Evaluation of blood lead among painters of buildings and cars

Abstract

Exposure to lead-based paints is a major threat to the health of painters. This study aimed to evaluate the blood concentration of lead (Pb) in painters of buildings and cars. The present study was a cross-sectional study in which a semi-structured questionnaire was used to collect the socio-demographic information. Lead concentration in blood samples was determined using the atomic absorption spectrometry method. A total of 32 male painters were selected based on inclusion criteria. The mean blood lead level (BLL) in the painters was 8.1 ± 4.93 μg/dL. Pb levels in car and building painters were 9.42 ± 5.5 μg/dL and 6.7 ± 1.85 μg/dL, respectively. Pb concentration in none of the blood samples was more than 30 μg/dL. The prevalence of BLL ≥ 5 μg/dL and BLL ≥ 10 μg/dL was 97% and 19%, respectively. According to the findings, the rate of BLL among car painters was higher than building painters. Considering the presence of Pb in all blood samples, it seems necessary to increase the awareness of painters about the adverse effects of lead exposure even in low concentrations. However, the sample size in this study was small and more investigations are required in this regard.

Keywords

lead occupational exposure blood lead levels building painters car painters

Introduction

Lead (Pb) is one of the most common toxic elements that exposure to it is a widespread human health issue. The World Health Organization (WHO) considers Pb as one of the top 10 chemicals of public health concern for which there is no safe level of exposure (WHO, 2019). Although acute exposure to Pb is less common, chronic exposure to low levels of Pb is still an essential public health issue in most countries (Tong et al., 2000; Control and Prevention, 2011). Exposure to high concentrations of Pb may result in muscle pain, fatigue, abdominal cramps, headache, vomiting, convulsions, coma, and death (Flora et al., 2012; Gordon et al., 2002). Moreover, chronic exposure to Pb may lead to disorders of the nervous system, anemia, gastrointestinal, renal, and cardiovascular diseases (Flora et al., 2012; Navas-Acien et al., 2007; Rastogi, 2008). In addition, inorganic Pb has been classified as toxin Group 2A by the International Agency for Research on Cancer (IARC) (Lyon, 1994) since it is probably carcinogenic to humans. Therefore, some countries have set standards to minimize occupational exposure to Pb. The US Occupational Safety and Health Administration (OSHA) and the European Union Scientific Committee have, respectively, established a maximum blood concentration of 40 and 30 μg/dL for occupational exposure to Pb (Ahmad et al., 2018). Additionally, the OSHA emphasizes that workers with BLL above 50 μg/dL should be removed from their jobs until their BLLs drop below 40 μg/dL (Dignam et al., 2019). However, BLL of male or female workers intending to have children should be maintained below 30 μg/dL so as to minimize adverse effects of Pb on developing fetus (Safety and Administration, 1991).

In the general population, exposure to Pb occurs mainly through the presence of small but hazardous concentrations of Pb in water, food, soil, and air (Kumar et al., 2020). However, the use of Pb in other materials has increased occupational and non-occupational exposure to this toxic metal (Mani et al., 2020). In the United States, occupational Pb exposure is a vital source of increased BLL in adults (Control and Prevention, 2011). Occupational exposure to Pb occurs mainly in the mining, battery, ceramic, glass, plastic, rubber, ammunition, pesticide, and printing industries (Mani et al., 2020; Fu and Boffetta, 1995). In addition, lead-based paint is an inevitable source of human exposure to Pb (O'Connor et al., 2018). Thus, the use of Pb compounds in paints has increased workers' exposure to this toxic metal (Mohammad et al., 2008).

Painters are exposed to a large number of hazardous substances which may be absorbed by the body. In fact, painters are mostly exposed to organic solvents, plastic monomers, and certain metallic pigments (Awan et al., 2018). Occupational exposure to Pb is a critical health problem in Iran (Karrari et al., 2012). According to a recent meta-analysis, Iranian workers are highly exposed to Pb (Azami et al., 2018). Furthermore, previous findings revealed that some of the Iranian paint samples had high concentrations of Pb (Clark et al., 2014). Given that few studies in Iran have examined the blood concentration of Pb in painters, the aim of this study was to assess the BLL in painters. Since the majority of painters in Iran work in the buildings and automobile sectors, the authors also compared BLL in these two occupational groups.

Materials and methods

Study population and ethical considerations

This study was a cross-sectional study done in Rafsanjan city (population = 160,000), southeast of Iran, during 2018–2019 (Hakimi et al., 2021). Inclusion criteria were including the age of 20 years or higher, no present smoking or smoking history during the last 3 years, and work experience over 3 years. All individuals completed a written informed consent before participation.

Semi-structured questionnaire

A three-part semi-structured questionnaire was used to collect data on socio-demographic status, anthropometrics, and personal hygiene. The first part of the questionnaire was related to the painters' demographic and anthropometric information including age, work experience, daily working hours, level of education, as well as weight, height, and body mass index (BMI). The second part of the questionnaire contained questions about personal hygiene, including washing hands before eating or drinking at work, taking a shower, and washing work clothes at the end of the day. In the last part of the questionnaire, the utilization of personal protective equipment such as respirators masks, coveralls, gloves, and goggles was questioned. Participants were also asked about the type of the paint used (water-based or solvent-based).

Sample collection and Pb quantification

Using a heparinized syringe, 4 mL of intravenous blood samples were taken from the participants and immediately transferred to a tube containing sodium heparin. Then, blood samples were stored at −20°C until analysis. In order to measure BLL, the collected blood sample was lysed using 4 mL of nitric acid (HNO3) and 1 mL of perchloric acid (HClO4). Then, the samples were incubated at 80°C for 1 h to complete the lysing process. After cooling, the residues were transferred to a flask and diluted with 15 mL of deionized water. The diluted samples were filtered through Whatman Filters (No. 1) prior to quantitative analysis by graphite furnace atomic absorption spectrophotometry. The limit of detection (LOD) for Pb was 2 μg/dL. Data analysis was performed in SPSS version 21.0, and the Mann–Whitney and Kruskal–Wallis tests were done in different subgroups. In all the statistical analysis, the level of significance was 5%.

Results

The demographic characteristics of participants

Of 135 painters asked to participate in this study, 71 painters (47 building painters and 24 automobile painters) were willing to take part in the study. However, 39 were not eligible according to the inclusion criteria. Therefore, the number of participants in each group decreased to 16 (Figure 1). The demographic characteristics of the 32 participants have been presented in Table 1. The mean age of the painters was 39.82 ± 11.9 years old, ranging from 21 to 67 years of age. The participants’ work experience varied from 3.1 to 40 years with a mean of 17.1 ± 10.8 and 19.5 ± 13 for car painters and for building painters, respectively. The mean daily working hour was 8.56 ± 1.3 h for car painters (varied from 7 to 12 h), while the mean daily working hour of the building painters was 7.44 ± 1.15 h (varied from 6 to 10 h). No statistical difference was found between the workers of both groups in terms of age (p = 0.521), weight (p = 0.706), height (p = 0.91), BMI (p = 0.91), work experience (p = 0.66), and duration of daily work (p = 0.081).

Table 1.

The demographic characteristics of the painters participating in this study.

Parameter	Group	N	Mean ± SD	Min–max	p-value
Age (year)	CP	16	39.34 ±12.82	23–67	0.521
	BP	16	40.43 ± 11.21	21–59
	Total	32	39.82 ± 11.9	21–67
Weight (Kg)	CP	16	80.22 ± 13.98	57–112.5	0.706
	BP	16	87.1 ± 25.45	65.5–117
	Total	32	83.66 ± 20.51	57–115
Height (cm)	CP	16	174.29 ± 6.66	165–184.5	0.910
	BP	16	174.68 ± 8.54	160–188
	Total	32	174.49 ±7.54	160–184.5
BMI (kg/m2)	CP	16	26.37±3.99	20.44–33.23	0.910
	BP	16	26.14 ± 4.07	21.04–34.49
	Total	32	26.26 ± 3.97	20.44–34.49
Work experience (year)	CP	16	17.1 ± 10.81	3.1–37	0.66
	BP	16	19.5 ± 13	4–40
	Total	32	18.3 ± 11.82	3.1–40
Daily working (hours)	CP	16	8.56 ± 1.3	7–12	0.081
	BP	16	7.44 ± 1.15	6–10
	Total	32	8.1±1.3	6–12

N: sample size; CP: car painters; BP: building painters; SD: standard deviation.

Prevalence and concentration of blood Pb

Pb levels were higher than those of the LOD (2 μg/dL) in all samples. The mean BLL for the 32 studied painters was 8.1 ± 4.93 μg/dL. The mean BLL in car painters was 9.42 ± 5.5 μg/dL, whereas it was 6.7 ± 1.85 μg/dL for the building painters (Table 2). The results revealed no significant difference between Pb levels in both groups (p = 0.23). The highest and lowest levels of Pb were 26.5 and 4.3 μg/dL, respectively. Almost three-quarters (78.1%) of the painters had BLL between 5 and 10 μg/dL. None of the measured BLLs were greater than 50 μg/dL; it was consistent with the findings of the present study. However, 6 out of the 32 participants (∼19%) had a BLL ≥ 10 μg/dL and 31 participants had BLL ≥ 5 μg/dL (Table 2).

Table 2.

Blood lead levels in painters in Rafsanjan City.

Group	N	Mean BLL ±SD (μg/dL)	Min–Max (μg/dL)	N (%) BLL <5 μg/dL	N (%) BLL ≥5–10 μg/dL	N (%) BLL >10–25 μg/dL	N (%) BLL >25 μg/dL
CP	16	9.42 ± 5.5	4.3–26.5	6.25	68.75	18.75	6.25
BP	16	6.7 ± 1.8	5–11	0	78.5	12.5	0
Total	32	8.1 ± 4.93	4.3–26.5	3.13	78.12	15.62	3.13

N: sample size; CP: car painters; BP: building painters; BLL: blood lead level; SD: standard deviation; μg/dL=microgram/deciliter.

Personal hygiene and personal protective equipment

This study examined the possible effect of using personal protective equipment on reducing Pb concentration. The levels of Pb in different subgroups are compared in Table 3. According to the results, using personal protective equipment did not have any significant influence on Pb concentrations in blood. The statistical results demonstrated a significant relationship between the education level and the concentration of Pb in blood, that is, BLL was higher in painters with lower education levels.

Table 3.

The effects of selected factors on mean Pb concentration in all painters (regardless of the type of activity).

Categories	Groups	N	Mean ± SD (μg/dL)	p value
Age (years)	≤35	13	8.95 ± 6.28	0.11
	>35	19	7.43 ± 3.82
Work experience (years)	≤10	8	9.35 ± 7.1	0.42
	>10	24	7.62 ± 3.11
Education level	Under Diploma	13	10.2 ± 7.1	0.047^a
	Diploma or University	19	6.6 ± 1.75
Taking a shower at the end of work (times/week)	≤2	20	9.5 ± 7.15	0.2
	>2	12	7.2 ± 2.81
Washing hands before eating or drinking (times/week)	Rarely	0	—	—
	Always	32	8.1 ± 4.93
Washing coveralls at the end of the day (times/week)	≤2	16	8.4 ± 5.59	0.71
	>2	16	7.7 ± 4.33
Using respirators	Yes	25	7.61 ± 4.45	0.796
	No	7	8.17 ± 5.17
Using gloves	Yes	19	9.82 ± 6.78	0.093
	No	13	6.84 ± 2.72
Using coveralls	Yes	16	6.79 ± 1.61	0.153
	No	16	9.31 ± 6.66
Using safety glasses	Yes	0	—	—
	No	32	8.1 ± 4.93

N: sample size; SD: standard deviation; μg/dL=microgram/deciliter.

^aAccording to non-parametric tests.

Discussion

Preventing workers' occupational exposure to Pb requires a combination of interventions including personal protective equipment utilization, worker training, and biological monitoring (Allaouat et al., 2020). Therefore, monitoring BLL is a way to achieve the aforementioned objectives. In the present study, the BLL was ≥5 μg/dL in most of the painters. In addition, the average BLL in car painters was higher than that of building painters, although this difference was not statistically significant.

Given that adults’ exposure to Pb occurs mainly at the workplace (Koh et al., 2015), OSHA has established guidelines for reducing Pb exposure and its induced damages. According to OSHA guidelines, BLL ≥ 50 μg/dL is considered a limit for temporary removal of workers from the workplace (Ahmad et al., 2018). Although none of the painters in this study had a BLL greater than ≥50 μg/dL, 19% of the participants had BLL ≥ 10 μg/dL and 97% had BLL ≥ 5 μg/dL. According to the recommendations of the Department of Health and Human Services, BLL in adults should be ≤10 μg/dL (Laidlaw et al., 2017). The results of several studies have indicated that there is a positive association between BLL ≥ 10 μg/dL and increased blood pressure as well as decreased renal function (Payton et al., 1994; Navas-Acien et al., 2004; Harari et al., 2018). Furthermore, a significant association was observed between BLL ≥ 5 μg/dL and adverse health effects in children and adults (NTP, 2012; Lanphear et al., 2018; Menke et al., 2006). Since the majority of the painters participating in this study had BLL ≥ 5 μg/dL, performing safety protocols seemed necessary in order to reduce Pb exposure in the study population.

Pb is a toxic metal used regularly for paint production in the past. Historically, Pb compounds were added to paints to improve color adhesion and reduce corrosion on metal surfaces (O'Connor et al., 2018). However, today Pb utilization has dramatically decreased in the paint production industry due to health-related concerns (Dignam et al., 2019). The present study showed that the average BLL in building and car painters was 6.7 and 9.42 μg/dL, respectively. According to the investigations conducted in the US, building painters had low BLL (6.8 μg/dL) (Ennever et al., 1995). Moreover, the average BLL in car painters was 78.0 μg/dL, 45.4 μg/dL, and 10.7 μg/dL in Pakistan, Nigeria, and Jordan, respectively, (Ahmad et al., 2018; Alli, 2015; Hunaiti et al., 1995).

There are several factors affecting BLL in car painters such as cleaning the previous paint with sand, repainting by sprayers, and high Pb concentration in some car paints (Ahmad et al., 2018). In the present study, all car painters continuously used sprayers as their painting instrument. Meanwhile, building painters mainly used brushes to paint surfaces. Furthermore, the frequent usage of water-based paints by building painters in comparison to solvent-based paints utilized in car painting could cause differences in BLL between these two occupational groups. According to some previous investigations, Pb concentration in water-based paints is lower than that in solvent-based paints (Al-Saleh and Coate, 1995; Huang et al., 2010). Therefore, solvent-based paints can increase respiratory exposure to toxic metals in car painters (Hsu et al., 2018). Therefore, the higher levels of BLL observed in car painters could be due to some factors such as pre-painting sanding, usage of sprayers, and exposure to solvent-based paints. In the present study, all car painters were only exposed to solvent-based paints, while building painters were mainly exposed to water-based paints.

According to our findings, the mean BLL in painters was 8.1 ± 4.93 μg/dL. However, the results of a recent meta-analysis indicated a high Pb exposure in Iranian workers, and the average BLL in this population was 43.1 μg/dL (95% 35.19–50.83). Moreover, the highest and the lowest blood Pb concentrations were estimated for people working in the textile industry (12.33 μg/dL [95%CI: 0–26.76]) and lead–zinc mines (72.58 μg/dl [95%CI: 26.06–119.10]), respectively (Azami et al., 2018). The BLL reported in the present study is comparable to the results obtained in Iran and other countries of the world. According to an investigation conducted in Mashhad, the mean blood concentration of Pb in 75 painters was 4.7 μg/dL (Nakhaee et al., 2019). A study carried out in Ghana revealed that the blood concentration of Pb in painters (n=40) was 7.43 μg/dL (Agyemang et al., 2020). In addition, a study of 83 painters in the United States showed that the average BLL in painters was 7 μg/dL (Range: 1.5–26.3 μg/dL), while 14.5% and 2.5% of participants had BLLs above 10 and 20 μg/dL, respectively (Reynolds et al., 1999).

It is quite obvious that making use of personal protective equipment and improving personal hygiene can be effective in reducing workers’ occupational exposure to Pb. According to a previous study, inadequate attention to personal hygiene at work led to severe Pb poisoning in painters (Ogawa et al., 2008). The results of the present study showed that washing hands before eating and drinking at work, taking a shower at the end of work, washing work clothes regularly, and using masks during working hours can reduce BLL in painters. A study of bridge painters in the United States showed lower BLL in individuals with higher scores of personal hygiene index (including items such as washing hands before eating or at the end of the day and taking a shower at the end of work) (Rodrigues et al., 2009). Examining hand wipe samples at a car repair shop in the United States indicated that washing hands before eating, drinking, and smoking can be effective in reducing Pb exposure in the workplace (Enander et al., 2004). According to our findings, education level was the only factor related to painters’ BLL. In this regard, a similar association was also observed between education levels and BLL among bridge painters and battery factories (Rodrigues et al., 2009; Chuang et al., 1999). People with higher education levels are less likely to be exposed to Pb probably because of their different lifestyles, and this seems to play a more effective role than their better knowledge of Pb exposure threats (Thanapop et al., 2007).

However, we had some limitations in this study including the small sample size. Perhaps this was the reason why, despite the notable differences between BLL in different groups, they were not statistically significant. Therefore, studies with larger sample sizes are recommended for future studies.

Conclusion

According to our findings, the average of BLL was not significantly different between car painters and building painters. However, Pb concentration among car painters is seemingly higher than building painters. Considering the presence of Pb in all collected blood samples, it seems necessary to increase the awareness of painters about the adverse effects of Pb exposure as well as improve the utilization of protective equipment and personal hygiene.

Footnotes

Acknowledgments

The authors of this manuscript wish to express their gratitude to Rafsanjan University of Medical Sciences, Rafsanjan, Iran.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Rafsanjan University of Medical Sciences, Rafsanjan, Iran. The funder has played no role in the design of the study or in the collection, analysis, or interpretation of the data.

Ethical approval

The present study was approved by the Ethics Committee of Rafsanjan University of Medical Sciences, Iran (confirmation reference number IR. RUMS.REC.1394.136).

ORCID iDs

Ali Ghaffarian-Bahraman

Alireza Taherifard

Abbas Esmaeili

Hassan Ahmadinia

Mohsen Rezaeian

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