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Determination of the elemental composition of aerosol samples in the working environment of a secondary lead smelting company in Nigeria using EDXRF technique
Nuclear Instruments and Methods in Physics Research B 194 (2002) 65–68 www.elsevier.com/locate/nimb
Determination of the elemental composition of aerosol samples in the working environment of a secondary lead smelting company in Nigeria using EDXRF technique E.I. Obiajunwa a
a,*
, F.O. Johnson-Fatokun a, H.B. Olaniyi b, A.F. Olowole
b
Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria b Department of Physics, Obafemi Awolowo University, Ile-Ife, Nigeria Received 11 September 2001; received in revised form 11 December 2001
Abstract Energy dispersive X-ray fluorescence technique was employed to determine the concentrations of elements in aerosol samples collected in the working environment of a secondary lead smelting company in Nigeria. Sampling was done using Whatman-41 cellulose filters mounted in Negretti air samplers at 10 locations within the factory. The concentrations of eight elements (K, Ca, Ti, Mn, Fe, Cu, Zn and Pb) were determined. The TSP values ranged from 70 to 7963 lg/m3 and the concentration of Pb was found to be between 2.98 and 538.47 lg/m3 . The high Pb concentration is a danger signal to the health of the factory workers. Ó 2002 Published by Elsevier Science B.V.
1. Introduction Environmental pollution and air quality studies have gained increasing attention both nationally and internationally in the last ten years. International and national agencies are setting up standards and regulations to minimise the man-made contributions to environmental pollution. However in a developing country such as Nigeria, where industrialisation is being encouraged, and with the establishment of many cottage industries, strict regulations for environmental and personnel
*
Corresponding author. Tel.: +234-36-233638; fax: +234-36232975. E-mail address: [email protected] (E.I. Obiajunwa).
protection are not rigorously enforced. Some industries with potentially hazardous emissions are sometimes located in residential areas. Previous studies in cement industries in Nigeria [1] and in the working environment of goldsmiths in Nigeria [2] have high-lighted the need for regular periodic monitoring of the working environment of industries/factories in the country for the purpose of environmental monitoring and protection. In this study we turn our searchlight to the working environment of a secondary lead smelting factory (an automobile battery manufacturing company). In this paper, we report the concentrations of the total suspended particulate matter as well as the elemental composition of aerosol samples collected in this working environment.
0168-583X/02/$ - see front matter Ó 2002 Published by Elsevier Science B.V. PII: S 0 1 6 8 - 5 8 3 X ( 0 2 ) 0 0 5 0 0 - 1
66
E.I. Obiajunwa et al. / Nucl. Instr. and Meth. in Phys. Res. B 194 (2002) 65–68
2. Materials and methods Aerosol sampling: Aerosol sampling in the working environment of a secondary lead smelting factory (an automobile battery manufacturing company located in Lagos metropolis) was carried out using Negretti air samplers and Whatman-41 filters. The filters were first left in a desiccator for 24 h and then weighed. Each of the weighed filters was put in labelled plastic bag and sealed. Ten different locations in the factory where workers spent most of their day were mapped out for sampling. Air particulate samples were collected from these locations with the aid of the Negretti samplers fitted with filter holders and the pre-weighed filters. The samplers were operated at flow rates of between 8 and 9 l/min, for between 1and 6 h during the working hours of the factory and when battery production was in progress. The samplers were strategically located to be regarded as a worker inhaling the air in the working environment. After the sampling in the factory, the exposed filters were weighed again after reconditioning in a desiccator for 24 h to determine the weight of particulate matter deposited on the filters for the duration of the sampling. The filters were analysed using a tube-excited energy dispersive X-ray fluorescence (EDXRF) spectrometer with a Mo anode. This equipment
has being described elsewhere [3,4] and runs under quantitative X-ray analysis system (QXAS) [5], which includes facilities for data acquisition, spectrum analysis and interpretation and quantitative analysis. The filters were mounted on sample holders and each filter was irradiated for 10 min at fixed tube operating conditions of 25 kV and 10 mA. The unfiltered Mo–Ka;b excitation allows determination of elements with characteristic K- or L-lines in the energy range 3.3–16 keV. A parameterless smooth-filter model in the AXIL program of the QXAS package was used for fitting the spectra over the energy region of interest. The conversions from peak areas to filter concentrations per unit area were obtained by running Micromatter calibration standard filters just before and immediately after running the aerosol filters. These standard filters with known elemental concentrations deposited on them were purchased from Micromatter Co., USA. We used K, Ca, Fe, Pb and Sr for our calibration.
3. Results and discussion The total suspended particulate matter (TSP) concentration measured at different locations in the factory are shown in Table 1. The TSP concentration at the factory gate was 219 lg/m3 and
Table 1 TSP concentration (lg/m3 ) measured in the factory Sampling location/site code
Vol. of air (m3 )
TSP
TSP/250
Opening space at the factory gate/AB12
2.736
219
0.876
Offices with factory Personnel Manager (air-conditioned)/AB 09 Stem/Store Keeper’s (air-conditioned)/AB 11 Production Manager’s (not air-conditioned)/AB 07 Foreman’s (not air-conditioned)/AB 08
2.84 2.178 2.84 2.565
70 138 141 273
0.28 0.552 0.56 1.092
2.32 2.88 1.62 0.54 2.136
1810 1458 741 7963 468 Annual 60–90 250
Factory production line Small parts section/AB 13 Assembly point/AB 30 Pasting section/AB 06 Oxide collection point/AB 02 Assembly finishing line/AB 05 Ambient air quality standard WHO FEPA
7.24 5.832 2.964 31.853 1.872
E.I. Obiajunwa et al. / Nucl. Instr. and Meth. in Phys. Res. B 194 (2002) 65–68
67
Table 2 Elemental concentrations (lg/m3 ) of aerosol samples in the working environment of a secondary lead smelting company Site code AB AB AB AB AB AB AB AB AB AB
02 05 06 07 08 09 11 12 13 30
Elements K
Ca
Ti
Mn
Fe
Cu
Zn
Pb
ND 5.265 ND ND ND ND ND 1.470 2.889 ND
11.685 29.662 6.445 1.609 0.689 0.885 3.470 8.635 17.435 0.847
ND 1.361 ND ND ND 1.108 ND ND 0.792 ND
ND 1.212 0.149 ND ND 0.133 ND 0.140 0.368 ND
12.159 39.256 15.230 2.802 0.875 2.122 6.225 10.130 22.343 1.180
5.047 18.691 2.610 1.243 1.076 ND ND ND ND ND
4520 4.506 2.152 1.070 ND ND 1.657 0.946 ND ND
538.469 70.201 249.722 16.779 53.160 48.013 4.243 2.983 13.746 172.216
ranged from 70 to 273 lg/m3 in offices within the factory, and 468–7963 lg/m3 at various sections of the factory production line. These TSP values for the factory production line are about 2–32 times the annual average of 250 lg/m3 [6] set by the national environmental regulatory agency, the Federal Environmental Protection Agency (FEPA). The situation becomes even more serious if the World Health Organization (WHO) standard of 60–90 lg/m3 annual average is used for the comparison. The results of the EDXRF analysis of the filters are shown in Table 2. Ca, Fe and Pb were detected in all the ten samples with concentration ranges (0.689–29.662), (0.875–39.256) and (2.983– 538.469) lg/m3 , respectively. Zn (0.946 4.520) lg/m3 was detected in six samples while Mn (0.133–1.212) lg/m3 and Cu (1.076–5.047) lg/m3 were detected in five samples. Ti (0.792–1.361) lg/m3 and K (1.470–5.265) lg/m3 were detected in three samples. Of all the trace elements detected, Pb is of primary interest in this study. Firstly Pb is a major raw material in the factory of study and secondly and more importantly, the toxic effects of lead are well known [7,8]. Although the Federal Environmental Protection Authority (FEPA) at present does not have a standard value for occupational exposure to Pb, it has specified the ambient air tolerance limit of 5 lg/m3 for Pb [6]. The WHO and European Union (EU) limits are 1.5 and 2 lg/m3 , respectively. Comparing the WHO and EU standard
limits with Pb concentrations at various sampled locations in the factory (Table 2), it was found that they all exceeded these limits by factors ranging from (2 to 359) times for WHO limit and (1.5–269) for EU limit. When compared to the FEPA ambient tolerance limit of 5 lg/m3 , only two locations (gate and store keeper’s office) were within this limit. All the other locations exceeded the FEPA limit by factors ranging from (2.7 to 107). These values are quite alarming, and more so given the fact that there are workers constantly at these locations each time the factory is running. More worrisome is the fact that many of the workers seem not to understand or appreciate the risk/ danger involved. Many do not use the nose masks and management were not seen to be insistent on their workers adhering to this safety rule. Analysis of blood samples of workers in the factory would have provided a clear evidence of the Pb levels in their blood and the risk these workers were been exposed to, but the company’s management did not allow blood samples to be taken from their workers.
4. Conclusion The EDXRF technique was used to determine the elemental concentrations of aerosol samples collected in the working environment of a secondary lead smelting company. The TSP concentrations at different locations within the factory exceeded the annual average set by the national
68
E.I. Obiajunwa et al. / Nucl. Instr. and Meth. in Phys. Res. B 194 (2002) 65–68
regulatory agency, FEPA, by factors ranging from 2 to 32 times. The elemental concentrations of Pb in the aerosol samples were particularly high, exceeding FEPAs ambient tolerance limit by factors ranging from 2.7 to 107 times. The health risk is very high and should be investigated. We strongly recommend a regular monitoring of this and similar factories to ensure compliance to set operational standards. References [1] F.A. Akeredolu, H.B. Olaniyi, J.A. Adejumo, I.B. Obioh, O.J. Ogunsola, O.I. Asubiojo, A.F. Oluwole, Nucl. Instr. and Meth. A 353 (1994) 542.
[2] C.A. Adesanmi, F.I. Ibitoye, S.A. Owolabi, A.A. Oladipo, F.A. Balogun, I.A. Tubosun, J. Environ. Syst. 25 (1997) 303. [3] J.I. Nwachukwu, E.I. Obiajunwa, I.B. Obioh, Petro. Geochem. Exploit. Afro-Asian Region, Proc. 5th Int. Conf. and Exbn., 2000, p. 139. [4] E.I. Obiajunwa, Nucl. Instr. and Meth. B 184 (2001) 437. [5] QXAS (Quantitative X-Ray Analysis System) Users Manual, International Atomic Energy Agency (IAEA), Vienna, 1993. [6] Guidelines and Standards for Environmental Protection Control in Nigeria, Federal Environmental Protection Agency (FEPA), 1991. [7] S.M. Pier, K.M. Bang, in: N.M. Trieff (Ed.), Environment and Health, Ann Arbor Science Inc., Ann Arbor, MI, 1980, p. 384. [8] C.M. Romo-Kroger, International Journal of PIXE 6 (1996) 311.
Determination of the elemental composition of aerosol samples in the working environment of a secondary lead smelting company in Nigeria using EDXRF technique E.I. Obiajunwa a
a,*
, F.O. Johnson-Fatokun a, H.B. Olaniyi b, A.F. Olowole
b
Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria b Department of Physics, Obafemi Awolowo University, Ile-Ife, Nigeria Received 11 September 2001; received in revised form 11 December 2001
Abstract Energy dispersive X-ray fluorescence technique was employed to determine the concentrations of elements in aerosol samples collected in the working environment of a secondary lead smelting company in Nigeria. Sampling was done using Whatman-41 cellulose filters mounted in Negretti air samplers at 10 locations within the factory. The concentrations of eight elements (K, Ca, Ti, Mn, Fe, Cu, Zn and Pb) were determined. The TSP values ranged from 70 to 7963 lg/m3 and the concentration of Pb was found to be between 2.98 and 538.47 lg/m3 . The high Pb concentration is a danger signal to the health of the factory workers. Ó 2002 Published by Elsevier Science B.V.
1. Introduction Environmental pollution and air quality studies have gained increasing attention both nationally and internationally in the last ten years. International and national agencies are setting up standards and regulations to minimise the man-made contributions to environmental pollution. However in a developing country such as Nigeria, where industrialisation is being encouraged, and with the establishment of many cottage industries, strict regulations for environmental and personnel
*
Corresponding author. Tel.: +234-36-233638; fax: +234-36232975. E-mail address: [email protected] (E.I. Obiajunwa).
protection are not rigorously enforced. Some industries with potentially hazardous emissions are sometimes located in residential areas. Previous studies in cement industries in Nigeria [1] and in the working environment of goldsmiths in Nigeria [2] have high-lighted the need for regular periodic monitoring of the working environment of industries/factories in the country for the purpose of environmental monitoring and protection. In this study we turn our searchlight to the working environment of a secondary lead smelting factory (an automobile battery manufacturing company). In this paper, we report the concentrations of the total suspended particulate matter as well as the elemental composition of aerosol samples collected in this working environment.
0168-583X/02/$ - see front matter Ó 2002 Published by Elsevier Science B.V. PII: S 0 1 6 8 - 5 8 3 X ( 0 2 ) 0 0 5 0 0 - 1
66
E.I. Obiajunwa et al. / Nucl. Instr. and Meth. in Phys. Res. B 194 (2002) 65–68
2. Materials and methods Aerosol sampling: Aerosol sampling in the working environment of a secondary lead smelting factory (an automobile battery manufacturing company located in Lagos metropolis) was carried out using Negretti air samplers and Whatman-41 filters. The filters were first left in a desiccator for 24 h and then weighed. Each of the weighed filters was put in labelled plastic bag and sealed. Ten different locations in the factory where workers spent most of their day were mapped out for sampling. Air particulate samples were collected from these locations with the aid of the Negretti samplers fitted with filter holders and the pre-weighed filters. The samplers were operated at flow rates of between 8 and 9 l/min, for between 1and 6 h during the working hours of the factory and when battery production was in progress. The samplers were strategically located to be regarded as a worker inhaling the air in the working environment. After the sampling in the factory, the exposed filters were weighed again after reconditioning in a desiccator for 24 h to determine the weight of particulate matter deposited on the filters for the duration of the sampling. The filters were analysed using a tube-excited energy dispersive X-ray fluorescence (EDXRF) spectrometer with a Mo anode. This equipment
has being described elsewhere [3,4] and runs under quantitative X-ray analysis system (QXAS) [5], which includes facilities for data acquisition, spectrum analysis and interpretation and quantitative analysis. The filters were mounted on sample holders and each filter was irradiated for 10 min at fixed tube operating conditions of 25 kV and 10 mA. The unfiltered Mo–Ka;b excitation allows determination of elements with characteristic K- or L-lines in the energy range 3.3–16 keV. A parameterless smooth-filter model in the AXIL program of the QXAS package was used for fitting the spectra over the energy region of interest. The conversions from peak areas to filter concentrations per unit area were obtained by running Micromatter calibration standard filters just before and immediately after running the aerosol filters. These standard filters with known elemental concentrations deposited on them were purchased from Micromatter Co., USA. We used K, Ca, Fe, Pb and Sr for our calibration.
3. Results and discussion The total suspended particulate matter (TSP) concentration measured at different locations in the factory are shown in Table 1. The TSP concentration at the factory gate was 219 lg/m3 and
Table 1 TSP concentration (lg/m3 ) measured in the factory Sampling location/site code
Vol. of air (m3 )
TSP
TSP/250
Opening space at the factory gate/AB12
2.736
219
0.876
Offices with factory Personnel Manager (air-conditioned)/AB 09 Stem/Store Keeper’s (air-conditioned)/AB 11 Production Manager’s (not air-conditioned)/AB 07 Foreman’s (not air-conditioned)/AB 08
2.84 2.178 2.84 2.565
70 138 141 273
0.28 0.552 0.56 1.092
2.32 2.88 1.62 0.54 2.136
1810 1458 741 7963 468 Annual 60–90 250
Factory production line Small parts section/AB 13 Assembly point/AB 30 Pasting section/AB 06 Oxide collection point/AB 02 Assembly finishing line/AB 05 Ambient air quality standard WHO FEPA
7.24 5.832 2.964 31.853 1.872
E.I. Obiajunwa et al. / Nucl. Instr. and Meth. in Phys. Res. B 194 (2002) 65–68
67
Table 2 Elemental concentrations (lg/m3 ) of aerosol samples in the working environment of a secondary lead smelting company Site code AB AB AB AB AB AB AB AB AB AB
02 05 06 07 08 09 11 12 13 30
Elements K
Ca
Ti
Mn
Fe
Cu
Zn
Pb
ND 5.265 ND ND ND ND ND 1.470 2.889 ND
11.685 29.662 6.445 1.609 0.689 0.885 3.470 8.635 17.435 0.847
ND 1.361 ND ND ND 1.108 ND ND 0.792 ND
ND 1.212 0.149 ND ND 0.133 ND 0.140 0.368 ND
12.159 39.256 15.230 2.802 0.875 2.122 6.225 10.130 22.343 1.180
5.047 18.691 2.610 1.243 1.076 ND ND ND ND ND
4520 4.506 2.152 1.070 ND ND 1.657 0.946 ND ND
538.469 70.201 249.722 16.779 53.160 48.013 4.243 2.983 13.746 172.216
ranged from 70 to 273 lg/m3 in offices within the factory, and 468–7963 lg/m3 at various sections of the factory production line. These TSP values for the factory production line are about 2–32 times the annual average of 250 lg/m3 [6] set by the national environmental regulatory agency, the Federal Environmental Protection Agency (FEPA). The situation becomes even more serious if the World Health Organization (WHO) standard of 60–90 lg/m3 annual average is used for the comparison. The results of the EDXRF analysis of the filters are shown in Table 2. Ca, Fe and Pb were detected in all the ten samples with concentration ranges (0.689–29.662), (0.875–39.256) and (2.983– 538.469) lg/m3 , respectively. Zn (0.946 4.520) lg/m3 was detected in six samples while Mn (0.133–1.212) lg/m3 and Cu (1.076–5.047) lg/m3 were detected in five samples. Ti (0.792–1.361) lg/m3 and K (1.470–5.265) lg/m3 were detected in three samples. Of all the trace elements detected, Pb is of primary interest in this study. Firstly Pb is a major raw material in the factory of study and secondly and more importantly, the toxic effects of lead are well known [7,8]. Although the Federal Environmental Protection Authority (FEPA) at present does not have a standard value for occupational exposure to Pb, it has specified the ambient air tolerance limit of 5 lg/m3 for Pb [6]. The WHO and European Union (EU) limits are 1.5 and 2 lg/m3 , respectively. Comparing the WHO and EU standard
limits with Pb concentrations at various sampled locations in the factory (Table 2), it was found that they all exceeded these limits by factors ranging from (2 to 359) times for WHO limit and (1.5–269) for EU limit. When compared to the FEPA ambient tolerance limit of 5 lg/m3 , only two locations (gate and store keeper’s office) were within this limit. All the other locations exceeded the FEPA limit by factors ranging from (2.7 to 107). These values are quite alarming, and more so given the fact that there are workers constantly at these locations each time the factory is running. More worrisome is the fact that many of the workers seem not to understand or appreciate the risk/ danger involved. Many do not use the nose masks and management were not seen to be insistent on their workers adhering to this safety rule. Analysis of blood samples of workers in the factory would have provided a clear evidence of the Pb levels in their blood and the risk these workers were been exposed to, but the company’s management did not allow blood samples to be taken from their workers.
4. Conclusion The EDXRF technique was used to determine the elemental concentrations of aerosol samples collected in the working environment of a secondary lead smelting company. The TSP concentrations at different locations within the factory exceeded the annual average set by the national
68
E.I. Obiajunwa et al. / Nucl. Instr. and Meth. in Phys. Res. B 194 (2002) 65–68
regulatory agency, FEPA, by factors ranging from 2 to 32 times. The elemental concentrations of Pb in the aerosol samples were particularly high, exceeding FEPAs ambient tolerance limit by factors ranging from 2.7 to 107 times. The health risk is very high and should be investigated. We strongly recommend a regular monitoring of this and similar factories to ensure compliance to set operational standards. References [1] F.A. Akeredolu, H.B. Olaniyi, J.A. Adejumo, I.B. Obioh, O.J. Ogunsola, O.I. Asubiojo, A.F. Oluwole, Nucl. Instr. and Meth. A 353 (1994) 542.
[2] C.A. Adesanmi, F.I. Ibitoye, S.A. Owolabi, A.A. Oladipo, F.A. Balogun, I.A. Tubosun, J. Environ. Syst. 25 (1997) 303. [3] J.I. Nwachukwu, E.I. Obiajunwa, I.B. Obioh, Petro. Geochem. Exploit. Afro-Asian Region, Proc. 5th Int. Conf. and Exbn., 2000, p. 139. [4] E.I. Obiajunwa, Nucl. Instr. and Meth. B 184 (2001) 437. [5] QXAS (Quantitative X-Ray Analysis System) Users Manual, International Atomic Energy Agency (IAEA), Vienna, 1993. [6] Guidelines and Standards for Environmental Protection Control in Nigeria, Federal Environmental Protection Agency (FEPA), 1991. [7] S.M. Pier, K.M. Bang, in: N.M. Trieff (Ed.), Environment and Health, Ann Arbor Science Inc., Ann Arbor, MI, 1980, p. 384. [8] C.M. Romo-Kroger, International Journal of PIXE 6 (1996) 311.