Cadmium in Chinese Postharvest Peanuts and Dietary Exposure

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A study of cadmium in Chinese post-harvest peanuts and dietary exposure assessment in associated population Xianhong Dai, Yizhen Bai, Jun Jiang, Xiaomei Chen, Haiyan Zhou, Nanri Yin, Lin Chen, Xiaoxia Ding, and Peiwu Li J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.6b02639 • Publication Date (Web): 26 Sep 2016 Downloaded from http://pubs.acs.org on September 27, 2016

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Journal of Agricultural and Food Chemistry 1 / 31

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A study of cadmium in Chinese post-harvest peanuts and dietary exposure assessment in associated population Xianhong Dai †,§, Yizhen Bai †,§,#, Jun Jiang †,‡,#, Xiaomei Chen†,‡,#, Haiyan Zhou†,‡,§,#, Nanri

3 4

Yin

†,§,#

, Lin Chen †,§,#, Xiaoxia Ding †,§, #,* , and Peiwu Li †,‡,§, #,*

5 6

†

7

China

8

‡

9 10 11 12 13 14 15

Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062,

Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of

Agriculture, Wuhan 430062, China §

Laboratory of Quality & Safety Risk Assessment for Oilseed Products (Wuhan), Ministry

of Agriculture, Wuhan 430062, China #

Quality Inspection & Test Center for Oilseed Products, Ministry of Agriculture, Wuhan

430062, China *

Corresponding author Tel: +86 27 86812943; Fax: +86 27 86812862; E-mail: [email protected], [email protected]

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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16 Abstract 17 Cadmium (Cd) in 8,698 peanut samples collected from China in 2009-2014 was studied 18 to evaluate its contamination level, distribution, and health risk. The average Cd 19

concentration was 0.1684 mg kg-1, the range of 2.5%-97.5%was 0.0191-0.4762 mg kg-1,

20 indicating the cadmium-contaminated peanut level was even lower. Some peanut strains 21

whose protein contents had a significant correlation (Pearson correlation coefficient r = 0.86**)

22 with the Cd concentration level should be concerned. Under the same soil Cd background, the 23 difference of the Cd content in different peanut varieties is extremely significant. For 24

example, the Cd concentration of Silihong is about 0.4522 mg kg-1, being seven times higher

25 than Zhonghua 6. According to the exposure assessment using the probabilistic simulation 26 method, the target hazard quotients (THQs) of all groups should be below 1. The THQ range 27 in this study was from 0.0035 to 0.0202, suggesting that there were no potential carcinogenic 28 effects in any group. 29

Keywords

30

Dietary exposure

Cadmium

Contamination

THQ

Peanut


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INTRODUCTION

32 Peanut (Arachis hypogaea), with large quantities of unsaturated fatty acids (UFAs) and 33 mineral elements, possesses plentiful nutritional, medicinal and cosmetic values, which are 34 beneficial to human health and commonly known as "longevity fruit" ,plays an important role 35 in food and oil

(https://en.wikipedia.org/wiki/Peanut).

36 According to Food and Agricultural Organization of the United Nations (FAO) statistics , 37 Chinese peanut dominates the international export trade since at least 2006 , with an average 38 annual export volume of 70 million tons accounting for about 40% of the world trade in 39 peanut products. Peanut was mainly exported to the countries and regions including the EU, 40 New Zealand, Southeast Asia, Japan and Korea. 41

Since the breakout of cadmium poisoning through food that resulted in itai-itai disease

42

in Japan in the 1960s1, cadmium pollution in food has attracted much attention. In recent

43

years, there have been many cases of food contamination by heavy metals especially

44

cadmium, arousing widespread concern of global consumers.

45

Cadmium (Cd), one of common heavy metal element in the Earth’s crust, is one of the

46

most well-known environmental toxicant to humans 2. Chinese soil has been proved seriously

47

polluted by Cd3. That smelting, mining, waste disposal, fertilizer and pesticide applications,

48

and vehicle exhaust mainly contribute to the content of cadmium in the soil

49

depending on their regions. The dominating sources of agricultural soil contamination include

50

sewage irrigation, atmospheric deposition, phosphorus fertilizers4, 6. Cadmium in soil

51

disperses into agricultural crops through a variety of biological paths and then pollutes

52

agricultural products

53

beings poses a horrible health threat7. Researches showed that varying degrees of cadmium

3

varing

5,6

. The consumption of cadmium-contaminated products by human



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pollution found in rice and other agricultural commodities5,8,9 resulted in potential harm to the

55

health of residents.

56

Peanut, flowering ground but fruiting underground, has a large superficial area in

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contact with soil within its long growth period, leading to a high probability of peanut

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contamination with cadmium from the soil. For Chinese peanut, about 35% of annual output

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is used for direct consumption, 53% for oil, 7% for seed and 5% for exports10. China’s total

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peanut consumption topped in the list in the world. Therefore, it is especially significant to

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verify the contamination level of cadmium in peanuts and evaluate the dietary intake hazards

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for different consumer groups.

63

Toxicological studies have shown that both non-carcinogenic and carcinogenic risks

64

could be induced by massive cadmium exposure. According to the classification defined by

65

the International Agency for Research on Cancer (IARC), Cd is recomfirmed as a non-cancer

66

element with a potential carcinogenic effect at 20122. Physiological researches have revealed

67

that cadmium intruding into human bodies may form cadmium metallothionine11,12 and then

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spread to cells travelling from the blood, meanwhile it may selectively accumulate in the

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kidneys and liver and destroy the functions of the enzyme system2. A toxicokinetic model

70

was used to estimate the dietary exposure required to reach this destructive cadmium

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concentration in the kidney cortex13. A recent estimate demonstrated an apparent cadmium

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half-life of 11.6 years in the kidney with a standard deviation of 3.0 years13. As cadmium is

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widely distributed in many foods at approximately constant levels, and daily dietary exposure

74

tends to be steady after slight fluctuations over a long term, the exposure estimates are

75

extrapolated on a monthly basis by multiplying daily exposure amount by 30. In 2011, the

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Joint FAO/WHO Expert committee on Food Additives (JECFA) decided to express the ACS Paragon Plus Environment

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tolerable intake in the form of a provisional tolerable monthly intake (PTMI) , and the PTMI

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established was 25 µg/kg bw13.

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Fifteen main planting provinces involved four main production regions14, and the

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previous study showed that the contamination level of soil cadmium in China was

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significantly different in these zones3, 15. Peanut is commonly regarded as a good source of oil

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and crude protein, plant genetics and breeding pointed out that peanut cultivars derived from

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different parental species vary greatly in content of oil and protein. Cadmium could bind to

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protein from blood forming cadmium metallothionine. Likewise, the immobilized plant

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proteins can effectively absorb Cd (II) from aqueous solution16. Compared with other

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vegetable protein, the crude protein in peanut is more easily digested and absorbed by

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human .In that way, the physiological relationship of cadmium with peanut protein need to be

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investigated further.

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The residents’ dietary risk in China through edible peanut consumption has been

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studied17, but this research mainly focuses on the estimation of the dietary risk for different

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consumer groups with their genders neglected18. To assess dietary exposure risks of cadmium,

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probability functions were introduced to investigate the occurrence, variability and

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uncertainty of risks, such as Monte Carlo simulation, which is a popular probabilistic risk

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assessment approach used in previous studies.

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The aims of this investigation are to determine the level of cadmium in Chinese peanut

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over a long span of time, to check their compliance with the existing maximum limits (MLs)

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and evaluate dietary exposure risks. Meanwhile, the relationship of cadmium with peanut

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protein need to be explored further. From 2009 to 2014, 8,698 samples were collected from

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15 provinces in four ecological regions, and the Cd concentrations of all these samples were ACS Paragon Plus Environment


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determined using atomic absorption spectrophotometer TAS-986(G). The variations of the Cd

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level in the classified peanut samples were calculated according to regions and strains. At

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2015, a field test has been carried out to verify the relationship of peanut Cd level with crude

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protein content .

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MATERIALS AND METHODS

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Sampling and preparation

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A total of 8,698 peanut samples were collected with their shells intact from the main

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production areas (Fig. 1) in China in 2009-2014. Fifteen major producing provinces were

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classified into four ecological regions: the northeast, north, south and Yangtze River. These

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regions extending from north to south were also intensively planted with other agricultural

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products with different cadmium levels in the background, plentiful mineral resources, and

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developed industries. Considering the background, location and peanut varieties, as well as

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cultivation methods, the main producing counties in these provinces were selected, and

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representative samples were randomly collected from each county after harvest. In 2015, we

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collected wide-planted and high-yielding peanut cultivars from the different main ecological

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regions and then choose ten of them planted .They are Silihong, Luhua 8, Huayu 22, Yuanza

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9102, Tianfu 11, Zhonghua 6, Yueyou 256, Zhanyou 75 and Heyou 12, respectively. Peanut

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grows best in light sandy loam soil. So we selected the Fuxin county of Liaoning province as

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the best test site, where those ten main cultivars from four ecological regions were planted

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and harvested. All peanut samples were harvested and packed by hand, then delivered to our

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laboratory in plastic net bags within one week. All collected samples were natural air and sun

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dried until the water content of peanut kernel was less than 10% and stored under ventilated

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and dry conditions waiting for analysis. The primary procedure of sample preparation were ACS Paragon Plus Environment

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shelled, sliced to 1 mm, homogeneously ground with a blender, and then stored in suitable

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glass containers. During the entire process, metal wares should be kept away from the

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samples, except slicing and grinding. All of these operations were completed within 4

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weeks19.

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Analytical procedure

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According to GB/T5009.15-200320, pretreatment of peanut samples with plentiful oil

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was performed as follows: weighed 0.2-0.3 g (accurate to 0.001g) of peanut samples and

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placed them in a digestion tube, added 5 mL concentrated nitric acid and 2 mL 30% hydrogen

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peroxide, holding for over 1.5 h. Prepared the microwave digestion conditions according to

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Table 1. At the end of digestion, cooled them down, transferred all of them to a 25 mL

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volumetric flask, and then washed the digestion tube 2-3 times with ultrapure water. Finally,

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immerse them with ultrapure water to the scale mark. At the same time, prepared blank and

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reference tests. Determined the cadmium contents by graphite furnace atomic absorption

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spectrophotometry

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spectrophotometer TAS-986 (G) produced by Purkinje General (Beijing, China) and

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Deuterium lamp and self-absorption correction method for background correction .

with

the

detection equipment,

which

was

atomic

absorption a

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According to GB/T 24318-200921, prepared peanut samples was performed as follows:

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weighed about 0.1 g (accurate to 0.001g) of peanut samples, wrapped and compacted them in

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a tinfoil, and then placed them at an autosampler for detection. Likewise weighed Ethylene

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Diamine Tetraacetic Acid (EDTA, the purity is more than 99%, Sigma-Aldrich,) 15.0, 20.0,

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30.0, 40.0, 50.0, 60.0, 70.0, 80.0, 100.0 and 120.0 mg processed as the peanut sample and

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detected peak area for drawing standard curve. The combustion reaction conditions for

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samples : temperature is 1200 ℃, the oxygen factor is 1.8 mL mg-1, oxygen flow rate is 400 ACS Paragon Plus Environment


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mL min- 1, the pressure of helium gas(≥99.999%), oxygen(≥99.999%), nitrogen(≥99.99%)

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are 0.2, 0.25 and 0.3 MPa. Gas emitted from samples combustion decomposition under high

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temperature by purification and removing impurity were transmitted by using helium as

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carrier gas and nitrogen oxide of which were reduced. After reaction, the mixed gas, in turn,

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pass through the detector (TCD) by adsorption and separation for detection. Eventually, the

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content of total nitrogen was calculated according to the EDTA standard curve. The

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calculation formula of crude protein content in the sample:

Crude protein content = 153

total nitrogen content ×F sample weight

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In which F is protein factor, namely the coefficient of conversion from nitrogen to

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protein, depending on characteristic parameter of crop type. In peanut sample, the value is

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5.46.

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and calculation of the crude protein content, using Dumas nitrogen determination apparatus

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NDA–701produced by Italy VELP company.

Determined the total nitrogen content according to the Dumas combustion principle

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Quality assurance

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The Cd reference materials were certified as the heavy metals and granted certificates by

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Chinese scientific community . Nitric acid and hydrogen peroxide used in this study were of

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ultrapure grade. Ultrapure water, with a resistivity of 18.2 MΩ cm, which was obtained from

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a Millipore system (USA) with the purified water purchased from Wahaha Corporation

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(Hangzhou, China). All glass wares were soaked in a nitric solutions (nitric acid : water = 1:4)

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for 24 h and rinsed with deionized water. National first level standard material (GBW10035) ,

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Pb, Cd, Cr in wheat powder (Chinese Academy of Geographical Sciences, Beijing, China)

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(74 ±3 µg kg-1 for Cd ) was used to determine the quality assurance during the detection

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process of cadmium . The limit of detection (LOD) for cadmium element was 0.1 µg kg-1, ACS Paragon Plus Environment

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and the limit of quantification (LOQ) was 0.3 µg kg-1. The results were found with a

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deviation of less than 5% from the GBW10035 wheat powder certified values.

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National second level standard material (GBW(E) 100126), crude protein in whole

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wheat flour (Chinese Academy of Geographical Sciences, Beijing, China) (15.8±0.3) %

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was used to determine the quality assurance during the detection process of crude protein .

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The LOD of the method for detecting total nitrogen content was 0.03 mg, and the LOQ was

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0.1mg. The relative deviation for detecting total nitrogen contents so that to calculate crude

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protein from crude protein in whole wheat flour (GBW(E) 100126 )is less than 2%.

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Statistical analysis

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To determine whether there are significant differences in the cadmium contents among

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different regions, years, strains of peanut, statistical analysis was conducted to calculate the

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sample size, mean, standard deviation, median, max, violation rate (%) and Duncun group .

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The calculations were mainly based on the SAS (SAS/PC 9.3, professional edition, USA)

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environment of univariate and general linear model (GLM) procedures. The statistical

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significance of the differences was assessed using Duncan’s multiple-range test. A

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probability of 0.05 was considered significant. Sampling and fitting were performed using the

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commercially available software package @Risk (Version 5.5, for Excel Professional edition,

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Palisade, UK).

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Assessment of the Cd risk through peanut consumption

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According to the guidelines for assessments of exposure to contaminants in foods22,

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regional average contaminant values and the Global Environment Monitoring System/Food

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Contamination Monitoring and Assessment Program from the World Health Organization

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(GEMS/food) consumption cluster diets were recommended for regional dietary exposure ACS Paragon Plus Environment


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estimates23. The weight and peanut consumption information required for the assessment of

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each group was from the report "2002-The Nutrition and Health Status of the Chinese

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People", The estimated monthly intake (EMI) of Cd depended on both the concentration of

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Cd in peanut and the amount of peanut consumption. The daily intake of Cd was determined

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by the following equation:

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EMI = (E F × Ε D × FIR × C × 30) (WAB × TA )

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EF is the exposure frequency (365 days/year); ED is the exposure duration (70 years); FIR

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is the peanut ingestion rate (g/person/day); C is the Cd concentration in peanut (mg kg-1);

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WAB is the average body weight24; TA is the average exposure time (EF × ED)25,26. FIR and

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WAB were shown in Table 2.

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Target hazard quotient (THQ)

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Non-carcinogenic risk assessments were frequently performed to estimate the potential

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health risks of contamination using the THQ, and the methodology for estimating the THQ

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was described in details by the United States Environmental Protection Agency (USEPA)26, 27

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During the 73rd meeting, the JEFCA concluded that the PTMI was appropriate for

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cadmium evaluation13, 28. The THQ for residents through consumption of Cd-contaminated

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peanut can be assessed by comparing the PTMI of Cd. Based on the methods modified29, the

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THQ was determined in the following equation:

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THQ = EMI/PTMI

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The applied PTMI of Cd was recommended by Joint FAO/WHO Expert Committee on

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Food Additives (JECFA) in 2011: 25 µg/kg bw/month13. If the estimated THQ value is below

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1, non-carcinogenic effects are believed to be safe; if it exceeds 1, non-carcinogenic effects

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are dangerous, and the risk probability is positively correlated with the THQ value30, 31. ACS Paragon Plus Environment

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Monte Carlo exposure assessment model

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Dietary exposure to Cd was calculated depending on the model construction theories,

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Monte Carlo method and bootstrap values. Latin hypercube sampling was operated multiple

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times (n) from the bootstrap samples. The statistics of individual samples such as the mean

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values and percentiles (P50, P90, P95, P97.5, P99 and P99.9 in this work) were obtained; the

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confidence intervals of all statistics were monitored, and the variability of EMI for all the

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samples could be convergence32. Additionally, the number of iterations (n) and number of

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simulations (B) in the simulation procedures were set to 100,000 and 2,000, respectively,

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which resulted in 2 × 108 (100,000 × 2,000) simulations to guarantee the reliability of the

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results.

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RESULTS AND DISCUSSION

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Cadmium concentrations in post-harvest peanuts

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The Cd concentrations in 8,698 peanut samples were determined in this study. The mean

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concentration of Cd in all samples was 0.1684 mg kg-1, which was slightly higher than

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0.1-0.17 mg kg-1 of the US17, and the range of 2.5%-97.5% was 0.0191-0.4762mg kg-1, which

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was nearly unchanged for six years (Table 3). The slight differences between years were

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mainly caused by the location and size ratio at the sampling points. Absolutely, there was also

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a little difference in the soil cadmium content in different years for the same area, which

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needed future research. The median value was 0.1351 mg kg-1, which was less than the

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average, indicating that the distribution of the cadmium samples deflected to the left and

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presented a right tail distribution. That is, the peanut Cd level of 0.1684 was substantially

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lower than the maximum level of the contaminant (0.5 mg kg-1 for Cd) in China according to

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Chinese standanrd GB 2762-2012

33

. Only 2.793% (243/8,698) of the peanut samples



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exceeded the ML, and a greater violation rate indicated a higher mean value of the Cd content.

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Thus, the Cd contamination in peanut produced in China was hardly a threat without taking

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into consideration of the residents’ age and gender or regional differences, but excessive

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samples should be paid more attention. However, China owns the largest amount of peanut

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consumption than any other countries, indicating that further risk assessment for Cd in peanut

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was necessary.

244 245

Regional distribution of Cd concentrations in peanuts According to Ding18, the 15 main peanut producing provinces were divided into four

246 ecological areas, consisting of the northeast, north, south and Yangtze River. The 247 concentrations of Cd in peanut samples collected from the four main peanut-producing areas 248 in China were determined (Table 4). The mean Cd concentration ranged from 0.1348 mg 249

kg-1 to 0.1998 mg kg-1 (less than 0.2 mg kg-1), and the maximum value was sparsely

250 populated in a few counties. Overall, the peanut in the four regions was slightly Cd-polluted, 251 and the one-way analysis of variance (ANOVA) results showed a significant difference in the 252 four ecological regions in terms of the peanut Cd level. The peanut Cd contamination 253 condition of Yangtze river ecological region was slightly higher than others region, the north 254 have the lowest mean level, which is mainly consistent with the soil Cd value from Yangtze 255 256 257

to northeast in descending order3. The Cd content in peanut collected from the Yangtze river is 0.1998 ± 0.1692 mg kg-1, which exceeds the north region (0.1348 ± 0.1211 mg kg-1). Cd is a mobile element and easily absorbed by roots34, previous research showed that the Cd (II)

258 adsorption was affected by the surrounding of the plant such as pH, temperature, contact time 259

and initial metal concentration16. Peanut is a crop flowering ground but bearing fruits

260 underground, which has a large surface and long growth period for contacting the soil and ACS Paragon Plus Environment

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261 irrigation water. The soil cadmium in the Yangtze River region is accumulated by metal 262 smelting/mining and atmospheric emissions, and some areas may also be impacted by 263 264

wastewater irrigation, such as in the Yangtze River Delta4. It was reported that the main contamination sources of Cd in peanut were soil Cd and sewage irrigation35. Additionally, Cd

265 accumulation characteristics for different main peanut varieties may be important internal 266 factors. 267

Difference of the cadmium concentration for peanut varieties

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Peanut samples were sorted by strains, the results showed that a highly significant

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correlation was found between the concentrations of Cd in peanut and the protein contents in

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different strains that were widely planted and the sample size was greater than 50 (Fig. 2).

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The correlation coefficient (r = 0.86**) revealed that the correlation was highly significant at

272

the 0.01 level. Toxicological studies have shown that Cd intruding into human bodies may

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form cadmium metallothionine36. Metallothionein (MT) is a kind of small protein localized to

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the membrane of the Golgi apparatus. MTs have the capacity to bind both physiological (such

275

as zinc, copper and selenium) and xenobiotic (such as cadmium, mercury, silver and arsenic)

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heavy metals (https://en.wikipedia.org/wiki/Metallothionein). Many researches showed that

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the MT levels increased at the highest Cd exposure in all species and tissues12. For example,

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MTs are present in a range of aquatic organisms and are important in the response of an

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organism to Cd exposure37, 38. From Figure 2, it was found that the higher the protein content

280

of the peanut variety is the more likely Cd becomes enriched. Furthermore, in order to be

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accurately acquainted with the Cd adsorption capacity of different peanut varieties, the

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following inquiry was designed. In Fuxin of Liaoning province, 95% reference range of the

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soil Cd concentration was 0.1213 (0.1084-0.1361) mg kg-1. The results of field validation ACS Paragon Plus Environment


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study (Fig. 3) showed that under the same soil Cd background, the difference in the Cd

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content in different peanut varieties was extremely significant. The Cd concentration of

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Silihong was about 0.4522 mg kg-1, which was seven times higher than Zhonghua 6,

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indicating that Silihong had a strong Cd adsorption capacity. The Cd concentrations in

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Zhonghua 6 and Luhua 8 were less than the soil background values, revealing that these two

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species had weak adsorption capacities of Cd, namely they were Cd-tolerant varieties. Other

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varieties had different degrees of enrichment with Cd. However, its molecular mechanism

291

needs to be further investigated. Anyhow, this inquiry is highly beneficial to peanut planting

292

in a high Cd soil background.

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Dietary exposure assessment of cadmium

294

The THQ has been recognized as the major parameter for assessing chronic

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non-carcinogenic risks associated with the consumption of food contaminated by toxic

296

elements. To estimate the percentile of the THQ, the distribution of Cd concentrations was

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applied based on the Latin hypercube simulation performed under the @Risk program. A

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total of 100,000 iterations and 2,000 simulations were conducted, and the THQ results of Cd

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in peanut for the Chinese population were listed in Tables 5 (in various age, environmental

300

and gender groups). During the simulation, the convergence tolerance was 3%, and the mean

301

confidence level was 95%, guaranteeing unbiasedness and accuracy of the results. For the

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THQ, the PTMI was always employed as a denominator of the equation. Owing to Cd’s

303

exceptionally long half-life, a monthly value was considered more appropriate. The

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provisional tolerable weekly intake (PTWI) of 7 µg/kg bw was therefore withdrawn and the

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PTMI of 25 µg/kg bw was established by JECFA in 2011 according to the latest

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epidemiological survey and toxicological study. ACS Paragon Plus Environment

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From Table 5, the values at P50 exhibited the median exposure of consumers to the

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distribution, whereas those at P97.5, P99 and P99.9 exhibited higher exposure. The THQs for

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all age, environmental and gender groups showed no mean or median values (0.0028−0.0202)

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exceeding 1, suggesting that the Chinese population did not encounter a significant

311

non-carcinogenic risk by consuming Cd-contaminated peanut. The THQ values for all groups

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were less than 1, and the THQs increased the rising exposure levels. At P99.9, the highest

313

exposure groups were 2-6 year-old boys from cities, and its THQ value was only 0.1264.

314

Therefore, there should be no potential carcinogenic effects in any of these areas.

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According to risk assessment, Australia approved a proposal to revise "Australia New

316

Zealand Food Standards Code", in which the ML of Cd in peanut was adjusted from 0.1 mg

317

kg-1 to 0.5 mg kg-1 in 2009.

318

In consideration of the tiny proportion of peanut consumption in the total diet, the Codex

319

Alimentarius Commission (CAC) abolished the ML value of Cd in peanut and did not impose

320

restriction requirements any longer. It has been reported that the total dietary consumption for

321

residents in China is about 1,162 g/day17, and the daily consumption of peanut is about 3.5

322

g/day, accounting for 0.31%. On the whole, the Cd content in peanut and its risk is low.

323

Therefore, the CAC practice would offer a good example on the amendment of the peanut Cd

324

limit in China. Although the daily intake of Cd through peanut consumption is an important

325

pathway for dietary exposure of the Chinese population, many studies have reported that

326

human beings are also significantly exposed to Cd through other food such as rice, vegetables,

327

shellfish, fish39-42 and water31, 43. It has been reported that the dermal pathway is the primary

328

source of soil Cd exposure3. Future researches should take into account of the contribution of

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Cd from other foods, including the peanut oil, and other exposure pathways to make a more ACS Paragon Plus Environment


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comprehensive risk assessment. To mitigate the health hazard from Cd in peanut for the

331

residents in China, some measures should be taken to control the Cd intake through peanut

332

consumption, especially in the more extensively Cd-contaminated regions, for example,

333

planting and culturing special peanut varieties with low protein content. Besides, reducing the

334

industrial and mineral Cd emission to the planting environments and controlling the Cd levels

335

in drinking water, as well as the atmosphere should not be ignored.

336

AUTHOR INFORMATION

337

Corresponding Author

338

*(XX.D.) Phone: +86 27 86812862. Fax: +86 27 86812862;

339

E-mail: [email protected]

340

*(PW.L.) E-mail: [email protected].

341

Funding

342

This work was supported by the Special Fund for Agro-scientific Research in the Public

343

Interest (201303088), the National Key Project for Agro-product Quality & Safety Risk

344

Assessment, PRC（GJFP2016001）.

345

Notes

346

The authors declare no competing financial interest.


Page 17 of 35


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Page 22 of 35 22 / 31

448

Figure legends

449

Figure 1. Geographical locations of the sampling sites of peanut in China

450

Figure 2. The relationship of the cadmium concentration with the protein content in

451 452

different peanut varieties Figure 3. The cadmium content in different peanut varieties


Page 23 of 35


453

Table 1. The Experimental Conditions of Microwave Digestion Steps

Power (W)

Time (Min)

Temp (℃)

1

800

5

120

3

2

800

4

150

5

3

800

15

200

10


Last-Time (Min)


Page 24 of 35 24 / 31

454

Table 2. Body Weights and Daily Intakes of Peanut for Chinese Residents Peanut Ingestion Age

Intakes (g/day)

Body wt (kg)

Rate to Body

Gender (g/kg/day)

(years)

Male

Female

rural

urban

rural

urban

rural

urban

2-6

0.3

1.9

17.3

19

0.0173

0.1000

6-18

2.7

1.5

40.1

43.3

0.0673

0.0346

18-45

3.3

3.7

64.1

67.5

0.0515

0.0548

45-75

3.9

3.9

60.4

66.6

0.0646

0.0586

≥75

2.7

3.2

57.3

63

0.0471

0.0508

2-6

0.8

1

16.9

15.4

0.0473

0.0649

6-18

1.4

2.9

37.1

41.9

0.0377

0.0692

18-45

2.6

3

55.9

56.1

0.0465

0.0535

45-75

2.5

2.7

54.2

57.8

0.0461

0.0467

≥75

1.5

1.8

49.8

56.1

0.0301

0.0321


Page 25 of 35


455

Table 3. Cadmium Levels (mg kg-1) in Post-Harvest Peanuts in Different Years Range Interval Sample

Mean

Standard

Median (2.5%-97.5%)

year size

-1

(mg kg )

Deviation

-1

(mg kg ) (mg kg-1)

2009

1066

0.1819

0.1179

0.1600

(0.0286-0.4750)

2010

1503

0.1485

0.1304

0.1143

(0.0186-0.4116)

2011

1933

0.1488

0.1340

0.1110

(0.0133-0.4442)

2012

1834

0.1885

0.1367

0.1600

(0.0278-0.4999)

2013

1306

0.1818

0.1613

0.1400

(0.0230-0.5014)

2014

1056

0.1673

0.1376

0.1300

(0.0139-0.5067)

Total

8698

0.1684

0.1380

0.1351

(0.0191-0.4762)



Page 26 of 35 26 / 31

456

Table 4. Regional Distribution of Cd Concentrations in Peanuts from 4 Main Production

457

Areas Range interval Production

Sample

Mean

Standard

Median

Duncan (2.5%-97.5%)

area

size

(mg kg-1) Deviation (mg kg-1)

Grouping -1

(mg kg ) Northeast

1024

0.1723

0.1370

0.1541

(0.0217-0.4453)

B

Northern

3375

0.1348

0.1211

0.1052

(0.0191-0.4039)

C

Southern

1423

0.1791

0.1378

0.1562

(0.0145-0.5238)

B

Yangtze river

2876

0.1998

0.1692

0.1772

(0.0336-0.5318)

A

Total

8698

0.1684

0.1380

0.1351

(0.0191-0.4762)


Page 27 of 35


27 / 31

458

Table 5. Dietary Exposure of Cd in Peanut for Different Age, Environmental and Gender groups (THQ for Noncarcinogenic Effects) Rural Gender Age(years) Mean

Male

P50

P90

P95

Urban P97.5

P99

P99.9

Mean

P50

P90

P95

P97.5

P99

P99.9

2—6

0.0035 0.0028 0.0069 0.0087 0.0107 0.0135 0.0219 0.0202 0.0161 0.0395 0.0501 0.0614 0.0776 0.1263

6—18

0.0136 0.0108 0.0266 0.0338 0.0414 0.0523 0.0851 0.0070 0.0056 0.0137 0.0174 0.0213 0.0269 0.0438

18—45

0.0104 0.0083 0.0203 0.0258 0.0316 0.0400 0.0650 0.0111 0.0088 0.0217 0.0275 0.0337 0.0426 0.0692

45—75

0.0130 0.0104 0.0255 0.0324 0.0397 0.0501 0.0816 0.0118 0.0094 0.0231 0.0294 0.0360 0.0455 0.0740

75—

0.0095 0.0076 0.0186 0.0236 0.0289 0.0366 0.0595 0.0102 0.0082 0.0201 0.0255 0.0312 0.0394 0.0642

2—6

0.0095 0.0076 0.0187 0.0237 0.0291 0.0367 0.0598 0.0131 0.0104 0.0257 0.0325 0.0399 0.0504 0.0820

6—18

0.0076 0.0061 0.0149 0.0189 0.0232 0.0293 0.0477 0.0140 0.0111 0.0273 0.0347 0.0425 0.0537 0.0874

Female 18—45

0.0094 0.0075 0.0184 0.0233 0.0286 0.0361 0.0588 0.0108 0.0086 0.0211 0.0268 0.0328 0.0415 0.0675

45—75

0.0093 0.0074 0.0182 0.0231 0.0283 0.0358 0.0583 0.0094 0.0075 0.0185 0.0234 0.0287 0.0363 0.0590

75—

0.0061 0.0048 0.0119 0.0151 0.0185 0.0234 0.0380 0.0065 0.0052 0.0127 0.0161 0.0197 0.0249 0.0405



Page 28 of 35 28 / 31

459

Fig. 1. Geographical locations of the sampling sites of peanut in China


Page 29 of 35


460 461

Fig 2. The relationship of cadmium concentration with protein content in different peanut

462

varieties



Page 30 of 35 30 / 31

463 464

Fig. 3. The Cadmium content in different peanut varieties


Page 31 of 35


465

Graphic for table contents

466



Geographical locations of the sampling sites of peanut in China 374x276mm (96 x 96 DPI)


Page 32 of 35

Page 33 of 35


The relationship of the cadmium concentration with the protein content in different peanut varieties 260x209mm (300 x 300 DPI)



The cadmium content in different peanut varieties 257x213mm (300 x 300 DPI)


Page 34 of 35

Page 35 of 35


Graphic for table contents 393x283mm (96 x 96 DPI)


Cadmium in Chinese Postharvest Peanuts and Dietary Exposure

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