Subscriber access provided by Heriot-Watt | University Library
Article
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
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 35
Journal of Agricultural and Food Chemistry 1 / 31
1 2
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
Page 2 of 35 2 / 31
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
ACS Paragon Plus Environment
Page 3 of 35
Journal of Agricultural and Food Chemistry 3 / 31
31
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
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 4 of 35 4 / 31
54
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
57
contact with soil within its long growth period, leading to a high probability of peanut
58
contamination with cadmium from the soil. For Chinese peanut, about 35% of annual output
59
is used for direct consumption, 53% for oil, 7% for seed and 5% for exports10. China’s total
60
peanut consumption topped in the list in the world. Therefore, it is especially significant to
61
verify the contamination level of cadmium in peanuts and evaluate the dietary intake hazards
62
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
68
spread to cells travelling from the blood, meanwhile it may selectively accumulate in the
69
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
71
concentration in the kidney cortex13. A recent estimate demonstrated an apparent cadmium
72
half-life of 11.6 years in the kidney with a standard deviation of 3.0 years13. As cadmium is
73
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
76
Joint FAO/WHO Expert committee on Food Additives (JECFA) decided to express the ACS Paragon Plus Environment
Page 5 of 35
Journal of Agricultural and Food Chemistry 5 / 31
77
tolerable intake in the form of a provisional tolerable monthly intake (PTMI) , and the PTMI
78
established was 25 µg/kg bw13.
79
Fifteen main planting provinces involved four main production regions14, and the
80
previous study showed that the contamination level of soil cadmium in China was
81
significantly different in these zones3, 15. Peanut is commonly regarded as a good source of oil
82
and crude protein, plant genetics and breeding pointed out that peanut cultivars derived from
83
different parental species vary greatly in content of oil and protein. Cadmium could bind to
84
protein from blood forming cadmium metallothionine. Likewise, the immobilized plant
85
proteins can effectively absorb Cd (II) from aqueous solution16. Compared with other
86
vegetable protein, the crude protein in peanut is more easily digested and absorbed by
87
human .In that way, the physiological relationship of cadmium with peanut protein need to be
88
investigated further.
89
The residents’ dietary risk in China through edible peanut consumption has been
90
studied17, but this research mainly focuses on the estimation of the dietary risk for different
91
consumer groups with their genders neglected18. To assess dietary exposure risks of cadmium,
92
probability functions were introduced to investigate the occurrence, variability and
93
uncertainty of risks, such as Monte Carlo simulation, which is a popular probabilistic risk
94
assessment approach used in previous studies.
95
The aims of this investigation are to determine the level of cadmium in Chinese peanut
96
over a long span of time, to check their compliance with the existing maximum limits (MLs)
97
and evaluate dietary exposure risks. Meanwhile, the relationship of cadmium with peanut
98
protein need to be explored further. From 2009 to 2014, 8,698 samples were collected from
99
15 provinces in four ecological regions, and the Cd concentrations of all these samples were ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 6 of 35 6 / 31
100
determined using atomic absorption spectrophotometer TAS-986(G). The variations of the Cd
101
level in the classified peanut samples were calculated according to regions and strains. At
102
2015, a field test has been carried out to verify the relationship of peanut Cd level with crude
103
protein content .
104
MATERIALS AND METHODS
105
Sampling and preparation
106
A total of 8,698 peanut samples were collected with their shells intact from the main
107
production areas (Fig. 1) in China in 2009-2014. Fifteen major producing provinces were
108
classified into four ecological regions: the northeast, north, south and Yangtze River. These
109
regions extending from north to south were also intensively planted with other agricultural
110
products with different cadmium levels in the background, plentiful mineral resources, and
111
developed industries. Considering the background, location and peanut varieties, as well as
112
cultivation methods, the main producing counties in these provinces were selected, and
113
representative samples were randomly collected from each county after harvest. In 2015, we
114
collected wide-planted and high-yielding peanut cultivars from the different main ecological
115
regions and then choose ten of them planted .They are Silihong, Luhua 8, Huayu 22, Yuanza
116
9102, Tianfu 11, Zhonghua 6, Yueyou 256, Zhanyou 75 and Heyou 12, respectively. Peanut
117
grows best in light sandy loam soil. So we selected the Fuxin county of Liaoning province as
118
the best test site, where those ten main cultivars from four ecological regions were planted
119
and harvested. All peanut samples were harvested and packed by hand, then delivered to our
120
laboratory in plastic net bags within one week. All collected samples were natural air and sun
121
dried until the water content of peanut kernel was less than 10% and stored under ventilated
122
and dry conditions waiting for analysis. The primary procedure of sample preparation were ACS Paragon Plus Environment
Page 7 of 35
Journal of Agricultural and Food Chemistry 7 / 31
123
shelled, sliced to 1 mm, homogeneously ground with a blender, and then stored in suitable
124
glass containers. During the entire process, metal wares should be kept away from the
125
samples, except slicing and grinding. All of these operations were completed within 4
126
weeks19.
127
Analytical procedure
128
According to GB/T5009.15-200320, pretreatment of peanut samples with plentiful oil
129
was performed as follows: weighed 0.2-0.3 g (accurate to 0.001g) of peanut samples and
130
placed them in a digestion tube, added 5 mL concentrated nitric acid and 2 mL 30% hydrogen
131
peroxide, holding for over 1.5 h. Prepared the microwave digestion conditions according to
132
Table 1. At the end of digestion, cooled them down, transferred all of them to a 25 mL
133
volumetric flask, and then washed the digestion tube 2-3 times with ultrapure water. Finally,
134
immerse them with ultrapure water to the scale mark. At the same time, prepared blank and
135
reference tests. Determined the cadmium contents by graphite furnace atomic absorption
136
spectrophotometry
137
spectrophotometer TAS-986 (G) produced by Purkinje General (Beijing, China) and
138
Deuterium lamp and self-absorption correction method for background correction .
with
the
detection equipment,
which
was
atomic
absorption a
139
According to GB/T 24318-200921, prepared peanut samples was performed as follows:
140
weighed about 0.1 g (accurate to 0.001g) of peanut samples, wrapped and compacted them in
141
a tinfoil, and then placed them at an autosampler for detection. Likewise weighed Ethylene
142
Diamine Tetraacetic Acid (EDTA, the purity is more than 99%, Sigma-Aldrich,) 15.0, 20.0,
143
30.0, 40.0, 50.0, 60.0, 70.0, 80.0, 100.0 and 120.0 mg processed as the peanut sample and
144
detected peak area for drawing standard curve. The combustion reaction conditions for
145
samples : temperature is 1200 ℃, the oxygen factor is 1.8 mL mg-1, oxygen flow rate is 400 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 8 of 35 8 / 31
146
mL min- 1, the pressure of helium gas(≥99.999%), oxygen(≥99.999%), nitrogen(≥99.99%)
147
are 0.2, 0.25 and 0.3 MPa. Gas emitted from samples combustion decomposition under high
148
temperature by purification and removing impurity were transmitted by using helium as
149
carrier gas and nitrogen oxide of which were reduced. After reaction, the mixed gas, in turn,
150
pass through the detector (TCD) by adsorption and separation for detection. Eventually, the
151
content of total nitrogen was calculated according to the EDTA standard curve. The
152
calculation formula of crude protein content in the sample:
Crude protein content = 153
total nitrogen content ×F sample weight
154
In which F is protein factor, namely the coefficient of conversion from nitrogen to
155
protein, depending on characteristic parameter of crop type. In peanut sample, the value is
156
5.46.
157
and calculation of the crude protein content, using Dumas nitrogen determination apparatus
158
NDA–701produced by Italy VELP company.
Determined the total nitrogen content according to the Dumas combustion principle
159
Quality assurance
160
The Cd reference materials were certified as the heavy metals and granted certificates by
161
Chinese scientific community . Nitric acid and hydrogen peroxide used in this study were of
162
ultrapure grade. Ultrapure water, with a resistivity of 18.2 MΩ cm, which was obtained from
163
a Millipore system (USA) with the purified water purchased from Wahaha Corporation
164
(Hangzhou, China). All glass wares were soaked in a nitric solutions (nitric acid : water = 1:4)
165
for 24 h and rinsed with deionized water. National first level standard material (GBW10035) ,
166
Pb, Cd, Cr in wheat powder (Chinese Academy of Geographical Sciences, Beijing, China)
167
(74 ±3 µg kg-1 for Cd ) was used to determine the quality assurance during the detection
168
process of cadmium . The limit of detection (LOD) for cadmium element was 0.1 µg kg-1, ACS Paragon Plus Environment
Page 9 of 35
Journal of Agricultural and Food Chemistry 9 / 31
169
and the limit of quantification (LOQ) was 0.3 µg kg-1. The results were found with a
170
deviation of less than 5% from the GBW10035 wheat powder certified values.
171
National second level standard material (GBW(E) 100126), crude protein in whole
172
wheat flour (Chinese Academy of Geographical Sciences, Beijing, China) (15.8±0.3) %
173
was used to determine the quality assurance during the detection process of crude protein .
174
The LOD of the method for detecting total nitrogen content was 0.03 mg, and the LOQ was
175
0.1mg. The relative deviation for detecting total nitrogen contents so that to calculate crude
176
protein from crude protein in whole wheat flour (GBW(E) 100126 )is less than 2%.
177
Statistical analysis
178
To determine whether there are significant differences in the cadmium contents among
179
different regions, years, strains of peanut, statistical analysis was conducted to calculate the
180
sample size, mean, standard deviation, median, max, violation rate (%) and Duncun group .
181
The calculations were mainly based on the SAS (SAS/PC 9.3, professional edition, USA)
182
environment of univariate and general linear model (GLM) procedures. The statistical
183
significance of the differences was assessed using Duncan’s multiple-range test. A
184
probability of 0.05 was considered significant. Sampling and fitting were performed using the
185
commercially available software package @Risk (Version 5.5, for Excel Professional edition,
186
Palisade, UK).
187
Assessment of the Cd risk through peanut consumption
188
According to the guidelines for assessments of exposure to contaminants in foods22,
189
regional average contaminant values and the Global Environment Monitoring System/Food
190
Contamination Monitoring and Assessment Program from the World Health Organization
191
(GEMS/food) consumption cluster diets were recommended for regional dietary exposure ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 10 of 35 10 / 31
192
estimates23. The weight and peanut consumption information required for the assessment of
193
each group was from the report "2002-The Nutrition and Health Status of the Chinese
194
People", The estimated monthly intake (EMI) of Cd depended on both the concentration of
195
Cd in peanut and the amount of peanut consumption. The daily intake of Cd was determined
196
by the following equation:
197
EMI = (E F × Ε D × FIR × C × 30) (WAB × TA )
198
EF is the exposure frequency (365 days/year); ED is the exposure duration (70 years); FIR
199
is the peanut ingestion rate (g/person/day); C is the Cd concentration in peanut (mg kg-1);
200
WAB is the average body weight24; TA is the average exposure time (EF × ED)25,26. FIR and
201
WAB were shown in Table 2.
202
Target hazard quotient (THQ)
203
Non-carcinogenic risk assessments were frequently performed to estimate the potential
204
health risks of contamination using the THQ, and the methodology for estimating the THQ
205
was described in details by the United States Environmental Protection Agency (USEPA)26, 27
206
During the 73rd meeting, the JEFCA concluded that the PTMI was appropriate for
207
cadmium evaluation13, 28. The THQ for residents through consumption of Cd-contaminated
208
peanut can be assessed by comparing the PTMI of Cd. Based on the methods modified29, the
209
THQ was determined in the following equation:
210
THQ = EMI/PTMI
211
The applied PTMI of Cd was recommended by Joint FAO/WHO Expert Committee on
212
Food Additives (JECFA) in 2011: 25 µg/kg bw/month13. If the estimated THQ value is below
213
1, non-carcinogenic effects are believed to be safe; if it exceeds 1, non-carcinogenic effects
214
are dangerous, and the risk probability is positively correlated with the THQ value30, 31. ACS Paragon Plus Environment
Page 11 of 35
Journal of Agricultural and Food Chemistry 11 / 31
215
Monte Carlo exposure assessment model
216
Dietary exposure to Cd was calculated depending on the model construction theories,
217
Monte Carlo method and bootstrap values. Latin hypercube sampling was operated multiple
218
times (n) from the bootstrap samples. The statistics of individual samples such as the mean
219
values and percentiles (P50, P90, P95, P97.5, P99 and P99.9 in this work) were obtained; the
220
confidence intervals of all statistics were monitored, and the variability of EMI for all the
221
samples could be convergence32. Additionally, the number of iterations (n) and number of
222
simulations (B) in the simulation procedures were set to 100,000 and 2,000, respectively,
223
which resulted in 2 × 108 (100,000 × 2,000) simulations to guarantee the reliability of the
224
results.
225
RESULTS AND DISCUSSION
226
Cadmium concentrations in post-harvest peanuts
227
The Cd concentrations in 8,698 peanut samples were determined in this study. The mean
228
concentration of Cd in all samples was 0.1684 mg kg-1, which was slightly higher than
229
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
230
was nearly unchanged for six years (Table 3). The slight differences between years were
231
mainly caused by the location and size ratio at the sampling points. Absolutely, there was also
232
a little difference in the soil cadmium content in different years for the same area, which
233
needed future research. The median value was 0.1351 mg kg-1, which was less than the
234
average, indicating that the distribution of the cadmium samples deflected to the left and
235
presented a right tail distribution. That is, the peanut Cd level of 0.1684 was substantially
236
lower than the maximum level of the contaminant (0.5 mg kg-1 for Cd) in China according to
237
Chinese standanrd GB 2762-2012
33
. Only 2.793% (243/8,698) of the peanut samples
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 12 of 35 12 / 31
238
exceeded the ML, and a greater violation rate indicated a higher mean value of the Cd content.
239
Thus, the Cd contamination in peanut produced in China was hardly a threat without taking
240
into consideration of the residents’ age and gender or regional differences, but excessive
241
samples should be paid more attention. However, China owns the largest amount of peanut
242
consumption than any other countries, indicating that further risk assessment for Cd in peanut
243
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
Page 13 of 35
Journal of Agricultural and Food Chemistry 13 / 31
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
268
Peanut samples were sorted by strains, the results showed that a highly significant
269
correlation was found between the concentrations of Cd in peanut and the protein contents in
270
different strains that were widely planted and the sample size was greater than 50 (Fig. 2).
271
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
273
form cadmium metallothionine36. Metallothionein (MT) is a kind of small protein localized to
274
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)
276
heavy metals (https://en.wikipedia.org/wiki/Metallothionein). Many researches showed that
277
the MT levels increased at the highest Cd exposure in all species and tissues12. For example,
278
MTs are present in a range of aquatic organisms and are important in the response of an
279
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
281
accurately acquainted with the Cd adsorption capacity of different peanut varieties, the
282
following inquiry was designed. In Fuxin of Liaoning province, 95% reference range of the
283
soil Cd concentration was 0.1213 (0.1084-0.1361) mg kg-1. The results of field validation ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 14 of 35 14 / 31
284
study (Fig. 3) showed that under the same soil Cd background, the difference in the Cd
285
content in different peanut varieties was extremely significant. The Cd concentration of
286
Silihong was about 0.4522 mg kg-1, which was seven times higher than Zhonghua 6,
287
indicating that Silihong had a strong Cd adsorption capacity. The Cd concentrations in
288
Zhonghua 6 and Luhua 8 were less than the soil background values, revealing that these two
289
species had weak adsorption capacities of Cd, namely they were Cd-tolerant varieties. Other
290
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.
293
Dietary exposure assessment of cadmium
294
The THQ has been recognized as the major parameter for assessing chronic
295
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
297
applied based on the Latin hypercube simulation performed under the @Risk program. A
298
total of 100,000 iterations and 2,000 simulations were conducted, and the THQ results of Cd
299
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
302
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
304
provisional tolerable weekly intake (PTWI) of 7 µg/kg bw was therefore withdrawn and the
305
PTMI of 25 µg/kg bw was established by JECFA in 2011 according to the latest
306
epidemiological survey and toxicological study. ACS Paragon Plus Environment
Page 15 of 35
Journal of Agricultural and Food Chemistry 15 / 31
307
From Table 5, the values at P50 exhibited the median exposure of consumers to the
308
distribution, whereas those at P97.5, P99 and P99.9 exhibited higher exposure. The THQs for
309
all age, environmental and gender groups showed no mean or median values (0.0028−0.0202)
310
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
312
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.
315
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
329
Cd from other foods, including the peanut oil, and other exposure pathways to make a more ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 16 of 35 16 / 31
330
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.
ACS Paragon Plus Environment
Page 17 of 35
Journal of Agricultural and Food Chemistry 17 / 31
347 348
REFERENCES (1)
Kasuya, M.; Aoshima, K.; Katoh, T. Natural history of Itai-itai disease: A long-term observation on
349
the clinical and laboratory findings in patients with Itai-itai disease. Edited Proceedings of the 7th International
350
Cadmium Conference, New Orleans, LA, 6–8 April 1992. Cook ME, Hiscock SA, Morrow H et al., editors.
351
London/Reston, VA: Cadmium Association/Cadmium Council, pp. 180–192.
352
(2)
353
(3) Wang, L.; Cui, X.; Cheng, H.; Chen, F.; Wang, J.; Zhao, X.; Lin, C.; Pu, X. A review of soil cadmium
354 355 356 357
I.A.R.C. Cadmium and Cadmium Compounds. World. Health. Organ. Tech. Rep. S. 2012,01,1-105.
contamination in China including a health risk assessment. Environ. Sci. Pollut. Res. 2015, 22, 16441-16452. (4) Zhao, F. J.; Ma, Y. B.; Zhu, Y. G.; Tang, Z.; McGrath, S. P. Soil Contamination in China: Current Status and Mitigation Strategies. Environ. Sci. Technol. 2015, 49, 750-759. (5) Qin, Y. S.; Zhan, S. J.; Yu, H.; Tu, S. H.; Wang, Z. Y. Distribution Characteristics of Soil Cadmium in
358
Different Textured Paddy Soil Profiles and Its Relevance with Cadmium Uptake by Crops. Spectrosc. Spectr.
359
Anal. 2013, 33, 476-480.
360 361 362
(6) Filipek-Mazur, B.; Mazur, K.; Gondek, K. The effect of organic fertilisers on distribution of heavy metals among fractions in soil. Rostl. Vyroba. 2001, 47, 123-128. (7) Franz, E.; Romkens, P.; van Raamsdonk, L.; Van Der Fels-Klerx, I. A Chain Modeling Approach To
363
Estimate the Impact of Soil Cadmium Pollution on Human Dietary Exposure. J. Food. Protect. 2008, 71,
364
2504-2513.
365 366 367 368 369
(8) Huang, Z.; Pan, X. D.; Wu, P. G.; Han, J. L.; Chen, Q. Health Risk Assessment of Heavy Metals in Rice to the Population in Zhejiang, China. Plos One. 2013, 8,e75007. (9)
Zhuang, P.; McBride, M. B.; Xia, H.; Li, N.; Lia, Z. Health risk from heavy metals via consumption
of food crops in the vicinity of Dabaoshan mine, South China. Sci. Total .Envir. 2009, 407, 1551-1561. (10) Du, X. H.; Ding, X. X.; Zhou, H. Y. Research on Sampling Methods in Risk Assessment for
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 18 of 35 18 / 31
370
Aflatoxins in Peanuts. Chinese J.Oil Crop Sci. 2015, 37, 876-880 (in Chinese with English abstract).
371
(11)
372
79(17): 4813.
373 374 375 376 377 378 379 380 381 382 383 384 385
Margoshes M, V. B. A cadmium protein from equine kidney cortex. J. Amer. Chem. Soc. 1957,
(12) Erk, M.; Ruus, A.; Ingebrigtsen, K.; Hylland, K. Cadmium accumulation and Cd-binding proteins in marine invertebrates--a radiotracer study. Chemosphere. 2005, 61, 1651-1664. (13)
JECFA(2011). Evaluation of Certain Contaminants in Food: Seventy-third Report of the Joint
FAO/WHO Expert Committee on Food Additives. World. Health. Organ. Tech. Rep. S. No.960, 2011. (14)
Chen, Y. Q.; Wang, H. O.; Peng, S. J. Overview of Peanut Cropping Patterns in Main Production
Area in China. Chinese Agric. Mechan. 2011, 6, 66-69 (in Chinese with English abstract). (15) Chen, H.; Teng, Y.; Lu, S.; Wang, Y.; Wang, J. Contamination features and health risk of soil heavy metals in China. Sci Total Envir. 2015, 512, 143-153. (16)
Huang, Z.; Li, L.; Huang, G.; Yan, Q.; Shi, B.; Xu, X. Growth-inhibitory and metal-binding proteins
in Chlorella vulgaris exposed to cadmium or zinc. Aquat.Toxicol. 2009, 91, 54-61. (17)
Chen, Z. J.; Song, W.; Li, P. W. Survey and Dietary Risk Assessment of Cadmium in Peanut
Produced in China. J.Agro-Envir. Sci. 2012, 31(2), 237-244. (18)
Herreros, M. A., Iñigo-Nuñez, S., Sanchez-Perez, E., Encinas, T., & Gonzalez-Bulnes, A.
386
Contribution of fish consumption to heavy metals exposure in women of child bearing age from a
387
Mediterranean country (Spain). Food Chem Toxicol. 2008, 46, 1591-1595.
388 389 390 391 392
(19)
Ding, X.; Li, P.; Bai, Y.; Zhou, H. Aflatoxin B1 in post-harvest peanuts and dietary risk in China.
Food Control. 2012, 23, 143-148. (20)
Ministry of Health P. R. China. GB/T 5009.15-2003: Determination of cadmium in foods. Beijing,
China, 2003 (in Chinese) . (21)
Ministry of Health P.R. China. GB/T 24318-2009: Determination of total nitrogen content in animal
ACS Paragon Plus Environment
Page 19 of 35
Journal of Agricultural and Food Chemistry 19 / 31
393
feeding stuffs by combustion according to the Dumas principle and calculation of the crude protein content,
394
Beijing, China, 2009 (in Chinese) .
395 396 397 398 399 400
(22)
Nordberg, G. F.; Nogawa, K.; Nordberg, M. Chapter 32 - Cadmium. In Handbook on the Toxicology
of Metals (Fourth Edition); Academic Press: San Diego, 2015; pp 667-716. (23)
Amzal, B.; Julin, B.; Vahter, M.; Wolk, A.; Johanson, G.; Akesson, A. Population toxicokinetic
modeling of cadmium for health risk assessment. Environ Health Perspect . 2009, 117, 1293-1301. (24)
Portier, K.; Tolson, J. K.; Roberts, S. M. Body weight distributions for risk assessment. Risk. Anal
2007, 27, 11-26.
401
(25)
U.S, E. P. A. Exposure factors handbook: EPA Report: Washington, DC1997.
402
(26)
U.S, E. P. A. Draft technical guidelines: Standard operating procedures for residential pesticide
403
exposure assessment: Submitted to the FIFRA Scientific Advisory Panel for review and comment, October 6-9,
404
2009; EPA Report.
405 406 407 408 409 410 411
(27)
U.S, E. P. A. Supplementary guidance for conducting health risk assessment of chemical mixtures:
EPA Report: Washington, DC2000. (28)
E.F.S.A. Cadmium in Food. Scientific Opinion of the Panel on Contaminants in the Food Chain. The
EFSA Journal, 2009,980: 1–139. (29)
Chien, L. C.; Hung, T. C.; Choang, K. Y.; Yeh, C. Y.; Meng, P. J.; Shieh, M. J.; Han, B. C. Daily
intake of TBT, Cu, Zn, Cd and As for fishermen in Taiwan. Sci. Total. Envir. 2002, 285, 177-185. (30)
Huang, Y.; Wang, M.; Mao, X.; Qian, Y.; Chen, T.; Zhang, Y. Concentrations of Inorganic Arsenic in
412
Milled Rice from China and Associated Dietary Exposure Assessment. J. Agr. Food. Chem. 2015, 63,
413
10838-10845.
414
(31)
415
Zheng, N.; Wang, Q.; Zhang, X.; Zheng, D.; Zhang, Z.; Zhang, S. Population health risk due to
dietary intake of heavy metals in the industrial area of Huludao city, China. Sci. Total. Envir. 2007, 387, 96-104.
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 20 of 35 20 / 31
416 417 418 419 420
(32)
Zheng, J. Y.; Frey, H. C. Quantitative analysis of variability and uncertainty with known
measurement error: Methodology and case study. Risk.Anal. 2005, 25, 663-675. (33)
Ministry of Health P. R. China. GB 2762-2012: Maximum Levels of Contaminants in Foods of
China, Beijing, China, 2012 (in Chinese) . (34)
Qin, Y. S.; Zhan, S. J.; Yu, H.; Tu, S. H.; Wang, Z. Y. Distribution Characteristics of Soil Cadmium
421
in Different Textured Paddy Soil Profiles and Its Relevance with Cadmium Uptake by Crops. Spectrosc. Spectr.
422
Anal. 2013, 33, 476-480.
423 424 425
(35)
Balkhair, K. S.; Ashraf, M. A. Field accumulation risks of heavy metals in soil and vegetable crop
irrigated with sewage water in western region of Saudi Arabia. Saudi J.Biological Sci. 2016, 23, S32-S44. (36)
Alvarado, N. E.; Quesada, I.; Hylland, K.; Marigomez, I.; Soto, M. Quantitative changes in
426
metallothionein expression in target cell-types in the gills of turbot (Scophthalmus maximus) exposed to Cd, Cu,
427
Zn and after a depuration treatment. Aquat. Toxicol. 2006, 77, 64-77.
428
(37)
Saif, M. M. S.; Kumar, N. S.; Prasad, M. N. V. Binding of cadmium to Strychnos potatorum seed
429
proteins in aqueous solution: Adsorption kinetics and relevance to water purification. Colloid.Surface.B. 2012,
430
94, 73-79.
431
(38)
Ferraz, P.; Fidalgo, F.; Almeida, A.; Teixeira, J. Phytostabilization of nickel by the zinc and
432
cadmium hyperaccumulator Solanum nigrum L. Are metallothioneins involved? Plant. Physiol. Biochem.. 2012,
433
57, 254-260.
434 435 436
(39)
Falco, G.; Llobet, J. M.; Bocio, A.; Domingo, J. L. Daily intake of arsenic, cadmium, mercury, and
lead by consumption of edible marine species. J. Agr. Food. Chem .2006, 54, 6106-6112. (40)
Herreros, M. A.; Inigo-Nunez, S.; Sanchez-Perez, E.; Encinas, T.; Gonzalez-Bulnes, A. Contribution
437
of fish consumption to heavy metals exposure in women of childbearing age from a Mediterranean country
438
(Spain). Food. Chem. Toxicol . 2008, 46, 1591-1595.
ACS Paragon Plus Environment
Page 21 of 35
Journal of Agricultural and Food Chemistry 21 / 31
439
(41)
Qian, Y.; Chen, C.; Zhang, Q.; Li, Y.; Chen, Z.; Li, M. Concentrations of cadmium, lead, mercury
440
and arsenic in Chinese market milled rice and associated population health risk. Food Control. 2010, 21,
441
1757-1763.
442
(42)
Shahbazi, Y.; Ahmadi, F.; Fakhari, F. Voltammetric determination of Pb, Cd, Zn, Cu and Se in milk
443
and dairy products collected from Iran: An emphasis on permissible limits and risk assessment of exposure to
444
heavy metals. Food Chem .2016, 192, 1060-1067.
445
(43)
Muñoz, O., Bastias, J. M., Araya, M., Morales, A., Orellana, C., Rebolledo, R.,. Estimation of the
446
dietary intake of cadmium, lead, mercury, and arsenicby the population of Santiago (Chile) using a Total Diet
447
Study. Food Chem. Toxicol . 2005, 43, 1647-1655.
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
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
ACS Paragon Plus Environment
Page 23 of 35
Journal of Agricultural and Food Chemistry 23 / 31
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
ACS Paragon Plus Environment
Last-Time (Min)
Journal of Agricultural and Food Chemistry
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
ACS Paragon Plus Environment
Page 25 of 35
Journal of Agricultural and Food Chemistry 25 / 31
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)
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
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)
ACS Paragon Plus Environment
Page 27 of 35
Journal of Agricultural and Food Chemistry
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
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 28 of 35 28 / 31
459
Fig. 1. Geographical locations of the sampling sites of peanut in China
ACS Paragon Plus Environment
Page 29 of 35
Journal of Agricultural and Food Chemistry 29 / 31
460 461
Fig 2. The relationship of cadmium concentration with protein content in different peanut
462
varieties
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Page 30 of 35 30 / 31
463 464
Fig. 3. The Cadmium content in different peanut varieties
ACS Paragon Plus Environment
Page 31 of 35
Journal of Agricultural and Food Chemistry 31 / 31
465
Graphic for table contents
466
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
Geographical locations of the sampling sites of peanut in China 374x276mm (96 x 96 DPI)
ACS Paragon Plus Environment
Page 32 of 35
Page 33 of 35
Journal of Agricultural and Food Chemistry
The relationship of the cadmium concentration with the protein content in different peanut varieties 260x209mm (300 x 300 DPI)
ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
The cadmium content in different peanut varieties 257x213mm (300 x 300 DPI)
ACS Paragon Plus Environment
Page 34 of 35
Page 35 of 35
Journal of Agricultural and Food Chemistry
Graphic for table contents 393x283mm (96 x 96 DPI)
ACS Paragon Plus Environment
