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Evaluation of samplers for airborne agricultural dusts
J. Aerosol Sci., Vol. 19, No. 7, pp. 1461 - 1463, 1 9 8 8 Printed in Great Britain
0021-8502/88$3.00. + 0.00 Pergamon Press plc
EVALUATION OF SAMPLERS FOR AIRBORNE AGRICULTURAL DUSTS W.D. Griffiths OMHL, 403 Edgware Road London NW2 6LN.
Introduction Exposure to airborne agricultural dusts is often a normal occupational hazard for farm workers. These dusts are, in general, mostly organic material. StrUm (1986) has outlined some of the associations between a number of respiratory illnesses and inhalation of agricultural dust. Pepys (1969) showed that the respiratory disease, farmer's lung (now known as extrinsic allergic alveolitis, or EAA), was immunological in origin rather than a fungal infection. Milder forms of the disease referred to as "organic toxic fever" also exist alongside bronchitis and occupational asthma (Rylander, 1986). Agricultural dusts may be derived from animal plant and soil sources and have constituent parts made of pieces of animal and plants and their products, along with micro-organisms, such as spores of fungi and actinomycetes, and bacteria. The small inorganic fraction is only significant during tillage and is generally considered to be a "nuisance dust". Agricultural workers come into contact with airborne dusts in a variety of ways (Lacey, 1986 and De Lucca, 1987 are examples of many). Modern farm machinery has given rise to more problems and to a disease known as "harvester's lung". In the last 20 or 30 years there has been a gradual increase in the use of animal confinement buildings. This has resulted in the production of an intense source of airborne agricultural dust. Dusts associated with the confinement of animals and poultry, for example danders, hair, feathers, urine, faeces, insects, mites, feed grain, hay, fungal spores, bacteria, bacterial endotoxins and microbial-proteinase, may be present in very high concentrations (Bruce and Sommer, 1987). TO assess the hazards to health associated with airborne agricultural dusts, these dusts must be qualitatively and quantitatively analysed. They must be effectively sampled and prepared i n order to do this.
Sampling - strategy and techniques
The s t r a t e g i c problems of sampling airborne agricultural (including micro-organisms) a r e v e r y much t h e same a s t h o s e associated with sampling inorganic, occupation aerosols; for example the number of samples required, duration, time and 1461
dust
1462
W. D. GRIFFITHS
position of the sampler. The type of sampler which is required (static or personal) also has to be decided upon. Gravimetric analysis of filter collected samples is often too insensitive and alternative techniques must be used. Some of these techniques collect airborne particles (sometimes in convenient size fractions) for direct microscope analysis or for analysis following culturing. Other techniques, such as those of particle counters, provide information concerning the number and size of the particles and do not retain a sample for any further analysis.These must allow an estimate of all airborne particles (including the micro-organisms) to be carried out such that all objectives of the investigation are met (Gregory and Monteiff, 1967). Sampling methods and their intercomparison Among the several excellent reviews of methods suitable for sampling airborne micro-organisms and aeroallergens are those of Gregory (1973), Chatigny (1983), Chatigny et al. (1983) and Crook et al.
(1988).
Sampling techniques can be subdivided into a number of subgroups - sedimentation, impaction on to solid/semi solid surfaces, impinging into liquids, filtration, precipitation, and miscellaneous methods including particle counting. There is not enough space to allow full details of all the possible methods and instruments to be given. These are dealt with, in full, by Griffiths (1988). A number of the instruments described by Griffiths are typical of those in general use for micro-organisms etc, and along with several previously untried (with agricultural aerosols) samplers have been selected for test purposes with a view towards their possible application to airborne agricultural dusts and micro-organisms. These are reviewed by Griffiths (1988). Gregory (1973) believed that under simple conditions it is not difficult to define an absolute standard for air sampling. However the more varied the population in species, size and state of aggregation, the harder it becomes to devise equipment to measure the microbial concentration. Chatigny (1983) describes the difficulties in comparing the recovery rates of viable micro-organisms from different classes of sampler, thus making intercomparison very difficult. Inspite of these problems, a number of investigators have carried out limited intercomparisons (collection efficiency and, when required, recovery rate of vaible organisms) between s~ecially selected samplers (eg. StrUm, 1986; Henningson and F~ngmark, 1987; Macher and Hansson, 1987; and Crook et al., 1988).
Investigation protocol In view of the difficulties in carrying out comprehensive intercomparison tests between individual types of sampler, it might prove more useful to determine the collection efficiency and micro-organsism recovery rate (where applicable) of a number of selected samplers.
Airborne agricultural dusts
1463
The collection efficiency of a sampler can be measured using of test aerosol, such as known concentraitons of monodisperse polystryrene latex (PSL) particles or a more numerically concentrated condensation aerosol (Prodi, 1972) and comparing it with the concentration of particles in the sample collected. This technique has been described by May (1975) and used by many, eg. Henningson and F~ngmark (1987). Micro-organism recovery rate tests can be carried out using a number of common bacteria, accounting for their robustness. References Bruce, J.M and Sommer, M. (1978) Editors "Environmental aspect of respiratory disease in intensive pig and poultry houses, including the implications for human health" Commission of the European Communities, Luxembourg. Chatigny, M.A. (1983) "Air Sampling Instruments". (Edited by Lioy, P.J. and Lioy, M.J.H.), Chapt. E. ACGIH, Ohio. Chatigny, M.A., Wolochow, H. and Hinton, D.O. "Air Sampling Instruments". (Edited by Lioy, P.J., and Lioy, M.J.H.), Chapt. ACGIH, Ohio.
F
Crook, B. Griffin, P., Topping, M.D. and Lacey, J. (1988 "Aerosols Their Generation, Behaviour and Applications". Proc. 2nd Ann. Conf. of The Aerosol Society, Bournemouth, 1988. (Edited by Griffiths, W.D.) pp. 327-333. The Aerosol Society, London. De Lucca, A.J. and Palmgren, 4_88, (2), 106-110. Gregory, edition,
M.S.
(1987) Am.
P.H. (1973) "The Microbiology Leonard Hill, Aylesbury.
Ind. Hyg. Assoc.
of the Atmopshere".
J.
2nd
Gregory, P.H. and Monteiff, J. L. (1967) Editors "Airborne Microbes". Proc. 17th Symp. of The Society for General Microbiology, London, April 1967. Univ. Press Cambridge. Griffiths,
W.D.
(1988)
HSE.
INT. REPORT IR/L/DS/88/.
Henningson, E. and F~ngmark, I. (1988) EXS 51. Birkhauser Verlag, Basel. Lacey,
J. (1986) Am. J. Ind. Med. iO,
Macher, J.M. and Hansson, (7), 652-655. May, K.R.
(1975)
H-C.
J. Aerosol
"Advances
in Aerobiology"
311-313.
(1987) Am.
Ind. Hyg. Assoc.
J. 48,
Sci. 6, 413-419.
Pepys, J. (1969) "Hypersensitivity diseases of the lungs due to fungi and organic dusts" S. Karger, New York. Prodi, V. (1972) "Assessment of Airborne Particles" (Edited by Mercer, J.J., Morrow, P.E. and St6ber, W.), pp.169-181. Charles C. Thomas, Springfield, Illinois. Rylander,
R.
(1986) Am. J. Ind. Med.
(10), 221-227.
StrUm, G. (1986) "Qualitative and Quantitative Analysis of Microorganisms Particularly Fungal Spores. Methodological Developments" Umea University Medical Dissertation, Umea.
0021-8502/88$3.00. + 0.00 Pergamon Press plc
EVALUATION OF SAMPLERS FOR AIRBORNE AGRICULTURAL DUSTS W.D. Griffiths OMHL, 403 Edgware Road London NW2 6LN.
Introduction Exposure to airborne agricultural dusts is often a normal occupational hazard for farm workers. These dusts are, in general, mostly organic material. StrUm (1986) has outlined some of the associations between a number of respiratory illnesses and inhalation of agricultural dust. Pepys (1969) showed that the respiratory disease, farmer's lung (now known as extrinsic allergic alveolitis, or EAA), was immunological in origin rather than a fungal infection. Milder forms of the disease referred to as "organic toxic fever" also exist alongside bronchitis and occupational asthma (Rylander, 1986). Agricultural dusts may be derived from animal plant and soil sources and have constituent parts made of pieces of animal and plants and their products, along with micro-organisms, such as spores of fungi and actinomycetes, and bacteria. The small inorganic fraction is only significant during tillage and is generally considered to be a "nuisance dust". Agricultural workers come into contact with airborne dusts in a variety of ways (Lacey, 1986 and De Lucca, 1987 are examples of many). Modern farm machinery has given rise to more problems and to a disease known as "harvester's lung". In the last 20 or 30 years there has been a gradual increase in the use of animal confinement buildings. This has resulted in the production of an intense source of airborne agricultural dust. Dusts associated with the confinement of animals and poultry, for example danders, hair, feathers, urine, faeces, insects, mites, feed grain, hay, fungal spores, bacteria, bacterial endotoxins and microbial-proteinase, may be present in very high concentrations (Bruce and Sommer, 1987). TO assess the hazards to health associated with airborne agricultural dusts, these dusts must be qualitatively and quantitatively analysed. They must be effectively sampled and prepared i n order to do this.
Sampling - strategy and techniques
The s t r a t e g i c problems of sampling airborne agricultural (including micro-organisms) a r e v e r y much t h e same a s t h o s e associated with sampling inorganic, occupation aerosols; for example the number of samples required, duration, time and 1461
dust
1462
W. D. GRIFFITHS
position of the sampler. The type of sampler which is required (static or personal) also has to be decided upon. Gravimetric analysis of filter collected samples is often too insensitive and alternative techniques must be used. Some of these techniques collect airborne particles (sometimes in convenient size fractions) for direct microscope analysis or for analysis following culturing. Other techniques, such as those of particle counters, provide information concerning the number and size of the particles and do not retain a sample for any further analysis.These must allow an estimate of all airborne particles (including the micro-organisms) to be carried out such that all objectives of the investigation are met (Gregory and Monteiff, 1967). Sampling methods and their intercomparison Among the several excellent reviews of methods suitable for sampling airborne micro-organisms and aeroallergens are those of Gregory (1973), Chatigny (1983), Chatigny et al. (1983) and Crook et al.
(1988).
Sampling techniques can be subdivided into a number of subgroups - sedimentation, impaction on to solid/semi solid surfaces, impinging into liquids, filtration, precipitation, and miscellaneous methods including particle counting. There is not enough space to allow full details of all the possible methods and instruments to be given. These are dealt with, in full, by Griffiths (1988). A number of the instruments described by Griffiths are typical of those in general use for micro-organisms etc, and along with several previously untried (with agricultural aerosols) samplers have been selected for test purposes with a view towards their possible application to airborne agricultural dusts and micro-organisms. These are reviewed by Griffiths (1988). Gregory (1973) believed that under simple conditions it is not difficult to define an absolute standard for air sampling. However the more varied the population in species, size and state of aggregation, the harder it becomes to devise equipment to measure the microbial concentration. Chatigny (1983) describes the difficulties in comparing the recovery rates of viable micro-organisms from different classes of sampler, thus making intercomparison very difficult. Inspite of these problems, a number of investigators have carried out limited intercomparisons (collection efficiency and, when required, recovery rate of vaible organisms) between s~ecially selected samplers (eg. StrUm, 1986; Henningson and F~ngmark, 1987; Macher and Hansson, 1987; and Crook et al., 1988).
Investigation protocol In view of the difficulties in carrying out comprehensive intercomparison tests between individual types of sampler, it might prove more useful to determine the collection efficiency and micro-organsism recovery rate (where applicable) of a number of selected samplers.
Airborne agricultural dusts
1463
The collection efficiency of a sampler can be measured using of test aerosol, such as known concentraitons of monodisperse polystryrene latex (PSL) particles or a more numerically concentrated condensation aerosol (Prodi, 1972) and comparing it with the concentration of particles in the sample collected. This technique has been described by May (1975) and used by many, eg. Henningson and F~ngmark (1987). Micro-organism recovery rate tests can be carried out using a number of common bacteria, accounting for their robustness. References Bruce, J.M and Sommer, M. (1978) Editors "Environmental aspect of respiratory disease in intensive pig and poultry houses, including the implications for human health" Commission of the European Communities, Luxembourg. Chatigny, M.A. (1983) "Air Sampling Instruments". (Edited by Lioy, P.J. and Lioy, M.J.H.), Chapt. E. ACGIH, Ohio. Chatigny, M.A., Wolochow, H. and Hinton, D.O. "Air Sampling Instruments". (Edited by Lioy, P.J., and Lioy, M.J.H.), Chapt. ACGIH, Ohio.
F
Crook, B. Griffin, P., Topping, M.D. and Lacey, J. (1988 "Aerosols Their Generation, Behaviour and Applications". Proc. 2nd Ann. Conf. of The Aerosol Society, Bournemouth, 1988. (Edited by Griffiths, W.D.) pp. 327-333. The Aerosol Society, London. De Lucca, A.J. and Palmgren, 4_88, (2), 106-110. Gregory, edition,
M.S.
(1987) Am.
P.H. (1973) "The Microbiology Leonard Hill, Aylesbury.
Ind. Hyg. Assoc.
of the Atmopshere".
J.
2nd
Gregory, P.H. and Monteiff, J. L. (1967) Editors "Airborne Microbes". Proc. 17th Symp. of The Society for General Microbiology, London, April 1967. Univ. Press Cambridge. Griffiths,
W.D.
(1988)
HSE.
INT. REPORT IR/L/DS/88/.
Henningson, E. and F~ngmark, I. (1988) EXS 51. Birkhauser Verlag, Basel. Lacey,
J. (1986) Am. J. Ind. Med. iO,
Macher, J.M. and Hansson, (7), 652-655. May, K.R.
(1975)
H-C.
J. Aerosol
"Advances
in Aerobiology"
311-313.
(1987) Am.
Ind. Hyg. Assoc.
J. 48,
Sci. 6, 413-419.
Pepys, J. (1969) "Hypersensitivity diseases of the lungs due to fungi and organic dusts" S. Karger, New York. Prodi, V. (1972) "Assessment of Airborne Particles" (Edited by Mercer, J.J., Morrow, P.E. and St6ber, W.), pp.169-181. Charles C. Thomas, Springfield, Illinois. Rylander,
R.
(1986) Am. J. Ind. Med.
(10), 221-227.
StrUm, G. (1986) "Qualitative and Quantitative Analysis of Microorganisms Particularly Fungal Spores. Methodological Developments" Umea University Medical Dissertation, Umea.