Contamination by hazardous elements in low-priced children’s plastic toys bought on the local markets of Karachi, Pakistan

Children’s plastic toys may contain toxic metals to which infants and young children can be orally exposed and may pose acute or chronic adverse health effects. This research aims to evaluate the total metal concentrations (TMCs) of Pb, Cd, Cr, Ni, Zn, Cu, and Mn in children’s plastic toys bought in the local markets of Karachi, Pakistan, and compare TMCs to different toy safety regulatory limits. A total of 44 children’s plastic toys sourced in the Karachi local markets were analyzed by an atomic absorption spectrophotometer for contamination of hazardous elements. Toy samples were divided into two groups: plastic toys (DCT) and plastic toys with paints or coatings (DPCT). For plastic toys, 83% (19) of samples had TMCs that exceeded European Union (EU) toy safety regulation limits for Pb, and 65% (15) of samples that exceeded for Cd. For plastic toys with paints or coating, 43% (9) of samples had TMCs that exceeded EU migration limits for Pb and 24% (5) for Cd. More than 20 samples exceeded the United States Consumer Product Safety Commission (US CPSC), Canadian, and Bureau of Indian Standards (BIS) toy safety regulation limits. In toy samples (n = 44), very high TMCs of Pb (64%), Cd (45%), Cr (5%), and Ni (2%) were observed. Zn, Cu, and Mn TMCs existed but were below the regulation limits. The contamination levels of Pb, Cd, Cr, and Ni and smaller extent of Zn, Cu, and Mn still pose health issues in children and may cause serious problems in their health.


Introduction
Children's toys and products may contain hazardous elements and other chemical compounds that are potentially harmful to the health and development of infants and young children. Young children are more vulnerable to harmful chemicals due to differences in their ability to metabolize, detoxify, and excrete them than adults. Hazardous elements include lead (Pb), cadmium (Cd), nickel (Ni), chromium (Cr), zinc (Zn), copper (Cu), manganese (Mn), and other elements. These elements are used in paint pigments, plasticizers, UV stabilizers, fillers, colorants, antioxidants, processing aids, and flame retardants (Godoi et al. 2009;Ozbek et al. 2015;Ratnakumar et al. 2017;Negev et al. 2018). Moreover, some elements are added intentionally to provide or improve the final product's brightness, softness, stability, and flexibility and make it more attractive for young children (Godoi et al. 2009;Negev et al. 2018).
Low-priced products' demand has motivated many manufacturers to purchase cheap and recycled raw materials and feedstocks to produce low-priced consumer goods and products and decrease manufacturing expenses. It is also noted that the use of metals as stabilizers in plastics during manufacturing, application of paint containing metal pigment in toys, and use of contaminated recycled plastic and electronic waste, or metals in toy production are the main reasons for hazardous metals contamination in children's toys (Guney and Zagury 2012).

Responsible Editor: Philippe Garrigues
Highlights • This research compared the metal levels in the context of two different toy groups.
• Results are compared from EU, BIS, US, and Canadian toy safety regulatory limits.
• 64% of samples detected Pb, and 45% showed Cd levels that exceeded EU regulatory limits.
Hazardous elements can be transmitted from toys when young children constantly chew, lick, and suck on their toys and consume a certain quantity of these poisonous and dangerous chemicals through their typical hand-to-mouth action. Heavy metals are weakly bonded to the surface of the painted toys, allowing them to be released and causing a hazardous impact in the long run (Cui et al. 2015;Guney and Zagury 2014;Le ha et al. 2017).
In young children, the blood-brain barrier is not entirely developed, and therefore, harmful chemicals may enter the central nervous system. Since rapid growth and development occur during infancy and early childhood, damage to the nervous, endocrine, and reproductive systems during this period can have profound life-long impacts. Finally, children have more time to develop diseases initiated by early exposures, such as cancer, neurogenerative disease, metal poisoning, slowed growth and development, learning disabilities, low IQ, anemia, kidney failure, bone defects, skin irritation, decreased bodyweight, and heart, liver, stomach, and intestinal irritation and damage (Greenway and Gerstenberger 2010;Brewer 2010;Sindiku and Osibanjo 2011;Njati and Maguta 2019;Charehsaz et al. 2014;O'Connor et al. 2018;Turner 2019).
Numerous studies on toy contamination by hazardous elements were reported in different countries; Greenway and Gerstenberger (2010) examined Pb in the plastic of children's toys collected from day-care centers in Las Vegas valley, Nevada. Sindiku and Osibanjo (2011) reported the level of Pb, Cd, Cr, and Ni in the plastic components of 51 children toys imported to Nigeria. Ahmad et al. (2012) analyzed Pb, Cd, Ni, Zn, Cr, Co, and Mn in leachates of 26 brands of plastic toys purchased from different districts of UP, India. Guney and Zagury (2013) examined As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Sb, and Se in 72 toys and jewelry items purchased from the North American Market. S. G. Kang and Zhu (2014) reported Pb, Cr, As, Cu, Ni, Ba, Cd, and Sb in 35 plastic toys bought on the Beijing market. Cui et al. (2015) tested for As, Cd, Sb, Cr, Ni, and Pb in 45 children's toys and jewelry purchased from Nanjing, China. Sobhanardakani and Babaei (2016) examined As, Pb, Cd, and Cr in 30 children's plastic toys collected from Hamadan City. Le ha et al. (2017) reported Zn, Cr, Cu, Ni, Mn, Pb, As, and Cd in 31 plastic toys in Hanoi, Vietnam. Turner (2018) analyzed As, Ba, Cd, Cr, Hg, Pb, Sb, and Se in 200 secondhand plastic toys sourced in the UK. Issa and Alshatteri (2019) examined 14 toxic metals in 6 s-hand plastic infant items collected from Kalar city, Iraq markets. Mohammed et al. (2020) assessed Pb, Mn, Ni, Cr, Cd, and Cu in 11 toys and 07 baby items sold in Trinidad and Tobago. All former literature indicated that toxic substances in children's items are of great concern and investigated from time to time.
Millions of toys have been recalled in recent years due to chemical safety hazards such as in June 2007, 1.5 million units were recalled that violated US Government standard for Pb in paints. In January 2010, CPSC recalled 55,000 units that contained high levels of Cd. In June 2010, 12 million promotional drinking glasses sold at McDonald's were recalled due to painted coating containing a high Cd level (Becker et al. 2010). The CPSC website for recall shows that more than 18 million items have been withdrawn from the market due to high Pb levels between 2007 and 2018, and recall data from Canada's official website included a more exhaustive list between 2007 and 2018; 1.6 million products have been officially recalled for Pb contamination in 138 incidents (Becker et al. 2010;Guney and Zagury 2012;Njati and Maguta 2019;Guney et al. 2020).
In the past, children's exposure to hazardous elements via ingestion of many consumer products has resulted in many cases with severe acute or chronic adverse effects, including death. Njati and Maguta (2019) mentioned some cases related to contaminated Pb injuries in toys from the USA and other countries; A girl diagnosed with seizure disorder had a toy horse which was recalled due to a high level of Pb contamination which may cause seizures. Another little girl was diagnosed with a high Pb level in her blood, playing with recalled toys. Another case was where a small boy's hand started itching after playing with a remote-controlled toy car that contained Pb. Another one where a little boy opened a set of toy cars after 5 min developed a huge red rash over his hands, and was diagnosed with Pb poisoning. The little boy experienced breathing problems and nausea and died the following day (Njati and Maguta 2019).
In order to reduce the adverse children's health influenced caused by contaminated children's toys, the monitoring of hazardous elements in children's toys is of high importance.
In Pakistan, to the author's knowledge, this is the first scientific investigation that evaluates the presence of toxic contaminations in low-priced children's plastic toys randomly collected from the local markets in Karachi. For this purpose, only low-priced items are selected for analysis in the first stage. Present research only focuses on total metal concentration (TMCs). If TMCs exceed high numbers, further bioaccessibility testing and health risk assessment are recommended. Past literature indicated that Pb and Cd are highly dangerous for children's health and are neurotoxin and nephrotoxin that is why Pb and Cd are the prime focus of present research, and Cr, Ni, Zn, Cu, and Mn are the secondary focus but are equally important.
To the author's knowledge, national-based toy safety regulation limits are absent in Pakistan. There are no Pakistan standards and quality control authority guidelines for toys to ensure children's safety. Results obtained from present research compared to other regulations available in different countries and regions are mentioned in Table 1

Sample selection and categorization
A total of 44 toy samples, including 23 plastic toys and 21 plastic toys containing paint or coating, were selected and purchased from different local markets in Karachi, Pakistan. Figure 1 shows the location of the sampling site. Toy samples were randomly picked from local markets, stalls, mall stores, bargain stores, roadside vendors, and retail shops. The samples were selected based on the possible mouthing factor by children below 5 years of age, selecting those lowpriced plastic toys, designed for small children around 3 to 5 years old, and mostly demanded too low-income groups. Collected samples include cars, soft baby' toys, animals toys, balls, fruits toys, soft dolls, fishes, ships, and planetype characters. All samples included in this research had grouped into two categories: children's plastic toys (DCT) and children's plastic toys with paint or coating (DPCT). All samples were coded and stored in their original packaging until sample preparation.
The following hazardous elements were tested in terms of total metal concentrations (TMCs); Pb, Cd, Ni, Zn, Cr, Cu, and Mn.

Sample preparation and analysis
Toy samples were weighted. Each sample was cut into small pieces, crushed, and ground into powder. To create one composite sample for each toy, different parts of the toy body were mixed and combined with a different color section. All toy composite samples were recorded and stored at room temperature until sample digestion.
The digestion of children's toys was performed according to the standard method 3030. In brief, the experiments were carried out by accurately weighing ± 1.0 g of toy sample and were digested with concentrated HNO 3 and H 2 O 2 on a hot plate. The cooled solution was gravity-filtered (Whatman #40). After adding 20 ml deionized water, the filtrate  was diluted to 100-ml volumetric glassware. Digestates and procedure blank were stored at 4 °C until analysis. Standards were prepared using 1000 ppm stock standard solutions of each element of interest obtained from Merck. The standard solutions were prepared in the concentration ranges of 1.0-8.0 ppm of Pb, Cd, Cr, Ni, Zn, and Mn, and 0.5-5.0 ppm of Cu.
All samples were analyzed (at Global Environmental Lab, Karachi, Pakistan (PNAC accredited lab)) using an atomic absorption spectrophotometer (Thermo Scientific Series iCE 3000 AAS). Atomic absorption spectroscopy is a wellestablished and precise method for elemental analysis giving concentration results from 1 ppt (parts per trillion) to 100 ppm (parts per million). It is widely used for elemental analysis because of its simplicity, robustness, and relatively interference-free. The detection limits for DPT and DPCT were as follows (mg/l): Pb 0.0035, Cd 0.0010, Cr 0.0050, Ni 0.0050, Zn 0.0010, Mn 0.0010, and Cu 0.0010. The total concentrations of elements in children's toys samples were expressed in mg/kg.

Quality assurance and quality control
The accuracy of the digestion protocol was assessed by analyzing standard reference material (Bottle Code:  for Ni, 96% for Zn, 95% for Mn, and 106% for Cu. The analysis of the reference standard was repeated after every eight samples to ensure quality. Analysis was only carried out when results were within 10% of certified values. Blank measurements and known standards prepared in HNO 3 and H 2 O 2 were also routinely checked as quality control against the working calibration curve.
All chemicals and reagents used were analytical grades obtained from Merck. All glassware and apparatus used in this research were soaked in 10% HNO 3 for 24 h and then double-rinsed with deionized water to avoid contamination.

Comparison of total metal concentrations with the EU Directive, the Canadian, the US, and the BIS toy safety regulation limits
Present research only focuses on total metal concentrations (TMCs). If TMCs exceed in high numbers, then further bioaccessibility testing and risk assessment are recommended. TMC results were compared with the BIS, US, Canadian, and EU toy safety regulation limits. Due to the absence of national standards for toy safety regulation in Pakistan, the obtained results have been compared to other regulations available in different countries and regions are mentioned in Table 1.
The results obtained from the present research are compared with the European Union (EU) Toy Safety Directive 2009/48/EC, 2009 (EN 71-3:2013) (European Council 2019). In the first stage, EU limits have been used in discussion and interpretation because the EU Toy Safety Directive delivers a more comprehensive approach to the chemical safety of toys than any other regulations. After all, it differentiates the migratable limits for various types or groups of toys, namely scraped-off toy material; liquid or sticky toy material; and dry, brittle, powder-like, or pliable toy material. In order to compare the TMCs, the EU limits for scraped-off toy material have been used.
The US Consumer Product Safety Commission (USCPSC) adopted the American society for testing and materials (ASTM) standard for toy safety F963-11. According to ASTM F963, 100mg/kg (total) Pb limits is set for substrates and 90mg/kg(soluble) for surface coating in children's products, and 75mg/kg(soluble) of surface coating and substrates other than clay for Cd. 60mg/kg(soluble) in surface coating and substrates for Cr (ASTM International 2017).
In Canada (Government of Canada, 2016), in consumer products or surface coating(soluble) 90mg/kg(total) limits is sets for Pb and 1000mg/kg in surface coating (soluble) and 130mg/kg(total) limits are set for Cd) (Government of Canada 2018).
In India, the Bureau of Indian Standards (BIS) is the national standards body of India under the Department of Consumer Affairs, Ministry of Consumer Affairs, Food and Public Distribution, the Government of India. It is a statutory body established under the Bureau of Indian Standards Act, 2016. One of the main functions of BIS is to prescribe standards for covering goods and systems under the BIS regime. BIS IS:9873 regulations governing heavy metals in children's toys set limits for Cd 75 mg/kg, Pb 90 mg/kg, and Cr 60 mg/kg (BIS IS 9873-3:1999). BIS limits are identical to the US limits.
TMCs detected in the present research are shown in Tables 2 and 3 for DCT and DPCT groups and evaluated in Table 4. Health hazardous elements Pb, Cd, Ni, Cr, Zn, Cu, and Mn were found in all toy samples. It should be noted that not all elements found in this research were exceeded regulatory limits but were present in some quantities. Seven elements were investigated; however, only Pb, Cd, Ni, and Cr have exceeded EU toy safety regulatory limits in Table 1. Pb was detected in high quantity. In total, 64% of samples exceeded EU limits at a mean concentration of 293 mg/kg and are summarized in Table 4 and presented in Fig. 2a. The 28 out of 44 samples had levels higher than EU limits, and the remaining samples also contained Pb, but their concentrations were within the permissible limits. The highest level of Pb was detected in painted car 4 (DPCT14) 1.19E + 03 mg/kg, crocodile (DCT07) 1.11E + 03 mg/kg, purple car2 (DPCT01) 1.01E + 03 mg/kg, and elephant (DCT03) 981 mg/kg, which is indicated that both groups of toys contained an extremely high level of Pb contents. Lowpriced samples lead to low-quality material, due to which contamination risk is also very high. For Pb, similar results were also reported in the literature (Decharat et al. 2013; Issa and Alshatteri 2019; S. Kang and Zhu 2015;Turner 2018). Pb is used as stabilizers and coloring agents. Lead(II) chromate, lead(II) carbonate, lead oxides, and lead molybdates are used to produce color pigments (Ismail et al. 2017;Njati and Maguta 2019;O'Connor et al. 2018). Basic Pb salts are commonly used as thermal stabilizers to enhance material properties and reduce material costs like fillers in plastic manufacturing and molding processes (Al-Qutob et al. 2014;Njati and Maguta 2019). Above all, recycled plastics are also one of the great sources of toxic contaminations, especially those obtained from electronic waste.< DL = Less than the calculated detection limit Cd was also detected in high quantity. In total, 45% of samples exceeded EU limits at a mean concentration of 63.2 mg/kg summarized in Table 4 and presented in Fig. 2a.
The 20 out of 44 samples had levels higher than EU limits, and the remaining samples also contained Cd, but their concentrations were within the permissible limits. The highest level of Cd was detected in lion (DCT11) 459 mg/kg, blue star (DCT13) 426 mg/kg, horse (DCT02) 398 mg/kg, and lion (DPCT15) 111 mg/kg, which indicated that mostly DCT samples contained more Cd than DPCT; likewise, Cd-based pigments are also used to color plastic material and work as a stabilizer in PVC together with the salt of Pb and Ba (Turner 2019 Cr and Ni were also found in exceeded levels, but as compared to Pb and Cd, their quantities were less in numbers, and only 5% Cr and 2% Ni exceeded EU limits at a mean concentration of 244 mg/kg and 362 mg/kg and are summarized in Table 4 and presented in Fig. 2a. Out of 44, only 2 samples for Cr and only 1 sample for Ni exceeded EU limits. Cr exceeded in samples including elephant (DCT03) 561 mg/ kg and crocodile (DCT07) 479 mg/kg; both of these samples were also contaminated from the high amount of Pb and Cd and also contained low levels of Zn, Ni, Cu, and Mn as Cr are also used in pigments Cr(VI) as the brightly colored yellow pigment of PbCrO4 (Turner 2018). Ni only exceeded 1 sample in the highest quantity that is study boy (DCT08) 3.00E + 03 mg/kg; however, Pb and Cd were not detected in that sample, although other elements Zn Cr, Mn, and Cu were detected in lesser quantities. TMC results were also compared with the US, Canadian, and BIS regulations and are shown in Table 1. BIS and the US limits are identical and are shown in similar results in Table 4 and combined, which is represented in Fig. 2b. In this case, Cr was higher in numbers, as in total, 45% of samples exceeded US limits and BIS limits. The 20 out of 44 samples showed a higher Cr level concerning US and BIS. For Pb, 30% of samples exceeded, and for Cd, only 16% exceeded respected limits. Thirteen toys for Pb and 7 toys for Cd were exceeded out of 44 samples in total, and for Canadian limits, 30% of samples that contained Pb levels    (7) 45% (20) ----Total toys (n = 44) sample exceed Canadian limits 30% (13) ------were above the total or soluble limit; 13 toy samples out of 44 exceeded. For Cd soluble limits, not a single sample exceeded Canadian limits. In Fig. 2a-b, if we compared toy safety regulation limits with TMCs, more samples contain Pb and Cd from EU limits than BIS, US, and Canadian limits. However, concerning BIS and US limits, more samples contain Cr as Cr has in higher percentage shown in Fig. 2b and a lower percentage in Fig. 2a.
In other words, the number of toys samples compared with the EU limit Pb > Cd > Cr > Ni pattern was observed. Alternatively, by comparing with US and BIS limits, Cr > Pb > Cd pattern was observed for the number of samples. Figure 3 concludes a total number of toy samples that exceeded toxic levels concerning EU limits of toy safety regulations which are the most comprehensive regulation in all.
Total samples (n = 44) were analyzed for toxic contamination, purchased from different sites of Karachi which indicated that 28 samples for Pb, 20 samples for Cd, 2 samples for Cr, and only 1 sample for Ni exceeded EU limits for scraped-off toy materials, but it should be noted that all 44 samples contained some amounts of Zn, Cu, Mn, Pb, Cr, Cd, and Ni. However, their levels were not crossed the permissible limits.

Total metal concentrations in low-priced plastics toys
DCT group contains 23 toy samples and is presented in Table 2 and summarized in Table 5a. Samples were coded as DCT01-DCT23. The majority of the toy samples in the DCT group contain high contamination levels. Results were compared with different toy safety regulation limits and are summarized in Table 1. The 83% of toy samples, 19 out of 23, exceeded EU limits of scraped-off toy material for Pb. The 65% samples, 15 out of 23 toys for Cd, 9% samples, 2 out of 23 toys for Cr, and 4% of toy, 1 out of 23 toy, samples for Ni were exceeded EU limits and are summarized in Table 5a and represented in Fig. 4a. The TMCs of Zn, Mn, and Cu were also detected, but levels were within the EU limits. For Pb, the results of DCT03, DCT05, DCT07, and DCT18 were extremely higher in numbers. For Cd, DCT02, DCT11, and DCT13 were extremely high. For Cr, DCT03, and DCT07 and Ni, only DCT08 was extremely higher than allowable scrap-off material limits set by EU-Derivative. In DCT, average values for Pb 205 mg/kg, Cd 85.6 mg/kg, Ni 226 mg/kg, Cr 153 mg/kg, Zn 221 mg/kg, Mn 895 mg/kg, and Cu 136 mg/  Table 5a. Contamination levels in the DCT group were summarized as Pb > Cd > Cr > Ni pattern. On the other hand, when comparing DCT results from US and BIS toy safety limits (Table 1), it is notable that 26% of toys, 6 out of 23, were higher from US and BIS limits for Pb, 13% of toys 3 out of 23 for Cd, and 48% of toys 11 out of 23 were higher for Cr and are summarized in Table 5a and represented in Fig. 4b. Compared to EU limits with US and BIS limits results, Fig. 4a-b indicates that level of Pb and Cd level was much higher in number of toys as compared to US and BIS; however, Cr levels were high in the number of toys with respect to US and BIS and low in the number of toys with respect to EU limits as shown in Fig. 4a-b. In brief, for EU limits, Pb > Cd > Cr > Ni > other metals and for the US and BIS Cr > Pb > Cd > other metal patterns were  (7) 9% (2) -43% (9) ---% samples exceed Canadian limit 33% (7) ------% sample exceed BIS limit 33% (7) 9% (2) -43% (9) --- observed. Meanwhile, by comparing the results from the Canadian limits, a similar pattern was also observed for Pb, but Cd levels were not exceeded Canadian limits.

Total metal concentrations in low-priced plastics toys with paint or coating
DPCT group contains 21 toy samples presented in Table 3 and summarized in Table 5b. Samples were coded as DPCT01-DPCT21. The 43% of painted toy samples, 9 out of 21 for Pb, and 24% samples 5 out of 21 for Cd exceeded EU limits for scraped-off toy materials and are shown in Fig. 5a. Ni, Cr, Zn, Cu, and Mn were also detected, but levels were within the EU limits. Compared to DCT, fewer contamination levels were observed in DPCT; only Pb and Cd were exceeded in number, but not a single sample was exceeded for Cr and Ni. In the same way, no Zn, Cu, and Mn were detected above the EU limits in DPCT. One of the reasons is that Pb, Cd, Cr, Ni, and many metals are used as pigments and stabilizers in paint production (Al Kindi  The results compared with US and BIS toy safety regulation limits are shown in Table 1. It is indicated that 33% of paint-coated toys (7 out of 21) for Pb, 43% (9 out of 21) for Cr, and 9% (2 out of 21) for Cd exceeded and are represented in Fig. 5b. A similar pattern of results was observed for Pb, where 33% of Pb in DPCT exceeded Canadian limits, and 7 out of 21 toys samples exceeded Canadian limits. By comparing the number of samples from EU, BIS, US, and Canadian limits, Fig. 5a-b summarize that with respect to EU, Pb was dominant in the number of samples, but with respect to US and BIS limits, Cr was dominant in the number of samples. In brief, for EU limits, Pb > Cd > other metals, whereas for the US and BIS limit, Cr > Pb > Cd > other metal patterns were observed.

Conclusion
Forty-four samples, including 23 plastic toys and 21 plastic toys containing paint or coating samples, were selected and purchased from different local markets in Karachi, Pakistan, collecting those plastic toys which were lowpriced, designed for small children around 3-5 years old, and mostly demanded too low-income groups. All samples The number of toy sample percentages exceeds US and BIS toy safety regulations limits in the DPCT group analyzed in the present research were grouped into two categories: children's plastic toys (DCT) and children's plastic toys with paint or coating (DPCT) and tested for Pb, Cd, Ni, Zn, Cr, Cu, and Mn contaminations in term of total metal concentration (TMCs). To the author's knowledge, this is the first scientific research design in Pakistan that assesses the presence of toxic metal contamination in children's plastic toys. However, there are no Pakistan standards and quality control authority guidelines, especially on toys, to ensure children's safety in Pakistan. Therefore, obtained results were compared from other regulations available in different countries and regions. Initially, results were compared with the EU Toy Safety Regulation limits because the EU provided a more comprehensive approach and categorized toys into different groups. Pb and Cd are known as poisons, neurotoxins, and nephrotoxins, that is why both metals are the main focus of present research. Results revealed that children's toys in Karachi local markets contain high Pb, Cd, Ni, and Cr levels and minor Zn, Cu, and Mn levels. In the DCT group, 83% Pb and 65% Cd were reported. However, in the DPCT group, 43% Pb and 24% Cd levels were detected low compared to DCT. Overall, toy samples contain 64% Pb, 45% Cd, 5% Cr, and 2% Ni. Low-priced items are easily available in local markets because of the lack of regulation and restrictions. These contaminated toys are easily entering the markets. However, investigations reveal that these toys are hazardous for children's health and may cause serious health issues and damage to their brain, kidney, bones, and nervous systems; even a tiny amount in the blood may affect a child's health so badly that is why future studies could fruitfully explore this issue further in children's toys. Health risk assessment associated with these contaminated toys should be considered in future experiments.