Analysis of Arsenic in Rice in Medan, North Sumatera Indonesia by Atomic Absorption Spectrophotometer

Introduction

Arsenic is one of the most toxic metals found in nature because it can cause toxicity and carcinogenicity, even at low concentration. Long-term exposure may lead to an increased risk for various cancers, carcinoma including skin cancer, bladder, lung, kidney, liver, and prostate.¹ Arsenic can be found in water, air, food, and soil including from volcanic eruptions, contamination from mines, the use of pesticides and fertilizers. According to the International Agency for Research on Cancer (IARC), arsenic is included in the first class as a carcinogenic substance and may cause lung, skin and bladder cancer in humans without a minimum threshold value in which small amounts of arsenic can be harmful to human health.²

Rice is a staple food that is widely consumed around the world, especially in Asia. Indonesia is the country with the second largest rice consumption in the world after Bangladesh. Based on the Badan Pusat Statistik (2017) that the amount of rice consumption in Indonesia is 200-350 g/day/person.Food Drug Administration United State from 2012 to 2013 from 200 samples of rice and rice products, found that the higher content of arsenic found in brown rice compared to white rice. It was reported that the total content of all rice circulating in the United States, contain arsenic with various levels ranging from 17.1 μg / kg in white rice and the highest level in red rice 963 μg / kg.³ The JOINT FAO / WHO Expert Committee on Food Addictives (JECFA, 2011) also reported that rice is the main source of arsenic exposure for humans today. Food is a potential way of exposure to arsenic and arsenic in rice is associated with soil contamination, fertilization, and pesticide use.Hence,(for this reason) the content of arsenic in food especially in rice has become a global concern.⁴

According to the American Environmental Protection Agency, rice is not the only source of arsenic-containing foods, some vegetables, fruits, and water may contain arsenic, but arsenic levels in brown rice are not at a safe level. The European Food Safety Authority (2010) reported that rice is the main source of arsenic-containing foods in European countries. Water used to cook rice contributes to the addition of arsenic in rice. While the process of cleaning and cooking rice, is not an effective way to remove arsenic in rice, this process only reduces the arsenic content to a maximum of 10 to 20% of the total arsenic contained in the rice.^5-6

Determination of arsenic in rice and food has been widely practiced around the world and the results obtained show an alarming level of arsenic for public health because it exceeds the WHO standard limit (2014) that is 0.3 mg /kg. In Indonesia there has never been done on arsenic content in rice, especially there is no  regulation and standards set by BPOM Republic of  Indonesia. The aim of this study was to analyze  arsenic levels in rice circulating in the city of Medan, the rice from  traditional markets and supermarkets.

Experimental

Sample Acquisition

Sample acquisition method was conducted by purposive sampling, which the samples were obtained from different markets around Medan to represent the rice commonly consumed by people.⁷ Sample were obtained from 4 traditional Markets in Medan were Pasar Sore Padang Bulan, Pasar Simpang Limun, Pasar Sei Sikambing, Pasar Besar Berastagi and 2 Supermarkets were Berastagi and Carrefour. A total of  20 rice samples consisted 11 white rice (2 organic and 9 inorganic), 3 brown rice (1 organic and 2 inorganic), 5 red rice (1 organic and 4 inorganic), 1 black  rice (organic).

Research Location and Time

The analyses of the samples were conducted at Laboratory of Agro Industry Center, Bogor, West Java, Indonesia  from  25^th  June to 5^th  November 2017.

Tools

Tools used in this research were microwave (SCP Science), label paper, blender, Whatmann No.41 filter paper, analytical balance (Mettler Toledo), an Atom Absorption Spectrophotometer (GBC 906AA) with an argon-air flame with arsenic cathode lamps.

Materials

Materials used in this research were distilled water and quality materials proanical output of E. Merck namely, nitrat acid 65%, hydrochloride acid 37%, the AAS for arsenic standard solution at 1000 μg/mL.

Arsenic Analysis in Rice

Rice were washed with water and dried. Rice were milled using a blender or grinder. Rice sample of  0.5 g  was transferred into a microwave vessel, added 5 mL of HNO₃ and 3 mL HCl. Then vessels were inserted in a microwave at a temperature of 180°C for 30 minutes until complete destruction  indicated by the presence of clear liquid. Then the destruction results were cooled and included in a 50 mL measuring flask fed with distilled water and filtered with Whatmann no 41 paper. Then the solution was measured using an atomic absorption spectrophotometer at a wavelength of 193.7 nm.⁷

Calibration Curve

Tenmililiters of 1000 μg/mL of arsenic standard solution was pipetted into a 100 mL well formed flask and added  distilled water. Then 5 mL of the solution was transferred into a 500 mL flash, then diluted with distilled water to prepare 1 µg/mL arsenic standard solution then it was pipetted 0.5 , 1, 1.5, 2, 2.5 mL into a 100 mL flash and this is as arsenic standard solution was used.

X = concentration of analyte in sample solution; V = total volume of sample solution examined.

Fp = Dilution factor of the decomposition results; W = Weight of sample.

Results and Discussion

The levels of arsenic in different analyzed rice samples presented in Table 1, Table 2 and Figure 1.

Table 1: Arsenic Levels in Analyzed Rice Samples marketed in Medan.

White Rice
No.	Rice	Brand Name	Market of Sample  collection	Arsenic Level (mg/kg)
1.	Organic	Export Quality Rice Organik	Swalayan Berastagi	0,0071
2.	Organic	Diabetes Holistik Super Organik	Swalayan Berastagi	0,0117
3.	Inorganic	Rice Tani Makmur Indosiar	Pasar Simpang Limun	0,0192
4.	Inorganic	Rice Cap Jambu Air	Pasar Simpang Limun	0,0818
5.	Inorganic	Rice Kuku Balam Super Berdikari 21	Pasar Simpang Limun	0,0604
6.	Inorganic	Rice Arias Aladin	Pasar Sore Padang Bulan	0,3316
7.	Inorganic	Rice Arwana	Pasar Sore Padang Bulan	0,0243
8.	Inorganic	–	Pasar Besar Berastagi	0,0191
9.	Inorganic	–	Pasar Besar  Berastagi	0,0248
10.	Inorganic	Rice Amco Gandapura (Beras IR 64)	Pasar Sei Sikambing	0,0548
11.	Inorganic	Rice IR 64 SM	Pasar Sei Sikambing	0,0720

 

Table 2: Arsenic Level in Color Rice in Medan.

Color Rice
Brown Rice
No.	Rice	Brand Name		Market of Sample  collection	Arsenic Level (mg/kg)
1.	Organic	Bio Cell Organik (Non Pesticide)		Swalayan Berastagi	3,4010
2.	Inorganic	–		Pasar Besar Berastagi	0,0462
3.	Inorganic	–		Pasar Besar Berastagi	3,3767
Red Rice
4.	Organic	Red Rice Tropicana Slim		Swalayan Carrefour	0,0061
5.	Inorganic	Red Rice Berasku		Pasar Sore Padang Bulan	3,7136
6.	Inorganic	Rice Cantik Manis 1022		Pasar Sei Sikambing	3,3030
7.	Inorganic	Red Rice Matahari Harum		Pasar Sei Sikambing	3,3446
8.	Inorganic	Red Rice Super Cantik Manis		Pasar Sore Padang Bulan	3,1793
9.	Organic	Black Rice Organic Hotel Grade	Swalayan Carrefour		0,1283

 

From the 20 samples of rice consisting of 11 white rice contain arsenic levels vary widely. The highest arsenic content of 0.33 mg/kg is found in non-organic white rice, where as the arsenic is still WHO 0.3 mg / kg. From 11 white rice is below the level of 0.3 mg / kg, and the lowest arsenic level 0.0071 mg / kg, contained in organic white rice. Research conducted by the United State Department of Agriculture (USDA) (2010), reported that of 76% of white rice in the United States arsenic levels in non-organic white rice is higher than organic white rice.⁹ Organic Trade Association USA (2015) states that rice organics have lower arsenic levels than inorganic rice and arsenic levels with much more inorganic types in an environment where rice is grown than organic arsen.¹⁰

Of the 9 color rice consisting of 3 brown rice, 5 red rice and 1 black rice obtained 3.7137 mg / kg the highest arsenic levels were found in inorganic red rice and there were 5 rice with high arsenic levels exceeding WHO 0.3 mg / kg. In brown rice which highest is organic brown rice  3.4010 mg / kg and arsenic levels in inorganic black rice 0.1283 mg / kg. Of the 9 samples of colored rice, the lowest levels of arsenic were found in organic red rice 0.0061 mg / kg.

The difference of arsenic levels of organic and inorganic white rice is due to the way of planting and the process during rice growth, ranging from the use of pesticides, fertilizers, water for irrigation, as well as land where rice grows.^11-13 The level of arsenic in rice also depends on the color of rice, which is white or colored rice, organic or inorganic, and where the growth of rice.^14-15 Research conducted in some countries, if the level of arsenic in water used for irrigation and land where the rice is grown in the country is low then the arsenic in rice is also low, otherwise it is closely related to other words where the environment of rice grow has been contaminated by arsenic and differences in varieties of rice also cause differences in arsenic levels.^16-17

From Table 1,2 it can be seen that of the all rice at Medan, non-organic Red Rice is the highest arsenic content (3.71 mg/kg) put of 5 samples with 1 organic and 4 non-organic) than the highest arsenic content white rice (0.33 mg/kg)  out of 11 samples with 2 organic and 9 non-organic), and the highest arsenic content in brown rice (3.40 mg/kg) out of  3 samples with 1 organic and 2 non-organic)  and organic black rice contain only 0.13 mg/kg. Of the 20 rice samples, 6 rice samples contain arsenic that exceeded the level of 0.3 mg / kg or even 10 times higher than maximum level made by WHO. The results of this study must be a warning as serious concern because arsenic can cause cancer and high intake of rice in Medan. This can be a serious concern for the government and for next researcher it is suggested to importance of researching the source of arsenic intake from other foodstuffs so it is known the total amount of arsenic intake in Medan, Indonesia, community besides it is suggested to do research on factors influencing arsenic level in rice circulating in Medan City.

Conclusion

From this research, it is obtained the arsenic of various types rice at medan were 3.71 mg/kg in Inorganic Red Rice,  0.33 mg/kg in Inorganic White Rice, 3.40 mg/kg in Organic Brown Rice and 0.13 mg/kg in Organic Black Rice.

Acknowledgement

The writer would like to express his sincere thanks to my Prof. Dr. Jansen Silalahi, M. App,Sc. Apt, as the first thesis supervisor, for his valuable suggestion and guidance during the course of this work, and to Prof. Dr. Rer.nat. Effendy De Lux Putra, SU., Apt. under his help in estimation of this writing and valuable discussion.

References

1. International Agency for Research on Cancer, Monographs on the Evaluation of the Carcinogenic Risks to Humans. 2014, 20
2. International Agency for Research on Cancer, Monographs on the Evaluation of the Carcinogenic Risks to Humans. 2012. 23
3. Food Drug Administration, USA, Arsenic in Rice and Rice Products Risk Assessment Report 2012. 2013.
4. JECFA,  Evaluation of Certain Contaminants in Food, (2011).
5. Andrea, R.; Christian, B.; Joerg, F.; Andrew, A.M.; J.  Environment. Monitoring. 2008, 11, 3
6. Manus, C.; Xiao, J.; Julia, G.F.; Andrew, A. M.; Research Article. 2015, 10, 3.
7. Method Analysis Food, Indonesia National Agency of Drug and Food Control. 2012. 57-61
8. Hamida, Khairuna, S.Zulaekah, Mutalazimah, Jurnal Kesehatan Masyarakat, Surabaya. 2012, 1, 1-2
9. United State Departement of Agriculture (USDA), National Nutrient Database for Standard Reference. 2010, 11-12
10. Organic Trade Association, USA. Arsenic in Food and Agriculture. 2015, 1-3
11. Baba, K.; Arao, T.; Maejima, Y.; Watanabe, E.; Eun, H.; Shizaka, M. L. J. Analys. Chem. 2008, 80, 16-17
    CrossRef
12. Bhattacharya, P.; Samal, A. C.; Majumdar, J.; Santra, S. C.; Banerjee, S.; (2013). India. J. Hazard. Mater. 2013, 262, 38
13. Diamond, G. D.; Cottingham, L. K.; Gruber, F. J.; Punshon, T.; Sayarath, V.; Gandolfi, J. A.; Baker, R. E.; Jackson, P. B.; Folt, L. C.; Karagas, R. M.. J. Enviro. Sci. 2011, 108, 51-53
14. William, P.N.; Price, A.H.; Raab, A.; Meharg, A. A. J. Enviro. Sci and Tech. 2005, 39, 15-16
15. Norton, G. J.; Pinson, S. R.; Alexander, J. J. Agri. Food. Chem. 2012, 52, 9-10
16. Meharg, A. A.; Rahman, M. M. J. Enviro. Sci. Tech. 2009, 37, 22-23
17. Ilion, S.; Alessandrelli, M.; Cresti, R.; Forte, G.; Caroli, S. J. Microchem. 2010, 73, 1-3

---

This work is licensed under a Creative Commons Attribution 4.0 International License.