HEALTH RISK ASSESSMENT OF SOME POTENTIALLY TOXIC ELEMENTS (PTES) IN RICE GROWN IN DEEKERNES SECTOR,

* H. M. Youssef, A. Kh. El-Fekky and M. M. El-Defrawy. Chemistry Department, Faculty of Science, Mansoura University, P.O. Box 35516, Mansoura, Egypt. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


ISSN: 2320-5407
Int. J. Adv. Res. 6(1), 1377-1382 1378 of this study was to investigate and monitor amounts of copper, cadmium, lead, chromium, nickel and iron in domestic cultivated rice collected from five different areas. Hazard Quotient (HQ) and Hazard Index (HI) were used to assess non-carcinogenic health risks from individual metals and the combined health risk from seven metals, respectively. The results of our study may provide some insight into PTE accumulation in the agricultural ecosystem and serve as a basis for comparison to other regions both in Egypt and worldwide. Furthermore, the levels of heavy metals in the selected rice samples were compared to the allowable limits set by FAO/WHO [10].

Study area
Our study area is located in Deekernes sector, Dakahleya governorate, Egypt. Five areas were selected for this study which are: Arab Weda manor with rice type of 104 (S1), Deyaba manor with rice type of 4.25 (S2), Kadayma manor with rice type of 4.25 (S3), Zohairy manor with rice type of 4.25 (S4), El-Bahr El-Kadeem manor with rice type of 4.25 (S5) and the irrigation source was Bahr El-dahab bank.

Sampling
5 samples (2 kg. each) collected in triplicate from Deekernes sector in 5 sites were washed with distilled water and air-dried to constant weight. The rice hulls were separated from the white rice grains using a mill. The white rice and rice hull samples passed through a 50 mesh (< 0.3 mm) sieve, sealed in a plastic box and stored at room temperature until future analysis.

Samples preparation and analysis
Rice samples were ashed at 450°C under gradual increase (<50°C/h). 6M HCl (1:1) is added, and the solution was evaporated to dryness. The residue is dissolved in 0.1 M HNO 3 [11]. The digested solution was analyzed for Pb, Cd, Cr, Ni, Cu, Fe and Zn contents using GBC, Sensaa Series Atomic Absorption Spectrometry (computerized AAS) with air-acetylene flame under the optimum instrumental conditions. Each sample was analyzed three times.

Human risk assessment of PTEs through rice consumption 2.4.1. Estimated daily intake (EDI)
According to some reports [13,14] the daily intake of PTEs depends on both the concentration of the element in food and the daily food consumption. Furthermore, human body weight can also influence tolerance of the pollutants [13]. The estimated daily intake (µg kg -1 day -1 Bw) of PTEs via rice consumption proposed to be calculated as following [15]: EDI = C × Con × EF × ED / Bw × AT where C (µg g -1 ) is the concentration of PTEs in the contaminated rice, Con (g person -1 day -1 ) is the daily average consumption of rice, Bw (kg person -1 ) represents body weight, EF is exposure frequency (365 days year -1 ), ED is exposure duration (70 years, equivalent to the average lifespan), and AT is average time (365 days year -1 number of exposure years, assuming 70 years in this study). The average daily rice intakes of adults and children were considered to be 389.2 and 198.4 g person -1 day -1 , respectively [15], and average adult and child body weights were considered to be 55.9 and 32.7 kg, respectively, as used in many previous studies [16][17][18][19].

Potential health risk of individual PTEs: Target hazard quotient (THQ)
According to standard EPA methods, the risk of non-carcinogenic effects is expressed as the ratio of the dose resulting from exposure to site media compared to a dose that is believed to be without risk of effects, even in sensitive individuals [15]. This ratio is referred to as the target hazard quotient (THQ). The THQ for the locals through consumption of contaminated rice can therefore be assessed based on the food chain and the reference oral dose (R f D) for each PTE. The applied R f D for Cr, Cu, Pb, Zn, Cd, Ni and Fe was 1500, 40, 3.5, 300, 1.0, 20 and 700 µg kg -1 day -1 , respectively. Oral reference doses were obtained from the Integrated Risk Information System [20], with the exception of Pb for which we used the formula R f D =PTWI/7, where PTWI is the provisional tolerable weekly intake (mg kg -1 day -1 ) by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) [21,22]. The THQ is determined as follows: THQ = EDI/R f D If the value of THQ is less than one it is assumed to be safe for risk of non-carcinogenic effects. If it exceeds one it is believed that there is a chance of non-carcinogenic effects, with an increasing probability as the value of THQ increases [15]. 1379

Potential health risk of combined PTEs: Hazard index (HI)
Some previous studies [15,23] reported that exposure to two or more pollutants may result in additive and/or interactive effects. THQs can therefore be summed across constituents to generate a hazard index (HI) for a specific receptor/pathway (e.g. diet) combination. The HI is a measure of the potential risk of adverse health effects from a mixture of chemical constituents in rice.
The HI through daily average consumption of rice for a human being was calculated as follows: HI = Σ THQ

Statistical analysis
The means, standard deviations (SD) and relative standard deviation percentage (RSD %) were calculated using Microsoft Office Excel.

Heavy metal levels in rice samples
The mean, standard deviations (SD) and relative standard deviation percentage (RSD %) of heavy metals in investigated rice samples are presented in Table 1: Table 1: Heavy metal levels in investigated rice samples:

Daily PTE intakes via rice consumption and the risk to human health 3.2.1. Dietary PTE intake
Although there are many pathways of human exposure to PTEs, rice consumption has been identified as one of the major pathways. Therefore, as rice consumption rises in Deekernes sector, human exposure to PTE contamination increases. Table shows the dietary intake of PTEs through rice consumption for adults and children in Deekernes sector on the assumption that the local population consumes mostly local rice. The mean dietary intakes of Cd, Cu, Fe, Pb, Ni, Zn, Cr through rice are estimated to be 2.0, 26.7, 1.2, 132.8, 0.1, 0.1, and 1.4 mg kg -1 day -1 for adults, and 1.8, 23.3, 1.0, 115.7, 0.1, 0.1, and 1.2 mg kg -1 day -1 for children. The mean estimated dietary intakes (MEDIs) of PTEs for adults are higher than those for children and this is in agreement with a previous study [15].

Potential health risks
In the present study, hazard index and carcinogenic risk approaches were used to evaluate the health risks of heavy metal exposure to rice. The non-cancer risk (HQ and HI) and cancer risks for adults and children are shown in Table  2 (a, b, c, d and e) The THQ of PTEs for children is similar to that for adults. Our results suggest that Cd ingestion has the highest potential health risk of adverse effects for adults and children and Fe ingestion has the minimum risk for adults and children.

Potential health risk of combined PTEs (HI)
The hazard index (HI) for a specific receptor/pathway combination can be calculated [15]. The HI values through consumption of rice for adults and children in samples listed in table   This indicates that adults and children may experience adverse health effects. The HI value for adults through rice consumption is slightly higher than that for children, suggesting that the risk of non-carcinogenic effects for adults is slightly higher than that for children. Cd is the key component contributing to the potential health risk of noncarcinogenic effects for adults and children, with Zn, Cu and Ni being secondary and Fe the least important.

Conclusion:-
The soil in the Deekernes sector, Dakahleya governorate, Egypt are primarily contaminated with Cd while Zn, Cu and Ni being secondary and Fe the least important.
The estimation of dietary intake of these PTEs by local inhabitants shows that the MEDIs for adults and children are all below their R f D but in some rice samples Cd (S1, S4), Cu (S4), Ni (S3) and Zn (S5) for adults and children are higher their R f D also the THQ values of individual elements was greater than 1 through rice consumption. The HI values through rice consumption for adults and children indicating that both adults and children may experience some adverse health effects. Cadmium is the key component contributing to the potential health risk of non-1382 carcinogenic effects for adults and children. Furthermore, considerable attention should also be paid to the potential health risks of PTEs through other exposure pathways.
In this study, locally produced rice is the main staple foodstuff and it makes the dominant contribution to the metal intake of residents. To avoid a large accumulation of toxic metals in the human body, local people are not recommended to grow rice crops in land irrigated with metal-contaminated water or to consume large quantities of these contaminated rice grains. Moreover, contaminated soils can endanger human health through oral intake.