish consumption, particularly for subsistence fishers and native communities. At this time, federal and state/provincial governments provide fish consumption advisories based solely on risk. Conclusions: Our knowledge of Great Lakes fish has critical gaps, particularly regarding the benefits of consumption. A risk–benefit analysis requires more information than is currently available on the concentration of omega-3 fatty acids in Great Lakes fish and their absorption by fish eaters in addition to more information on the social, cultural, and health consequences of changes in the amount of fish consumed.

Ochratoxin A in wine and grape juice sold in Canada.

Ochratoxin A (OTA) was determined in 251 samples of wines and grape juice collected over 3 years in Canada. In total, 25/84 samples of red wine, 22/96 samples of white wine, 3/46 red grape juices and 1/25 white grape juices contained OTA levels above the limit of quantitation (LOQ). Canadian wines, when compared with imported products, showed both a lower OTA occurrence, noted as positive (19 versus 48% above the limit of detection (LOD) for wines), and a lower level of OTA contamination (upper bound mean of 17.5 versus 163 pg ml−1 for wines). Wines from the USA contained no quantifiable levels of ochratoxin A. OTA was found in Canadian and US grape juice samples, with 12.9% above the LOD and an upper bound mean of 13.3 pg ml−1. It was extracted from a wine or grape juice sample by passing it through an immunoaffinity column. The sample matrix was washed off the column with water. OTA was eluted from the column with methanol and quantitatively determined by liquid chromatography using a fluorescence detector. The presence of OTA was confirmed by esterification with boron trifluoride-methanol. The LOQ of OTA was estimated as 20 pg ml−1 in white wine (S/N 10:1) and 40 pg ml−1 in red wine, white grape juice and red grape juice (S/N 20:1). The LOD was estimated as 4 pg ml−1 for white wine and 8 pg ml−1 for red wine and white and red grape juices (S/N 3:1).

Surveys of rice sold in Canada for aflatoxins, ochratoxin A and fumonisins

Approximately 200 samples of rice (including white, brown, red, black, basmati and jasmine, as well as wild rice) from several different countries, including the United States, Canada, Pakistan, India and Thailand, were analysed for aflatoxins, ochratoxin A (OTA) and fumonisins by separate liquid chromatographic methods in two different years. The mean concentrations for aflatoxin B1 (AFB1) were 0.19 and 0.17 ng g−1 with respective positive incidences of 56% and 43% (≥ the limit of detection (LOD) of 0.002 ng g−1). Twenty-three samples analysed in the second year also contained aflatoxin B2 (AFB2) at levels ≥LOD of 0.002 ng g−1. The five most contaminated samples in each year contained 1.44–7.14 ng AFB1 g−1 (year 1) and 1.45–3.48 ng AFB1 g−1 (year 2); they were mostly basmati rice from India and Pakistan and black and red rice from Thailand. The average concentrations of ochratoxin A (OTA) were 0.05 and 0.005 ng g−1 in year 1 and year 2, respectively; incidences of samples containing ≥LOD of 0.05 ng g−1 were 43% and 1%, respectively, in the 2 years. All positive OTA results were confirmed by LC-MS/MS. For fumonisins, concentrations of fumonisin B1 (FB1) averaged 4.5 ng g−1 in 15 positive samples (≥0.7 ng g−1) from year 1 (n = 99); fumonisin B2 (FB2) and fumonisin B3 (FB3) were also present (≥1 ng g−1). In the second year there was only one positive sample (14 ng g−1 FB1) out of 100 analysed. All positive FB1 results were confirmed by LC-MS/MS.

Altered Fatty Acid Homeostasis and Related Toxicologic Sequelae in Rats Exposed to Dietary Potassium Perfluorooctanesulfonate (PFOS)

Perfluorooctanesulfonate (PFOS) is one of a class of industrial chemicals known as perfluoroalkyl acids, which have a wide variety of uses as surfactants and stain repellants. The presence of fluorochemical residues in human blood, plasma, or serum from sample populations worldwide is indicative of widespread human exposure. Previous studies demonstrated that PFOS alters fatty acid metabolism in the liver of rodents and that this leads to peroxisome proliferation. This study was undertaken to (1) confirm the effects of PFOS on rat liver, (2) identify additional target organs and systems, and (3) further explore the biochemical and molecular changes associated with PFOS exposure. The results confirmed that liver was a primary target for PFOS. Hepatomegaly, decreased serum triglycerides and cholesterol, and increased expression of the genes for acyl-coenzymeA oxidase 1 (ACOX1) and cytochrome P-450 4A22 (CYP4A22) were indicative of exposure to a peroxisome proliferator. Changes in liver fatty acid profiles included increased total monounsaturated fatty acid levels and decreased total polyunsaturated fatty acids, as well as an increase in linoleic acid levels and a decrease in longer chain fatty acids. These changes were similar to those induced by relatively weak peroxisome proliferators. Disruptions in hepatic fatty acid metabolism may contribute to changes in red blood cell membranes, resulting in increased lysis and cell fragility. Serum thyroid hormone levels were decreased in PFOS-treated rats, while the kidney and cardiovascular systems were not significant targets. Residue analyses indicated that PFOS accumulation in tissues was dose dependent, appearing preferentially in the liver at lower doses but increasing in serum and other organs relative to liver at higher doses.

Survey of breakfast and infant cereals for aflatoxins B1, B2, G1 and G2.

Three hundred and forty-nine breakfast and infant cereal samples were collected at retail level across Canada from 2002 to 2005. They included rice-, soy-, barley-based and mixed-grain infant cereals, corn-, wheat-, rice-based and mixed-grain breakfast cereals, and were analysed for aflatoxins B1, B2, G1 and G2 using a modified AOAC International official method. An immunoaffinity column was used for the cleanup and purification of extracts. Determination of aflatoxins was by LC using post-column derivatization with pyridinium hydrobromide perbromide and fluorescence detection. Results indicated that 50% of both breakfast and infant cereals had detectable levels (limit of detection = 0.002 ng g−1) of aflatoxin B1, which is the most toxic of the four toxins. The levels found varied from 0.002 to 1.00 ng g−1 for aflatoxin B1, from 0.002 to 0.14 ng g−1 for aflatoxin B2, from 0.008 to 0.27 ng g−1 for aflatoxin G1, and from 0.008 to 0.048 ng g−1 for aflatoxin G2. Only 4% of the breakfast cereals and 1% of the infant cereals had aflatoxin B1 levels exceeding 0.1 ng g−1, which is the European Union maximum limit for aflatoxin B1 in baby foods and processed cereal-based foods for infants and young children.

Survey of aflatoxins in beer sold in Canada

Between March 1998 and March 2002, 304 samples of domestic (Canadian) and imported beers from 36 countries were picked up for the determination of aflatoxins B1, B2, G1 and G2. Twelve samples were positive with aflatoxins greater than the limit of quantitation (LOQ) (aflatoxin B1, 4.4 ng l−1; aflatoxin B2, 3.4 ng l−1; aflatoxin G1, 11.2 ng l−1; and aflatoxin G2, 6.2 ng l−1). Five samples from Mexico, two samples from Spain and one from Portugal contained aflatoxin B1. Four samples from India contained aflatoxins B1 and B2. The remaining samples contained less than the LOQ for aflatoxins B1, B2, G1 and G2. The analytical method for this survey was based on that of Scott and Lawrence (Scott PM, Lawrence GA. 1997. Determination of aflatoxins in beer. Journal of AOAC International 80:1229–1234.). Aflatoxins B1, B2, G1 and G2 were determined at parts per trillion (ng l−1) levels in beer by immunoaffinity column cleanup followed by derivatization with trifluoroacetic acid and reversed-phase liquid chromatography with fluorescence detection.

Survey of Dry Pasta for Ochratoxin A in Canada

Ochratoxin A (OTA) was determined in 274 samples of dry pasta sold across Canada in 2004 to 2006. Ground sample was extracted with acetonitrile-water (6:4 [vol/vol]), filtered, diluted with phosphate-buffered saline, and cleaned with an immunoaffinity column. Analysis was by reversed-phase liquid chromatography with fluorescence detection, and in the second year by liquid chromatography-electrospray tandem mass spectrometry as well. For 2004 and 2005, the limit of quantitation was approximately 0.5 ng of OTA per g (signal-to-noise ratio of 10:1). In 2006, the limit of quantitation was estimated to be 0.2 ng of OTA per g. Incidence of contamination above 0.5 ng of OTA per g was 21, 18, and 66% in the years 2004, 2005, and 2006, respectively, reflecting the contamination variability of durum wheat crops and showing the importance of multiyear surveillance. Mean levels of OTA found in these 3 years were, respectively, 0.30, 0.28, and 0.76 ng/g, and maximum levels were, respectively, 1.8, 1.4, and 3.3 ng/g.

Application of isotope dilution mass spectrometry: determination of ochratoxin A in the Canadian Total Diet Study.

Analytical methods are generally developed and optimized for specific commodities. Total Diet Studies, representing typical food products ‘as consumed’, pose an analytical challenge since every food product is different. In order to address this technical challenge, a selective and sensitive analytical method was developed suitable for the quantitation of ochratoxin A (OTA) in Canadian Total Diet Study composites. The method uses an acidified solvent extraction, an immunoaffinity column (IAC) for clean-up, liquid chromatography-tandem mass spectrometry (LC-MS/MS) for identification and quantification, and a uniformly stable isotope-labelled OTA (U-[13C20]-OTA) as an internal recovery standard. Results are corrected for this standard. The method is accurate (101% average recovery) and precise (5.5% relative standard deviation (RSD)) based on 17 duplicate analysis of various food products over 2 years. A total of 140 diet composites were analysed for OTA as part of the Canadian Total Diet Study. Samples were collected at retail level from two Canadian cities, Quebec City and Calgary, in 2008 and 2009, respectively. The results indicate that 73% (102/140) of the samples had detectable levels of OTA, with some of the highest levels of OTA contamination found in the Canadian bread supply.

Toxicologic effects of 28-day dietary exposure to the flame retardant 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (TBECH) in F344 rats

The brominated flame retardant TBECH is used as an additive to delay ignition and inhibit fires in construction materials and consumer goods. Trends in human exposure are not clear, although humans may be exposed to TBECH via indoor dust and air. In birds and fish there is some evidence of disruption in endocrine and reproductive parameters due to TBECH. In vitro studies indicate that TBECH is an androgen receptor agonist. In this study rats were exposed to 0, 10, 50, 250, 1250 or 5000mg/kg technical TBECH for 28days in diet, corresponding to 0, 0.9, 4.2, 21.3, 98.0 or 328.9mg TBECH/kg bw/d in males and 0, 0.8, 3.9, 19.4, 91.7 or 321.4mg TBECH/kg bw/d in females. Dose-dependent increases in α- and β- TBECH were detected in serum, liver and adipose. Rats in the 5000mg/kg group lost weight rapidly and were euthanized after 15-18days. At study termination rats displayed dose-dependent clinical and histopathological changes consistent with mild hepatic and renal inflammation. In male rats, evidence of gender-specific alpha2u-globulin nephropathy was not considered predictive of renal toxicity in humans. Frank immunosuppression or inappropriate immunostimulation were not apparent, nor was there a primary effect of TBECH on adaptive immunity. Some evidence of hormone disruption was observed, including changes in serum testosterone levels in males and changes in serum T3 and T4 levels in females. Apparent increases in thyroid follicular cell hypertrophy and hyperplasia in male and female rats were not statistically significant. Benchmark dose (BMD) modelling indicated that clinical changes indicative of mild nephrotoxicity and increased blood monocyte numbers indicative of inflammation and tissue damage were the most sensitive outcomes of TBECH exposure that could be modelled. Preliminary evidence of hormone disruption supports the need for rodent studies using more sensitive models of growth, development and reproduction.

Polychlorinated Biphenyls and Polychlorinated Dioxins–Furans in Lake Trout and Whitefish Composite Samples from Commercial Fisheries in Lakes Erie, Huron, and Superior

Polychlorinated biphenyls (PCBs; sum of 36 congeners) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs; sum of 17 2,3,7,8-substituted congeners) were measured in 93 composite samples prepared from individual lake trout (Salvelinus namaycush) and whitefish (Coregonus clupeaformis) samples collected from Lake Erie, Lake Huron, and Lake Superior. All samples had detectable concentrations of PCBs and PCDD/Fs; maximum PCB concentrations in both trout (750 ng g-1 whole weight [ww]) and whitefish (210 ng g-1 ww) were found in composites from fish collected from Lake Huron. The maximum toxic equivalent concentration was found in a lake trout composite sample from Lake Huron (53 pg g-1 ww). PCB and PCDD/F congener profiles were comparable to patterns observed in fishes collected from other regions of Canada, although concentrations were above those found in other regions. A positive correlation was found between PCB concentrations determined using the historical Aroclor equivalency method and those determined using the sum of the congeners measured (r2 = 0.871; Spearman correlation r = 0.917) or using the six indicator PCB congeners (28, 52, 101, 138, 153, and 180; r2 = 0.850; Spearman correlation r = 0.935). PCBs were the dominant contributor to the overall toxic equivalent concentrations in the fish composite samples tested. These findings provide insight into PCB and PCDD/F concentrations in two commercially important fish species over a discrete time period.