Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tfac20 Food Additives & Contaminants: Part A ISSN: 1944-0049 (Print) 1944-0057 (Online) Journal homepage: www.tandfonline.com/journals/tfac20 Styrene in foods and dietary exposure estimates Xu-Liang Cao, Melissa Sparling, Luc Pelletier & Robert Dabeka To cite this article: Xu-Liang Cao, Melissa Sparling, Luc Pelletier & Robert Dabeka (2018) Styrene in foods and dietary exposure estimates, Food Additives & Contaminants: Part A, 35:10, 2045-2051, DOI: 10.1080/19440049.2018.1512760 To link to this article: https://doi.org/10.1080/19440049.2018.1512760 Published online: 27 Aug 2018. Submit your article to this journal Article views: 401 View related articles View Crossmark data Citing articles: 12 View citing articles https://www.tandfonline.com/action/journalInformation?journalCode=tfac20 https://www.tandfonline.com/journals/tfac20?src=pdf https://www.tandfonline.com/action/showCitFormats?doi=10.1080/19440049.2018.1512760 https://doi.org/10.1080/19440049.2018.1512760 https://www.tandfonline.com/action/authorSubmission?journalCode=tfac20&show=instructions&src=pdf https://www.tandfonline.com/action/authorSubmission?journalCode=tfac20&show=instructions&src=pdf https://www.tandfonline.com/doi/mlt/10.1080/19440049.2018.1512760?src=pdf https://www.tandfonline.com/doi/mlt/10.1080/19440049.2018.1512760?src=pdf http://crossmark.crossref.org/dialog/?doi=10.1080/19440049.2018.1512760&domain=pdf&date_stamp=27 Aug 2018 http://crossmark.crossref.org/dialog/?doi=10.1080/19440049.2018.1512760&domain=pdf&date_stamp=27 Aug 2018 https://www.tandfonline.com/doi/citedby/10.1080/19440049.2018.1512760?src=pdf https://www.tandfonline.com/doi/citedby/10.1080/19440049.2018.1512760?src=pdf Styrene in foods and dietary exposure estimates Xu-Liang Cao a, Melissa Sparlinga, Luc Pelletierb and Robert Dabekaa aFood Research Division, Bureau of Chemical Safety, Health Canada, Ottawa, Ontario, Canada; bChemical Health Hazard Assessment Division, Bureau of Chemical Safety, Health Canada, Ottawa, Ontario, Canada ABSTRACT Low levels of styrene may be found in foods as a result of possible migration from polystyrene- based food packaging and as a result of its formation during the biodegradation of a wide variety of naturally occurring compounds with structures similar to styrene. In this study, composite food samples from a recent (2014) Canadian Total Diet Study were analysed for styrene, and levels of styrene in samples of most food types were low in general with a few exceptions (e.g. 4934 ng/g in herbs and spices). Dietary exposures to styrene were estimated for different age-groups based on the occurrence data and the food consumption data for all persons, and they are 0.17–0.38 µg/kg body weight/day for children and 0.12–0.16 µg/kg body weight/day for adults, similar to air intakes (0.085–0.27 µg/kg body weight/day). Thus, for the general population, both food and air contribute similar portions of the total daily intake of styrene for all age groups. However, for the smoking population, intakes from cigarettes are still the major route of exposure to styrene. ARTICLE HISTORY Received 3 July 2018 Accepted 8 August 2018 KEYWORDS Styrene; total diet; food; dietary intake; exposure; headspace; SPME; GC-MS Introduction Styrene is an important industrial chemical and is used mainly for the production of polystyrene (PS) and styrene copolymers (Tang et al. 2000). Polystyrene is the second most widely used polymer in food packaging (Nerin et al. 1998), with expand- able PS (EPS) being used for beverage cups and as trays for packaging meat, poultry, cheese, fruits and vegetables, and high impact PS (HIPS) packaging being used for beverage cups, yogurt, sandwich clamshells packaging, etc. Residual styrene mono- mer present in polystyrene can migrate into foods (Withey 1976;Murphy et al. 1992; Jickells et al. 1993; Ehret-Henry et al. 1994; Gramshaw andVandenburg 1995; Lickly et al. 1995; Tawfik and Huyghebaert 1998), thus styrene can be detected at low levels in foods (Withey 1976; Withey and Collins 1978; Steele et al. 1994; Nerin et al. 1998). Styrene concentrations of 550 ppb (µg/kg) in avocado (Fleming-Jones and Smith 2003) and 111.2 µg/kg in ready-to-eat meals (Vinci et al. 2015) have been reported. Styrene can also be formed during the biodegradation of a wide variety of naturally occurring flavouring compounds with structures similar to styrene (e.g. cinnamic acid, cinnamic aldehyde, cinnamyl acetate, cinnamyl alcohol, cinnamyl benzoate, cinnamyl cinnamate), and has been detected in cinnamon at levels as high as 39.2 mg/kg (Steele et al. 1994) and 524 mg/kg (Lafeuille et al. 2009). Title 21, Part 165 of the United States Food and Drug Administration’s (U.S. FDA) Code of Federal Regulations (CFR) specifies a maximum allowable styrene concentration of 0.1 mg/L in bottled water (UDFDA 2017). In addition to affecting sensory properties at low levels in foods (Ehret-Henry et al. 1994), exposure to styrene may also be a health concern; styrene has been classified as possibly car- cinogenic to humans (Group 2B), on the basis of limited evidence in animals and humans, by the International Agency for Research on Cancer (IARC 2002). The previous Canadian assessment of human exposure to styrene was conducted through the Government of Canada’s Priority Substances List (PSL) initiative more than 20 years ago (Government of Canada 1993). Due to the limita- tions of the available data on concentrations in the environment, the principal route of exposure to styrene for the general population of Canada could not be clearly identified. Because of the volatility of CONTACT Xu-Liang Cao xu-liang.cao@canada.ca Food Research Division, Bureau of Chemical Safety, Health Canada, AL: 2203D, Ottawa, Ontario K1A 0K9, Canada FOOD ADDITIVES & CONTAMINANTS: PART A 2018, VOL. 35, NO. 10, 2045–2051 https://doi.org/10.1080/19440049.2018.1512760 © 2018 Crown Copyright http://orcid.org/0000-0002-8094-062X http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/19440049.2018.1512760&domain=pdf styrene, ambient air and indoor air were estimated to contribute a substantial portion of the total daily intake for all age groups. Contribution from food in that assessment was considered to be an overesti- mate as dietary intakes were calculated using analy- tical detection limits. Styrene was not detected in food samples from the only survey conducted in Canada in the early 1990s and considered in the PSL assessment (Government of Canada 1993) and therefore concentrations in food were assumed to be equivalent to the detection limits. Since 1969, the Canadian Total Diet Study (TDS) has been playing an important role in mon- itoring the presence of various chemical contami- nants in the Canadian food supply and generating occurrence data for human exposure assessments. Recently, food samples from the 2014 Canadian Total Diet Study were analysed for styrene and various volatile organic compounds (VOCs). The purpose of this paper is to report and discuss in depth the occurrence data of styrene and to esti- mate updated dietary exposures for different age groups of the Canadian population. This will determine the significance of dietary exposure to styrene for the general population of Canada. Materials and methods Materials and reagents Sodium chloride (> 99.0%) was obtained from VWR (Mississauga, Ontario, Canada). Styrene-d8 (99.2 atom % D) and other labelled volatile organic com- pound (VOC) standards were purchased from C/D/ N Isotopes Inc. (Pointe-Claire, Quebec Canada), and the following chemicals were purchased from Sigma-Aldrich (Mississauga, Ontario, Canada): methanol (99.8%), and EPA VOC Mix 2 in metha- nol containing styrene and other VOCs at 2000 µg/mL. The 100 µm polydimethylsiloxane (PDMS) SPME fibre was purchased from Supelco (Bellefonte, PA, USA). The 20-mL SPME crimp amber glass vials were purchased from Labsphere (Quebec, Canada). Stock composite standard solution of deuter- ated VOCs was prepared in methanol at a con- centration of 100 ng/µL. Composite standard solutions in methanol with deuterated VOCs at ca 2 ng/µL and native VOCs at different concentrations (ca 0, 0.2, 1, 3, 5, 8 and 10 ng/µL) were prepared by adding 200 µL stock solution of deuterated VOCs (100 ng/µL) and 0, 1, 5, 15, 25, 40 and 50 µL EPA VOC Mix 2 to 10 mL methanol. Composite standard solutions in water with deut- erated VOCs at ca 4 ng/mL and native VOCs at different concentrations (ca 0, 0.4, 2, 6, 10, 16 and 20 ng/mL) were prepared by adding 20 µL stock solution of deuterated VOCs (2 ng/µL) and native VOCs (0, 0.2, 1, 3, 5, 8 and 10 ng/µL) to 10 mL water. All solutions were stored at 4°C. Sample collection and preparation Food samples were collected from four different stores in Winnipeg, Canada, over a 5 week period in 2014. The foods were prepared as for consump- tion according to the established procedures (Dabeka and Cao 2013), and individual samples of each type of food were combined into a total of 159 different food composites. Composites for foods that can be consumed both raw and cooked (e.g. cauliflower, carrots, broccoli, tomatoes, spi- nach) were prepared as a mixture of the raw and cooked (1:1). The food composites covered a vari- ety of food categories including dairy products, meat, poultry, fish, cereal, vegetable, fruit, bev- erages and other miscellaneous foods. As part of the standard preparation procedures, kitchen staffs do not use any perfumes, hair spray, cologne, fragrant soap, make-up or talcum pow- der. Stainless steel or glass vessels were used for all processing. Drinking water was used for food pro- cessing. Food composites were stored frozen in 250-mL glass jars at −20°C until analysis. About 5 g of NaCl (pre-heated at 650°C over- night and then stored at 200°C) was weighed into a 20-mL amber glass vial then cooled to 4°C. For most of the samples, about 1 g of sample was weighed into the 20-mL vial, but smaller amounts were weighed for samples containing fat due to matrix effects. Each sample was spiked with inter- nal standard solution, followed by adding 10 mL of deionised water. The vial was capped and then vortexed for 10 – 15 s to speed up dissolution of NaCl and mixing of the sample with water. All vials containing samples were placed on a metal tray, cooled with ice and samples were spiked 2046 X.-L. CAO ET AL. within 15 s to minimise any loss of target com- pounds during sample preparation. Headspace solid phase micro-extraction and instrument conditions An Agilent 6890 gas chromatograph (GC) coupled to a 5973 mass selective detector (MSD) was used for analysis. The GC-MSD was equipped with a MultiPurpose Autosampler (MPS 2) from Gerstel (Baltimore, MD, USA) set-up in SPME operation mode. At the beginning of analysis, the sample vial was transported from the tray to the agitator held at 30°C. After incubating for 1 min, the PDMS SPME fibre was inserted through the septum into the headspace. Vial penetration depth was set at 25 mm. Agitation speed was set at 250 rpm. After the extraction for 10 min, the SPME fibre was inserted into the GC injector fitted with a 0.75 mm I.D. liner for desorption. The injector temperature was set at 250°C. Injection penetration depth was set at 65 mm, and the SPME fibre was desorbed for 5 min in splitless mode. Analytes were separated on a DB-624 capillary column (60 m x 0.25 mm x 1.4 µm, Agilent Technologies). The GC oven temperature programme was set at an initial temperature of 50°C for 5 min, raised to 250°C at 10°C/min, and held for 5 min. The flow rate of the helium carrier gas was 1.2 mL/min. The MSD was operated with electron impact ionisation in selected ion monitoring (SIM) mode. The ions selected for the native and labelled VOCs can be found elsewhere (Cao et al. 2016), and they were m/z 104 and 78 for styrene, and 112 for styrene-d8. The GC-MSD interface and the MS system source temperature were 260 and 230°C, respectively. Quantitation and quality control The calculation of concentrations in samples was based on the isotope dilution method. Confirmation of compound identity was based on the retention time and the ion ratio of the analytical standard. For each batch of analysis, each sample was analysed in four replicates, two of which were spiked with both native and deuterated VOCs to check accuracy, and the other two were spiked with deuterated VOCs only to determine VOC concentrations in the sample. Three blank samples (water) were also included in each batch. Some VOCs were not detected in blanks while blank levels of other VOCs were low: 0.028 ng for styrene. Results for all samples were corrected for method blanks. Each new PDMS SPME fibre was initially cleaned by heating at 260°C for 30 min prior to use. This fibre was also cleaned after analysis of each sample by heating in the injector (250°C) for an additional five minutes after desorption of the exposed fibre. Carryover was not observed. Dietary intake estimates Dietary intakes of styrene for different age-sex groups of children and adults were calculated by multiplying the average concentration of styrene in a food composite by the average consumption rate for all persons of that food product for various age groups, obtained from the 2004 Canadian Community Health Survey (CCHS), Cycle 2.2 (Statistics Canada 2004). The total styrene exposures for each age category were then calculated by sum- ming the individual intakes from each food compo- site. Estimates were converted to a body weight basis using measured and self–reported body weight data from the 2004 CCHS. Results and discussion The headspace SPME GC-MS method has been previously validated for styrene and other VOCs (Cao et al. 2016). Linearity of the instrument and the headspace SPME method was demonstrated using six standard solutions (0.4–20 ng/mL) and R2 values for the styrene calibration plots were better than 0.999 for the calibration plots of styr- ene. The average recoveries for styrene were 103 ± 0.24% for water spiked at 5 ng/ml, and 104 ± 1.4% for water spiked at 20 ng/ml. Since styrene was detected in method blanks, at about 0.028 ng, the method detection limit (MDL) for styrene was calculated as 10 times the standard deviation of method blanks and also 10 times the signal to noise ratio for each food sample, and the higher value was taken as the MDL for styrene in this food sample. The MDLs for styrene for the FOOD ADDITIVES & CONTAMINANTS: PART A 2047 159 different food composite samples ranged from 0.023 to 10.7 ng/g with an average of 1.1 ng/g. A total of 159 different composite food samples from the 2014 TDS were analysed for styrene and other VOCs, and styrene concentrations in these food samples are shown in Table 1. Each result is the average of two replicate analyses, with an average relative difference of 8.6% for all samples, and with an average accuracy of 94.8% of recoveries from all samples. Table 1. Concentrations (ng/g) of styrene in composite food samples from 2014 TDS. Composite Conc (ng/g) Composite Conc (ng/g) Composite Conc (ng/g) Dairy Vegetable Fat and oil Milk, whole 0.73 Baked beans, canned 3.6 Cooking fats and salad oils < 8.7 Milk, 2% 1.1 Beans, string 1.2 Margarine < 6.8 Milk, 1% 0.63 Beets 0.16 Mayonnaise 4.1 Milk, skim 0.33 Broccoli < 0.15 Salad dressing < 5.7 Evaporated milk, canned < 0.73 Cabbage < 0.21 Baby food Cream 1.8 Carrots 1.4 Cereals, mixed 0.92 Ice cream 1.7 Cauliflowers < 0.13 Desserts 0.54 Yogurt 19 Celery 0.30 Dinners, cereal + vegetable + meat 0.46 Cheese 4.6 Corn 1.6 Dinners, meat or poultry + vegetable 0.48 Cheese, cottage 0.40 Cucumbers 0.87 Formulae, milk base 0.92 Cheese, processed 1.7 Lettuce 0.37 Formulae, soya base < 0.43 Butter 18 Mushrooms 0.41 Fruit, apple or peach 0.12 Chocolate milk, 1% 6.8 Onions < 0.070 Meat, poultry or eggs < 1.8 Butter milk, 1% 6.1 Peas < 0.30 Vegetables, peas < 0.11 Meat Peppers 2.1 Fast food Beef, steak 2.7 Potatoes, peeled and boiled < 0.10 Popcorn, microwave 4.4 Beef, roast 0.92 Potatoes, chips < 4.7 Frozen entrees 1.0 Beef, ground 6.7 Rutabagas < 0.14 Pizza 33 Pork, fresh 3.9 Vegetable juice, canned 0.060 French fries 24 Pork, cured 3.4 Tomatoes 0.82 Hamburger 7.0 Veal, cutlets 1.5 Tomatoes and tomato sauce, canned < 0.12 Chicken burger 9.8 Lamb < 1.0 Spinach 0.34 Hot dogs 5.8 Luncheon meats, cold cuts 3.8 Asparagus 1.2 Chicken nuggets 15 Luncheon meats, canned 1.5 Brussel sprouts 0.22 Beef chow mien, carry-out 21 Organ meats 0.94 Potatoes, baked with skins 0.23 Fried rice (Chicken and veg) 49 Wieners and sausages 6.0 Corn chips < 3.4 Prepared Breakfast sandwiches 19 Poultry Fruit Fast food sandwiches 6.0 Eggs < 1.4 Applesauce, canned 0.086 Others Poultry, chicken and turkey < 0.54 Apples, raw 1.0 Chocolate bars 12 Poultry, liver pate 15 Bananas 0.29 Candy 0.86 Fish Blueberries 2.2 Gelatine dessert 0.077 Fish, marine 0.60 Cherries 0.070 Honey, bottled 0.59 Fish, fresh water 2.0 Citrus fruit, raw < 0.080 Jams 0.32 Fish, canned 2.3 Grapes < 0.090 Peanut butter 19 Shellfish 0.92 Melons 0.43 Puddings 12 Soup Peaches 0.41 Sugar, white < 0.14 Soups, meat, canned 0.16 Pears 1.5 Syrup < 0.062 Soups, creamed, canned 0.23 Pineapple, canned 0.12 Seeds, shelled 11 Soups, broth, canned 0.070 Plums and prunes 0.10 Nuts 595 Soups, dehydrated < 0.081 Raisins < 0.79 Chewing gum 12 Cereal Raspberries 15 Condiments 4.1 Bread, white 34 Strawberries 0.23 Salt < 0.020 Bread, whole wheat 30 Kiwi fruit 0.18 Baking powder < 0.18 Bread, rye 21 Apricot 1.3 Yeast 21 Cake 9.8 Beverage Vanilla extract 1.2 Cereal, cooked wheat 0.33 Apple juice, canned 0.12 Herbs and spices 4934 Cereal, corn 0.61 Citrus juice, frozen 0.12 Soya sauce 0.061 Cereals, oatmeal 0.35 Citrus juice, canned 0.19 Cereals, rice and bran 2.1 Grape juice, bottled 0.10 Cookies 60 Fruit drinks (cocktails) 0.17 Crackers 16 Alcoholic drinks, beer 4.0 Danish, donuts and croissants 42 Alcoholic drinks, wine 0.23 Flour, white (wheat) 17 Coffee 0.15 Muffins 41 Soft drinks, canned 0.23 Pancakes and waffles 5.9 Tea < 0.039 Pasta, mixed dishes 1.0 Soy beverage, fortified < 0.30 Pasta, plain < 0.37 Tap water, kitchen < 0.073 Pie, apple 63 Tap water, sample area < 0.030 Pie, other 34 Water, natural spring < 0.028 Rice 0.10 Water, natural mineral 0.070 Buns and rolls 39 Breads, other 11 2048 X.-L. CAO ET AL. Although styrene was detected frequently among all the composite samples analysed (125 of 159 sam- ples or 78.6%), the concentrations of styrene in the composite samples of most food types were gener- ally low with a few exceptions. Styrene was detected at the highest level of 4934 ng/g in the composite sample of herbs and spices which was prepared as a mixture of black pepper, oregano, basil, and cinna- mon in equal portions. Styrene can be formed dur- ing biodegradation of some naturally occurring compounds with structures similar to styrene and it has been previously detected in cinnamon at levels up to 524 mg/kg (Lafeuille et al. 2009). Therefore, the level of styrene in the herbs and spices composite sample may be attributed to the presence of cinna- mon. Assuming styrene is not present or present at low levels in the other herbs and spices (black pep- per, oregano and basil) of the composite sample, styrene concentration in the cinnamon could be greater than 20 mg/kg, approaching the level of 39.3 mg/kg reported by Steele et al. (1994). The next highest level of styrene was found in the com- posite sample of nuts (595 ng/g) which was prepared as a mixture of roasted and unsalted peanuts and walnuts at a ratio of 3:1. The presence of styrene in the roasted nuts is a new observation, and the sources of styrene in roasted nuts are not clear. Further research is planned to investigate the con- sistency of the occurrence of styrene in roasted nuts by analysing roasted nuts samples from future total diet studies, and to investigate if styrene could be formed during roasting. Among the dairy food samples, concentrations of styrene in yogurt and butter are slightly higher, at 19 and 18 ng/g, respectively. One of the sources for styrene in yogurt could be migration from its poly- styrene packaging. The styrene concentration in yogurt found in this study is similar to those reported by others (Ehret-Henry et al. 1994; Nerin et al. 1998). Styrene was also detected at concentrations in the present study ranging from 20 to 63 ng/g in certain grain-based foods and fast foods such as bread, cookies, muffins, pie, pizza and French fries. The exact source for styrene in these samples is not clear, but it is unlikely to be derived from the Maillard reaction (Goldmann et al. 2009). The presence of styrene in certain baked products, such as cookies and muffins, could be related to the use of cinnamon. The average dietary exposures to styrene were estimated for different age-groups based on the occurrence data from 2014 TDS and the food con- sumption data for all persons from the 2004 CCHS, Cycle 2.2 (Statistics Canada 2004) and are shown in Table 2. The per cent of styrene exposure from different food groups to the total dietary exposures was also calculated for different age groups, and the results are shown in Table 3. Dietary exposures to styrene are mainly from dairy (12.9–46.3%), grain- based foods (11.8–39.4%) and nuts (2.9–36.2%). In general, dietary exposures to styrene are lower for children, ranging from 1.4 µg/day for infants (6–11 months) to 5.7 µg/day for toddlers (2–3 years), and increase for older age groups as exposure estimates range from 8.1 to 11 µg/day for adults, which are similar to the estimated daily intake of Table 3. Per cent (%) of styrene exposures from different food groups relative to the total dietary exposures of styrene for different age groups. Age groups Dairy Meat Poultry Fish Soup Grain-based Vegetable Fruit Fat Nuts Beverage Baby food Fast food Herbs and spices 6–11 months 46.3 0 0 0 0 11.8 0.44 2.07 0 0 0 39.3 0 0 1 year 32.1 3.75 0 0.60 0.14 40.0 1.77 9.53 0.073 2.9 0 1.79 0.081 7.31 2–3 years 32.9 3.46 0 0.37 0.15 35.4 1.58 4.63 0.10 13.4 0.076 1.04 0.11 6.76 4–8 years 26.8 4.13 0 0.36 0.079 39.4 1.41 3.61 0.16 14.5 0.17 0.0088 0.13 9.28 9–13 years 24.2 4.01 0 0.34 0.12 38.3 1.30 3.49 0.27 19.7 0.32 0 0.18 7.71 14–18 years 21.8 4.71 0 0.34 0.10 37.0 1.45 2.37 0.41 20.3 2.18 0 0.14 9.19 19–30 years 17.4 3.88 0 0.38 0.10 29.2 1.66 2.53 0.37 26.5 7.26 0 0.12 10.6 31–50 years 14.5 4.10 0 0.69 0.11 27.5 1.87 2.96 0.35 33.0 6.01 0 0.11 8.92 51–70 years 12.9 3.72 0 0.89 0.13 26.6 2.17 3.56 0.31 36.2 4.81 0 0.083 8.58 71+ years 16.5 3.88 0 1.04 0.22 33.3 2.35 4.14 0.25 35.6 2.38 0 0.030 0.29 Table 2. Average dietary exposures to styrene for different age groups. Age groups µg/day µg/kg body weight/day 6–11 months 1.4 0.20 1 year 3.3 0.22 2–3 years 5.7 0.38 4–8 years 7.7 0.31 9–13 years 9.5 0.21 14–18 years 10 0.17 19–30 years 11 0.15 31–50 years 11 0.16 51–70 years 11 0.15 71+ years 8.1 0.12 FOOD ADDITIVES & CONTAMINANTS: PART A 2049 6.6 µg/person/day from food packaging presented recently by the Plastics Foodservice Packaging Group in the United States to the US FDA (Plastics Foodservice Packaging Group 2015). On a body weight basis, dietary exposures to styrene for chil- dren (0.17 – 0.38 µg/kg body weight/day) are higher than those for adults (0.12–0.16 µg/kg body weight/ day). Higher exposure estimates on a body weight basis for younger age groups would be expected as children tend to consume more food per unit of body weight than adults. Dietary exposure estimates to styrene from this study are also comparable with the intake estimates from ambient and indoor air determined in the early 1990s for non-smokers (0.096–0.24 µg/kg body weight/day for 7 months– 4 years; 0.107–0.27 µg/kg body weight/day for 5–11 years; 0.096–0.23 µg/kg body weight/day for 12–19 years; and 0.085–0.21 µg/kg body weight/day for 20–70 years) (Government of Canada 1993). This suggests that both food and air (ambient and indoor) may contribute similar proportions of the total daily intake of styrene for all age groups but they are at least an order of magnitude lower than that reported from cigarettes for adults and adoles- cents (Government of Canada 1993). In contrast, the study by Tang et al. (2000) found that air intake accounts for the majority of the total intake of styrene (> 90%), estimated at 0.3–0.8 µg/kg body weight/day, compared with food intake at 0.003–0.017 µg/kg body weight/day. It should be mentioned that a daily respiratory intake of 30 m3 of air was used for air intake estimates by Tang et al. (2000) while different daily respiratory intakes of air (2–23 m3) were used in the Canadian assessment for different age groups (Government of Canada 1993). However, dietary exposure estimates from this cur- rent study are well below, by at least 20-fold, the tolerable daily intake (TDI) of 7.7 µg/kg of body weight established by World Health Organization (WHO 2003), and at least 300-fold lower than the tolerable daily intake of 120 µg/kg body weight per day derived for oral exposure to styrene as part of the PSL critical review (Government of Canada 1993). In summary, levels of styrene in most of the total diet food samples are very low. Of the TDS samples, styrene was detected at higher levels in some dairy foods, cereal and fast food samples, with the highest levels found in herbs and spices. The current dietary intakes estimated using occurrence data from the 2014 TDS confirm the previous assessment (Government of Canada 1993) that food may also contribute a similar portion to the total daily intake of styrene for all age groups (non-smoking), in addi- tion to air. However, considering the high levels of exposure to styrene (2.86 and 3.51 μg/kg bw/day) for smoking adults and teens estimated in the previous assessment (Government of Canada 1993), intakes from cigarettes are still the major route of exposure to styrene for the smoking population. Acknowledgements The authors thank the Canadian Food Inspection Agency for the collection of the individual food items, Karen Pepper (Health Canada) for coordination of the total diet study and Masresha Asrat (Health Canada) for sample allocation. Xu-Liang Cao also thanks the two reviewers for the critical comments and suggestions. Disclosure statement No potential conflict of interest was reported by the authors. ORCID Xu-Liang Cao http://orcid.org/0000-0002-8094-062X References Cao X-L, Sparling M, Dabeka R. 2016. Occurrence of 13 volatile organic compounds in foods from the Canadian total diet study. Food Additives Contaminants: Part A. 33:373–382. Dabeka R, Cao X-L. 2013. The Canadian total diet study design: 1992-1999. Food Additives Contaminants: Part A. 30:477–490. Ehret-Henry J, Ducruet V, Luciani A, Feigenbaum A. 1994. Styrene and ethylbenzene migration from polystyrene into dairy products by dynamic purge-and-trap gas chromato- graphy. J Food Sci. 59:990–1001. Fleming-Jones ME, Smith RE. 2003. Volatile organic com- pounds in foods: a five year study. J Agric Food Chem. 51:8120–8127. Goldmann T, Davidek T, Gouezec E, Blank I, Bertholet M-C, Stadler R. 2009. Formation of styrene during the Maillard reaction is negligible. Food Addit Contam. 26:583–594. Government of Canada. 1993. Canadian Environmental Protection Act (CEPA) Priority Substances List Assessment Report – Styrene. accessed 2018 Jan 31. https://www.canada.ca/content/dam/hc-sc/migration/hc- sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contami nants/psl1-lsp1/stryene/styrene-eng.pdf. 2050 X.-L. CAO ET AL. https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/psl1-lsp1/stryene/styrene-eng.pdf https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/psl1-lsp1/stryene/styrene-eng.pdf https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/psl1-lsp1/stryene/styrene-eng.pdf Gramshaw JW, Vandenburg HJ. 1995. Compositional analy- sis of samples of thermoset polyester and migration of ethylbenzene and styrene from thermoset polyester into pork during cooking. Food Addit Contam. 12:223–234. [IARC] International Agency for Research on Cancer. 2002. Monographs on the evaluation of carcinogenic risks to humans, Volume 82, some traditional herbal medicines, some mycotoxins, naphthalene and styrene. accessed 2018 Jan 31. http://monographs.iarc.fr/ENG/Monographs/ vol82/mono82.pdf. Jickells SM, Gancedo P, Nerin C, Castle L, Gilbert J. 1993. Migration of styrene monomer from thermoset polyester cookware into foods during high temperature application. Food Addit Contam. 10:567–573. Lafeuille J-L, Buniak M-L, Vioujas M-C, Lefevre S. 2009. Natural formation of styrene by cinnamon mold flora. J Food Sci. 74:M276–M283. Lickly TD, Lehr KM, Welsh GC. 1995. Migration of styrene from polystyrene foam food-contact articles. Fd Chem Toxic. 33:475–481. Murphy PG, MacDonalde DA, Licky TD. 1992. Styrene migra- tion from general-purpose and high-impact polystyrene into food-simulating solvents. Fd Chem Toxic. 30:225–232. Nerin C, Rubio C, Cacho J, Salafranca J. 1998. Parts-per- trillion determination of styrene in yoghurt by purge-and- trap gas chromatography with mass spectrometry detec- tion. Food Addit Contam. 15:346–354. Plastics Foodservice Packaging Group. 2015. The safety of styrene-based polymers for food-contact use 2013. accessed 2018 May 22. https://www.plasticfoodservicefacts.com/wp- content/uploads/2017/10/Polystyrene-Report.pdf. Statistics Canada. 2004. Canadian community health sur- vey – nutrition (CCHS). Detailed information for 2004 (Cycle 2.2). Ottawa (ON): Statistics Canada. accessed 2018 Jan 31. http://www23.statcan.gc.ca/imdb/p2SV.pl? Function=getSurvey&SDDS=5049&lang=en&db= imdb&adm=8&dis=2 Steele DH, Thornburg MJ, Stanley JS, Miller RR, Brooke R, Cushman JR, Cruzan G. 1994. Determination of styrene in selected foods. J Agric Food Chem. 42:1661–1665. Tang W, Hemm I, Eisenbrand G. 2000. Estimation of human exposure to styrene and ethylbenzene. Toxicology. 144:39–50. Tawfik MS, Huyghebaert A. 1998. Polystyrene cups and containers: styrene migration. Food Addit Contam. 15:592–599. [USFDA] United States Food & Drug Administration. 2017. CFR – code of federal regulations title 21. accessed 2018 Jan 31. https://www.accessdata.fda.gov/scripts/cdrh/ cfdocs/cfcfr/CFRSearch.cfm?fr=165.110. Vinci RM, Jacxsens L, De Meulenaer B, Deconink E, Matsiko E, Lachat C, De Schaetzen T, Canfyn M, Van Overmeire I, Kolsteren P, et al. 2015. Occurrence of volatile organic compounds in foods from the Belgian market and dietary exposure assessment. Food Control. 52:1–8. Withey JR. 1976. Quantitative analysis of styrene monomer in polystyrene and foods including some preliminary stu- dies of the uptake and pharmacodynamics of the mono- mer in rats. Environ Health Perspect. 17:125–133. Withey JR, Collins PG. 1978. Styrene monomer in foods: a limited Canadian survey. Bull Environ Contam Toxicol. 19(1):86–94. [WHO] World Health Organization. 2003. Styrene in drinking-water. Background document for develop- ment of WHO guidelines for drinking-water quality. Geneva: WHO/SDE/WSH/03.04/27. accessed 2018 Mar 5. http://www.who.int/water_sanitation_health/dwq/ chemicals/styrene.pdf FOOD ADDITIVES & CONTAMINANTS: PART A 2051 http://monographs.iarc.fr/ENG/Monographs/vol82/mono82.pdf http://monographs.iarc.fr/ENG/Monographs/vol82/mono82.pdf https://www.plasticfoodservicefacts.com/wp-content/uploads/2017/10/Polystyrene-Report.pdf https://www.plasticfoodservicefacts.com/wp-content/uploads/2017/10/Polystyrene-Report.pdf http://www23.statcan.gc.ca/imdb/p2SV.pl?Function=getSurvey%26SDDS=5049%26lang=en%26db=imdb%26adm=8%26dis=2 http://www23.statcan.gc.ca/imdb/p2SV.pl?Function=getSurvey%26SDDS=5049%26lang=en%26db=imdb%26adm=8%26dis=2 http://www23.statcan.gc.ca/imdb/p2SV.pl?Function=getSurvey%26SDDS=5049%26lang=en%26db=imdb%26adm=8%26dis=2 https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=165.110 https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=165.110 http://www.who.int/water_sanitation_health/dwq/chemicals/styrene.pdf http://www.who.int/water_sanitation_health/dwq/chemicals/styrene.pdf Abstract Introduction Materials and methods Materials and reagents Sample collection and preparation Headspace solid phase micro-extraction and instrument conditions Quantitation and quality control Dietary intake estimates Results and discussion Acknowledgements Disclosure statement References