A total of 46 different types of samples of metallic (aluminium) cookware for human use were collected from the local market of Riyadh city and transported to the environmental research laboratory at Al-Imam Mohammad Ibn Saud Islamic University for elemental analysis. The aluminium pots were firstly washed with distilled water many times to remove any possible contamination. Afterward, 0.9. liters of distilled water were added to the aluminium cookware pots, then allowed to boil for 30 minutes at 100 ºC in order to allow prolonged contact to take place between the distilled water and the cookware wall, finally, 15 mL of the remaining water was taken for elemental analysis.

All the standard stock solutions of heavy metals were certified reference materials that were purchased from Agilent Technologies (USA). HNO₃ and H₂O₂ were heavy metal analysis grade and purchased from Wako Chemical Co. (USA). Reagent water, toluene, and acetone were of analytical reagent grade purchased from J.T. Baker (USA).

The measurements were performed using a Genesis ICP optical emission spectrometer (Spectro Analytical Instruments, Kleve, Germany) with axial plasma observation. The instrument includes a Paschen-Runge mount spectrometer, constructed employing the optimized Rowland circle alignment (ORCA) technique. It consists of two hollow section cast shells, designed for direct thermal stabilization and small volume. 15 pre-aligned linear CCD detectors are installed on the outside of the optics body, which allow fast, simultaneous spectrum capture of the wavelength range between 175 nm and 777 nm. For UV access (< 200 nm), the optical system was purged with argon. The purge rate during normal operation is 0.5 L/min. To enable the method, intelligent calibration logic (ICAL) transfer between individual instruments, was used to normalize the wavelength and the intensity scale of the optical system to a reference optic (“optic master”). Stability of the forward power in the case of rapidly changing sample loads was achieved through the use of an air-cooled ICP-generator, based on a free running 27.12 MHz system. All ICP operating parameters were software controlled. The ICP-OES instrument was initialized and allowed to achieve thermal equilibrium over 30 min. ICP-OES determinations of elements concentration were performed using the emission lines 228.802, 267.716, 324.752, 238.204, 285.213, 259.372, 231.604, 220.353, 213.857, 189.641, 196.090, 384.401 and 311.071 λ (nm) for the elements Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As and Al respectively.

An adequate quality control method and vigilance were carried out in order to get reliable results. Throughout the experiments, all glass ware and equipment were cautiously washed beginning with acetone followed by 5 % HNO₃ and ending with repeated rinsing distilled water to prevent contamination. Reagent blank determinations were used to correct the readings. The lower detection limit values of the elements were found to be 0.001 mg/L for Cr, 0.001 mg/L for Cu, 0.0001 mg/L for Zn, 0.002 mg/L for Fe, 0.0001 mg/L for Mn, 0.0001 mg/L for Cd, 0.001 mg/L for Al, 0.001 mg/L for Ni, 0.01 mg/L for Se, 0.004 for Pb and 0.01 mg/L for As in this study. Samples were measured tow time and the recovery values were nearly quantitative (95 %) for digestion method. The relative standard deviations were less than 10 % for all investigated elements. Multi-element solution standards obtained from Agilent technology were used to calibrate and for quantitative sample results.

Determination of metals released from imported cookware is very important, since several elements play major roles in various metabolic processes in the human body. Moreover, some of these elements are toxic if consumed in excessive quantities (Baran et al. 2019). In this study, 10 elements (i.e. Mn, Fe, Cu, Cr, Zn, Ni, Al, Pb, As and Cd) in 46 items of cookware collected from a local market in Riyadh were investigated using an inductively coupled plasma-optical emission spectrometer (ICP-OES), as shown in (Table I and Table II).

TABLE I
STATISTICAL SUMMARY OF Cd, Cr, Cu, Fe AND Mn CONCENTRATION RELEASED FROM IMPORTED METALLIC COOKWARE (mg/L).

Where: LDL = Lower than detection limit, Min = Minimum, Max = Maximum, Avg = Average and Std = Standard deviation.

TABLE II
STATISTICAL SUMMARY OF Ni, Zn, Al, Pb AND As CONCENTRATION RELEASED FROM IMPORTED METALLIC COOKWARE (mg/L).

Where: LDL = Lower than detection limit, Min = Minimum, Max = Maximum, Avg = Average and Std = Standard deviation.

Iron was detected in all measured samples and ranged from 0.002 to 0.574 mg/L and an average value of 0.057 mg/L. Iron is an important element for human beings and animals (Shukla et al. 2018), and is an essential component of hemoglobin (Balarabe et al. 2019). It facilitates the oxidation of carbohydrates, proteins and fats to control body weight, which is an extremely important factor in diabetes; furthermore, an iron deficiency can induce anaemia (Zhang et al. 2018).

Manganese is essential in many biological pro- cesses such as, blood sugar regulation and bone growth, as well as being a cellular antioxidant (Pfalzer and Bowman 2017). Manganese was detected in 91.30 % of the samples, within a range of 0.001 to 0.505 mg/L, with an average value of 0.073 mg/L. Cu was detected in 97.82 % of the samples and found to be in the range of 0.001 to 0.175 mg/L, with an average value of 0.014 mg/L. Copper has numerous functions in the human body, and they are essential nutrients that play important roles in the pro- duction of hemoglobin for human health; however, an excessive intake of copper has been reported to be toxic (Ahmed et al. 2005).

Chromium is important to make use of glucose as reported by Yagi et al. (2013). Chromium was detected in 67.39 % of the samples, The Cr concentration varied from 0.001 to 0.017 mg/L, with an average value of 0.002 mg/L.

Cadmium was detected in 10.86 % of the 46 samples. Cadmium is an extremely toxic metal found naturally in the soil, but also spread in the environment due to human activity. Over exposure to cadmium can lead to lung, liver, skeletal and renal problems and cancer (Djordjevic et al. 2019).

Zinc was detected in 76.08 % of the samples and the concentrations varied from 0.03 to 0.017 mg/L with an average value of 0.001 mg/L. Zinc has essential function in carbohydrate and cholesterol metabolism (Ahmed et al. 2005). Acute zinc poison- ing is a rare event, except in very high doses (Plum et al.2010).

Nickel was detected in 63.043 % of the samples and the concentrations varied from 0.002 to 0.213 mg/L with an average value of 0.007 mg/L. Trace amounts of nickel may be beneficial as an activator of some enzyme systems, but its toxicity at higher levels is more prominent (Fangkun 2011).

The arsenic content of the samples was detected in 69.56 % of the samples and found to be in the range from 0.012 to 0.505 mg/L with an average value of 0.073 mg/L.Arsenic is a naturally occurring element that can be toxic to humans, animals and plants; however, its toxicity varies, depending on what form it is (Hare et al. 2019).

Aluminum concentration was analyzed in all samples and ranged from 0.01 to 0.175 mg/L, with an average of 0.014 mg/L. The toxicity of Al to humans is mainly related to neurotoxicity and the development of neurodegenerative diseases (Chris- topher 2012). Lead was detected in 69.56 % of the samples. Its concentration ranged from 0.099 to 0.574 mg/L with an average of 0.057 mg/L. Lead is a naturally occurring element, and is a common industrial metal that has become widespread. Lead contamination varies and manifests itself in other ways than in green plants (Ahmad et al. 2019). Lead has severe health effects even at relatively low levels in the body, and can cross the placenta and damage developing foetal nervous systems (Khan and Khan 2017). Lead causes both acute and chronic poisoning; it has adverse effects on the kidneys, liver, heart and both the vascular and immune systems (Zhang 2001).

* Author for correspondence: hjoidriss@gmail.com