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Indian Journal of Occupational and Environmental Medicine, Vol. 11, No. 1, January-April, 2007, pp. 6-8 Original Article Lead exposure and hair lead level of workers in a lead refinery industry in Iran Azimi Pirsaraei SeyedReza Department of Occupational Health, Zanjan University of Medical Sciences, Faculty of Health and Paramedical Sciences, Parvin Etesaami Street, 45158, Zanjan city Code Number:oe07003 Abstract This study was carried out on the workers of a lead refinery industry and two control groups in Zanjan city in Iran. The scalp hair samples were collected from 25 workers who were occupationally exposed to lead contamination as a case group and from 25 subjects among the staff of the same industry and 25 subjects among Zanjan citizens as the first and second control groups respectively. A flame atomic absorption spectrophotometer used to determine lead level in all of the samples. The age of all subjects in the three groups was matched. The mean concentrations of hair lead in the workers (case group), the staff (control groupA) and the citizens (control group B) were 131.7±93.4 µgr/gr, 21.1±13.2 µgr/gr and 27.9±14.1 µgr/gr respectively. The mean concentration of hair lead in the case group was more than hair lead of normal range found in humans (0-30 µgr/gr). The mean of hair lead level in the citizens who had used gas vehicles was statistically higher than who had not used it (36.9±12.2 µgr/gr vs. 16.6±4.9 µgr/gr, P <0.001).Keywords: Hair lead level, lead, occupationally exposure, refinery industry, workers exposure Introduction Lead is a heavy metal and toxic for human. However, it is a useful metal in industry and is still being utilized in various industries in Iran, for example, in battery manufacturing factories, in producing of lead bullets and is used as a smelter metal for purifying gold and silver. Thus, the workers who work in such workplaces, especially in lead refinery industry, are easily exposed to the dusts or fumes of lead. Zanjan city in Iran has a few lead and zinc mines. A lead refinery factory was established adjacent to the Zanjan city for purifying the concentrated lead ores and producing the lead bullions. The workers who worked in several plants of this factory were exposed to lead fumes, especially in the refinery furnace plant. Although, urine lead and blood lead levels also urine coproporphyrine level are important indices for distinguishing lead poisoning, some of workers have not desired to introducing these samples. Since lead can be distributed in soft tissues (e.g., bone marrow, liver, renal and muscles) and highly cumulated in teeth, nail and hair, [1],[2],[3] therefore hair analyzing and determining its lead level could be an adequate biological index for evaluating the history of worker exposure to lead. [4] In addition, it would be short term, inexpensive and like a noninvasive method and the workers would not object to give hair samples (result of abuse drugs or alcohol consumption etc.). [5] The object of this study was the relationship between working in the lead refinery factory and hair lead level.Materials and Methods This study was conducted in a lead refinery industry in Zanjan city, Iran. It has produced lead bullions for several years and up to one hundred employees worked there. Thus, 25 workers were included in the study as a case group. Twenty-five subjects as a control A group were selected from the staff of the same plant and 25 subjects selected from Zanjan citizens as a control B group. These two control groups had not been occupationally exposed to lead. The hair samples were collected from the occipital region of the scalp and the proximal centimeter taken for analysis. One hundred milligrams of hair samples were weighed and placed in Teflon beakers and washed successively with magnetic stirring for 10 min in 125 ml portions of acetone, water, water, water and acetone. [6],[7] The washed samples were allowed to dry at 50°c for one hour. After this time, the samples were weighed into digestion vessels and treated with 3 ml of acid mixture made from 5 parts concentrated nitric acid (65%) and 1 part of concentrated perchloric acid (70%). The digestion vessels were closed and placed in an oven maintained at 150°c for one hour. Then the contents of digestion vessels were transferred to polypropylene volumetric flasks and diluted to 10 ml with high purity distilled water. [6],[7],[8],[9] For determining the lead, triplicate 1 ml injections were made from each flask into the flame atomic absorption spectrophotometer method using a shimadzu AA- 670/GV-8 model (the flame was made from acetylene- air). Also this method was used for analyzing the hair samples of the two control groups. A questionnaire was completed for all subjects in this research reason for identifying the nonoccupational confounding factors, which contained the following points: age, cigarette-smoking habit (smoker, nonsmoker), hair color, using the gas vehicle or not and working life. Statistical analysis of the data was based on the calculation of the mean, standard deviation and range. The differences between the means were compared using Student's t test and Mann Whitney non-parametric test. The statistics analysis was done using the statistical program SPSS Windows Version 9 Statistical Software.Results The 25 workers (case group); 25 staff personnel (control A group) from the same lead refinery industry; and 25 subjects from Zanjan citizens (control B group) were matched by sex, age and working life. All of subjects in this research were male. The subjects mean age in case group; control A group and control B group were 36.7 yrs ± 6.5; 35 yrs ± 4.8 and 34.2 yrs ± 5.1 respectively and there was not significantly different (P>0.05). The subjects mean working life in case group; control A group and control B group were 6.8 yrs ± 3.3; 7 yrs ± 3.8 and 8 yrs ± 4.2 respectively and there was not significantly different (P>0.05). The main characteristics of studied groups are shown in [Table - 1]. The mean hair lead level in the workers was 131.7± 93.4 µgr/gr; the staff was 21.1 ± 13.2 µgr/gr and Zanjan citizens was 27.9 ± 14.1 µgr/gr. The Mann Whitney non-parametric test has shown that is significantly different in the mean hair lead level of the case group and the control groups (P< 0.001), also the mean hair lead level in the control A group and the control B group was significantly different (P< 0.05). The results are shown in [Table - 2]. The significantly different was not in mean hair lead level in the case group and the control A group according to hair color (P>0.05), but in the control B group was found the statistical significance of the difference among colors (P=0.0213). With respect to smoking habit in the groups was not found significantly difference in its hair lead level (P>0.05). The statistical analysis was indicated significantly different in mean hair lead level in the control B group according to using gas vehicles (P=0.002), but not found in others studied groups (P>0.05). The results are presented in [Table - 3].Discussion From these data, it is clear that the mean hair lead level in the case group was higher than in compared with the others groups (6.2 times the staffs and 4.7 times Zanjan citizens). Since the normal value of lead in hair is defined 0%30 µgr/gr, (the range is variable according to diet etc.), [10] this study indicated that the mean hair lead level in the workers who worked in this lead refinery factory increased from the normal range however, the lower hair lead value was found 38.6 µgr/gr. Although the mean hair lead level in the control A group and control B group was 21.13 µgr/gr and 27.92 µgr/gr respectively and is in the normal range (0-30 µgr/gr), the statistical significantly different was found as (P< 0.05). The upper hair lead values was 61.56 µgr/gr and 60.2 µgr/gr respectively, that may be results from environmental air pollutants or diet styles or using the gas vehicles so as it requires the comprehensive researches. Also, the mean hair lead level in the subjects of the control A group and the control B group that was been using the gas vehicle was more than those not using it. The mean hair lead level was 23.4 µgr/gr ± 15.6 and 36.9 µgr/gr ± 12.2 versus 17.8 µgr/gr ± 7.9 and 16.6 µgr/gr ± 4.9 respectively. The statistical significantly different was found (P< 0.0001) and this difference may be a result of the citizens travelling through gas vehicle traffic and air pollution in Zanjan city. Zaborwska et al [11] reported the mean hair lead level was 17.5, 25.7 and 29 µgr/gr respectively in three selected workers groups and the mean hair lead level in the control group was 4.2 µgr/gr. Niculescu et al. [12] indicated that the lead content of hair in workers occupationally exposed was correlated with the blood lead concentration. In their research, two groups of male workers with differing occupational experience were studied: group 1 comprised 31 subjects exposed to high concentrations of lead in air and group 2, 33 subjects with low exposure and the control group with 10 men who were never exposed to lead. A significant correlation was observed between the blood lead and hair lead concentrations and a regression analysis showed an exponential accumulation of the lead content in hair, simultaneously with the increase of the values in blood. The color of the hair and age of the subjects did not influence the lead accumulation in hair in the occupationally exposed subjects. The finding of the present study (in the case group and the control A group) is also corresponded with that research but in the control B group significant difference was found (P< 0.05) according to color of the hair. In the other study, Schahmacher et al. [13] showed that in Tarragona state citizens in Spain (from 1990 to 1995) the mean blood and hair lead level decreased from 12 µgr/dlit to 6.3 µgr/dlit in blood and from 8.8 µgr/gr to 4.1 µgr/gr in the hair respectively. Its loss resulted from the lead content limitation and decreasing in gas. Burguera et al. [7] determined the hair lead level in gas stations workers and a control group. The mean hair lead level was 48.7 µgr/gr ± 17.5 in the workers and 17.2 µgr/gr ± 8.1 in the control group. Also in his research, the relationship between the lead concentration in hair and hair color, washing and digestion methods, smoking habits and time duration exposure to lead air contamination was studied. That study found that the mean hair lead level in the control group was in the normal range (0-30 µgr/gr) whereas the mean hair lead level in gas station workers was beyond the normal range. Conclusion The spite of fact that the presence a lead refinery industry in adjacent Zanjan city (up to 15 km far from there), the findings this research indicated that the mean hair lead level in the staff and Zanjan citizens was in the normal range (0-30 µgr/gr), however the minimum of the hair lead level in the workers who were occupationally exposed to lead was found to be 38.6 µgr/gr that higher than the normal range. Thus, working in such workplaces in which the air was contaminated with lead and workers occupationally exposed could have increased the hair lead level. It seems that the determination of lead in hair is considered as a useful screening test in estimating occupational exposure and is a short-term, inexpensive and non-invasive method.Acknowledgements The author is grateful to the managers, their staff and all the workers of the lead refinery industry in Zanjan, Iran for providing necessary facilities and their valuable cooperation for this study. My thanks is due to Mr. Khavanin Ali, Mr. Asilian Hassan, Mr. Soleimanian Ardalan, Occupational Hygiene Department, Tarbiat Modarres University. This study was supported by funds from the research assistant of Zanjan University Medical Sciences.References
Copyright 2007 - Indian Journal of Occupational and Environmental Medicine The following images related to this document are available:Photo images[oe07003t2.jpg] [oe07003t3.jpg] [oe07003t1.jpg] |
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