Health risk assessment of airborne Cd, Cu, Ni and Pb for electronic waste dismantling workers in Buriram Province, Thailand

Journal of Environmental Management 252 (2019) 109601

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Research article

Health risk assessment of airborne Cd, Cu, Ni and Pb for electronic waste dismantling workers in Buriram Province, Thailand

T

Suthima Puangpraserta, Tassanee Prueksasita,b,∗ a

Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand Research Program of Municipal Solid Waste and Hazardous Waste Management, Center of Excellence on Hazardous Substance Management (HSM), Bangkok, 10330, Thailand

b

ARTICLE INFO

ABSTRACT

Keywords: Electronic waste dismantling Inhalation exposure Hazard quotient Lifetime cancer risk Cadmium Copper Nickel Lead

This study aimed to assess the risk levels of electronic waste dismantling workers in Buriram Province from exposure to cadmium (Cd), copper (Cu), nickel (Ni) and lead (Pb) via inhalation. The study area was Dang-Yai subdistrict, Baan Mai Chaiyapot district, Buriram province, Thailand. The sampling of particulate matter of less than 10 μm (PM10) was performed from 8 a.m. to 5 p.m. each day between 14th and 18th December 2015 inclusively. The PM10 was collected on a glass fiber filter using a nylon cyclone connected to a personal air pump with an air flow rate of 1.7 L/min. The samples were extracted by a microwave digester, and the metals were analyzed by inductively coupled plasma optical emission spectrometry. The average exposure concentrations of the workers to Cd, Cu, Ni and Pb were 0.0073 ± 0.0084, 0.2083 ± 0.6362, 0.3499 ± 0.3738 and 0.1297 ± 0.1746 μg/m3, respectively. The hazard quotients (HQs) of the non-carcinogenic effect of Cd, Cu and Ni, had 95% confidence intervals (CIs) of 0.067–0.167, 0.012–0.018 and 0.333–0.913, respectively. All HQs were less than 1, which indicated that there was no concern of increased non-carcinogenic health risks. The lifetime cancer risk (70 y) of the workers estimated for a 30-y exposure period showed 95% CIs of 7.55–18.6 × 10−5, 1.69–4.66 × 10−5 and 3.26–9.66 × 10−7 for Cd, Ni and Pb, respectively. Thus, the possible cancer risk levels from exposure to Cd and Ni for these workers were higher than the acceptable criterion of 10−6, which indicated that the workers have the potential to get cancer from electronic waste dismantling, due to cadmium and nickel exposure.

1. Introduction The production and consumption of electrical and electronic products has increased rapidly in Thailand and led to a large amount of waste electrical and electronic equipment (WEEE), also known as ewaste, after new products with advanced technology are released (Vassanadumrongdee and Manomaivibool, 2012). Due to a significant increase in the amount of WEEE, the complexities and various compositions of electrical and electronic products, and a lack of an appropriate waste management system, e-waste has become a critical environmental problem in many areas of Thailand. Up to now, there is currently no specific law relating to the management of e-waste and municipal hazardous waste in Thailand. Rather, relevant government agencies are required to enforce existing non-specific laws to try to ensure electronic waste is handled properly. The enforcement of laws related to electronic waste management in Thailand is summarized in Table S1 in the Supporting Information.

∗

From this situation, the Pollution Control Department (PCD) of Thailand has prepared and proposed the draft Act on the Management of WEEE and Other End-of-Life Products according to the legislative procedure. This specific law on WEEE management is based on stakeholder participation and extended producer responsibility (EPR) principles. The law emphasizes that manufacturers must design environmentally friendly products by reducing hazardous substances and making them easily recycled (Pollution Control Department, 2019b). The draft Act was approved by the cabinet in 2015 and was revised after consideration of the Council of State (Pookkasorn and Sharp, 2016). Recently, The National Legislative Assembly convened to consider in January 2019 and agreed to accept the principles of this first draft law. This law is still in the process of improvement before considering to promulgate. The PCD stated that the volume of WEEE generated in 2018 was 414,600 tons, an approximate 3.2% and 30.0% increase from 2017 (401,387 tons) and 2007 (308,845 tons), respectively, (Pollution

Corresponding author. Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand. E-mail addresses: [email protected] (S. Puangprasert), [email protected] (T. Prueksasit).

https://doi.org/10.1016/j.jenvman.2019.109601 Received 15 March 2019; Received in revised form 4 September 2019; Accepted 16 September 2019 0301-4797/ © 2019 Elsevier Ltd. All rights reserved.

Journal of Environmental Management 252 (2019) 109601

S. Puangprasert and T. Prueksasit

Control Department, 2018, 2019a). This waste mostly comes from electrical equipment, such as televisions, air conditioners, refrigerators, washing machines, telephones, CD or DVD players, and computers (Phrompak, 2012). Typically, valuable metals can be found inside electrical equipment. For example, some heavy metals can be separated and recycled from printed circuit boards (PCBs) at approximately 30% by weight (wt%), including 16 wt% copper (Cu), 3 wt% iron (Fe) and 2 wt% nickel (Ni) (Fang et al., 2013), while PCBs make up a large part of e-waste and include high concentrations of high-value metals, such as Cu, Ni, Fe and silver. The recovery of such metals is of interest from both an environmental and economic point of view (Souza et al., 2018), making the separation of valuable metals from e-waste an attractive occupation for many local people in Thailand. Although e-waste separation in Thailand is necessary, it is difficult without a complete and effective waste recycling system and, in particular, an e-waste collection system (Vassanadumrongdee and Manomaivibool, 2012). Up to now, Thai government regulations about e-waste disassembly, open burning, and disposal in landfills in rural areas are not strictly enforced. Thailand has a large number of areas for separating e-waste, especially in the northeastern provinces of the country, including Kalasin and Buriram Province. Buriram province is a new area for separating e-waste and workers make an average income of approximately 2000–2500 USD/y. Many of the residents in these regions have the motivation to change careers from agriculture to e-waste dismantling. Due to the high cost of an e-waste recycling system, most e-waste is separated by the private sector through inappropriate methods. Therefore, the development of an effective e-waste management system, including collection, recycling, treatment and disposal, in Thailand should be considered (Kanchanapiya et al., 2011). Besides separating the main valuable materials, the hazardous components in electronic waste, including cathode ray tubes (CRTs), batteries, and PCBs, are also separated by e-waste dismantling workers (Julander et al., 2014). The local people in rural areas typically use primitive methods, such as drilling, cutting and milling, and burning of the PCBs and other electrical components to separate out the precious metals. This separation method practiced in Thailand is similar to that also used in India, Vietnam and Ghana, where primitive recycling, occupational and waste management methods are adopted (Singh et al., 2018; Oguri et al., 2018; Srigboh et al., 2016; Zieliński et al., 2018). As outlined above, e-waste consists of many hazardous chemicals, such as heavy metals and volatile organic compounds, which may have an effect on both human health and the environment (Manomaivibool et al., 2009). Not only has the amount of e-waste increased, but high levels of heavy metals and metalloids are also being released into the environment, resulting in human health problems in the long run. In northeastern Thailand, Regional Environment Office 11 (Nakhon Ratchasima) and the PCD found the concentration of arsenic (As) and lead (Pb) in the soil samples taken from a dumping site of municipal solid waste mixed with the residue from e-waste dismantling at DangYai and Ban-Pao Subdistricts, Buriram Province, were 14 and 4.7 mg/kg for As and 4501 and 1812 mg/kg for Pb, respectively. These levels were over the soil quality standards for the residential and agricultural areas, which are set at 3.9 mg/kg for As and 400 mg/kg for Pb (Puengcharndum and Dankul, 2014). There is some evidence of adverse health effects in e-waste dismantling workers in some countries, where Pb exposure among separating electronic waste workers has been of concern, especially for pregnant workers. Prenatal exposure to Pb has been shown to have an effect on the developing child (Bellinger, 2013; Bellinger et al., 1987). Studies from China indicate that high levels of cadmium (Cd) in the blood can lead to impaired growth, adaptability, and behavioral issues of children who live with parents working in e-waste areas (Liu et al., 2011; Zheng et al., 2008). Likewise, some e-waste separating workers in

Agbogbloshie, Ghana were found to have Cd and Pb levels in the blood above the U.S. CDC/NIOSH reference level of 50 μg/L (67%), and urinary As levels above U.S. ATSDR value levels of 100 μg/L (39%) (Centers for Disease Control and Prevention, 2015; Agency for Toxic Substances and Disease Registry, 2007; Srigboh et al., 2016). Moreover, Cd and Ni are known carcinogens and so if workers are continuously exposed to inhalation of these metals, they can cause respiratory problems (Department of Health and Department of Disease Control, 2015). The rapidly increased consumption rates of electrical and electronic equipment in Thailand without a comprehensive take-back system being offered by manufacturers and retailers leads to the problem of a large proportion of valued WEEE being transferred from junk shops or waste dealers to local people in rural areas for further improper dismantling and separation. The increasing number of community to informal dismantling e-waste sites has become a burden to local administrative organizations, which do not have the appropriate treatment and disposal facilities for the enormous amount of invaluable parts left after the dismantling. While the specific law on WEEE management has not yet promulgated, the occupation of e-waste dismantling is rapidly expanding in many regions of Thailand due to the ability to earn a better income from it that from agriculture alone and from a lack of knowledge and understanding of the hazards to long-term health. Providing facts about the exposure levels of hazardous substances and the short- and long-term health risks to this group of people, especially understanding the negative consequences, may result in increasing their concern of self-protection and prevention of environmental degradation. However, the evidence of multiple element exposure and possible health effects of e-waste workers, as well as the current health risk situation of the local workers in Thailand has not been investigated. Buriram province has the second-largest e-waste dismantling community in Thailand, where TVs, refrigerators, washing machines, computers, VCD/DVD players, and air conditioning units are the main end-of-life appliances taken for the local people to disassembly. The process of disassembly uses a primitive method without any control and can release heavy metals in particular, Cd, Cu, Ni, and Pb into the surrounding atmosphere. These metals are mainly used in the manufacture of batteries, metal-plating and plastics, wire and sheet metal, CRTs, and PCBs, which are a common part of electrical and electronic equipment (U.S. Environmental Protection Agency, 2001b). During the dismantling, workers can be directly exposed to airborne metals into their body through breathing. Thus, this study investigated the occupational exposure to Cd, Cu, Ni, and Pb in the particulate matter of less than 10 μm size (PM10) formed by e-waste dismantling workers in Buriram province via the inhalation pathway. The metal content in the PM10 distributed in e-waste dismantling areas was evaluated and compared with the dismantling activity, and used to estimate the possible health risk of the workers from exposure to these metals in the PM10. Since there is currently no information on the release of heavy metals and the exposure level of workers in this dismantling area, the results would be useful as background data to supplement current information for the local government administrators, and potentially serve as a rough guide for other locations in Thailand and elsewhere that use similar procedures. 2. Materials and methods 2.1. Study area Thailand has e-waste dismantling communities in approximately 100 communities, but Buriram Province is a wide-spreading e-waste separation area in Thailand, and the highest density of local people working on this activity is in the Dang-Yai subdistrict, Baan Maichaiyapot district. The numerous local e-waste separation workers

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S. Puangprasert and T. Prueksasit

Fig. 1. Location of the study area in Dang-Yai subdistrict, Baan Maichaiyapot district, Buriram Province. (Source: Google map, accessed 11 February 2019)

live in four out of a total of nine villages in the Dang-Yai subdistrict, which was selected as the target area for this study (Fig. 1).

including the working time (h/d) and daily e-waste dismantling activities. The questionnaire was collected through in-person interviews not only from the six workers who contributed to the air sampling but was also extended to other 24 voluntary workers in the same village. The age of the workers ranged from 33 to 63 y old. Some of the quantifiable variables from these 30 individuals (19 males and 11 females) were used for further calculating the health risk level.

2.2. Personal air sampling and additional information collection Personal air sampling of the PM10 was performed to determine the concentration of heavy metals in the air and the exposure by inhalation of the e-waste dismantling workers, as well as the calculation of their possible health risk level. From the e-waste dismantling pattern of the workers in this community and the dismantling process dependent on the type of e-waste entry each day, sampling during the daily working period of 8 a.m.–5 p.m. was assigned to represent the worker's exposure. A total of 30 p.m.10 samples was designated to characterize the exposure probability range of the representative target worker group at a site, and was considered as the minimum sample size needed to support statistical analyses. This sample size accounted for 20% of all the accessible population (150 workers approximately) who worked for at least 5 d a week and for longer than 2 y. The samples were collected from six voluntary workers at two households for five consecutive days, during the 14th-18th December 2015. The working position of all the workers at each house during the sampling period is illustrated in Fig. S1 in the Supporting Information. Before sampling, the personal air pump was calibrated and set at a flow rate of 1.7 L/min. At each house, the sampling equipment was placed at three points near the e-waste separating area to represent the breathing zone of the worker. The flow rate of the personal pump was measured after finishing each sampling. The sample filter was then kept in a filter cassette and transported to the laboratory for further analysis. For quality control of PM10 weighing, all glass fiber filters were weighed to seven digits using a UMX2 ultra microbalance with a 0.001 mg sensitivity either before or after sampling. During each weighing, 100 mg and 200 mg standard weights were measured by the microbalance to verify its reliability. With respect to the health risk assessment, a questionnaire was selfanswered by each participant to gather information about their general personal profile, gender, age, and body weight, and occupational data,

2.3. Analysis of heavy metals in the PM10 samples The collected filter samples were microwave digested in 10 mL of 65% HNO3 for 1 h according to U.S. EPA method 3051 and then analyzed the concentration of Cd, Cu, Ni, and Pb, by inductively coupled plasma optical emission spectrometry (ICP-OES) using an iCAP6500 (Thermo Scientific) instrument. For quality control, a blank was also analyzed by the same method for calculating the limit of detection (LOD) and limit of quantification (LOQ) of the ICP-OES. The LOD of Cd, Cu, Ni, and Pb was 0.0994, 0.3157, 0.1273, 0.6292 ng/ml, respectively, and those of LOQ was 0.3315, 1.0522, 0.4244, and 2.0974 ng/mL, respectively. 2.4. Data analysis The SPSS software for Windows, version 25, was utilized for statistical analysis in this study. The difference between exposure concentrations of heavy metals for both households and all workers was compared using a t-test and one-way ANOVA. A p-value of less than 0.05 was accepted as significant in all cases, while a 95% confidence interval (CI) was used to assess the range for carcinogenic and noncarcinogenic risks. 2.5. Health risk assessment The inhalation health risk of electronic waste dismantling workers was assessed for both cancer and noncancer risk following the Environmental Protection Agency (EPA) guideline. The Risk

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concentrations of a total of 30 samples of each metal were averaged. The average concentration of Cd, Cu, Ni, and Pb in the PM10 was 0.0073 ± 0.008, 0.2083 ± 0.636, 0.2916 ± 0.636, and 0.1297 ± 0.175 μg/m3, respectively. The concentration range of Cd, Cu, Ni, and Pb that individual workers were exposed to during the 5-d sampling period are presented in Fig. 2. The variation in each metal concentration was analyzed together with the data for each day's dismantling activity. The most enriched metal was Ni, because it was in hard disks, PCBs, motors, and stainless steel, and was released through the activity of drilling, cutting, and milling e-waste during the sampling. The differences in the Cd, Cu, Ni and Pb levels between the work environment of dismantling workers in household 1 (worker No. 1–3) and household 2 (worker No. 4–6), as examined using an independent ttest, were not significantly different. The heavy metal concentrations measured in this study were lower than the time weight average (TWA) values defined by ACGIH, NIOSH, and OSHA, as shown in Table 2. The concentrations of Cd, Cu, Ni, and Pb were also comparable to the permissible exposure limit provided by Thailand labor law, according to the Notification of the Ministry of Interior regarding working safety in respect to environmental conditions. However, the concentrations were lower than Thailand's exposure limits. When compared with previous studies (Table 3), the e-waste being dismantled in the working area in this study was similar to that found at Hung Yen province, north Vietnam. The concentration range of Cd, Cu, Ni, and Pb exposed to the workers in this study was in the same range as in the Vietnamese site (Oguri et al., 2018). At a recycling plant involving TV-sets, computers, electronic tools, toys, and small and large household appliances in Sweden, the workers' exposure level was found to span over a very wide range (Julander et al., 2014). Considering the specific recycling of waste PCBs in a closed workshop at an industryscale in China, the Cd concentration was about four-fold lower than the average concentration observed in the present study, whereas the average Ni and Pb levels were approximately four-fold higher (Xue et al., 2012). In addition to the Cd, Cu, Ni, and Pb levels in the PM10, they were also found in the PM2.5 collected from a manual dismantling workshop processing heating integrated circuit boards, and burning metal and plastic scraps at an e-waste recycling site in southeast China (Deng et al., 2006). It should be pointed out that dismantling e-waste in either a recycling plant or in a local community can contribute a significant amount of heavy metals, such as Cd, Cu, Ni, and Pb, to the environment including in the air as PM10 and PM2.5. This is supported by the study of Julander et al. (2014), which found significantly higher concentrations of Cd, Cu, and Pb for workers in a dismantling process compared to those of working outdoors.

Table 1 Description of the variables used in the health risk calculations. Source: (a) U.S. Environmental Protection Agency, 2011; (b) U.S. Environmental Protection Agency, 2001a; (c) U.S. Environmental Protection Agency, 2001b; (d) Office of Environmental Health Hazard Assessment, 2009). Variable C CF IR ET EF

Definition

Unit

Source 3

μg/m mg/μg m3/h h/d d/y

Sampling in this study – 2.1 for the average adulta Questionnaire (7.25 ± 1.06) 350b

ED BW

Concentration Conversion factor Inhalation rate Exposure time Exposure frequency Exposure duration Body weight

y kg

AT

Average time

RfC

Reference concentration

hour (noncancer) d (cancer) mg/m3

30b Questionnaire (59.05 ± 12.8 for male and 55.64 ± 8.1 for female) ED × 365 × 24 h for non-cancer 70 × 365 d for cancer

CSF

Cancer slope factor

(mg/kg. d)−1

2.00 × 10−5 for Cdc 2.00 × 10−3 for Cuc 1.50 × 10−4 for Nic 1.50 × 10−2 for Cdd 4.20 × 10−2 for Cud 9.10 × 10−1 for Nid

Assessment Guidance for Superfund (RAGS) Volume I: Human Health Evaluation Manual was used for the risk assessment (U.S. Environmental Protection Agency, 2009). The exposure concentration (EC) (μg/m3) (Eq. (1)) and the Chronic Daily Intake (CDI) (mg/kg.day) (Eq. (2)) were estimated for the noncancer and cancer risk, respectively, with all variables in the equations explained in Table 1. The values of the inhalation rate (IR), exposure frequency (EF), exposure duration (ED), and averaging time (AT) in Eqs. (1) and (2) were as recommended by the EPA. Whilst the exposure time (ET) and body weight were derived from the questionnaire and are shown in Table 1. EC = C × CF × ET × EF × ED / AT

(1)

CDI = (C × CF × IR × ET × EF × ED) / (BW × AT)

(2)

The Hazard Quotient (HQ) was used to evaluate the noncancer risk, as expressed in Eq. (3). The inhalation reference concentration (RfC) and cancer slope factor of Cd, Pb, and Ni were retrieved from the database of the EPA and the Office of Environmental Health Hazard Assessment (Office of Environmental Health Hazard Assessment, 2009), as shown in Table 1. If the HQ was less than or equal to 1, then the noncarcinogenic effects are considered to not be of concern, whereas if the HQ was greater than 1, then adverse health effects may be possible. For carcinogenic metals, the risk characterization and interpretation of lifetime cancer risk were determined using Eq. (4), indicating that any value more than 10−6 represented a potential carcinogenic effect of concern, whereas values equal to or less than 10−6 were considered as not of significant concern. HQ = EC / RfC

(3)

Cancer risk = CDI × CSF

(4)

3.2. Mass content of Cd, Cu, Ni and Pb in PM10 distributed during e-waste dismantling The Cd, Cu, Ni, and Pb contents in the air (including as PM10) during e-waste dismantling in two households are presented in Fig. 3. The metal content is defined as the mass of heavy metals contained in the PM10 that was released from dismantling e-waste and to which the workers were possibly exposed. The metal content values in the PM10 for Cd, Cu, Ni, and Pb were 0.1159 ± 0.125, 1.0852 ± 1.465, 4.5614 ± 4.874, and 1.7588 ± 1.240 μg/g, respectively. All four metal content values in the PM10 showed the same trend as that presented in the personal air concentration. The Ni content in PM10 was the highest, which was similar to the concentration in the air. This may support that almost all activities involved with dismantling, cutting, and drilling PCBs, motors, and hard discs contributed a high amount of Ni. Workers No. 1–3 from household 1 were exposed to higher amounts of the airborne metals than those from household 2. This might be caused by the difference in the amount and types of e-waste dismantled

3. Results and discussion 3.1. Personal exposure concentrations of Cd, Cu, Ni and Pb in PM10 The exposure concentration demonstrated which heavy metals were released into the air and exposed to the workers. The exposure

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Fig. 2. Exposure concentrations of (a) Cd, (b) Cu, (c) Ni, and (d) Pb in PM10 for the six e-waste dismantling workers at households 1 and 2. Data are shown as the range of 95%CI and median. Table 2 Comparison of heavy metal concentrations with occupational limits. Source: (a) Department of Labour Protection and Welfare, 2017); (b) Agency for Toxic Substances and Disease Registry, 2012; (c) Agency for Toxic Substances and Disease Registry, 2004; (d) Agency for Toxic Substances and Disease Registry, 2005; (e) Agency for Toxic Substances and Disease Registry, 2019. Heavy metal

Cd Cu Ni Pb

Concentration (μg/m3)

TWA1 (μg/m3)

Max

Min

Average

TLV2 Thai Labor Lawa

TLV2 ACGIH

REL3 NIOSH

PEL4 OSHA

0.0448 3.5672 1.4735 1.0068

0.0008 0.0252 0.0040 0.0368

0.0073 0.2083 0.2960 0.1297

5 – 1000 50

10b 1000c 100d 50e

9000b 1000c 15d 50e

5b 1000c 1000d 500e

Remark: 1TWA = time weight average, 2TLV = threshold limit value, 3REL = recommended exposure limit, and 4PEL = permission exposure limit.

by the workers, which were dependent on each round of e-waste received from the junkshops. Interestingly, some extra high values (outliers) of Cd, Cu, and Pb that were outside of the detectable range were observed. When considering the daily e-waste dismantling activities record, the values for Cd of 0.5598 and 0.0448 mg/g from worker No. 2 and 3, respectively, were involved with opening a small metallic pot containing refrigerants with fire heating on Day 4. The maximum Cu value (6.5317 mg/g) detected for worker No. 2 (Day 4) was caused by burning wires at an open dumping site. Whilst separating the CRT monitor and PCBs could have resulted in the relatively high Pb contents found at 4.1990,

5.3293, 3.5953 and 5.2227 mg/g for worker No. 1 (Day 3), 2 (Day 4), 3 (Day 5) and 5 (Day 3), respectively. For Ni, the two outliers at 6.2642 and 6.6347 mg/g for worker No. 4 and 5, respectively, were still within the detectable range of the other four workers. The metal contents found in this study were compared with previous studies, as summarized in Table 4. The Cd content in the air at the compiled mixed e-waste dismantling sites in this study was higher than that at a factory recycling only PCBs in China (Xue et al., 2012; Zhou et al., 2014) and about 30-fold higher than the level measured in the surface dust at a manual dismantling workshop of an e-waste recycling plant in India (Singh et al., 2018). However, a similar metal content 5

Journal of Environmental Management 252 (2019) 109601

Deng et al. (2006) 0.329

3.3. The mass contribution of Cd, Cu, Ni and Pb in PM10 in association with e-waste dismantling

0.126 0.00726 Heating integrated circuit boards to soften, burning metal and plastic scraps

The average mass content of all four metals in the PM10 that each worker was exposed to was calculated as a percentage contribution, and is shown in Fig. 4. The average mass contribution of all the metals that the workers were exposed to was similar. The highest percent contribution in the PM10 was Ni, which accounted for approximately 30–58%, followed by Cu and Pb at approximately 20–34%, while Cd represented less than 3%. From the actual observation during the sampling, as presented in Fig. 5, the distribution of heavy metals in the air that the workers inhaled each day was related to their activities during the dismantling process. From Fig. S1, worker No. 4, 5 and 6 at household No. 2 completed almost the same e-waste separation activity throughout the 5-d sampling period, resulting in similar metal contents during days 1–5 (D1–5). The activity of the workers in this household started from worker No. 4 cutting the outer plastic of WEEE, then worker No. 5 drilled the small parts and finally worker No. 6 separated and collected the valuable metals in boxes or big bags for selling later. Workers in household No. 1 had different activities from those observed in household No. 2 on some days (Fig. S1), for example, they performed wire burning and drilling CRTs at the open dumping site and opened a compressor with fire heating. Considering the activity data record of the workers and the mass contribution of the metals, the activities that were the possible main source of each heavy metal are summarized in Table 5. The process of cutting, drilling, and milling electronic parts, such as hard disks, PCBs, and motors, released Ni. Milling TV monitors and CRTs could release Pb, and the mechanical processes and burning wires caused emission of Cu. Small amounts of Cd came from opening a small metallic pot containing refrigerants with fire heating. Based on the proportion of the four heavy metals found in this study, the workers had the opportunity to be affected by inhalation into the body, especially for Ni, Cu, and Pb, which are the most common. Chronic inhalation exposure to Ni in humans results in respiratory effects, including asthma as a direct effect and an increased risk of chronic respiratory tract infections. Respiratory irritation can also be caused by inhalation exposure to Cu, as well as anorexia, nausea, and occasional diarrhea have also been reported after exposure to high concentrations of airborne Cu. For Pb, the primary effect of chronic exposure is the nervous system, in which the severity depends on the blood Pb levels, and other effects include blood pressure and kidney

ND = Not detectable, - means not reported.

E-waste recycling site in southeast China

E-waste processing area in the vicinity of the family house (ambient air sampled in the main living area or bedroom of each house) Roof of a three-story building involved in e-waste recycling. Manual dismantling workshop (PM2.5)

Manual dismantling workshop (PM10)

Printed circuit boards (PCBs) recycling factory, China Bui Dau village, Vietnam

range to this study was reported in a recycling factory that had a manual dismantling workshop of both PCBs and CRTs using similar methods as the workers in this study did, and most of the activity was dismantling waste televisions (Fang et al., 2013). The Cu content found in this study was also close to the result observed in India, where the workers operated with a compiled mixed ewaste as well, but was lower than in the other studies. This might be because Cu is the main component of electrical wires and, especially for very small wires, cannot be easily separated and so the workers collected it until they had enough to burn at a site away from the house. Thus, the workers would be exposed to a high Cu content in the days they performed wire burning, as reflected in the Cu values of 5.8057 (worker No.1) and 6.5317 mg/g (outlier value for worker No.2) shown in Fig. 3. The average Pb content was within the same range of Pb contents found at a PCB recycling factory but less than that of CRT recycling factory in a particular mechanical process in China. The automatic PCBs production process within a closed system in China and the manual dismantling in an e-waste recycling site in India released an approximately 5- and 2-fold lower average Pb content, respectively, than that of the present study. Interestingly, a relatively high content of Ni in PM10 was observed in this study and this was higher than those found in the other studies.

0.00719

Oguri et al. (2018) 0.034–0.048 0.0064–0.042 0.0013–0.0021

–

Xue et al. (2012) 0.56 0.88 0.016

–

Julander et al. (2014) 0.011–130 0.085–59

Manual dismantling of e-waste, including TV-sets and computers (flat and Cathode ray tubes (CRTs) screens), electronic tools, toys, and small and large household appliances (not including freezers and fridges) Automatic recycling line for waste PCBs in a closed industryscale workshop Dismantling of power cables and circuit boards, and sorting of metal and plastic electrical parts Personal breathing zone air sampled from recycling workers (Inhalable PM)

0.0011–11

0.0089–15

0.0368–1.0068 ND–1.4735 0.0252–3.5672 0.0008–0.0448 Compiled mixed e-waste Manual dismantling workshop (PM10)

Cu Cd

E-waste dismantling sites in Thailand E-waste recycling plant in Sweden

Working conditions and dominant e-waste being handled Characteristic area Location

Table 3 Comparison of the personal exposure concentration of heavy metals in this study with previous studies.

Metals concentration (μg/m3)

Ni

Pb

This study

References

S. Puangprasert and T. Prueksasit

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Fig. 3. Mass content of (a) Cd, (b) Cu, (c)Ni, and (d) Pb in the PM10 that the six e-waste dismantling workers were potentially exposed to at households 1 and 2. Data are shown as the range of 95%CI and median. Table 4 Comparison of the metal contents in this study with previous studies. Location

E-waste dismantling sites in Thailand Cathode ray tubes (CRT) recycling factory, China Printed circuit boards (PCBs) recycling factory, China PCBs manufacturing plant, China

E-waste recycling sites in India

Characteristic area

Manual dismantling workshop 1) Manual dismantling workshop 2) Mechanical workshop Manual dismantling workshop 1) Raw material warehouse 2) Cutting process 3) Drilling process 4) Milling process Manual dismantling workshop (Surface dust Sample)

Working conditions and dominant ewaste being handled

Metals content (mg/g) Cd

Cu

Ni

Pb

Compile mixed e-waste PCBs and CRTs of waste televisions

0.1159 0.398 0.108 0.079

1.8052 31.80 27.76 4.35

4.5764 0.459 0.472 –

1.7588 2.043 12.34 2.77

This study Fang et al. (2013)

0.056 0.036 0.023 0.045 0.004

7.88 18.23 6.54 56.31 1.564

0.20 0.18 0.25 0.13 0.089

0.35 0.26 0.42 0.40 0.819

Zhou et al. (2014)

Automatic recycling line for waste PCBs in a closed industry-scale workshop Automatic workshop of PCBs production processes Unspecified types of e-waste

function, interference with vitamin D metabolism, and reproductive effects. Although there was a small amount of Cd, its serious health effects, including abnormal kidney function, bronchitis, and emphysema, cannot be ignored. Moreover, Ni, Cd, and Pb have been classified by EPA as Class A (known human carcinogens), Group B1, and Group B2 (probable human carcinogen), respectively, (U.S. Environmental Protection Agency, 2001b). As the dismantling activity takes place adjacent to their own house

References

Xue et al. (2012)

Singh et al. (2018)

(Fig. S1), the possible health effects will not only occur to the workers but might also affect the children living together and neighbors who live nearby (see Fig. 1) as well. 3.4. Health risk assessment of the workers exposed to Cd, Cu, Ni and Pb in PM10 via inhalation According to U.S. EPA guidelines, the exposure of non-carcinogenic 7

Journal of Environmental Management 252 (2019) 109601

S. Puangprasert and T. Prueksasit

over the acceptable level, which indicated that some workers had the possibility of a high exposure to Ni because they were often involved with the processes of cutting, drilling, and milling hard disks, PCBs, and motors. The 95% CI for the lifetime cancer risk of Cd (7.55–18.6 × 10−5) was higher than Ni (1.69–4.66 × 10−5) and Pb (3.26–9.66 × 10−7), respectively. The average and 95% CI of the total lifetime cancer risk via inhalation exposure were 1.63 × 10−4 and 1.06–2.19 × 10−4, respectively, which exceeded the acceptable criteria (10−6) indicating that the workers may have a chance of getting cancer from this occupation. Considering the individual carcinogenic risk level, most of the 95% CI for Cd and Ni were not in the acceptable range, especially for Cd. Interestingly, even though Cd was found at a low proportion of the metals the workers were exposed to (< 3% of total metal content), they could have a higher potential of cancer risk from Cd than from the other metals. The lifetime cancer risk of the workers in this study site was approximately two-to five-magnitudes higher than those examined in China and India (Table 8). When considering the risk assessment results of the workers’ exposure to heavy metals for non-carcinogenic (Cd, Cu, and Ni) and carcinogenic (Cd, Ni, and Pb) effects, it was evident that workers were exposed to a potential risk of both non-carcinogenic and carcinogenic diseases. Therefore, finding ways to reduce the risk of exposure to such substances is very important. The formula for calculating the risk (Risk = Hazard × Exposure) is based upon the two important factors of (1) the hazard of the metals, which is very difficult to control, and (2) the exposure, which is then the key factor to reduce the risk especially for long-term latent diseases, such as cancer. The variables in the exposure include the exposure concentration, time, and duration and were used in Eq. (2) for calculating the CDI in the step of exposure assessment, the reduction of any of which could reduce the risk. In this case, reducing the working time (ED) from 30 y to 5 y and the ET from 8 h/d to 4 h/d (Table 9) reduced the risk level, but it still exceeds the acceptable value (10−6). Thus, there is a need to avoid exposure to high concentrations of the metals, such as by advising the

Fig. 4. The average mass contribution of Cd, Cu, Ni, and Pb in PM10 obtained from the individual worker's exposure level. Data are shown as %wt.

substances was evaluated for the workers over an average exposure duration of 30 y as well as the lifetime cancer risk of the workers exposed to Cd, Ni, and Pb was investigated assuming a lifespan of 70 y and working for 30 y (U.S. Environmental Protection Agency, 2001a). The results of the exposure concentration, 95% CI of non-carcinogenic risk (HQs and HI), CDI, and 95% CI of lifetime cancer risk are shown in Tables 6 and 7 respectively. For inhalation, the HQ of Ni (0.3334–0.9126) was the highest, followed by Cd (0.0670–0.1675) and Cu (0.0118–0.0177). The average HI via inhalation exposure was 0.7734. Therefore, both the HQ and HI for Cd, Cu, and Ni were less than 1, suggesting that the non-carcinogenic effect was negligible. This is in accordance with the risk level of the workers in the CRT and PCB recycling factory in China, and e-waste recycling sites in India (Table 8). Nevertheless, 20% of the individual HQ values for Ni (6 in 30 samples with a range of exposure concentration of 0.4853–1.4735 μg/m3) were

Fig. 5. The daily mass contribution of Cd, Cu, Ni, and Pb in the PM10 exposed to the workers at (a) household 1 and (b) household 2. Data are shown as %wt. (Remark: W1D1 means worker at household 1 on day 1 of the sampled period).

8

Journal of Environmental Management 252 (2019) 109601

S. Puangprasert and T. Prueksasit

Table 5 Predominant metal content in association with the e-waste dismantling processes. Heavy metal

Product/activity

Reference worker and activity date

Cd Cu Ni Pb

Opening a small metallic pot containing refrigerants with a fire heating Burning, cutting, drilling and milling wires Cutting, drilling, and milling hard disk, printed circuit boards (PCBs), motors Milling TV monitor and Cathode ray tubes (CRT)

W3D4, W6D5 W1D4 W1D1–D2, W2D1–D2, W3D1–D2, W4D1–D5, W5D1–D5, W6D1–D4 W1D3, W1D5, W2D3, W2D5, W3D3, W3D5

(Remark: W1D1 means worker at household 1 on day 1 of the sampling period). Table 6 Non-carcinogenic risk level for the e-waste dismantling workers. Metal

Exposure concentration (μg/m3)

RfC1 (mg/m3)

Average

95% CI of HQ2

%Unacceptable risk

Cd Cu Ni Hazard index (HI3)

0.0003–0.0143 0.0081–1.1402 0.0013–0.4710

2.0 × 10−5 2.0 × 10−3 1.5 × 10−4

0.1172 0.0147 0.6230 0.7734

0.0670–0.1675 0.0118–0.0177 0.3334–0.9126 0.4800–1.0667

0 0 20

Remark: 1RfC = reference concentration, 1HQ = hazard quotient, 3HI = hazard index. Table 7 Lifetime cancer risk of the electronic waste dismantling workers. Metal

CDI1 (mg/kg.d)

CSF2 (mg/kg.d)−1

Average

95% CI of cancer risk

%Unacceptable risk

Cd Ni Pb Total lifetime cancer

1.01–52.3 × 10−7 4.67–1830 × 10−7 4.57–118 × 10−6 risk

1.52 × 102 4.20 × 10−2 9.10 × 10−1

1.30 × 10−4 3.17 × 10−5 6.46 × 10−7 1.63 × 10−4

7.55–18.6 × 10−5 1.69–4.66 × 10−5 3.26–9.66 × 10−7 1.06–2.19 × 10−4

100 80 10

Remark: 1CDI = chronic daily intake, 2CSF = cancer slope factor.

workers to wear an effective mask to prevent breathing of the respirable dust and wearing personal protective equipment during dismantling WEEE, including ventilation fan units. This suggestion corresponds to the management strategy proposed by Zhou et al. (2014), that wearing a mask during working hours can obviously reduce the harmful health impacts of PM10 and PM2.5. A mask of a suitable type that can protect the wearer from small particles and vapors, that is hence suitable for working and meets the 42CFR Part 84 standard, as approved by the NIOSH and the Department of Health and Human Services (DHHS), such as the R-series or N-series with a filter efficiency of not less than 95% should be recommended. The results revealed that such devices could help reduce the risk level up to 95%, and so were mostly within the acceptable criteria. This research represents a starting point for verifying the health risks arising from the occupation of e-waste separation. However, the health risk level obtained in this study might be underestimated due to that it was focused on a single route of exposure (inhalation) and restricted to four selective metals (Cd, Cu, Ni, and Pb). Thus, further studies should be performed with a wide range of chemicals, including other heavy metals/metalloids as well as other highly toxic organic substances, such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls, in addition to other routes of exposure, such as through dermal absorption and ingestion. Moreover, other sources of exposure to these and other heavy metal/metalloid sources, such as use of contaminated ground water for drinking should be taken into account. Should these workers intend to continue this occupation for a long time, the potential short- and long-term effects on their body might not be negligible. Accordingly, it is important to extend this study and health risk assessment using suitable biomarkers of exposure, that is the products of metabolism corresponding to the chemical which the workers are exposed to. Biomarkers of exposure can be measured in the urine, blood, saliva, nail and/or hair, resulting in a more clear evidence of the exposure level and likely effect. With respect to the risk of adverse effects on the e-waste dismantling

workers' health, the preventive measure of reducing inhalation exposure to heavy metals should be introduced. Initially, they should be encouraged to aware of the dangers of their work and the potential shortand long-term effects on the body. The potential for negative consequences should be conveyed through a risk communication process so that all stakeholders, i.e., workers, subdistrict and local administration organizations, district and provincial public health, and government agencies, perceive the health risks involved. Not only the measure of selfprotection from dismantling work, but the relevant agencies should also emphasize the community to participate in corporate social responsibility for preventing the deterioration of air quality, which would lead to a better overall local environmental quality. In the event that there is no regulation governing this occupation, a health surveillance program of the workers themselves is considered necessary, and public health agencies can extend the long-term health database of the community for educating people in other areas who anticipate earning the benefit over the risk from this occupation. 4. Conclusions The e-waste disassembly activity of the local community in Buriram Province could cause PM10 contamination with Cd, Cu, Ni and Pb in the air surrounding the working area. The highest level was found for Ni, followed by Cu, Pb, and Cd. Cutting, drilling, and milling hard disks, PCBs, and motors, led to Ni in the PM10, while those activities on TV monitors and CRTs released Pb. Detection of Cu was evident upon the burning of wires, while opening a metallic refrigerants pot with fire heating released small amounts of Cd. Although the average non-carcinogenic risk of the workers exposure to Cd, Cu, and Ni were not over the acceptable criteria (HI < 1), 20% of the individuals involved with the processes of cutting, drilling, and milling hard disks, PCBs, and motors were found to have a HQ from exposure to Ni over the acceptable level. The lifetime cancer risk exceeded the acceptable criteria (10−6), in particular for Cd and Ni exposure. 9

Journal of Environmental Management 252 (2019) 109601

Singh et al. (2018)

Reduction value

% Risk reduction

95% CI of cancer risk

ET1 ED2 C3

4 h/d 5y 95% decreasing (i.e., 0.05 × C)

50 83 95

8.44–23.3 × 10−6 2.81–7.77 × 10−6 8.44–23.3 × 10−7

4.14 × 10−4

Acknowledgments This study was financially supported by the grant of the Research Program of Municipal Solid Waste and Hazardous Waste Management, Center of Excellence on Hazardous Substance Management (HSM), the S&T Postgraduate Education and Research Development Office (PERDO), the Office of Higher Education Commission (OHEC), Thailand, HSM-PJ-CT-17-02. The heavy metal analysis was greatly helped and supported by Associate Professor Apichat Imyim, Department of Chemistry, Chulalongkorn University, Thailand. Finally, sincere gratitude is extended to all local authorities organizations and all voluntary workers participated in this research.

8.94 × 10 9.04 × 10−7 3.95 × 10−7 4.65 × 10−7 7.68 × 10−5

–

Xue et al. (2012) Zhou et al. (2014) –

Exposure factor

Remark: 1ET = exposure time, 2ED = exposure duration, 3C = concentration.

−7

–

3.91 × 10−5

References

0.00009

0.00009

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E-waste recycling sites in India

Printed circuit boards (PCBs) recycling factory, China PCBs recycling factory, China

Supplementary data to this article can be found online at https:// doi.org/10.1016/j.jenvman.2019.109601.

0.0002

3.83 × 10 – –

–

1.61 × 10−9 0.000006 0.000002

–

−7

Fang et al. (2013)

6.46 × 10−7 (3.26–9.66 × 10−7) 9.93 × 10−7 5.61 × 10−6 3.18 × 10 (1.69–4.66 × 10−5) 6.56 × 10−6 9.43 × 10−6

1.30 × 10 (7.55–18.6 × 10−5 2.03 × 10−6 1.52 × 10−6

Manual dismantling workshop Manual dismantling workshop Mechanical workshop Manual dismantling workshop Warehouse Cutting process Drilling process Milling process Manual dismantling workshop (Surface dust sample) E-waste dismantling community, Thailand Cathode ray tubes (CRT) recycling factory, China

0.1172 (0.0131–0.7155) 0.00001 0.000003

0.0147 (0.0040–0.5701) 0.000003 0.00001

0.6230 (0.0100–3.1400) 0.000007 0.000005

−4

Cu Cd

Area

Non-carcinogenic metals (HQ)

Table 9 Unacceptable cancer risk reduction scenarios.

Appendix A. Supplementary data

Location

Table 8 Comparison of the health risk assessment via inhalation exposure with previous studies.

Ni

Carcinogenic metals Cancer risk

−5

Pb Ni Cd

This study

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Srigboh, R.K., Basu, N., Stephens, J., Asampong, E., Perkins, M., Neitzel, R.L., Fobil, J., 2016. Multiple elemental exposures amongst workers at the Agbogbloshie electronic waste (e-waste) site in Ghana. Chemosphere 164, 68–74. U.S. Environmental Protection Agency, 2001a. Appendix C risk characterization equations. January 2001. https://archive.epa.gov/epawaste/hazard/tsd/td/web/pdf/ 05hhrapapc.pdf, Accessed date: 5 March 2019. U.S. Environmental Protection Agency, 2001b. Appendix Q human health benchmarks. January 2001. https://archive.epa.gov/epawaste/hazard/web/pdf/appndxq-w.pdf, Accessed date: 20 July 2019. U.S. Environmental Protection Agency, 2009. Risk Assessment Guidance for Superfund Volume I: Human Health Evaluation Manual (Part F) Final. Office of Superfund Remediation and Technology Innovation. Environmental Protection Agency, Washington, D.C. U.S. Environmental Protection Agency, 2011. Exposure Factors Handbook 2011 Edition. Washington, D.C. Vassanadumrongdee, S., Manomaivibool, P., 2012. (January 2012). Electronic Waste: a New Problem in High Technology Society, vol. 1. E-waste Management, pp. 1–7. (In Thai). http://www.hsm.chula.ac.th/research/paper/e-wate_management/e-wate_ management1.pdf, Accessed date: 5 March 2019. Xue, M., Yang, Y., Ruan, J., Xu, Z., 2012. Assessment of Noise and heavy metals (Cr, Cu, Cd, Pb) in the ambience of the production line for recycling waste printed circuit boards. Environ. Sci. Technol. 46, 494–499. Zheng, L., Wu, K., Li, Y., Qi, Z., Han, D., Zhang, B., Gu, C., Chen, G., Liu, J., Chen, S., Xu, X., Huo, X., 2008. Blood lead and cadmium levels and relevant factors among children from an e-waste recycling town in China. Environ. Res. 108, 15–20. Zhou, P., Guo, J., Zhou, X., Zhang, W., Liu, L., Lui, Y., Lin, K., 2014. PM2.5, PM10 and health risk assessment of heavy metals in a typical printed circuit boards manufacturing workshop. J. Environ. Sci. 26, 2019–2026. Zieliński, E., Wielgus, A., Sas, K., Zukow, W., 2018. Health hazards resulting from the WEEE combustion at illegal e-waste yards in developing countries on the example of Agbogbloshie. J Educ. Health and Sport 8, 363–369.

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