CONFERENCE PROCEED
the factors for water, water, soil, and agricultural products pollution. Sources of heavy metal pollution also come from human activities.
Cadmium is known to come from cigarettes, fossil fuels, and fertilizers [1]. In addition, heavy metal contamination of lead is also known to come from the printing of books, and the reuse of batteries and shades [2]. Heavy metal contamination can be through three pathways, including inhalation, dermal and oral. Heavy metal contamination through these various pathways will go to target organs based on risk agents that enter the body. Contamination through inhalation can come from contaminated air which is then inhaled, while contamination through dermal can come from activities touching soil or water contaminated with risk agents such as heavy metal contamination [3].
Besides that, contamination of agent risk such as heavy metals also found through an oral pathway. One of the oral contaminations is found in food, specifically rice. One of the causes of heavy metal pollution in rice is the use of pesticides at the time of planting [4]. In addition, it is known that the use of fertilizers has an impact on the concentration of heavy metals in agricultural soils and agricultural products [5].
The presence of heavy metals is also naturally influenced by soil pH conditions [6]. Some of these sources are the cause of heavy metal contamination in both agricultural land and rice.
The use of pesticides causes the pesticide to fall on the leaves, and other parts of the plant and, the soil. Plant roots are known to absorb contaminants that have an impact on agricultural products [7-9]. A study in China found the heavy metal arsenic in rice with concentrations exceeding the safe limit [10]. In addition, a study in Vietnam found contamination of arsenic, cadmium, lead, and copper in rice from mining areas [11]. A study in Indonesia itself showed that the concentration of arsenic in white rice exceeds safe standards [12].
The consumption of rice which contains heavy metals in small concentrations in large quantities is known to have an impact on health problems. Although the concentration of heavy metals is found in small amounts, the level of
toxicity is known to be high. Arsenic contamination is known to cause acute and long-term health problems [13]. In addition, it can cause muscle cramps, abdominal pain, and an irregular heartbeat [14]. On the other hand, rice is a food commonly consumed by people in Indonesia, especially in Palembang. According to data from the statistical agency in 2017, Indonesian people's rice consumption reaches 200-350 grams per day per person [15]. There are two types of rice that are usually consumed by the people of Palembang, namely Pulen rice and Pandan wangi rice. Consumption of this large amount can be one of the potential risks to public health. Study in Indonesia found the carcionegic risk related arsenic exposure in white rice [12, 16]. Therefore, a study were needed to determine the concentration of heavy metals, calculate non- carcinogenic risk and carcinogenic risk in local white rice in Palembang, South Sumatra.
2. Methods
This research was a preliminary study conducted in Palembang, South Sumatra, Indonesia. Palembang is the capital city of South Sumatra, which is located in the south part of Sumatra Island. Rice is known to be the staple food of the people in the city of Palembang. The two types of rice commonly consumed by the people of Palembang are Pulen rice and Pandan Wangi rice. The samples used were collected from the 3 largest markets in the city of Palembang. The three biggest markets are located in the right area, the middle area, and the left area of the Musi River in Palembang. Musi River is a river that divides Palembang city to be three areas. Shop was chosen by random sampling in each market. Each shop collected two types of rice with the total sample was 6 sample. Rice was sent to the Health Laboratory Center of Palembang. 100 grams of rice samples were sent.
The initial stage of analysis was sample preparation. At this stage, the rice was converted into a smaller form such as flour [17]. Rice was washed with deionized water and dried at 70-100 C using a microwave. The next stage is the digestion stage. This stage changes the sample from compounds to elements. Then 0.5 gram
sample was mixed with 5mL HNO3 and 1 ml HCl which was then put into the microwave at 200°C for 15 minutes. After this step was completed, the sample was transferred to a 50 mL volumetric flask and supplemented with ultrapure water [18].
The final stagewas heavy metal analysis with inductively coupled plasma (ICP-OES). This stage uses electric and magnetic as energy sources by using special tools and gases. With this method, multi-heavy metal analysis can be carried out in a relatively fast time.
The potential risk was calculated with certain formula. Laboratory analysis results and subject data from secondary data were used to calculated the non-carcinogenic risk and carcinogenic risk.
The average daily dose was calculate with this following formula [19] : ADD = C x IR x ED x EF/ Wb x AT. The average daily dose (ADD) use for non carcinogenic calculation meanwhile the carcinogenic use lifetime average daily dose (LADD). After the average daily dose was
calculated, the potential risk for non-carcinogenic risk was calculated with : HQ = ADD/RfD and HI
= ΣHQ if the results of both values were morethan one, it is indicate there may be non-carcinogenic risk related heavy metals contaminations in local white rice. The cancer risk was calculated with CR = LADD x SF and TCR = ΣCR if the results of both values were more than 1 x 10-06, it is indicate there may be carcinogenic risk related heavy metals contaminations in local white rice [20].
3. Results 3.1. Type of rice.
Rice was commonly eaten food daily by the people in Palembang. Based on the survey results, Palembang people consume rice 2-3 times a day on average. The types of rice consumed were Pandan wangi rice and Pulen rice. Fig. 1 shown the picture of the two types of rice namely Pandan wangi rice (a), Pulen rice (b) and comparison of two rice (c).
(a) (b)
(c)
Fig. 1. Type of rice
(source: Primary data from research observation)
Table 1. Concentrations of heavy metals
Type of Rice As (ug/gr) Cd (ug/gr) Pb (ug/gr) Cu (ug/gr)
Pandan wangi <0.800
<0.800
<0.800
<0.038
<0.038
<0.038
<0.839
<0.839
<0.839
0.2551 0.7922 1.6163
Pulen <0.800
<0.800
<0.800
<0.038
<0.038
<0.038
<0.839
<0.839
<0.839
0.9501 1.2302 1.1743
Mean <0.800 <0.038 <0.839 1.00
Note: 1= first market, 2= second market, and 3= third market
Based on the physical form, there was no significant difference between the two types of rice. From the picture above (c), we can see the different between this types of rice. Left side was Pandan wangi rice and right side was Pulen rice.
Both rice were cylindrical. However, the shape of Pandan wangi rice tends to be incomplete or not perfectly cylindrical and shorter than Pulen rice.
In addition, in terms of color, Pulen rice was known to have a whiter color or tranparant than Pandan wangi rice. The quality of Pulen rice was known to be better than Pandan wangi rice. The price of Pulen rice was also known to be more expensive than Pandan wangi rice. The most noticeable difference was when the rice was cooked. Raw Pulen rice will increase 2.1 times after cooking, while Pandan wangi rice will increase 1.8 times after cooking. In addition, Pandan wangi rice has a pandan aroma after cooking. Meanwhile, Pulen rice has a fluffier texture when cooked.
3.2. The concentration of heavy metals
Heavy metal contamination in rice was known to be found in rice. Some study found heavy metals in rice and known have potential risk to human. There are four heavy metals that are commonly found in heavy metals, including arsenic (As), cadmium (Cd), lead (Pb), and copper (Cu). Table 1 shown the results of the analysis of these four heavy metals.
Based on the analysis above, shows that the concentrations of three heavy metals, namely arsenic (As), cadmium (Cd), and lead (Pb) were below the detection limit using the ICP-OES tool.
Generally, the Limit of Detection (LOD) for arsenic and lead in the ICP-OES method is 25-50 ug/gr. Meanwhile, cadmium has a lower detection limit of 2.5-5 ug/gr. This heavy metal detection limit value was obtained from the results of repeated analyzes and related to the conditions at the time of analysis. In the results of this analysis, the detection limit of three heavy metals was lower than the LOD value in general. For heavy metals arsenic and lead, the concentrations were known to be below 0.800 ug/gr and 0.839 ug/gr, respectively. While in cadmium the concentration of heavy metals was below the LOD of 0.038 ug/gr.
On the other hand, copper was known to be above the detection limit but remains within safe limits. The average concentration of copper in Pulen rice is known to be 1.12 ug/gr and in Pandan wangi rice it is 0.89 ug/gr. The concentration of Pulen rice was known 1.2 times higher than Pandan wangi rice. The highest concentration of Pulen rice was obtained from market B with a concentration of 1,230 ug/gr and the lowest in market A at 0.950 ug/gr. Meanwhile, in Pandan Wangi rice, the highest copper concentration was obtained from market C at 1.616 ug/gr and the lowest from market A at 0.255 ug/gr.
3.3. Risk Assessment
Enviromental health risk assessment is a method used to predict health risks due to exposure to chemical agents from water, soil, food and air. This method predicts non-carcinogenic and non-carcinogenic health risks. Health risks due to consumption of rice containing
Table 2. Parameter
Parameter Symbol Unit Defaut Number Reference
Concentration C ug/gr Table 1 This study analysis
Ingestion Rate IR kg/day 0.25 BPS, 2017 [15]
Exposure day ED Years Adults : 30
Kids : 6
Pedoman ARKL
(Environmental Health Risk Assessment Guideline), 2012 [21]
Exposure frequency
EF days/year 350 days/year Pedoman ARKL
(Environmental Health Risk Assessment Guideline), 2012
Weight Wb kg Adults : 55
Kids : 15
Pedoman ARKL
(Environmental Health Risk Assessment Guideline), 2012
Average time AT days Non-carcinogenic :
10950
Carcinogenic : 25550
Pedoman ARKL
(Environmental Health Risk Assessment Guideline), 2012 Reference dose RfD mg/kg.day As : 3.0 x 10-4
Pb : 3.5 x 10-3 Cu : 0.37 Cd : 1.0 x 10-3
US EPA, 2012 US EPA, 2012 US EPA, 2012 US EPA, 2012
Slope factor SF mg/kg.day-1 As : 1.5
Pb : 8.5 x 10-3 Cu : N/A Cd : 15
US EPA, 2012 US EPA, 2012 -
Zeng et al., 2015 [22]
Table 3. Risk assessments
HQ (PW) HQ (P) CR (PW) CR (P)
As Adults 11.623 11.623 5.23 x 10-3 5.23 x 10-3
Kid 8.524 8.524 1.92 x 10-2 1.92 x 10-2
Pb Adults 1.045 1.045 3.11 x 10-4 3.11 x 10-4
Kid 0.766 0.766 1.14 x 10-3 1.14 x 10-3
Cu Adults 0.010 0.013 N/A N/A
Kid 0.008 0.010
Cd Adults 0.166 0.166 2.48 x 10-3 2.48 x 10-3
Kid 0.121 0.121 9.11 x 10-3 9.11 x 10-3
heavy metals are not only influenced by the concentration of heavy metals but also other parameters. Table 2 shown the parameters used to conduct the assessment in this study.
Table 2, the risk assessment was calculated based on the type of rice for adults and children.
Table 3 shown the results of the risk assessment of the four heavy metals.
From this table we can see that arsenic was only one heavy metals showed the value more than 1. We can see that arsenic only one heavy
metals which have the non-carcinogenic risk between four heavy metals. Meanwhile the hazard index showed the non-carcinogenic risk by consuming the two types of rice both for adults and kids by HI > 1. The value for Pandan wangi rice showed the risk for adults and kids as much as 12.844 and 9.418 respectively. There was a slight difference with Pulen rice where the HI values are 12.846 and 9.42 in adults and children, respectively. On other hand the total cancer risk (TCR) showed the same value for the two types
Fig. 2. Hazard Index
Fig. 3. Total Cancer Risk
of rice. The TCR were showed the value of 8.03 x 10-3 for adults and 2.94 x 10-2 for kids. The value was higher than standar for carcinogenic which were 1 x 10-06. As we can see, the carcinogenic risk was higher in kids than in adults. (Fig. 2 and 3) 4. Discussion
The concentration of heavy metals in rice in the city of Palembang was known to be still within safe limits. This was in line with previous studies where the arsenic concentration was found to be 0.06-0.30 mg/kg and was within the safe limit set by WHO, which was 0.3 mg/kg [23].
However, in this study, it was found that there was a potential risk due to rice consumption even though the arsenic concentration was still within the safe limit according to WHO [16]. As for the
heavy metal arsenic, the concentration is below the detection limit of the ICP-OES method. This was in contrast to research in Argentina, where arsenic was detected at concentrations of 0.87-3.16 mg/kg [24]. In addition to arsenic, lead concentrations are still below the detection limit.
This contrasts with a study from Iran where the detected lead was very high, reaching 35 mg/kg [25]. This far exceeds the safe limit set by the WHO of 0.2 mg/kg [26].
The last heavy metal that below the detection limit is cadmium. The detection limit value of cadmium using the ICP-OES method was known to be the highest compared to other heavy metals.
This study contrasts with previous studies where cadmium was detected at concentrations of 0.008-0.01 mg/kg [27]. However, this study and
1.00E-03
1.00E-02
1.00E-01
1.00E+00
TCR (PW) TCR (P)