RESEARCH ARTICLE
Assessment of the health risk related to exposure to ultrafine, fine,
and total particulates and metals in a metal finishing plant
Burcu Onat1 &Nevran Sultan Çalışkan1&Ülkü Alver Şahin1&Burcu Uzun1 Received: 11 February 2019 / Accepted: 28 October 2019
# Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract
The materials and byproducts of the processes used in the metal finishing industry are released as particle contaminants into the air in the workplace. The present study aimed to determine the concentrations and size distributions of these particles and of elements chromium, nickel, copper, manganese, cobalt, and lead (Cr, Ni, Cu, Mn, Co, and Pb, respectively) in a metal finishing industry and evaluate their potential health risks. Particles that are airborne from the dipping baths in the plant were sampled using a Sioutas cascade impactor at five different size fractions (PM>2.5, PM1.0–2.5, PM0.5–1.0, PM0.25–0.5, PM<0.25) and gravimetric analyses were conducted on the sampled filters. The GF-AAS 600 graphite atomic absorption spectrophotometer (PerkinElmer Corporation, Waltham, MA, USA) was used to analyze the elements and the method of USEPA was used to assess the health risk. The ratio of fine particles (PM2.5) to total suspended particles (TSPs) was 0.6. We observed that 50% of TSPs were composed of PM1.0and that 68–88% of the metals were found in the fine particle fractions. Pb, Cr, and Mn were significantly positively correlated in the PM1.0fraction, and the highest linear relationship was found between Pb and Cr (r = 0.85, p < 0.01). The total hazard quotient (HQ) for PM2.5was 1.43, which is higher than the acceptable limit of 1.0. The excess lifetime cancer risk (ELCR) for hexavalent chromium (Cr[VI]) in PM2.5was 6.09 × 10-5for female workers and 6.54 × 10-5for male workers, which are higher than the acceptable limit of 1.0 × 10-6, while total ELCRs for female and male workers were 6.21 × 10-5and 6.21 × 10-5, respectively. The lifetime cancer risk associated with Cr(VI) in Cr electroplating plants should be taken into consideration as a significant health risk for the workers.
Keywords Metal finishing . Electroplating . Chromium . Exposure . Particle size distribution . Health risk
Introduction
The materials and byproducts of the processes used in the metal finishing industry are released as contaminants into the air at the workplace. The metal finishing industry contains
various processes, such as degreasing, plating (e.g., electroplating, chromium [Cr] plating, anodic coating), cleaning metals with acids and alkalis, rinsing, coloring, and fixing. An electroplating process uses an electrode to be plated (substrate or cathode), a second electrode to complete the cir-cuit (anode), an electrolyte containing the metal ions to be deposited, and a direct current power source (U.S. Environmental Protection Agency [USEPA], 2016). During the electroplating process, hydrogen and oxygen gases form and evolve as small gas bubbles at the metal surfaces of the anode and cathode electrodes. When these small bubbles rise to the bath surface and burst, particles are formed (Pilat and Pegnam2006). The process of Cr electroplating or anodic coating uses many toxic, corrosive, and irritating chemicals at high concentrations in the dipping baths (Roff et al.2004). High amounts of particles are generated from the dipping baths and the generation of airborne particles depends on the concurrent efficiency of the process, metallic ion concentra-tion, density, bath additives, and temperature. Exposure to Responsible editor: Philippe Garrigues
* Burcu Onat
[email protected] Nevran Sultan Çalışkan [email protected] Ülkü AlverŞahin [email protected] Burcu Uzun
1 Faculty of Engineering, Environmental Engineering Department,
Istanbul University-Cerrahpasa, 34320 Istanbul, Avcılar, Turkey
Published online: 10 December 2019
aerosols from the dipping baths is associated with respiratory diseases, dermatitis (National Institute for Occupational Safety and Health [NIOSH]1998), and various types of can-cer (Hengstler et al. 2003). The workers in the Cr and electroplating industry face health problems such as nasal sep-tum lesions (Lin et al.1994; Kuo et al.1997), higher nickel (Ni) levels in plasma and urine (Tola et al.1979), higher Cr levels in urine (Wu et al.2001) and erythrocytes (Zhang et al. 2011), deterioration of lung function (Kuo et al.1997; Caglieri et al.2005), and asthma (Bright et al.1997). The type of lung disease caused by exposure to these metals depends on the dose and its physicochemical form (Nemery 1990). In an electroplating plant, exposure to an inhalable aerosol fraction of the metals is higher than that to the total aerosol fraction (Tsai et al.1996). Thirty-three percent of fine particles or “particulate matter” with a diameter < 2.5 μm (PM2.5) are deposited in the pulmonary region and 17% in tracheobron-chial region (Rajput et al.2018), and this industry-sourced PM2.5has high oxidative potential (Borlaza et al.2018). The amounts and concentrations of these particles and the surface area are significantly higher in the metal industries, but con-centrations of mass are lower (Pavloska et al.2016). Aerosol samples from the metal industry contained toxic metal parti-cles (Almeida et al.2010; Pavloska et al.2016). Aerosols of soluble and particulate forms of the metals are present in a metal finishing workplace (Gordon2004), and electroplating workers have high exposure to these airborne pollutants be-cause 77% of the elements are contained in these particles (Menezes et al. 2002). Both trivalent Cr (Cr(III)) and hexavalent Cr (Cr(VI)) are used for Cr plating, and workers are exposed to this metal just by breathing the air within the workplace. Although Cr(III) has low toxicity, Cr(VI) has been the highest concern for human health related to both acute and chronic exposures because it causes adverse health effects (USEPA2016).
There are very few studies on the characteristics and size distribution of aerosols emitted from electroplating processes. In these studies, cascade impactors (Koropchak and Roychowdhury1990; Hsien-Wen et al. 1997) and optical methods (Bonin et al.1995; Bonin and Holve1996) were used to determine size distribution. Occupational exposure to the particles was determined by measuring respirable, inhalable, and total particle concentrations (Pilat and Pegnam2006; Hsien et al. 1997; Tsai et al.1996). Menezes et al. (2002) used biomonitoring to investigate the health effects of Cr in an electroplating plant. The exposure of total Cr, Cr(VI) (Pilat and Pegnam 2006; Hsien et al. 1997), and Ni (Tsai et al. 1996) was investigated, but the characteristics of the different size fractions of the particles has not been explored.
In Turkey, several studies have been conducted on PM10, PM2.5, and respirable dust, and on the concentrations of vol-atile organic compounds (VOCs) (Şahin and Kurutaş2012) and trace elements (Bağlarbunarı2010) in the workplaces of
some metal industries, but there is a lack of knowledge on the size distribution, metal composition, and health risks associ-ated with aerosols creassoci-ated from the electroplating process. Further research on particle exposure parameters are needed to evaluate the health risk and reduce the uncertainties associ-ated with risk calculations (Mousavian et al.2017). The aim of this study was to determine the size distribution and element concentrations of metal particles in Cr electroplating and an-odic coating and determine the occupational health risk of toxic elements in an electroplating workplace.
Material and methods
Metal finishing industry
This study was conducted in a metal finishing plant located within the Kurtköy organized industrial zone in Pendik, Istanbul, Turkey. The industry has been operating for 23 years and plates approximately 5 million metal pieces per year. Cr electroplating and anodizing are used to make products that are resistant to heat, wear, and tear. Two types of Cr plating— Cr(III) and Cr(VI)—are used in the plant. The metal pieces are lubricated, rinsed, neutralized, plated, colored, fixed, and dried. There are 15 dipping baths in the plant. A variety of chemicals (e.g., nitric acid [HNO3], sodium hydroxide [NaOH], cobalt sulfate [CoSO4], boric acid [H3BO3], Cr(III), and Cr(VI)) are used to provide the color, durability, and smoothness of the products.
Sampling
The size distributions and mass concentrations of the aerosols in the plant were determined using a five-stage Sioutas cas-cade impactor with a Leland Legacy pump (SKC Inc., PA, USA). The cascade impactor is preferred for determining the size distribution of particles in indoor workplaces (Taner et al. 2013; Dahlman-Höglund et al.2016). The pump flow rate was 9 L/min. Pump flow was calibrated using a DryCal DC-2 calibrator (Bios International Corporation, Butler, NJ, USA). The samples were collected in the following five size ranges: > 2.5, 1.0–2.5, 0.50–1.0, 0.25–0.50, and < 0.25 μm. Particle size cutoff points were 2.5, 1.0, 0.50, and 0.25 μm. Each cutoff point samples were collected on a 25 -mm polytetrafluoroethylene filter at the appropriate stage with par-ticles < 0.25μm collected on a 37-mm after-filter. The tem-perature was between 18.1 and 23.1 °C during sampling.
The samples were collected at a height of 1.5 m, which was determined to be the “breathing level” of the workers at a sampling point approximately 2 m from the dipping baths. The sampling time was 8 h during a work shift. Ten samples were taken and 50 filtered samples were created. Approximately 30% of the filters were excluded from the
evaluation because of technical problems during the sampling and decomposition steps. Gravimetric analysis of the filtered samples was done using a Mettler Toledo (Mettler Toledo Ltd., USA) electronic balance with an accuracy of 0.01 mg. Before and after sampling, the filters were kept in a temperature-controlled (20 ± 2 °C) room for 48 h with a rel-ative humidity of 40 ± 5%.
Elemental analyses
The sampling filters were dissociated using a microwave sys-tem (CEM MARSXpress digestion syssys-tem, Matthews, NC USA). For the digestion process, we added 5 mL HNO3 (65%), 1 mL HCl (30%), and 0.5 mL hydrogen fluoride to the filters and put all of them into the microwave vessels. The digestion process took 35 min. At each step of the digestion process, a blank filter was decomposed along with the sample filters. After completing the digestion process, the vessels were allowed to cool, after which the solution in the vessels was diluted to 25 mL with deionized distilled water and kept in a refrigerator at + 3 °C until analysis. The GF-AAS 600 graphite atomic absorption spectrophotometer (PerkinElmer Corporation, Waltham, MA, USA) was used to analyze Cu, Ni, Mn, Pb, Cr, and Co. The accuracy of the measurements was confirmed when the repeatability of the measurement for each sample was < 2%. Three readings were conducted on each sample.
Health risk assessment
Health risk assessment is a scientific method by which the existence of adverse health effects is estimated and safe levels of exposures to protect people’s health are developed (Singh et al.2015). Human health risk assessment comprises the fol-lowing four basic steps: (1) hazard identification, (2) dose– response assessment, (3) exposure assessment, and (4) risk characteristics (USEPA1991). In this study, the method of USEPA was used to assess the health risk. The health risk analysis was conducted using the average element concentra-tions found in the fine particle fraction (Mohseni Bandpi et al. 2018; Hernández-Pellón et al.2018; Voutsa et al.2015; Taner et al.2013).
In the first step, the element concentrations were deter-mined in five different PM sizes, and the average element concentrations in PM2.5 were determined. Second, for the noncarcinogenic (Ni, Mn, and Cr(VI)) and the carcinogenic elements (Ni, Pb, and Cr(VI)), the reference concentration for inhalation exposure (RfC) and the inhalation unit risk (IUR) values were provided by the USEPA Integrated Risk Information System (1987) and California EPA (2016). In the third step, the exposure concentration (EC,μg/m3) was calculated according to Eq. (1):
EC ¼ Cð air ET EF EDÞ=AT ð1Þ
whereCairis the pollutant concentration (μg/m3), ET is expo-sure time (8 h/24 h), EF is expoexpo-sure frequency (250 days/365 days), ED is exposure duration (25 years), AT is averaging time (in terms of days), and the value of carcinogenic effect is 80.8 years× 365 days/year for female and 75.3 years × 365 days/year for male workers, and the value of noncarcinogenic effects is 25 years × 365 days/year (TUIK 2019; USEPA 2009).
After calculating EC, the hazard quotient (HQ) was deter-mined for the noncarcinogenic elements according to Eq. (2).
HQ ¼ EC=RfC ð2Þ
Finally, the excess lifetime cancer risk (ELCR) was calcu-lated for the carcinogenic elements as follows (USEPA2009):
ELCR ¼ IUR EC ð3Þ
In this study, total Cr concentration was analyzed. Koropchak and Roychowdhury (1990) have shown that the ratio of Cr(VI) to Cr(III) increased as particle size decreased in a Cr plating workplace and determined that the ratio of Cr(VI) to Cr (III) varied between 4 and 6 in the PM2.5fraction. In this study, the ratio of Cr(VI) to Cr(III) was 5 in the PM2.5fraction.
Results and discussion
Concentrations of particles and elements
In the workplaces, the recommended guidelines for the values and legal limits of particles have been established for total suspended particles (TSP) and respirable particles (particle diameter, dp < 4μm). The five-stage Sioutas cascade impactor (SKC Inc.) used in this study allowed us to sample five dif-ferent particle fractions, as explained above. The sum of the five different fraction concentrations corresponds to TSP. We considered that the fractions of PM<0.25, PM<2.5, and PM>2.5 were ultrafine, fine, and coarse particles, respectively. Table1 shows the recommended guidelines for values and legal limits for workplace exposure to aerosols and chemical elements. OSHA established an 8-h time-weighted average limit of 15 mg/m3, measured as total particulates, and retained the 5-mg/ m3limit for respirable particulates for all particulates not oth-erwise regulated, as in the Turkish National Standard (ÇSGB 2013a,b).
The mean concentration and standard deviation of particles and elements in the five different particle fractions collected from the metal finishing plant are given in Table2. The mean TSP concentration and standard deviation were 318.8 ± 112.2 μg/m3
workplace was less than the National Dust Control Regulation of 5 mg/m3for respirable particles, and less than that in the OSHA permissible exposure limit (PEL). Hsien et al. (1997) have measured airborne particle levels in Cr and Cr–Ni electroplating factories and found particle concentrations that were near the electroplating tank in the Cr electroplating fac-tory had a mean of 0.41 ± 0.40 mg/m3and a range of 0.022– 0.812 mg/m3, and in the Cr–Ni electroplating factory a mean of 0.36 ± 0.28 mg/m3. A box plot of particle concentrations according to the different particle fractions is illustrated in Fig. 1. The mean mass concentrations and standard deviations of PM<0.25, PM0.25–0.50, PM0.5–1.0, PM1.0–2.5, and PM>2.5were 0.09 ± 0.03 mg/m3, 0.05 ± 0.02 mg/m3, 0.03 ± 0.01 mg/m3, 0.04 ± 0.02 mg/m3, and 0.12 ± 0.05 mg/m3, respectively. We observed that the ratio of fine particles (PM2.5) to TSP was 0.6.
We also determined that 80% of the particles in PM2.5 consti-tuted PM1.0, approximately 50% of TSP was composed of PM1.0, and 28% of TSP was composed of PM<0.25. The over-all results showed that the concentration of fine particles in the workplace was higher than that of coarse particles. The parti-cle size distribution for hard Cr plating on the bath surface defined by USEPA and the cumulative percentage of total PM was 9.1% for PM0.5, 48.3% for PM2.4, and 59.6% for PM8.0(USEPA,1996). Our results indicated that the cumula-tive percentage of total PM was 42.4% for PM0.5and 62% for PM2.5. Comparing the results, PM2.5and PM2.4percentages were not similar to those of PM0.5. One of the reasons for this difference could be the distance of the sampling points from the dipping bath; the samples were not taken from the bath surface in our study. Bonin et al. (1995) have reported that
Table 2 Mean particle and element concentrations and standard deviations (SD) in different size fractions Mean ± SD (mg/m3)
PM size (μm) PM Cu Ni Mn Pb Cr Co
PM>2.5 0.12 ± 0.05 61.7E-6± 66.2E-6 16.0E-6± 12.6E-6 27.2 E-6± 20.8E-6 69.1E-6± 38.2E-6 23.2E-6± 22.9E-6 34.0E-6± 38.8 E-6
PM1.0-2.5 0.04 ± 0.02 42.4E-6± 63.0E-6 9.5E-6± 12.5E-6 6.6E-6± 5.2E-6 43.4E-6± 39.6E-6 13.6E-6± 9.7E-6 12.1E-6± 11.3E-6
PM0.5-1.0 0.03 ± 0.01 12.4E-6± 10.6E-6 19.5E-6± 30.8E-6 4.8E-6± 3.1E-6 25.7E-6± 14.1E-6 10.5E-6± 5.0E-6 6.3E-6± 4.5E-6
PM0.25-0.50 0.05 ± 0.02 18.8E-6± 16.8E-6 13.6E-6± 27.3E-6 16.4E-6± 13.0E-6 37.2E-6± 13.6E-6 11.7E-6± 6.6E-6 14.6E-6± 17.2E-6
PM<0.25 0.09 ± 0.03 70.9E-6± 82.9E-6 22.7E-6± 25.0E-6 18.4E-6± 8.7E-6 98.7E-6± 49.9E-6 51.0E-6± 10.0E-6 2.9E-6± 3.0E-6
PM1 0.16 ± 0.06 102.1E-6± 103.5E-6 55.7E-6± 78.0E-6 39.6E-6± 20.9E-6 161.6E-6± 65.6E-6 73.2E-6± 11.7E-6 23.8E-6± 22.6E-6
PM2.5 0.20 ± 0.07 144.5E-6± 143.6E-6 65.3E-6± 88.9E-6 46.2E-6± 25.8E-6 205.1E-6± 95.1E-6 86.7E-6± 17.3E-6 35.9E-6± 22.0E-6
TSP 0.32 ± 0.11 206.2E-6± 173.4E-6 81.3E-6± 89.5E-6 73.3E-6± 44.8E-6 274.2E-6± 118.4E-6 109.9E-6± 38.4E-6 69.9E-6± 44.5E-6
Cumulative percentages
PM1/PM2.5 0.80 0.70 0.80 0.85 0.79 0.84 0.66
PM0.5/TSP 0.42 0.43 0.44 0.47 0.49 0.57 0.25
PM1/TSP 0.50 0.49 0.68 0.54 0.59 0.66 0.34
PM2.5/TSP 0.62 0.70 0.80 0.63 0.74 0.78 0.51
PM, particulate matter; TSP, total suspended particles; Cu, copper; Ni, nickel; Mn, manganese; Pb, lead; Cr, chromium; Co, cobalt; E-6
= 10-6 Table 1 Comparison of
recommended guidelines for the values and legal limits (regulatory requirements) for exposure to aerosols and chemical elements in the workplace
8-h time-weighted average (TWA) limits (mg/m3)
Particles Cr(VI) Total
Cr Mn Cu Co Ni Pb Total Respirable OSHA-PEL8 15 5 0.0053 1 5 1 0.1 1 0.053 NIOSH-REL9 15 No REL 0.0002 0.5 14 14 0.054 0.0154,5 0.053 ACGIH-TLV10 3 0.00021,2 0.00052 0.5 0.027 0.16 1 0.02 1.56 0.05 Turkish National Standards11 15 5 2 - - - - 0.15
Cu, copper; Ni, nickel; Mn, manganese; Pb, lead; Cr, chromium; Cr(VI), hexavalent Cr; Co, cobalt
1
Short-term exposure limit; 2Water soluble;3Cal/OSHA-PEL;410-h TWA;5Carcinogen;6Inhalable;
7
Respirable;8Occupational Health and Safety Administration;9National Institute for Occupational Safety and Health;10American Conference of Governmental Industrial Hygienists;11National Dust Control Regulation and Regulation on Health and Working with Chemical Substances, The Ministry of Labor and Social Security
particle size decreases the farther the particle is from the dip-ping baths in the Cr plating process, and after taking measure-ments directly above the bath, they found that particle size distribution was outside the instrumentation measurement limits (0.3–25 μm). In addition, the properties of the chemical or electrochemical activity in the tank might have affected particle size. Particle formation increases with the amount of activity in the dipping baths, the strength and temperature of the solution, and the density of the current in the plating tanks. For many metals, plating baths have high cathode efficiencies so that the generation of particles is minimal, but cathode efficiency in Cr plating baths is very low (10–20%), which
generates a substantial amount of Cr particles (USEPA,1996). The particle generation rate from the cathode (97% based on weight) is higher than that from the anode (3%) (Pilat and Pegnam2006).
Even if the exposure level to PM in the workplace is less than the legal and recommended limits, the occupational ex-posure to the chemicals in the particles is substantial and causes adverse health effects on the workers. Adverse health effects increase as particle size gets smaller, and finer particles can travel into the alveoli of the lungs (Zhang and Kleinstreuer 2004). The high concentration of fine particles makes the in-vestigation of particle characteristics in the workplace more
Extremes Outliers Maximum 75% of data Mean 25% of data Minimum Fig. 1 Box plot of particulate
matter (PM), nickel (Ni), manganese (Mn), lead (Pb), chromium (Cr), cobalt (Co), and copper (Cu) concentrations for each particle fraction. The boxes represent the interquartile range (IQR, 25th to 75th percentile), the whiskers represent 10th and 90th percentile, and the middle line is median
important. In this study, the concentration of six elements were determined within five particle fractions; the mean element concentrations are given in Table2and the box plots of ele-ment concentrations within the different particle fractions are demonstrated in Fig.1. The element concentrations in TSP were observed in the following order: Pb > Cu > Cr > Ni > Mn > Co. The mean concentration and standard deviations of Pb, Cr, and Ni in TSP were 274.2 E-6± 118.4 E-6, 109.9 E-6± 38.4 E-6, and 81.3 E-6± 89.5 E-6mg/m3, respectively. We observed that all element concentrations in TSP conformed
to the legal and recommended values (Table1). Hsien-Wen et al. (1997) have found the Cr concentration near the electroplating tank in a Cr electroplating factory was within a range of 5.0E-4–6.0E-3mg/m3and in a Cr–Ni electroplating factory within a range of 2.0 E-4–6.0 E-4mg/m3. They mea-sured worker exposure to Cr and found that the concentration of airborne Cr(VI) was within a range of 1.0 E-4–40.0 E-2mg/ m3.
In the plant, the proper color and properties of the metal pieces are dictated by the customer; therefore, the coating type
Fig. 3 Scatterplots and Pearson correlation coefficient among the metals in PM1.0and PM>1.0
fractions. The numbers indicate significant correlation coefficients atp values (**p < 0.01; *p < 0.05). PM, particulate matter; Cu, copper; Ni, nickel; Mn, manganese; Pb, lead; Cr, chromium; Co, cobalt
0% 20% 40% 60% 80% 100% Percentage Metals <0.25 0.25-0.50 0.5-1.0 1.0-2.5 >2.5 Fig. 2 The percentage rates of the
elements in the five particle fractions. Notes: Cu, copper; Ni, nickel; Mn, manganese; Pb, lead; Cr, chromium; Co, cobalt
and chemicals used in the dipping baths can vary. During the study period, the workplace samples were taken on random days. During those sampling days, we observed that the num-ber of Cr(III) and Cr(VI) electroplating coating and anodic coating applications in the plant were approximately equal. The wide range of concentrations of total Cr and particles could be the result of different manufacturing processes. For many metals, plating baths have high cathode efficiencies; therefore, particle generation is minimal. However, the cath-ode efficiency of Cr plating baths is very low (10–20%), which generates a substantial amount of chromium particles (USEPA,1996). In addition, the particle generation rate from the cathode (97% based on weight) is higher than that from the anode (3%) (Pilat and Pegnam2006).
The percentage rates of the elements in the five particle frac-tions are provided in Fig.2, which shows that the metal concen-trations in the five particle fractions varied. In general, we found that 68–88% of the metals were collected in the fine particle fractions. The Pb percentages were similar in each particle size fraction. The highest percentages of Mn and Co were observed in PM>2.5and PM0.25–0.50. We observed that approximately 78% of total Cr concentrations were in the PM2.5fraction.
Previous studies on the metal concentrations in the differ-ent particle fractions from a metal finishing plant are limited. On the bath surface in a hard Cr plating workplace, the cumu-lative percentages of Cr(VI) in PM0.5, PM2.4, and PM8were 6.9, 67.7, and 82.6%, respectively (USEPA,1996). In our study, the cumulative percentage of total Cr was 57% for PM0.5and 78% for PM2.5. As with the particle size fraction, the percentages of Cr in PM2.5and PM2.4were similar but differed in PM0.5. The probable causes for these differences could be from considering total Cr, differences in processes, and differences in the sampling points in our study.
Correlations among the elements in PM1.0and PM>1.0 frac-tions are illustrated in Fig. 3. Pb, Cr, and Mn were
significantly positively correlated in PM1.0fraction, and the highest linear relationship was found between Pb and Cr (r = 0.85,p < 0.01). Mn showed a significant correlation with Cr (r = 0.47,p < 0.05) and Pb (r = 0.52, p < 0.05).
In the PM>1.0 fraction, we found significant positive linear relationships among more elements. The highest positive correla-tions were observed between Cr and Mn (r = 0.76, p < 0.01), Co and Ni (r = 0.71, p < 0.01), and Co and Cr (r = 0.68, p < 0.01). Cu was not significantly correlated with any other elements except Pb (r = 0.74, p < 0.01). There was also a significant linear rela-tionship between Pb and Mn (r = 0.64, p < 0.05) and Ni and Cr (r = 0.57,p < 0.05). It is difficult to explain the reasons for these correlations because the processes applied and chemicals used in the dipping baths varied widely during the sampling period. The properties of the electroplating process affect the particle genera-tion rate, particle content, and particle size (e.g., particles are not formed during trivalent Cr plating but are formed during Cr(VI) plating) (USEPA, 1996). In addition, noncoating and coating conditions affect particle size. Bonin et al. (1995) have reported that there is an appreciable quantity of material released from the bath surface, even in the absence of plating activity. They calcu-lated the ratio of plating to nonplating number density and found the smallest ratio at small particle sizes and the greatest ratio at large sizes. Plating duration varies—decorative Cr plating re-quires shorter plating times and operates at lower current densities than hard Cr plating—(USEPA,1996). During our sampling campaign, the plant used different types of electroplating and anodizing processes. In addition, the linear relationships among the elements could be affected by the particle emissions from the electroplating baths during nonplating conditions.
Health risk assessment
The HQ and ELCR values for noncarcinogenic and carci-nogenic elements in PM2.5are given in Table 3. The HQ Table 3 Estimates of occupational health risks from PM2.5
Elements Cair1(μg/m3) RfC2(mg/m3) EC(air)3(μg/m3) HQ4 IUR5(μg/m3) ELCR6 Source
Noncarcinogenic Cal EPA7
Nickel 0.065 1.40E-5 1.48E-2 1.06E+0 IRIS8
Manganese 0.046 5.00E-5 1.05E-2 2.10E-1 IRIS
Chromium (VI) 0.072 1.00E-4 1.64E-2 1.640E-1
∑ = 1.43E+0
Carcinogenic EC9(air)-female EC9(air)-male ELCRfemale ELCRmale
Nickel 0.065 4.59E-3 4.93E-3 2.40E-4 1.10E-6 1.18E-6 Cal EPA
Lead 0.205 1.44E-2 1.55E-2 1.20E-5 1.73E-7 1.86E-7 Cal EPA
Chromium (VI) 0.072 5.08E-3 5.45E-3 1.20E-2 6.09E-5 6.54E-5 IRIS
∑ = 6.21E-5 ∑ = 6.67E-5 1
Mean concentrations of the metals in PM2.5fraction;2Reference concentration for inhalation exposure;3Exposure concentration;4Hazard quotient; 5
Inhalation unit risk;6Carcinogenic risk;7California Environmental Protection Agency,2016;8Integrated Risk Information System;9ED was accepted 80.8 years for female workers, 75.3 years for male workers
values for Mn and Cr(VI) were lower than the acceptable limit of 1.0 (USEPA1991), while HQ for Ni was higher. Total HQ at 1.43 was higher than the acceptable limit of 1.0. The ELCR value was calculated for Ni, Pb, and Cr(VI) and the total ELCR was 7.19 × 10-5, which is higher than the acceptable limit of 1.0 × 10-6 (USEPA 1991). The individual average ELRC values of female and male workers were 1.1 × 10−6 and 1.18 × 10-6 for Ni, 1.73 × 10–7 and 1.86 × 10-7 for Pb, 6.09 × 10–5 and 6.54 × 10-5 for Cr(VI), respectively. ELCR for Ni and Cr(VI) were higher than the acceptable limit of 1.0 × 10-6, while ELCR for Pb was lower. The International Agency for Research on Cancer (IARC) has classified Ni and Cr(VI) as class 1 carcinogenic elements, while Pb is a class 2B carcinogenic element (IARC 2006; 2012); consequently, the total cancer risk was 62.1 times for female workers and 65.4 times for male workers higher than that for the acceptable limit of 1.0 × 10-6, and this result shows that ~ 62 for female and 65 for male in 1,000,000 metal finishing workers might have contracted cancer because inhaling these three elements in PM2.5.
Conclusion
This study summarized the size distribution and concen-tration of elements in airborne particles in a Cr electroplating and anodic coating plant and the occupa-tional health risk of toxic elements in the workplace. Total particle and element concentrations conformed to the Turkish National Standards (ÇSGB 2013a, b) and OSHA-PEL legal limits. The metal percentages in PM2.5 were between 68 and 88%, while the cumulative percent-age of total Cr was 57% for PM0.5and 78% for PM2.5. Pb and Cr were significantly correlated in PM1.0 fraction. The results of the health risk assessment indicated that the total HQ for PM2.5 was 1.43, which was higher than the acceptable limit of 1.0. The individual ELCR of Cr(VI) for female and male workers were 6.09 × 10-5 and 6.54 × 10-5, respectively, while total ELCR was 6.21 × 10-5 for female workers and 6.67 × 10-5 for male workers. This information could be useful in assessing and controlling potential health hazards in the Cr electroplating plants. ELCR associated with Cr(VI) should be taken into account as a significant factor for a worker’s health.
Funding information Funding for this project was provided by the Research Fund of the University of Istanbul with the projects number 58394 and 54454. The authors declare no conflict of interest relating to the material presented in this Article.
Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of interest.
Disclaimer The article contents, including any opinions and/or conclu-sions expressed, are solely those of the authors.
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