Levels of total mercury in predatory fish sold in Canada in 2005.

Total mercury was analysed in 188 samples of predatory fish purchased at the retail level in Canada in 2005. The average concentrations (ng g(-1), range) were: sea bass 329 (38-1367), red snapper 148 (36-431), orange roughy 543 (279-974), fresh water trout 55 (20-430), grouper 360 (8-1060), black cod 284 (71-651), Arctic char 37 (28-54), king fish 440 (42-923), tilefish 601 (79-1164) and marlin 854 (125-2346). The Canadian standard for maximum total mercury allowed in the edible portions of fish sold at the retail level is 1000 ng g(-1) for shark, swordfish, marlin, orange roughy, escolar and both fresh and frozen tuna. The standard is 500 ng g(-1) for all other types of fish. In this study, despite the small number of samples of each species, the 1000 ng g(-1) maximum was exceeded in five samples of marlin (28%). The 500 ng g(-1) maximum was exceeded by six samples of sea bass (20%), four of tilefish (50%), five of grouper (24%), six of king fish (40%) and one of black cod (13%).

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-[(13)C(20)]-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.

Concentrations of bisphenol A in the composite food samples from the 2008 Canadian total diet study in Quebec City and dietary intake estimates.

A total of 154 food composite samples from the 2008 total diet study in Quebec City were analysed for bisphenol A (BPA), and BPA was detected in less than half (36%, or 55 samples) of the samples tested. High concentrations of BPA were found mostly in the composite samples containing canned foods, with the highest BPA level being observed in canned fish (106 ng g(-1)), followed by canned corn (83.7 ng g(-1)), canned soups (22.2-44.4 ng g(-1)), canned baked beans (23.5 ng g(-1)), canned peas (16.8 ng g(-1)), canned evaporated milk (15.3 ng g(-1)), and canned luncheon meats (10.5 ng g(-1)). BPA levels in baby food composite samples were low, with 2.75 ng g(-1) in canned liquid infant formula, and 0.84-2.46 ng g(-1) in jarred baby foods. BPA was also detected in some foods that are not canned or in jars, such as yeast (8.52 ng g(-1)), baking powder (0.64 ng g(-1)), some cheeses (0.68-2.24 ng g(-1)), breads and some cereals (0.40-1.73 ng g(-1)), and fast foods (1.1-10.9 ng g(-1)). Dietary intakes of BPA were low for all age-sex groups, with 0.17-0.33 µg kg(-1) body weight day(-1) for infants, 0.082-0.23 µg kg(-1) body weight day(-1) for children aged from 1 to 19 years, and 0.052-0.081 µg kg(-1) body weight day(-1) for adults, well below the established regulatory limits. BPA intakes from 19 of the 55 samples account for more than 95% of the total dietary intakes, and most of the 19 samples were either canned or in jars. Intakes of BPA from non-canned foods are low.

N-methyl carbamate pesticide residues in conventional and organic infant foods available on the Canadian retail market, 2001-03.

Seven parent N-methyl carbamate insecticides, in addition to two transformation products of aldicarb (aldicarb sulfoxide and aldicarb sulfone), and a single transformation product of carbofuran (3-hydroxycarbofuran) were measured in infant and junior foods available on the Canadian retail market between 2001 and 2003. Carbaryl and methomyl were the only analytes present at levels above the limits of detection in juice, cereals, fruit, vegetables or meat samples analysed. Carbaryl was the most frequently (7.6%) detected compound and concentrations ranged from 0.6 to 18 ng g-1. Detectable levels of carbaryl were most frequently found in foods prepared with fruit. Methomyl was detected (0.8 ng g-1) in one chicken with broth sample analysed in the present study. In all cases, the concentrations observed were orders of magnitude below the maximum residue limits established for these compounds in the corresponding raw food commodities in Canada (100-10 000 ng g-1). Dietary intakes of carbaryl and methomyl based on the consumption of infant foods tested ranged between 0.2-343 and 0.4-2.0 ng kg-1 body weight day-1, respectively.

Canadian Total Diet Study in 1998: pesticide levels in foods from Whitehorse, Yukon, Canada, and corresponding dietary intake estimates.

The Canadian Total Diet Study is a national survey to determine the level of chemical contaminants in the Canadian food supply. Food samples were collected from Whitehorse, Yukon, supermarkets as part of the study in 1998. Whitehorse was chosen as a sampling centre, despite its small population (n = 19,000), to determine if residue levels were different in foods available in northern communities relative to levels observed in previous studies in the more populated south. Foods were prepared as for consumption before pesticide residue analysis. Residue levels observed in most foods were similar to levels observed in samples from previous surveys from southern Canadian cities. Malathion and DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), a transformation product of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl(ethane), were the two most frequently detected compounds (26.4 and 25.8%, respectively). The majority of pesticides, however, had a detection frequency of < 5%. In general, pesticides in food composites were well below maximum residue limits established in the Canadian Food and Drug Regulations. Chlorpropham and captan had the highest dietary intakes (2.16 and 1.94 micrograms (kg body weight-day)-1, respectively), based on the results from Whitehorse. No dietary intakes above the acceptable daily intakes, however, were observed for any of the 39 pesticides investigated in any age-sex category, where an acceptable daily intake has been proposed.

Methylmercury levels in predatory fish species marketed in Canada.

Mercury was detected in all analysed samples of swordfish, marlin, shark and tuna purchased from major supermarket outlets and fish retailers in three cities across Canada. Total mercury and methylmercury levels ranged up to 3845 and 2346 ng g(-1), respectively. Swordfish contained the highest levels, followed by shark, fresh/frozen tuna and marlin. Levels in canned tuna were considerably less than the other examined samples. Methylmercury was extracted with toluene from enzymatically hydrolysed samples after the addition of sulphuric acid and potassium bromide. An L-cysteine back-extraction was used to separate the methylmercury from most organic co-extractives. Analysis of methylmercury (as methylmercury bromide) was by gas chromatography with pulsed discharge detection.

Survey of total mercury in total diet food composites and an estimation of the dietary intake of mercury by adults and children from two Canadian cities, 1998-2000.

Total mercury was measured in 259 total diet food composites from two Canadian cities. Levels were generally low, with 46% of the composites having concentrations below the limit of detection, which ranged from 0.026 to 0.506 ng g(-1). The fish category contained the highest mercury concentrations, which averaged 67 ng g(-1) and ranged from 24 to 148 ng g(-1). All composites were below the Canadian guideline for total mercury in fish of 0.5 ppm. Dietary intakes of mercury averaged 0.022 microg kg(-1) body weight/day (microg kg(-1) day(-1)), and ranged from 0.012 microg kg(-1) day(-1) for females over 65 years old to 0.062 microg kg(-1) day(-1) for 0-1-month-old infants. For fish consumers, fish contributed to more than half of the ingested mercury. All intakes were well below Joint FAO/WHO Expert Committee on Food Additives Provisional Tolerable Weekly Intakes, expressed on a daily basis, of 0.71 microg kg(-1) day(-1) total mercury and 0.47 microg kg(-1) day(-1) methyl mercury, and also below a recent Health Canada recommended maximum methyl mercury intake of 0.2 microg kg(-1) day(-1) for children and women of child-bearing age.

Survey of bottled drinking waters sold in Canada for chlorate, bromide, bromate, lead, cadmium and other trace elements.

Mineral, spring and other bottled drinking waters sold in Canada in the winter of 1995-96 were surveyed for chlorate, bromide, bromate, Cr(VI), Li, B, Al, Mn, Cu, Zn, Sr, Ba, Be, V, Cr, Co, Ni, As, Se, Mo, Ag, Cd, Sb, Tl, Pb, Na, K, Ca and Mg. Chlorate and bromide were determined by ion chromatography (IC) with conductivity detection, Cr(VI) by IC with colorimetric detection, bromate by solvent extraction and gas chromatography (GC), trace elements by inductively coupled plasma mass spectrometry (ICPMS), and Na, K, Ca and Mg by flame atomic absorption spectrometry (FAA). Most chemicals in the 199 samples analysed were well within national and international drinking water guidelines. World Health Organization and/or Canadian drinking water guidelines were exceeded for B (22 samples), Al (9), Cr (1), Mn (5), Ni (1), As (10), Se (24) and Pb (1). Bromate levels are reported for information purposes and are considered as the maximum concentrations in the samples. In three distilled water products, unexpectedly high concentrations of Cu (88-147 micro g l(-1)) and Ni (16-35 micro g l(-1)) were found, and a comparison of distilled and non-distilled waters from two of the brands suggested the likely cause to be contamination during the distillation process. Li concentration in one sample was at a therapeutic dose and could pose an overdose risk to individuals on Li medication.

Lead contamination of raisins sold in Canada.

Graphite-furnace atomic absorption spectrometric analysis of raisins imported in 1993-95 from different countries into Canada showed that raisins from Turkey had unusually high lead levels. The Turkish raisins (n = 18) contained a mean (range) of 0.93 (0.056 3.1) mg kg(-1) lead, whereas five samples from Australia, South Africa, Iran, Mexico and Chile contained a mean of 0.0085 (0.005-0.010) mg kg(-1). Acid-washing studies showed that most of the lead in the Turkish raisins was on the surface of the fruit. The impact of eating the raisins on the dietary intake of lead was estimated for Canadians of different ages and sexes. For example, eating raisins from Turkey would increase the dietary intake of lead by 1-4-year-old children from 0.97 to approximately 2.2 microg kg(-1) body weight day(-1). The source of the lead was traced to use of a copper fungicide contaminated with high lead levels. Currently, lead levels in raisins imported from Turkey are low and approach levels in raisins from other countries. Uncontaminated raisins contain approximately 0.01 mg lead kg(-1), and a maximum tolerance for lead in raisins of 0.1 mg kg(-1) is achievable irrespective of the type of raisin or country of origin. Therefore, consideration should be given to proposing this level as a maximum tolerance for lead in raisins.

Survey of lead, cadmium, fluoride, nickel, and cobalt in food composites and estimation of dietary intakes of these elements by Canadians in 1986-1988.

During the period 1986-1988, foods were purchased at the retail level in 5 Canadian cities and, for each city, prepared for consumption and combined into 113 composites and 39 composite subsets. Lead and cadmium were determined in all the samples; fluoride, in samples from Winnipeg; and cobalt and nickel, in samples from Montreal. Means and ranges of concentrations (ng/g) found in individual samples were lead, 23.2 (< 0.4-523); cadmium, 9.96 (< 0.02-167); fluoride, 325 (11-4970); nickel, 196 (< 0.6-2521); and cobalt, 9.4 (< 0.3-75.7). Estimated dietary intakes (microgram/day) of the elements over all ages and sexes were lead, 24; cadmium, 13; fluoride, 1763; nickel, 286; and cobalt, 11. During the period 1985-1988, the average level of lead in canned foods decreased from 73.6 to 46 ng/g.

Survey of arsenic in total diet food composites and estimation of the dietary intake of arsenic by Canadian adults and children.

During a comprehensive total diet study extending from 1985 to 1988, foods were collected in 6 Canadian cities (in one of them, a pilot study was conducted twice). For each of the 7 collections, foods were processed into 112 composites (105 in the initial pilot trial). Total arsenic was determined in all samples. The mean, median, and range of arsenic concentrations in all samples were 73.2, 5.1, and < 0.1-4830 ng/g, respectively. Food groups containing the highest mean arsenic levels were fish (1662 ng/g), meat and poultry (24.3 ng/g), bakery goods and cereals (24.5 ng/g), and fats and oils (19.0 ng/g). The estimated daily dietary ingestion of total arsenic by the average Canadian was 38.1 micrograms and varied from 14.9 micrograms for the 1- to 4-year-old group to 59.2 micrograms for 20- to 39-year-old males.

Organic and total lead in selected fresh and canned seafood products.

Various fresh and canned seafood products were examined for ionic alkyl lead, tetraalkyl lead and total lead. Dimethyl lead, diethyl lead, trimethyl lead and triethyl lead were extracted with diphenylthiocarbazone (dithizone) at pH 8 and 9 from enzymically hydrolysed samples. Butyl derivatives were formed by Grignard reaction prior to analysis by gas chromatography-atomic absorption spectrometry (GC-AAS). Tetraalkyl lead was extracted from the hydrolysates with hexane. Total lead was determined by reductive coprecipitation with palladium in the presence of ascorbic acid after nitric-perchloric digestion. Many of the samples contained low (less than 0.09-0.7 ng g-1) levels of trimethyl- and dimethyl lead. Triethyl lead was found at similar levels in several samples. Total lead levels were higher with values ranging from less than 5 ng g-1 to 2.9 micrograms g-1. Detection limits for the organolead and total lead methods were 0.07-0.2 and 3-19 ng Pb g-1 respectively.

Aluminium levels in Canadian infant formulate and estimation of aluminium intakes from formulae by infants 0-3 months old.

Aluminium was determined in 282 cans of infant formulae and evaporated milks sold in Canada using graphite furnace atomic absorption spectrometry. Milk-based formulae contained average (range) concentrations of 0.129 (0.010-0.36), 0.217 (0.17-0.56) and 0.717 (0.19-2.49) micrograms/g ('as sold') in ready-to-use, concentrated liquid and powder formulae, respectively. The corresponding concentrations in the soy-based formulae were 1.98 (0.40-6.4), 1.41 (0.59-2.29) and 9.44 (3.15-18.0) micrograms/g. Evaporated milk contained 0.093 (0.022-0.34) micrograms/g. The levels varied extensively according to formula brand; e.g. for ready-to-use formulae, the range of average concentrations by formula brand were 0.42-3.28 micrograms/g for soy-based and 0.020-0.22 micrograms/g for milk-based products. Estimated aluminium ingestion from formula or milk by infants up to 3 months old ranged from 0.5 microgram per kg body weight per day (microgram/kg/day) or 2 micrograms/day for 0-1 month olds fed cow milk exclusively to 219 micrograms/kg/day (1260 micrograms/day) for 1-3 month olds fed only soy-based formulae. Consumption of only the formulae brand having the highest mean aluminium level (3.28 micrograms/g) by 1-3 month old infants could result in an intake of 363 micrograms/kg/day (2088 micrograms/day). The estimates assume that the sole source of aluminium is the formula or milk and do not include any potential contribution from other foods or water.

Survey of lead, cadmium, cobalt and nickel in infant formulas and evaporated milks and estimation of dietary intakes of the elements by infants 0-12 months old.

Lead, cadmium, cobalt and nickel were determined in 282 infant formulas and evaporated milks using a graphite-furnace atomic absorption coprecipitation method capable of determining background levels in all samples. On an "as sold" basis, lead in ready-to-use (RTU), concentrated liquid, and powder formulas averaged 1.6, 3.7 and 12.6 ng g-1, respectively. Evaporated (evap.) milks in lead-free and lead-soldered cans contained 2.8 and 95 ng g-1, respectively. Average concentrations of cadmium, cobalt and nickel in evap. milk, milk-based RTU formulas and soy-based RTU formulas were: Cd, 0.38, 0.35 and 3.39 ng g-1; Co, 0.89, 0.46 and 2.79 ng g-1; and Ni, 4.7, 6.0 and 63.7 ng g-1, respectively. In milk-based formulas, cobalt and nickel concentrations were statistically higher in those fortified with iron. Dietary intakes of lead, cadmium, cobalt and nickel by 0-12-month-old infants from food and water used to dilute concentrated foods averaged 1.81 micrograms per kilogram body weight per day (micrograms kg-1 day-1) (13.2 micrograms day-1), 0.44 micrograms kg-1 day-1 (3.5 micrograms day-1), 0.52 micrograms kg-1 day-1 (3.93 micrograms day-1), and 5.0 micrograms kg-1 day-1 (38.2 micrograms day-1), respectively. Lead and cadmium intakes were below the respective FAO/WHO provisional tolerable daily intakes (PTDI) of 3.6 and 0.96-1.2 micrograms kg-1 day-1, except the lead intake of 6 micrograms kg-1 day-1 by infants fed evap. milk stored in lead-soldered cans.

Graphite-furnace atomic absorption spectrometric determination of lead, cadmium, cobalt and nickel in infant formulas and evaporated milks after nitric-perchloric acid digestion and coprecipitation with ammonium pyrrolidine dithiocarbamate.

A graphite-furnace atomic absorption method, developed for lead and cadmium, was modified to enable simultaneous determination of lead, cadmium, cobalt and nickel in infant formulas and evaporated milks. The method was assessed on the basis of analytical quality assurance results during routine analysis of samples. Detection limits (ng g-1 based on 10 g sample size for ready-to-use formulas) were 0.04-0.21 for lead, 0.004-0.015 for cadmium, 0.04-0.2 for cobalt and 0.06-0.26 for nickel. Within-series repeatability and day-to-day reproducibility (among series) coefficients of variation (CVs) were, respectively, 11.7 and 16% for lead, 2.5 and 7.5% for cadmium, 7.2 and 18.8%for cobalt, and 8.1 and 8.6% for nickel at respective concentrations of 1.89, 0.40, 1.25 and 11.8 ng g-1.

Lead and cadmium levels in commercial infant foods and dietary intake by infants 0-1 year old.

Lead and cadmium levels were determined in 131 infant foods. Mean lead and cadmium levels were 19.3 and 3.3 ng/g for meats, 8.4 and 4.1 ng/g for vegetables, 14.9 and 0.58 ng/g for fruits and desserts, 9.6 and 0.53 ng/g for juices and drinks, and 32.8 and 33.6 ng/g for dry infant cereals. These data, combined with those from other recent surveys, yielded average dietary (food and water) intakes of lead and cadmium by infants 0-1 year old of 2.4 and 0.37 microgram/kg/day, respectively. Lead intakes were most strongly influenced by storage of infant formulas in lead-soldered cans. For infants 0-1 month old, they ranged from 0.5 microgram/kg/day when human or cow milk was fed to infants to 5.3 micrograms/kg/day (exceeding the FAO/WHO provisional tolerable daily intake, PTWI, of lead by children of 3.5 micrograms/kg) when ready-to-use formula stored in lead-soldered cans was fed. Cadmium intakes were most strongly affected by soya based formulas, and ranged, for 0-1 months olds, from 0.16 microgram/kg/day for infants fed human or cow milk to 0.50 microgram/kg/day for infants fed soya-based concentrated liquid formula. Cadmium intakes were all below the FAO/WHO PTDI of cadmium by adults of 0.96-1.2 micrograms/kg.

Total arsenic in foods after sequential wet digestion, dry ashing, coprecipitation with ammonium pyrrolidine dithiocarbamate, and graphite-furnace atomic absorption spectrometry.

A graphite-furnace atomic absorption (GFAAS) method is described for determining total arsenic (organic and inorganic compounds) in foods. Samples ranging from 1 to 40 g (depending on moisture content) were digested with HNO3 and dry-ashed at 500 degrees C overnight after addition of MgO. After dissolution in HCl, the arsenic was reduced with iodide and ascorbic acid and precipitated with ammonium pyrrolidine dithiocarbamate (APDC) in the presence of nickel carrier. Precipitates were collected on 0.3 micron cellulose acetate filters and dissolved in 10% HNO3 containing modifier. Ba(NO3)2 was added to remove a sulfate interference resulting from decomposition of APDC. Arsenic was determined using GFAAS. Accuracy of the method was good for 7 U.S. National Bureau of Standards (NBS) Standard Reference Materials and 3 National Research Council of Canada (NRCC) round-robin samples. Recovery of arsenic(V) from foods averaged 99.2% for peak heights and 97.1% for peak areas, with relative standard deviations (RSD) of 2.2% for peak heights and 3.3% for peak areas for all NBS and NRCC materials. Detection limit of the method was ca 10 ng arsenic.

Lead, cadmium, and fluoride levels in market milk and infant formulas in Canada.

Lead, cadmium, and fluoride were determined in 68 samples of market milk and about 115 infant formulas. Mean and median levels (ranges) in ng/g found for cow milk were as follows: lead, 1.12, 1.19 (0.01-2.48); cadmium, 0.10, 0.039 (0.005-0.74); and fluoride, 41, 40 (7-86). In canned, ready-to-use formulas, lead, cadmium, and fluoride levels averaged 37.3, 1.50, and 840 ng/g, respectively. In concentrated liquid formulas, the respective levels were 21, 3.54, and 600 ng/g. In powder formula concentrates, respective levels were 73.7, 6.78, and 1130 ng/g. On the basis of this study and literature data, lead levels in market milk exceeding 5 ng/g appeared to signify contamination of the milk either directly or via the cow. For formulas considered on an as-consumed basis, lead levels exceeding about 10-15 ng/g were attributed to contamination from either the can used to store the formula or the formula ingredients. Infant formulas in lead-free cans contained about 1.7 ng/g of lead on a ready-to-use basis. Milk-based formulas contained about 0.26 ng/g of cadmium on a ready-to-use basis. Soy-based or milk-free formulas contained about 8-15 times more cadmium than did milk-based formulas. Canadian and U.S. ready-to-use formulas contained 900 and 230 ng/g fluoride, respectively, and this difference was attributed to the level of fluoride in the processing water used by the manufacturers.

Dietary intakes of lead, cadmium, arsenic and fluoride by Canadian adults: a 24-hour duplicate diet study.

Twenty-four hour duplicate diets, including drinking water and snacks, were collected from 24 adults living in five Canadian cities. Each diet was separated by the participants into 10 food categories, and each of the samples was analyzed in duplicate for lead, cadmium, arsenic and fluoride. Minimum detection limits for the respective elements in foods were about 0.1, 0.01, 0.3 and 5 ng/g. Mean dietary intakes were 53.8 micrograms/day or 0.80 micrograms/kg/day for lead, 13.8 micrograms/day or 0.21 micrograms/kg/day for cadmium, and 16.7 micrograms/day or 0.26 micrograms/kg/day for arsenic. The median intakes were 42.7 micrograms/day or 0.57 mu/kg/day for lead, 11.9 micrograms/day or 0.17 micrograms/kg/day for cadmium, and 9.79 micrograms/day or 0.139 micrograms/kg/day for arsenic. Half of the participants lived in communities with 1 microgram/g fluoride in the drinking water, and half lived in cities with less than 0.2 microgram/g fluoride in the water. The dietary intake of fluoride for the former was 2802 micrograms/day or 39.7 micrograms/kg/day; while that of the latter was 563 micrograms/day or 8.5 micrograms/kg/day. The respective median intakes of fluoride were 2090 micrograms/day or 30.3 micrograms/kg/day, and 414 micrograms/day or 7.0 micrograms/kg/day. Contribution of individual foods and food categories to the dietary intakes is discussed.