Abstract
Background:
The major portion of lead in the body resides in skeletal system. The bone turnover affects the release of lead into the circulation from bones. The bone turnover biomarkers (BTM) in lead-battery workers with long-term exposure to lead have not been explored yet.
Objective:
To evaluate the BTM (formation and resorption) in lead-battery workers with long-term exposure to lead in lead-battery manufacturing plant.
Methods:
176 male lead-exposed workers and 80 matched comparison group were studied. All participants were examined for blood lead levels (BLLs), bone formation biomarkers—serum osteocalcin (OC), alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BALP)—and bone resorption biomarkers—serum pyridinoline (PYD), deoxypyridinoline (DPYD), tartarate-resistant acid phosphatase-5b (TRACP-5b), and urinary hydroxyproline (UHYP).
Results:
We found a significantly higher bone formation biomarkers such as BALP (p=0.007) and bone resorption biomarkers, eg, PYD (p=0.048), TRCAP-5b (p=0.001), and UHYP (p=0.001) in lead-exposed workers. A significant (p=0.041) negative correlation (ρ -0.128) was noted between BLLs and OC. A significant positive correlation was noted between BLLs and TRACP-5b (ρ 0.176, p=0.005) and UHYP (ρ 0.258, p=0.004). Serum OC (p=0.040) and UHYP (p=0.015) levels changed significantly with BLL level. Bone resorption biomarkers levels—PYD, TRACP-5b, and BALP—were higher among those with higher BLLs levels. The duration of exposure was significantly associated with BALP (p=0.037), DPYD (p=0.016), TRACP5b (p=0.001), and UHYP (p=0.002) levels.
Conclusion:
Long-term lead exposure affects the bone turnover.
Keywords: Osteocalcin, Tartrate-resistant acid phosphatase, Alkaline phosphatase, Pyridinoline, Lead, Hydroxyproline, Deoxypyridinoline, Bone resorption
TAKE-HOME MESSAGE
BLLs and bone turnover biomarkers were significantly higher among lead-exposed workers compared to the comparison group.
Bone formation biomarker was negatively associated with BLL. Bone resorption markers were positively associated with BLL.
Long-term lead exposure results in altered bone turnover markers.
Introduction
Lead-acid storage batteries manufacturing process involves use of hazardous chemicals of lead oxide (PbO2), spongy lead, and sulfuric acid (H2SO4). Lead levels are expected to be high in the atmosphere of manufacturing unit.1 Occupational exposure to lead occurs through inhalation and ingestion. Recent studies on lead-battery manufacturing workers have reported high musculoskeletal disorders with markers of inflammation,2 mucocutaneous changes,3 oxidative stress,4 altered serum magnesium fractions,5 elevated blood lead levels (BLLs),6,7 reticulocytosis,8 altered genetic polymorphisms of δ-aminolevulinic acid dehydratase (ALAD),9 impaired biogenic amino acids with neurobehavioral function,10 genotoxicity,11 impaired coagulation function,12 health problems,13,14 male reproductive function,15 ocular changes,16 impaired hematological parameters,17 and altered calcium metabolism by inhibiting the kidney 1-𝛼-hydroxylase enzyme, which is required for 1, 25 dihydroxy-vitamin D3 synthesis18.
Bone is crucial for locomotion, body support, and organ protection.19 Lead is deposited in cement lines of bone and associated with demineralization.20 After long-term exposure, lead replaces the bivalent ions such as Ca2+, Mg2+, and Fe2, inhibits the bone fracture healing due to delayed cartilage formation, increased resorption of collagen molecule and bone marrow oxidative stress.21,22 A significant association was noted between BLLs and calcified cartilage turnover markers.23 Potula, et al ,24 reported that lead exposure from lead-smelting process is associated with increased levels of bone resorption markers, pyridinoline (PYD) and deoxypyridinoline (DPYD), among post-menopausal women workers. High risk of bone fracture and osteoporosis was also reported in female lead-battery workers.25 Lead-battery workers from China have reported decreased bone mineral density (BMD),26,27 increased risk of osteoporosis,28 increased urinary levels of hydroxyproline (UHYP), bone specific alkaline phosphatase (BALP), and osteocalcin (OC).29 BLL was reported to be positively associated with DPYD among middle-aged lead-exposed men.26 Levels of bone turnover biomarkers (BTM) reflect the bone formation as well as bone resorption and are responsible for bone remodeling status.30 These biomarkers have been used for early diagnosis of osteoporosis.31 The present study was conducted to evaluate the BTM of bone formation and bone resorption among workers with long-term exposure to lead in a lead-battery plant.
Materials and Methods
In a cross-sectional study, all male workers engaged in a lead-battery manufacturing plant who had been occupationally exposed to lead for at least two years were examined. The study group consisted of 176 workers working in a lead-battery plant located in Tamilnadu, India. A comparison group comprising of 80 office workers with no occupational exposure to lead were also studied. The comparison group was matched for age and socio-economic status with the study group.
Ethics Committee of the institution approved the study protocol. The study participants were informed of the study purpose and gave informed written consent to participate in the study. Demographic details, occupational history and habits of the participants (smoking and alcohol consumption) were collected by using a pre-structured questionnaire.
Sample Collection
From each participant 5 mL (2 mL in heparinized tube and 3 mL in plain tubes) of whole blood and urine samples were collected. The 2-mL sample was used for estimation of BLL. The 3-mL sample was centrifuged at 3000 RPM for 10 min at 4 °C to obtain the serum for measuring BTMs. Spot urine samples were used for the measurement of UHYP and creatinine.
Blood Lead Levels
The 2-mL blood sample was stored at -20 °C until analysis. Using ETHOS-D, (Milestone Microwave Laboratory Systems, Italy), the sample was digested with 2 mL of nitric acid and 0.2 mL of hydrogen peroxide while maintaining power, temperature, and duration of process. The digested samples were made up to 5 mL using distilled water and centrifuged. The concentration of lead was measured using an atomic absorption spectrophotometer (GBC Avanta P, Australia). A standard solution of 20 µg/dL of lead was prepared from the stock of a standard solution obtained from the Merck and added to the lowest concentration of the sample. The analysis found 100% recovery with %RSD at <0.5 for three replicates.
Bone Formation Biomarkers
Serum alkaline phosphatase (ALP), serum BALP and OC levels were used as bone formation biomarkers. Serum ALP was measured using IFCC-AACC method.32 Prietest clinical chemistry reagents (Robonik, India, private Ltd) were used for the estimation. In this approach, the p-nitro-phenyl phosphate is converted to p-nitrophenol and phosphate using alkaline phosphatase. The rate of formation of p-nitrophenol corresponds to ALP activity in the sample.
Quantification of BALP activity was done by using phenylalanine inhibition technique.33 In this approach, part of serum sample was incubated with 11 mM phenylalanine solution for 20 minutes. After incubation, residual ALP activity was measured by using the standard IFCC-AACC method.32 The amount of BALP was calculated by subtracting the residual activity from total ALP activity.
Serum OC concentration was measured using enzyme-linked immunosorbent assay (ELISA) (YH Biosearch Laboratory, China). The absorbance of standard specimens and samples were measured using Thermo Scientific Multiskan EX-reader (USA) at 450 nm. The concentration of unknown sample was calculated using standard curve with linear regression. The range of method was 0.5–150 ng/mL; the sensitivity of the method was 0.026 ng/mL.
Bone Resorption Biomarkers
Serum pyridinoline (PYD), deoxypyridinoline (DPYD), tartarate-resistant acid phosphatase-5b (TACRP-5b), and urinary hydroxyproline (UHYP) were considered bone resorption biomarkers. Serum concentration of PYD was measured with ELISA (YH Biosearch Laboratory, China). The absorbance of standard specimens and samples were measured using Thermo Scientific Multiskan EX-reader (USA) at 450 nm. The concentration of unknown sample was calculated by using standard curve with linear regression. The assay range of method was 0.5–200 ng/mL; the sensitivity of the method was 0.024 ng/mL.
The concentration of serum DPYD was measured with ELISA (YH Biosearch Laboratory, China). The absorbance of standards and samples were measured using Thermo Scientific Multiskan EX-reader (USA) at 450 nm. The concentration of unknown sample was calculated using standard curve with linear regression. The assay range of method was 0.005–1 nmol/mL; the sensitivity of the method was 0.005 nmol/mL.
Serum TRACP-5b was measured using Sarvari, et al , method.34 In this method, serum samples were diluted 10-fold with distilled water and incubated for 1 hour at 37 °C. Then, 50 μL of the diluted sample was added to 50 μL of substrate solution in a microplate. The reaction was carried out for 1 hour at 37 °C and quenched by adding 50 μL of 1 M NaOH. A calibration curve was prepared using p-nitrophenol solution of known concentrations (5–25 μg/mL in 0.05 M NaOH). The absorbance of standards and samples were measured using a Multiskan Microplate reader (Thermo Scientific) at 405 nm. The concentrations of unknown samples were determined using calibration curve with linear regression equation. One unit (1 U) of TRACP-5b activity was defined as the amount of enzyme required to hydrolyze 1 μmol of p-nitro phenyl phosphate (pNPP) per minute at 37 °C.
Quantification of UHYP was done using the modified method of Neuman and Logan.35 In this method, hydroxyproline was treated with CuSO4 and H2O2 in an alkaline solution with resultant formation of pyrroline-4-caroxylic acid, which is converted to pyrrole-2-caboxylic acid. This product is condensed with p-dimethyl-amino-benzaldehyde to give a red complex, which is measured in spectrophotometer at 540 nm (Elico-SL159).
Statistical Analysis
SPSS® for Windows® ver 16 was used for data analysis. Student's t test was used to compare the means of continuous normally distributed variables between the study and comparison group. The Spearmen's correlation test was used to examine the association between BLLs and BTM. Analysis of variance (ANOVA) was used to evaluate the effect of BLLs and duration of exposure on BTM. A p value <0.05 was considered statistically significant.
Results
Demographic details of study and comparison groups are presented in Table 1. The age, blood pressure, body mass index (BMI), and frequency distributions of alcohol consumption and smoking among study participants were matched with comparison group. The mean BLL in the study group was significantly (p=0.001) higher than that in the comparison group. The BLL among the comparison group was lesser than the World Health Organization threshold of 40 µg/dL for adults.
| Table 1: Demo g raphic characteristics of the study and comparison groups. Values are either mean (SD) or n (%). | |||
| Parameter | Study group (n=176) | Comparison group (n=80) | p value |
| Age (yrs) | 36.6 (4.0) | 37.4 (10.0) | 0.361 |
| BMI (kg/m2) | 25.7 (2.9) | 25.3 (3.4) | 0.339 |
| Exposure duration (yrs) | 13.3 (3.3) | 0 | — |
| Diastolic blood pressure (mm Hg) | 77.7 (10.7) | 74.8 (12.7) | 0.059 |
| Systolic blood pressure (mm Hg) | 127.8 (14.6) | 127.5 (19.1) | 0.890 |
| Alcohol consumption | 95 (54%) | 39 (49%) | 0.437 |
| Smoking | 38 (22%) | 19 (24%) | 0.700 |
| Blood lead level (µg/dL) | 32 (12) | 20 (6) | 0.001 |
BALP, a bone formation biomarker, was significantly (p=0.007) higher in the study group as compared with the comparison group (Table 2). The levels of bone resorption biomarkers, PYD (p=0.048), TRACP-5b (p=0.001), and UHYP (p=0.001), were also significantly higher in the study group as compared with the comparison group.
| Table 2: Mean (SD) of bone turnover biomarkers measured in the studied groups | |||
| Biomarkers | Study group (n=176) | Comparison group (n=80) | p value |
| Alkaline phosphatase (U/L) | 93 (28) | 87 (21) | 0.088 |
| Bone-specific alkaline phosphatase (U/L) | 42 (25) | 34 (13) | 0.007 |
| Osteocalcin (ng/mL) | 15.6 (10.0) | 16.0 (5.0) | 0.735 |
| Serum pyridinoline (ng/mL) | 35 (17) | 31 (9) | 0.048 |
| Serum deoxypyridinoline (nmol/mL) | 0.241 (0.900) | 0.235 (0.400) | 0.949 |
| Serum TRACP-5b (U/L) | 3.8 (2.5) | 2.2 (0.7) | 0.001 |
| Urinary hydroxyproline (µg/g creatinine) | 7.0 (4.5) | 4.0 (3.0) | 0.001 |
BLL had a significant negative correlation (ρ -0.128, p=0.041, Table 3) with serum level of osteocalcin and positive correlations with TRACP-5b (ρ 0.176, p=0.005) and UHYP (ρ 0.258, p=0.004).
| Table 3: Spearmen's correlation coefficient (ρ) between blood lead level (BLL) and bone turnover markers | |||||||
| Parameters | BLL | OC | ALP | BALP | PYD | DPYD | TRACP-5b |
| Osteocalcin (ng/mL) | -0.128* | 1 | |||||
| ALP (U/L) | -0.002 | -0.038 | 1 | ||||
| BALP (U/L) | 0.048 | 0.028 | 0.706† | 1 | |||
| Pyridinoline (ng/mL) | 0.051 | 0.063 | 0.004 | -0.013 | 1 | ||
| Deoxypyridinoline (nmol/mL) | 0.080 | 0.126* | 0.048 | -0.004 | 0.269† | 1 | |
| TRACP-5b (U/L) | 0.176† | -0.081 | 0.120 | 0.110 | -0.017 | -0.064 | 1 |
| UHYP (μg/g creatinine) | 0.258† | -0.091 | 0.068 | 0.101 | 0.003 | 0.028 | 0.265† |
|
*p<0.05; †p<0.01 BLL: Blood lead level; OC: Osteocalcin; ALP: Alkaline phosphatase; BALP: Bone-specific alkaline phosphatase; PYD: Pyridinoline; DPYD: Deoxypyridinoline; TRACP-5b: Tartarate-resistant acid phosphatase-5b; UHYP: Urinary hydroxyproline | |||||||
BMTs significantly varied with BLLs (Table 4). An increasing trend of bone resorption biomarkers such as PYD and DPYD was noticed with higher levels of BLL, however this was not statistically significant. The bone formation biomarkers, eg , BALP, and bone resorption biomarkers, namely, DPYD, TRACP-5b, and UHYP, were significantly associated with the duration of occupational exposure to lead.
| Table 4: Bone turnover markers levels in different groups of workers stratified by blood lead level and work experience (level of exposure) | |||||||||
| Independent variable | n | Bone formation biomarkers | Bone resorption biomarkers | ||||||
|
OC (ng/mL) |
ALP
(U/L) |
BALP (U/L) |
PYD
(ng/mL) |
DPYD
(nmol/mL) |
TRACP-5b (U/L) | UHYP (μg/g Cr) | |||
| Blood lead level (µg/dL) | |||||||||
| ≤15 | 51 | 16.6 (8.9) | 90 (26) | 37 (20) | 33 (15) | 0.237 (0.700) | 3.0 (2.0) | 5.0 (3.9) | |
| 16–25 | 76 | 16.6 (9.8) | 92 (23) | 40 (22) | 33 (17) | 0.253 (0.900) | 3.4 (2.3) | 5.8 (4.7) | |
| 26–35 | 58 | 14.2 (7.1) | 90 (26) | 41 (25) | 34 (14) | 0.239 (0.700) | 3.0 (2.0) | 5.3 (2.5) | |
| 36–45 | 40 | 12.9 (4.4) | 90 (28) | 41 (22) | 32 (10) | 0.234 (0.800) | 3.8 (2.5) | 7.8 (5.4) | |
| >45 | 31 | 18.5 (12.0) | 92 (34) | 41 (26) | 36 (17) | 0.239 (0.700) | 4.1 (2.2) | 5.4 (3.2) | |
| p value (ANOVA) | 0.040 | 0.982 | 0.897 | 0.841 | 0.446 | 0.052 | 0.015 | ||
| Exposure (yrs) | |||||||||
| ≤5 | 85 | 15.7 (4.7) | 88 (23) | 35 (14) | 31 (9) | 0.237 (0.400) | 2.5 (2.3) | 3.5 (2.4) | |
| 6–10 | 30 | 17.9 (11.0) | 99 (32) | 48 (30) | 36 (23) | 0.232 (0.700) | 4.1 (2.6) | 7.3 (7.0) | |
| 11–15 | 100 | 15.6 (11.0) | 92 (27) | 41 (26) | 35 (18) | 0.255 (0.900) | 3.8 (2.3) | 5.3 (5.0) | |
| >15 | 41 | 14.5 (9.4) | 89 (27) | 41 (23) | 34 (10) | 0.212 (0.700) | 3.4 (2.0) | 4.8 (4.0) | |
| p value (ANOVA) | 0.458 | 0.275 | 0.037 | 0.363 | 0.016 | <0.001 | 0.002 | ||
|
OC: Osteocalcin; ALP: Alkaline phosphatase; BALP: Bone-specific alkaline phosphatase; PYD: Pyridinoline; DPYD: Deoxypyridinoline; TRACP-5b: Tartarate-resistant acid phosphatase-5b; UHYP: Urinary hydroxyproline | |||||||||
Discussion
BLL is considered a reliable indicator of recent lead exposure.36 We found that the mean BLL in the study group was 1.6 times higher than that of the comparison group. A recent study also reports significantly higher BLLs in similar occupational group.37 BTM has been used for the assessment of early stage osteoporosis.38 Animal studies of lead intoxication have reported higher lead accumulation in osteoblast cultures,39 decreased bone density,40 delayed fracture healing,21 and increased BTMs41. The changes of bone formation and bone resorption markers lead to osteocalcin-dependent osteopenia.42
Workers with occupational exposure to lead have reported deteriorated bone mineral density and osteoporosis.26,27 General population with higher urinary lead levels has increased odds of osteopenia and osteoporosis.43 Potula, et al,24 reported significantly higher levels of bone resorption markers (UPYD and UDPYD) in women engaging in lead-smelting process. Sun, et al , also reported significant higher levels of BALP, OC and UHYP in lead-battery workers.29 In the current study, we noted a significantly higher bone formation and bone resorption markers in male workers with chronic exposed to lead in a lead-battery manufacturing plant.
An animal study indicated that long-term lead-exposure causes deterioration of bone microstructures.44 We found that the bone resorption biomarkers were significantly affected. Sun, et al , also reported a positive and significant association between BLL and bone biomarkers (OC, BALP, and UHYP) in lead-battery workers.29 We found that BLL had a significant negative correlation with osteocalcin and a significant positive correlation with TRACP-5b and UHYP. The bone formation biomarkers (eg , BALP) and bone resorption biomarkers (eg , DPYD, TRACP-5b, and UHYP) were significantly associated with the duration of exposure. In conclusion, long-term exposure to lead results in high BLLs and altered BTM.
Conflicts of Interest:
None declared.
Financial Support:
Indian Council of Medical Research (ICMR) has financially supported this study.
Cite this article as: Ravibabu K, Barman T, Bagepally BS. Assessment of bone turnover biomarkers in leadbattery workers with long-term exposure to lead. Int J Occup Environ Med 2020;11:140-147. doi: 10.34172/ijoem.2020.1951
References
- 1.Ibiebele DD. Air and blood lead levels in a battery factory. Sci Total Environ. 1994;152:269–73. doi: 10.1016/0048-9697(94)90317-4. [DOI] [PubMed] [Google Scholar]
- 2.Ravibabu K, Bagepally BS, Barman T. Association of musculoskeletal disorders and inflammation markers in workers exposed to lead (Pb) from Pb-battery manufacturing plant. Indian J Occup Environ Med. 2019;23:68–72. doi: 10.4103/ijoem.IJOEM_192_18. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Rerknimitr P, Kantikosum K, Chottawornsak N. et al. Chronic occupational exposure to lead leads to significant mucocutaneous changes in lead factory workers. J Eur Acad Dermatol Venereol. 2019;33:1993–2000. doi: 10.1111/jdv.15678. [DOI] [PubMed] [Google Scholar]
- 4.Qu W, Du GL, Feng B, Shao H. Effects of oxidative stress on blood pressure and electrocardiogram findings in workers with occupational exposure to lead. J Int Med Res. 2019;47:2461–70. doi: 10.1177/0300060519842446. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Kalahasthi R, Tapu B. Assessment of serum magnesium fractions in workers exposed to Pb from Pb-Battery plant. J Res Health Sci. 2018;18:e00430. [PMC free article] [PubMed] [Google Scholar]
- 6.Nouioui MA, Araoud M, Milliand ML. et al. Biomonitoring chronic lead exposure among battery manufacturing workers in Tunisia. Environ Sci Pollut Res Int. 2019;26:7980–93. doi: 10.1007/s11356-019-04209-y. [DOI] [PubMed] [Google Scholar]
- 7.Kalahasthi R, Barman T. Assessment of lead exposure and urinary-δ-aminolevulinic acid levels in male lead acid battery workers in Tamil Nadu, India. J Health Pollut. 2018;8:6–13. doi: 10.5696/2156-9614-8.17.6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Kalahasthi R, Barman T. Effect of lead exposure on the status of reticulocyte count indices among workers from lead battery manufacturing plant. Toxicol Res. 2016;32:281–7. doi: 10.5487/TR.2016.32.4.281. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Da Cunha Martins Jr A , Mazzaron Barcelos GR, Jacob Ferreira ALB. et al. Effects of Lead Exposure and Genetic Polymorphisms on ALAD and GPx Activities in Brazilian Battery Workers. J Toxicol Environ Health A. 2015;78:1073–81. doi: 10.1080/15287394.2015.1055527. [DOI] [PubMed] [Google Scholar]
- 10.Ravibabu K, Barman T, Rajmohan HR. Serum neuron-specific enolase, biogenic amino-acids and neurobehavioral function in lead-exposed workers from lead-acid battery manufacturing process. Int J Occup Environ Med. 2015;6:50–7. doi: 10.15171/ijoem.2015.436. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Chinde S, Kumari M, Devi KR. et al. Assessment of genotoxic effects of lead in occupationally exposed workers. Environ Sci Pollut Res Int. 2014;21:11469–80. doi: 10.1007/s11356-014-3128-9. [DOI] [PubMed] [Google Scholar]
- 12.Barman T, Kalahasthi R, Rajmohan HR. Effects of lead exposure on the status of platelet indices in workers involved in a lead-acid battery manufacturing plant. J Expo Sci Environ Epidemiol. 2014;24:629–33. doi: 10.1038/jes.2014.4. [DOI] [PubMed] [Google Scholar]
- 13.Ahmad SA, Khan MH, Khandker S. et al. Blood lead levels and health problems of lead acid battery workers in Bangladesh. ScientificWorldJournal. 2014:974104. doi: 10.1155/2014/974104. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Kalahasthi RB, Barman T, Rajmohan HR. The relationship between blood lead levels and morbidities among workers employed in a factory manufacturing lead-acid storage battery. Int J Environ Health Res. 2014;24:246–55. doi: 10.1080/09603123.2013.809702. [DOI] [PubMed] [Google Scholar]
- 15.Sadeghniat Haghighi K, Aminian O. et al. Relationship between blood lead level and male reproductive hormones in male lead exposed workers of a battery factory: A cross-sectional study. Iran J Reprod Med. 2013;11:673–6. [PMC free article] [PubMed] [Google Scholar]
- 16.Ekinci M, Ceylan E, Cagatay HH. et al. Occupational exposure to lead decreases macular, choroidal, and retinal nerve fiber layer thickness in industrial battery workers. Curr Eye Res. 2014;39:853–8. doi: 10.3109/02713683.2013.877934. [DOI] [PubMed] [Google Scholar]
- 17.Malekirad AA, Kalantari-Dehaghi R, Abdollahi M. Clinical, hematological, and neurocognitive findings in lead-exposed workers of a battery plant in Iran. Arh Hig Rada Toksikol. 2013;64:497–503. doi: 10.2478/10004-1254-64-2013-2385. [DOI] [PubMed] [Google Scholar]
- 18.Dongre NN, Suryakar AN, Patil AJ. et al. Biochemical Effects of Lead Exposure on Battery Manufacture Workers with Reference to Blood Pressure, Calcium Metabolism and Bone Mineral Density. Indian J Clin Biochem. 2013;28:65–70. doi: 10.1007/s12291-012-0241-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Fernandes TAP, Goncalves LML, Brito JAA. Relationships between Bone Turnover and Energy Metabolism. Journal of Diabetes Research. 2017 doi: 10.1155/2017/9021314. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Pemmer B, Roschger A, Wastl A. et al. Spatial distribution of the trace elements zinc, strontium and lead in human bone tissue. Bone. 2013;57:184–93. doi: 10.1016/j.bone.2013.07.038. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Haleagrahara N, Chakravarthi S, BangraKulur A, Radhakrishnan A. Effects of chronic lead acetate exposure on bone marrow lipid peroxidation and antioxidant enzyme activities in rats. Afr J Pharm Pharmacol. 2011;5:923–9. [Google Scholar]
- 22.Rodriguez J, Mandalunis PM. A review of metal exposure and its effects on bone health. Journal of Toxicology. 2018 doi: 10.1155/2018/4854152. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Nelson AE, Chaudhary S, Kraus VB. et al. Whole blood lead levels are associated with biomarkers of joint tissue metabolism in African American and white men and women: the Johnston County Osteoarthritis Project. Environ Res. 2011;111:1208–14. doi: 10.1016/j.envres.2011.08.002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Potula V, Henderson A, Kaye W. Calcitropic hormones, bone turnover, and lead exposure among female smelter workers. Arch Environ Occup Health. 2005;60:195–204. doi: 10.3200/AEOH.60.4.195-204. [DOI] [PubMed] [Google Scholar]
- 25.Raafat BM, Hassan NS, Aziz SW. Bone mineral density (BMD) and osteoporosis risk factor in Egyptian male and female battery manufacturing workers. Toxicol Ind Health. 2012;28:245–52. doi: 10.1177/0748233711410912. [DOI] [PubMed] [Google Scholar]
- 26.Sun Y, Jin TY, Sun DH. et al. [Effects of occupational lead exposure on bone mineral density and bone metabolism in workers. ] Zhonghua Lao Dong Wei Sheng Zhi Ye Bing ZaZhi. 2007;25:25762. [in Chinese]. [PubMed] [Google Scholar]
- 27.Akbal A, Tutkun E, Yılmaz H. Lead exposure is a risk for worsening bone mineral density in middle-aged male workers. Aging Male. 2014;17:189–93. doi: 10.3109/13685538.2013.836482. [DOI] [PubMed] [Google Scholar]
- 28.Sun Y, Sun D, Zhou Z. et al. Osteoporosis in a Chinese population due to occupational exposure to lead. Am J Ind Med. 2008;51:436–42. doi: 10.1002/ajim.20567. [DOI] [PubMed] [Google Scholar]
- 29.Sun Y, Sun D, Zhou Z. et al. Estimation of benchmark dose for bone damage and renal dysfunction in a Chinese male population occupationally exposed to lead. Ann Occup Hyg. 2008;52:527–33. doi: 10.1093/annhyg/men031. [DOI] [PubMed] [Google Scholar]
- 30.Mason HJ, Evans G, Moore A. Urinary biomarkers and occupational musculoskeletal disorders in the lower limbs. Occup Med (Lond) 2011;61:341–8. doi: 10.1093/occmed/kqr108. [DOI] [PubMed] [Google Scholar]
- 31.Kuiper J, Verbeek J, Everts V. et al. Serum markers of collagen metabolism: construction workers compared to sedentary workers. Occup Environ Med. 2005;62:363–7. doi: 10.1136/oem.2004.016998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Tietz NW, Burtis CA, Duncan P. et al. A reference method for measurement of alkaline phosphatase activity in human serum. Clin Chem. 1983;29:751–61. [PubMed] [Google Scholar]
- 33.Roudsari JM, Mahjoub S. Quantification and comparison of bone-specific alkaline phosphatase with two methods in normal and Paget's specimens. Caspian J Intern Med. 2012;3:478–83. [PMC free article] [PubMed] [Google Scholar]
- 34.Sarvari BKD, Sankara Mahadev D, Rupa S, Mastan SA. Study of serum TRACP 5b as a sensitive and specific bone resorption marker of bone metastases in prostate cancer patients in comparison with bone scintigraphy. International Journal of Scientific & Engineering Research. 2013;4:420–6. [Google Scholar]
- 35.Neuman RE, Logan MA. The Determination of Hydroxyproline. J Biol Chem. 1950;184:299–306. [PubMed] [Google Scholar]
- 36.Barbosa Jr F, Tanus-Santos JE, Gerlach RF, Parsons PJ. A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations, and future needs. Environ Health Perspect. 2005;113:1669–74. doi: 10.1289/ehp.7917. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Sudjaroen Y, Suwannahong K. Biomarker related lead exposure of industrial battery's workers. Ann Trop Med Public Health. 2017;10:194–8. [Google Scholar]
- 38.Kuo TR, Chen CH. Bone biomarker for the clinical assessment of osteoporosis: recent developments and future perspectives. Biomark Res. 2017;5:18. doi: 10.1186/s40364-017-0097-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Paisrisarn P, Tepaamorndech S, Khongkow M. et al. Alterations of mineralized matrix by lead exposure in osteoblast (MC3T3-E1) culture. Toxicology Lett. 2018;299:172–81. doi: 10.1016/j.toxlet.2018.10.008. [DOI] [PubMed] [Google Scholar]
- 40.de Figueiredo FA, Gerlach RF, da Veiga MA. et al. Reduced bone and body mass in young male rats exposed to lead. Biomed Res Int. 2014;2014:571065. doi: 10.1155/2014/571065. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 41.Monir AU, Gundberg CM, Yagerman SE. et al. The effect of lead on bone mineral properties from female adult C57/BL6 mice. Bone. 2010;47:888–94. doi: 10.1016/j.bone.2010.07.013. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 42.Brito JAA, Costa IM, Silva AME. et al. Changes in bone Pb accumulation: cause and effect of altered bone turnover. Bone. 2014;64:228–34. doi: 10.1016/j.bone.2014.04.021. [DOI] [PubMed] [Google Scholar]
- 43.Tsai TL, Pan WH, Chung YT. et al. Association between urinary lead and bone health in a general population from Taiwan. J Expo Sci Environ Epidemiol. 2016;26:481–7. doi: 10.1038/jes.2015.30. [DOI] [PubMed] [Google Scholar]
- 44.Sheng Z, Wang S, Zhang X. et al. Long-Term Exposure to Low-Dose Lead Induced Deterioration in Bone Microstructure of Male Mice. Biol Trace Elem Res. 2019;2:1–8. doi: 10.1007/s12011-019-01864-7. [DOI] [PubMed] [Google Scholar]