Motivation: The investigation of agricultural respiratory hazards has lagged behind
the investigation of hazards in mining and other heavy industries. Relatively few
epidemiological data are available addressing pulmonary infections in the context of
the agricultural work environment, especially for the South African population.
Poultry house dust was generally considered nuisance or inert, meaning it has little
adverse effect on human lungs. New research shows that because poultry house
dust is largely organic and contain bacteria and other bioactive substances, it cannot
be considered inert. Several published research manuscripts document that the
legal and recommended exposure limits for the toxic substances found in the
agricultural environment are to high for concentrated animal feeding operations
(CAFO's). In CAFO's there is a mixture of biologically active agents that can work
synergistic to produce respiratory and systemic effects at much lower levels. Most of
the current legal exposure limits used in South Africa are adopted from international
limits and guidelines. Because of the influence of geography, climate and degree of
industrialisation on the agricultural air quality, the relevance of the foreign exposure
limits is questionable.
Aim: To determine if there is a correlation between occupational exposure to poultry
farm dust and the lung function of poultry farm workers in the Potchefstroom district,
South Africa. Also to determine if the current legal exposure limits used for ammonia
and particulate matter (PM) in South Africa, offer adequate worker protection for
poultry farm workers exposed to biologically active dust.
Methodology: This was an observational, cross-sectional pilot study. A target
population of fifty contract workers concerned with the removal and disposal of
poultry manure were identified in the Potchefstroom district and a random sample of
nineteen was drawn for participation in this study. Exposure to total and respirable
dust were determined by means of personal sampling for the full duration of the time averaging
period (8-hour TWA). Area monitoring for ammonia and bio-aerosols were
done in poultry houses in three specific demarcated areas around Potchefstroom,
and weather conditions were taken into account. Lung function tests (spirometry)
were conducted before and after each work shift. Interviewer administered
questionnaires were used to assess occupational and exposure histories and to
detect symptoms of organic dust exposure.
Results and conclusions: The mean total- and respirable dust concentrations
complied with the legal limits of OSHA, NlOSH and the Regulations for hazardous
chemical substances of 1995. However, fifty five percent of the measured total dust
concentrations and all of the respirable dust measurements exceeded Donham's
recommended values for human health. The spirometric values of the subjects were
normal; there was no statistical difference between the mean baseline FEV1/FVC and
the mean predicted FEV1/FVC. Results also show no statistically significant cross
shift changes in any of the measured variables and there is no significant correlation
of the measured dust concentrations to any of the spirometric measurements. It can
be concluded that occupational exposure to ammonia, particulate matter and
micro-organisms on poultry farms in the Potchefsroom district, South Africa, do not
have any adverse effects on the workers' lung function and the workers are
adequately protected in the short term, by the legal limits that are currently used in
South Africa. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2006.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/988 |
| Date | January 2005 |
| Creators | De Jager, Anna Catharina |
| Publisher | North-West University |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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