dc.description.abstract |
South African data regarding the extent of aerosol exposure and health effects in
the workplace are limited. Furthermore, a shortage of industrial hygiene- and
epidemiological data from large scale studies exist. Given the increasing concern
about the health of industrial metal workers, an inhalation exposure study of South
African iron foundry workers and welders at a large engineering plant in
Bloemfontein, was undertaken. The aim of the study was to compile a source
inventory, identifying and characterising all health related inorganic aerosols to
which metal workers of the plant are potentially or actually exposed. In addition,
the exposure risk was assessed by the integration of aerosol concentrations and
biological data from urine analyses.
Aerosols were sampled by means of time sequence particulate sampling on
streaker filter frames and analysed with Particle Induced X-ray Emission (PIXE) on
the Tandem van de Graaff accelerator of the University of the Witwatersrand,
Johannesburg. The streaker is analysed in 1 mm steps, corresponding to 1 hour
of exposure. PIXE analysis yielded concentrations or detection limits of elements
AI, Si, P, S, CI, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, In, Br and Pb.
The urine of selected exposed workers was sampled according to NIOSH method
8310 and analysed using Atomic Absorption (AA) spectrometry for the urine-metal
concentrations In, Cd, Co, Ni, Mn, Cu, Cr, AI, Fe, Pb, Si and V.
Forced vital capacity (FVC), forced expiratory volume in one second (FEV1
), peak
expiratory flow (PEF), peak inspiratory flow (PI F), average expiratory flow between
25 % and 75 % of FVC (FEF25-7S), expiratory flow at 25 % of FVC (Vmax2S),
expiratory flow at 50 % of FVC (VmaxSO) , expiratory flow at 75 % of FVC (Vma>c7S) and
forced expiration time (100 % FVC) (FET1oo), was conducted with a Cosmed Pony
spirometer. This was done to provide a physical image of the workers' lungs.
A new method for the assessment of aerosol inhalation exposure risk, called ,~ER,
using aerosol concentrations and metal urine concentrations, is proposed for
estimation of the inhalation risk. The assumptions and calculation for the new
method are presented.
A number of sources or source categories have been identified in the foundry's
and welding shop's air by making use of patterns of time variations and elemental
ratios. Six sources namely crustal particles, sulphur, In-Pb-CI, two distinct
components of different castings and other heavy metals were identified as sources. The main pollutants and the relative contributions from other sources
have been identified for iron foundries and welding shops with recognised air
quality problems. Overexposure occurred during specific operations which was
also quantified for rectification.
The urine analysis of the foundry workers yielded high concentrations of Cd, Cu,
Fe and Si. It is assumed that the Fe and Si concentrations are exposure related.
The analysis of urine from the welders yielded high concentrations of Ni, Cr and
Fe. Although Ni concentrations in the workroom air were low, the occurrence of all
three elements in the urine may be as a result of chronic exposure to welding
fumes in their workplace. Except for vanadium, no statistical significant differences
(P > 0.05) were found between the different metal urine concentrations of the
workers of the two localities.
The total exposed foundry population showed a significant decrease in FEV1 and
FVC which indicates that the pollution in the workplace contributes to the
development of restrictive lung disorders in foundry workers. The dust created
during the welding of steel in the welding shop is a contributing agent in the
development of obstructive respiratory disorders in the welder population.
Examination of the relationship between elemental variations has allowed
identification of several sources and activities contributing to airborne particles.
The aerosol profiles did not show similar diurnal time variation patterns in the
foundry or the welding shop due to irregularities in the continuation of the
processes.
The AIER for the foundry resulted in a maximum value of 92.3 % while the
corresponding value for the welding environment was 71.7 %. The resu lts pres~t
the worst case scenario during winter conditions and it is expected that conditions
will be more healthy during summer time when windows and doors are open. The
planning and prioritisation for the improvement of indoor air quality in both
workplaces can proceed, using the data on the sources of the pollutants.
It can be concluded that workers exposed to conditions as found during this
project, will experience health problems after chronic exposure. The results
emphasised the importance of exposure characterisation in order to provide for
identification of pollutants, control of sources and the application of industrial
hygiene principles for the protection of human health. It is recommended that all
industries implement exposure characterisation programmes as a tool in applying
good occupational and environmental hygiene. |
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