Occurrence of Methylmercury in Rice-based Infant Cereals and Estimation. of Daily Dietary Intake of Methylmercury for Infants

Transcription

1 Supporting Information Occurrence of Methylmercury in Rice-based Infant Cereals and Estimation of Daily Dietary Intake of Methylmercury for Infants Wenbin Cui 1, Guangliang Liu 1, 2, Mayara Bezerra 1#, Danielle Alexis Lagos 1##, Yanbin Li 3, 1, 2, 4 * and Yong Cai 1 Department of Chemistry & Biochemistry, Florida International University, Miami, Florida, USA 2 Southeast Environmental Research Center, Florida International University, Miami, Florida, USA 3 Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, China 4 Institute of Environment and Health, Jianghan University, Wuhan, China # Current Address: Federal University of Pernambuco, Recife, Pernambuco, Brazil ## Current Address: College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA * Corresponding Author Yong Cai, Department of Chemistry & Biochemistry, Florida International University, SW 8 th Street, Miami, Florida 33199, USA Telephone: ; cai@fiu.edu S1

2 Infant cereal samples and sampling locations This study was intended to sample the common infant cereals that can be representative of the cereals available for the consumers in the major markets in the US and China. A total of 119 infant cereal samples were purchased, among which 58 samples were from four big cities in different regions of the U.S. (Miami, FL; New York, NY; San Jose, CA; and Chicago, IL) and 61 samples from four different cities in China (Beijing, Wuhan, Nanjing, and Qingdao). These cities were selected because they can be representative of the typical market for each country and they are located geographically in different areas, 1 representing possible rice based food sources that infants would expose to in these two countries (Fig. S1). For instance, San Jose can be regarded as an area impacted by the legacy of mercury pollution from the excessive historical gold mining in California bay area, and as part of Silicon Valley nowadays, it could be affected by pollution associated with manufacturing of electronic components during the last few decades. Chicago used to be a major manufacturing center, and the industrial pollution due to the rapid growth of the steel industry during the middle of last century could have impacted the area. The environmental issues in the New York area might be related to the historical release of waste from factories located along the upper Hudson River and the coal fired power plants. In contrast to the other three US cities, Miami has been less affected by industrial pollution due to a smaller scale of industries. In contrast to the cities in the US, the selected four cities in China all have industrial pollution as the biggest source of air pollution, due to the rapid growth of the manufacturing industries and economy in China during last few decades. The emission and waste released form industrial production, coal combustion and vehicle exhaust as well as S2

3 soil dust contributed to the major environmental problems in these sampling areas in China. Despite the differences in the sampling locations, it should be borne in mind that the locations of samples purchasing are probably not directly linked to the sources of rice grains used for cereal production, as evidenced by the same cereal samples (with the same manufacture product lot numbers) available for different cities. The selection of these cities was mainly based on the consideration that they are representative of typical markets in the US and China, and the selection of these cities would be reflective of the common infant cereal markets in these two countries (one is developed and the other developing). The cereal samples used here include common brands available in the market. For the US, the major three brands selected in this study have a market share of over 90%, while for China the three top brands (different brands from the US market) have approximately a 75% of the total market share and the other brands account for 25%. 2,3 After grouping the samples into three categories based on the main grains they are made from (i.e. rice-, multigrain-, and other grain-based cereals), the rice-based cereal samples were further differentiated according to manufacturers. For each brand, the number of the rice-based cereal samples are as follows: brand A (n=10), B (n=5), C (n=8), D (n=2), E (n=2), F (n=2), G (n=3), H (n=6), I (n=10), J (n=10), K (n=2), L (n=4), and M (n=3). In addition, there are 12 other brands with only one sample for each brand, and they were classified as group N (12 samples for 12 brands). These cereal samples were supplied in tin cans, cardboard boxes, or plastic bottles package. The product information provided by the manufacturers about the products includes the contents of total fat, carbohydrate, and protein per serving. This information is used in sample classification and data interpretation without further validation. The contents of S3

4 carbohydrates, fat, and proteins in these samples were in the range of %, % and %, respectively. Details of sample preparation and analysis of THg and MeHg in cereals Digestion of cereal and flour samples for THg analysis was performed using a hot block at 140 ⁰ C for 4 h, following addition of 0.2 g sample to a premixed acid composed of concentrated nitric acid (8 ml) and sulfuric acid (2 ml) in a pre-cleaned 50 ml glass digestion tube. 4 After cooling down, 2 ml of hydrogen peroxide was added into the digestion tubes and the tubes were heated at 95 ⁰ C for 1 h. Five to ten folds dilution was applied with ultrapure deionized water before the samples were analyzed by using a PSA Mercury Analyzer (P S Analytical) in the purge and gold-trap preconcentration mode. Hg concentration was expressed in µg/kg Hg in dry weight. For MeHg determination, 5 briefly, 0.5 g of cereal and flour sample was digested with 6 ml of KBr/H 2 SO 4 /CuSO 4 solution and the MeHg present in the digest was extracted into 10 ml of CH 2 Cl 2. Then, 0.1 to 1 ml of CH 2 Cl 2 extract was pipetted into a 40-ml amber glass vial containing 30 ml of ultrapure deionized water. The vial was purged with N 2 to completely volatilize the CH 2 Cl 2, leaving MeHg in the aqueous solution. MeHg in the aqueous solution was then derivatized with 150 µl of 1% (w/v) NaBEt 4 to convert MeHg to volatile methylethylmercury which was then purged and trapped on a Tenax trap followed by analysis on GC-CVAFS MeHg system. S4

5 References 1. Hutchison, R., Encyclopedia of Urban Studies. SAGE Publications: Los Angeles, CA, USA, Chen, V., The Evolution of the Baby Food Industry, Jnl of Competition Law & Economics 2010, 6 (2), Yang, W.; ShuLai, X.; Yu, Z.; Rong, R.; FengXia, G.; FengHai, W., Development status, problems and countermeasures of the infant rice cereal in China. J. Food Safety and Qual. 2014, 5 (2), Horvat, M.; Nolde, N.; Fajon, V.; Jereb, V.; Logar, M.; Lojen, S.; Jacimovic, R.; Falnoga, I.; Liya, Q.; Faganeli, J., Total mercury, methylmercury and selenium in mercury polluted areas in the province Guizhou, China. Sci. Total Environ. 2003, 304 (1), Cai, Y.; Tang, G.; Jaffe, R.; Jones, R., Evaluation of some isolation methods for organomercury determination in soil and fish samples by capillary gas chromatography-atomic fluorescence spectrometry. Int. J. Environ. Anal. Chem. 1997, 68 (3), S5

6 Table S1 General Information and Mercury Levels of the Tested Cereal Samples ID Brand Location Type THg (µg/kg, n=3) MeHg (µg/kg, n=3) MeHg/THg (%) Fat% Protein% Carbohydrate% R1 A MIA Rice 3.07± ± R2 A MIA Rice 4.92± ± R3 A MIA Rice 2.35± ± R4 B MIA Rice 1.82± ± R5 B MIA Rice 2.21± ± R6 E MIA Rice 4.87± ± R7 D MIA Rice 1.47± ± R8 C MIA Rice 11.74± ± R9 C MIA Rice 1.97± ± R10 C MIA Rice 2.39± ± R11 A NY Rice 4.23± ± R12 A NY Rice 3.25± ± R13 B NY Rice 2.76± ± R14 D NY Rice 1.62± ± R15 A SJ Rice 3.39± ± R16 A SJ Rice 3.12± ± R17 B SJ Rice 2.17± ± R18 E SJ Rice 6.43± ± R19 A CHI Rice 3.51± ± R20 A CHI Rice 3.2± ± R21 B CHI Rice 2.44± ± S6

7 Table S1 continued R22 C MIA Rice 15.88± ± R23 C MIA Rice 14.84± ± R24 C MIA Rice 12.73± ± R25 C MIA Rice 10.37± ± R26 C MIA Rice 10.03± ± R27 F BJ Rice 2.55± ± R28 G BJ Rice 2.34± ± R29 A BJ Rice 3.33± ± R30 N BJ Rice 2.76± ± R31 N BJ Rice 2.9± ± R32 H BJ Rice 2.96± ± R33 I BJ Rice 2.34± ± R34 J BJ Rice 3.22± ± R35 N BJ Rice 3.41± ± R36 I BJ Rice 1.71± ± R37 N BJ Rice 3.23± ± R38 N BJ Rice 4.49± ± R39 H BJ Rice 2.80± ± R40 K QD Rice 2.96± ± R41 N QD Rice 1.63± ± R42 M QD Rice 3.54± ± R43 I QD Rice 1.87± ± R44 K QD Rice 3.40± ± S7

8 Table S1 continued R45 N QD Rice 2.11± ± R46 N QD Rice 4.89± ± R47 N QD Rice 6.02± ± R48 N QD Rice 3.30± ± R49 N QD Rice 4.15± ± R50 N QD Rice 3.66± ± R51 F QD Rice 4.87± ± R52 J QD Rice 1.95± ± R53 I NJ Rice 1.91± ± R54 H NJ Rice 3.30± ± R55 J NJ Rice 3.16± ± R56 I NJ Rice 2.03± ± R57 I NJ Rice 4.75± ± R58 J NJ Rice 2.43± ± R59 I WH Rice 1.80± ± R60 J WH Rice 2.18± ± R61 J WH Rice 4.98± ± R62 J WH Rice 5.96± ± R63 J WH Rice 3.40± ± R64 H WH Rice 4.18± ± R65 H WH Rice 3.77± ± R66 H WH Rice 4.96± ± R67 J WH Rice 2.11± ± S8

9 Table S1 continued R68 J WH Rice 2.11± ± R69 I WH Rice 3.43± ± R70 I WH Rice 3.36± ± R71 I WH Rice 2.20± ± R72 L WH Rice 4.78± ± R73 L WH Rice 2.64± ± R74 L WH Rice 1.95± ± R75 L WH Rice 3.71± ± R76 M WH Rice 2.05± ± R77 M WH Rice 1.90± ± R78 G WH Rice 1.75± ± R79 G WH Rice 1.69± ± M1 A MIA Multi grain 1.04± ± M2 A SJ Multi grain 1.15± ± M3 A NY Multi grain 1.25± ± M4 A CHI Multi grain 1.00± ± M5 G BJ Multi grain 1.30± ± M6 H NJ Multi grain 0.94± ± M7 H WH Multi grain 2.91± ± M8 I WH Multi grain 1.43± ± M9 G WH Multi grain 1.39± ± N1 A MIA Other grain 0.68± ± N2 A MIA Other grain 0.80± ± S9

10 Table S1 continued N3 A MIA Other grain 1.10± ± N4 A MIA Other grain 0.88± ± N5 A MIA Other grain 0.72± ± N6 A MIA Other grain 1.00± ± N7 C MIA Other grain 0.68± ± N8 E MIA Other grain 0.63± ± N9 D MIA Other grain 0.61± ± N10 C MIA Other grain 0.83± ± N11 A NY Other grain 0.81± ± N12 A NY Other grain 0.65± ± N13 C NY Other grain 0.65± ± N14 D NY Other grain 0.57± ± N15 A SJ Other grain 1.08± ± N16 A SJ Other grain 0.94± ± N17 A SJ Other grain 0.90± ± N18 A SJ Other grain 0.70± ± N19 A SJ Other grain 0.84± ± N20 B SJ Other grain 0.80± ± N21 E SJ Other grain 0.40± ± N22 C SJ Other grain 0.35± ± N24 A CHI Other grain 0.65± ± N25 B CHI Other grain 0.98± ± N26 C CHI Other grain 0.79± ± S10

11 Table S1 continued N27 C CHI Other grain 1.04± ± N28 D CHI Other grain 1.08± ± N29 N BJ Other grain 1.14± ± N30 N BJ Other grain 0.66± ± N31 G WH Other grain 0.54± ± S11

12 Fig. S1 Sampling locations for the infant cereals purchased in the US and China S12