Inhalable and Respirable Dust, Bacteria and Endotoxins in the Air of Poultry Houses M. Saleh, J. Seedorf, J. Hartung Institute for Animal Hygiene, Animal Welfare and Behaviour of Farm Animals, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17p, 30559 Hannover, Germany Telephone: ++49 (0)511 953-8832, telefax: ++49 (0)511 953-8588, e-mail:
[email protected]
Abstract The air in livestock buildings contains a large variety of different gases, micro-organisms and considerable amounts of dust. These particles have a complex nature, can carry substances such as endotoxins and antibiotic residues, can remain suspended in the air for longer periods because of their minute dimensions and can therefore be inhaled by animal and man. Strong epidemiological evidence suggests that dust associated with bacteria can cause directly infectious and allergic diseases in animals and farm workers. Major quantities of these compounds are emitted in the environment where the health of nearby residents may be harmed by regular exposure and where the small particulates may contribute to atmospheric pollution and global dimming. However, our knowledge is still poor about the concentration of dust in different animal housing systems. This paper summarises some quantitative data from a recent study on occurrence of dust, micro-organisms and endotoxins in different keeping systems for laying hens and for broilers, turkeys and ducks. Highest inhalable dust concentrations (up to 10 mg/m³) were found in the air of broiler houses at the end of the 4th fattening week which is 2.5-times higher than the German occupational health threshold for workers (4 mg/m³); airborne total bacteria (predominantly Staphylococcae) count was up to 140 x 106 cfu/m³ in winter. Fungi vary considerably in concentration and can reach nearly 300,000 cfu/m³ in the turkey barn. Highest endotoxin concentrations (14,000 EU/m³) were found in the inhalable dust of the broiler barn in winter. Inhalable dust concentrations between 1.3 and 9.5 mg/m³ were found in the air of the aviary, 0.2-2.3 mg/m³ in conventional cages and 0.4-3.5 mg/m³ in the furnished cage system with respective respirable dust concentrations of 0.2-4.4, 0.01-1.30 and 0.1-0.99 mg/m³. The airborne bacterial counts ranged from 10,000 to 8 million cfu/m³. Endotoxins ranged between 50 to 3,600 EU/m³ in the inhalable dust and 5 to 1,800 EU/m³ in the respirable fraction. The presented data demonstrate that there are high to very high concentrations of air pollutants such as dust, micro-organisms and endotoxins in the air of animal houses which are also emitted in the environment. The data can help to identify those animal production systems where most urgently mitigation techniques should be applied in order to improve performance and welfare of animal and man indoors as well as to reduce emissions. Future animal farming systems should be sustainable in relation to animal health and welfare, environment and occupational health aspects. Key words: Air hygiene, poultry farming, dust, bacteria, endotoxin Introduction Providing good air quality in farm animal housing is important for health and well-being of farm animals and staff and for the outdoor environment of farming enterprises (Cargill and Hartung 2001, Seedorf and Hartung 2002, Radon et al. 2002). Modern animal production systems are however increasingly regarded as a source of air pollutants which can be both aggravating and environmentally harmful. Human and animal respiratory health may be compromised indoors by pollutants such as gases, dust, microorganisms and endotoxins, also addressed as bioaerosols (e.g. Baekbo 1990, Hamilton et al. 1993, Hartung 1994, Seedorf 2003, Hartung 2005) and particulate emissions such as dust and microorganisms from buildings are supposed to play a role in respiratory affections in people living in the vicinity of animal enterprises (Müller and Wieser 1987, Hartung 1995, Seedorf 2004). 1
The number of farmers and employees complaining about respiratory symptoms during and after work in animal houses has risen in recent years. Obstructive airway diseases caused by allergic compounds rose from about 90 in the year 1981 to approximately 700 in 1994, a slightly smaller increase from 8 to 50 was observed for obstructive diseases caused by chemical irritants or toxic compounds (Agricultural Occupational Health Board in Lower Saxony, 1996). A study comprising 1861 farmers in the north of Germany revealed that about 22 % of the pig farmers, 17 % of the cattle farmers and 13 % of the poultry farmers displayed airway problems such as asthma, asthma like syndrome, chronic bronchitis, mucous membrane irritation and organic dust toxic syndrome (Nowak 1998, Radon et al. 2002). The number of employees in animal farming receiving a pension from the professional sick fund because of an obstructive respiratory disease in Germany (BK 4301, 4302) rose from 17 in 2002 to 27 in 2003 (Prevention Report of the Agricultural Occupational Health Board in Lower Saxony and Bremen 2003). The relative low level of complaints by poultry workers is mainly biased by the fact that most cattle and pig farmers in Germany work on their own farms which they do not easily abandon even in case of health problems while poultry workers are usually employees who can more easily change their work place in case of health problems (“healthy worker effect”). Although the causes for the relatively high incidence of health problems associated with animal farming are not yet completely understood, it seems that high concentrations of air pollutants, the composition of the bioaerosols, insufficient ventilation and poor system management may play a sensible role. These viable and non-viable particles can remain suspended in the air for longer periods because of their minute dimensions of between 10-4 and approximately 10² µm and can therefore easily be inhaled by animal and man or can be transported into the environment by the exhaust ventilation air. The bioaerosols have a complex nature, can carry micro-organisms, viruses and substances such as endotoxins and antibiotic residues and can cause directly infectious or allergic diseases in animals and farm workers. Particularly high amounts of dust (Takai et al. 1998), micro-organisms and endotoxins (Seedorf et al. 1998, Saleh et al. 2003) are reported from poultry houses, however, little is known about the concentrations of airborne dust, micro-organisms and endotoxins in the recently introduced new animal-friendly (alternative) aviary and enriched cage systems. This paper summarises recent study on occurrence and amounts of dust (inhalable, respirable), bacteria and endotoxins in different keeping systems for laying hens (conventional, enriched cage, aviary), broilers, turkeys and ducks and relates the airborne dust levels to German occupational health limits (OHL), the so called MAK values (maximum concentrations at the work place). Material and Methods The investigations were carried out in three different types of laying hen houses of the laying hen research centre Ruthe of the University of Vererinary Medicine Hannover. 1500 birds were kept in groups of ten to thirty animals in a three tier system of enriched cages (AK), (type Aviplus, Fa. Big Dutchman, Vechta). Each cage was equipped with perches, a separate laying area and a dust bath. A floor area of 750 cm² per bird was provided. The second animal house was equipped with conventional four tired battery cages for 1350 animals providing 600 cm² per bird. The third animal house was built as an aviary where the 2300 birds can roam freely on three tiers and reach food and water in each of the three levels. The alleys were covered with litter for scratching. Along the walls nest boxes were installed. The birds had access to an outdoor scratching area littered with straw. This area was open for the animals daily after laying eggs. For more details see Briese et al. (2001). All birds were of a special layer breed called ,,Silver,, (Fa. Lohmann, Cuxhaven) delivered from the same parent flock 2
the same day. The forced ventilated broiler barn housed approx. 9000 birds on straw bedding. The 2000 tom turkeys (B.U.T.) were kept in a “Louisiana-type barn” on wood chips and on straw which was regularly supplied. The about 4000 Moscovy ducks were kept on perforated floor above a slurry pit in a forced ventilated building. Measurements were carried out during the course of one year always on the first Monday each month over a period of 24 h from 6.00 h a.m. to 6.00 h a.m. the next day. In each of the buildings two sampling positions were defined for the sampling heads of inhalable (IOM, Institute of Occupational Medicine, Edinburgh, UK) and respirable (SKC Zyklone, Fa. Blandford Forum, UK) dust. These places were draught free, easy to reach for installation, out of the reach of the animals (about 150 cm above floor level representing approximately the inhaling height of humans) and as far as possible representative for air composition. One sampling point was erected in the scratching area and another one was outside the building in a distance of about 20 m to take samples in the ambient air. Dust was sampled on glass fibre filters (Whatman International Ltd., Maidstone, UK) and weighed (Feinwaage, Fa. Sartorius AG, Göttingen) in a conditioned laboratory (23 °C ± 2 temperature, 45 ± 5 % relative humidity) before and after sampling. The air flow of the pumps was controlled by critical air speed nozzles (IOM: 2.0 l/min; SKC: 1.9 l/min). Endotoxins (ET) were analysed from the dust by the Limulus Amebocyte Lysate Test (LALTest, Biowhittaker, Maryland, USA) according to standardised chromogen-kinetic procedure (Kinetic-QCL). The controls were calibrated using the reference standard endotoxin E. coli-6 of the American Food and Drug Administration. The results are given in Endotoxin Units (EU). Micro-organisms were sampled for 24 h (2 l/min) on polycarbonate filters (Whatman, UK, pores 0.8 µm, diameter 25 mm) in IOM collecting heads with subsequent incubation at 37 °C for 48 h. Results Air Pollutants in Laying Hen Houses Table 1 summarises the results of the measurements in the three different laying hen houses. The min – max values demonstrate the high variations in all components which are related to the season and the activity of the animals. In winter time the concentration of the air pollutants are usually distinctly higher than in summer when high ventilations rates are applied. There are also variations during the course of the day. High pollutant levels are observed, when the birds are active compared to resting and sleeping periods. Inhalable dust concentrations between 1.3 and 9.5 mg/m³ were found in the air of the aviary for laying hens, 0.2-2.3 mg/m³ in conventional cages and 0.4-3.5 mg/m³ in the enriched cage system with respective respirable dust concentrations of 0.2-4.4, 0.01-1.30 and 0.01-0.99 mg/m³. The bacterial counts ranged from 10,000 to 8,000,000 cfu/m³ showing distinct differences between housing systems. E. coli came to 10 and 1,000 cfu/m³ with a slight tendency to higher concentrations in the air of the aviary. Endotoxins ranged between 50 to 3,600 EU/m³ in the inhalable dust and 5 to 1,800 EU/m³ in the respirable dust fraction. In general, highest concentrations of bacteria, fungi and dust are regularly found in the aviary system compared to the cage systems. Figures 1 and 2 demonstrate these differences for inhalable and respirable dust as examples. Figure 1 shows clearly that the highest concentrations of both inhalable und respirable dust were found in the aviary, followed by conventional cage and furnished cage. In the aviary the 3
German occupational health threshold at the workplace for inhalable dust ist regularly exceeded. In the outdoor scratching area the avarage values are around 0.27 mg/m³ but can also reach 0.5 mg/m³. These large differences depend very much on the opening times of the scratching area and the activities of the birds. Figure 2 shows the concentrations of the respirable dust in the three laying hen housing systems which follow the same pattern as the inhalable dust. The highest concentrations are found again in the aviary followed by the conventional cage and the furnished cage system. In the aviary the average value exceeds the German occupational health threshold at the workplace for respirable dust Air pollutants in broiler, turkey and duck houses Table 2 summarises the results of the measurements in three different fattening poultry houses. The min – max values demonstrate the high variations in all components which are related to the season and the activity of the animals. In winter time the concentration of the air pollutants are usually distinctly higher than in summer when high ventilations rates are applied. There are also variations during the course of the day. High pollutant levels are observed, when the birds are active compared to resting and sleeping periods. Highest inhalable dust concentrations were found in the air of broiler and turkey (up to 10 mg/m³) houses which is 2.5-times higher than the German occupational health threshold at the work place (4 mg/m³). Mean airborne total bacteria (predominantly Staphylococcae) count was 69 x 106 cfu/m³. In the 3rd and 4th fattening week in winter at animal level (0.3 m) up to 140 x 106 cfu/m³ can be reached. E. coli was found between 500 and 3000 cfu/m³. Fungi vary considerably in concentration and can reach 98,000 cfu/m³ in the turkey barn. Highest endotoxin concentrations (up to 13,930 EU/m³) were found in the inhalable dust of the broiler barn in winter. Discussion and Conclusions The presented data demonstrate that there are high and partly very high concentrations of air pollutants such as dust, micro-organisms and endotoxins in the air of poultry houses. They are supposed to contribute to respiratory disorders in animal and man. Aerial pollutants can also reduce animal performance and well-being. They are also emitted in the environment where they can cause complaints from nearby neighbours who are concerned that their health may be affected by these substances. In addition, fine dust particles from animal farming seem to contribute to the dimming processes which enhance global warming. It is important to identify low emission animal farming systems, including poultry production because most of the alternative systems display high particulate emission potentials as demonstrated in this investigation. The results of this study may help to identify those poultry production systems where most urgently mitigation techniques should be applied in order to improve performance and welfare of animal and man indoors as well as to reduce emissions. New keeping systems for farm animals should always be tested before wide introduction in practice on its sustainability in relation to animal health and welfare, environmental impact and last but not least occupational health aspects.
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Acknowledgement This study was kindly supported by a grant from the Al-Bath University, Hama, Syria and by the Ministry of Rural Areas, Food, Agriculture and Consumer Protection of the State of Lower Saxony, Germany. References Baekbo, P.: Air quality in Danish pig herds. Proceedings 11th Congress of the International Pig Veterinary Society 1-5 July 1990, Lausanne, p. 395. Briese, A., Sewerin, K., Knierim, U., Hartung, J. (2001): Ausgestaltete Käfige in der Legehennenhaltung – rechtliche Rahmenbedingungen und Ansatzpunkte für ihre wissenschaftliche Beurteilung. Dtsch. tierärztl. Wschr. 108, 105109 Cargill, C., Hartung, J.: Air quality – from an OH&S perspective. In: Proceedings Australian Association of Pig Veterinarians, Pan Pacific Conference on Consistent Pork, Melbourne, 2001, 14.05. – 15.05.01, 93-101. Hamilton, T.D.C., Roe, J. M., Taylor, F.G.R., Pearson, G., Webster, A.J.F.: Airial Pollution: An exacerbating factor in atrophic rhinitis of pigs. Proceedings of 4th International Livestock Environment Symposium, Warwick, American Society of Agriculture and Engineer, 1993, pp. 895-903. Hartung, J.: The effect of airborne particulates on livestock health and production. In: I. AP Dewi, R. F. E. Axeford, I. Fayez, M. Marai, H. Omed (eds.): Pollution in Livestock Production Systems. CAB International, Wallingford, UK, 55-69, 1994. Hartung, J.: Gas- und partikelförmige Emissionen aus Ställen der Tierproduktion. Dtsch. tierärztl. Wschr. 1995, 102, 283-288. Müller, W. and Wieser, P.: Dust and microbial emissions from animal production. In: Strauch, D. (ed.), Animal Production and Environmental Health. Elsevier, Amsterdam, Oxford, New York, Tokyo, 1987, pp. 47-89. Nowak, D.: Die Wirkung von Stallluftbestandteilen, insbesondere in Schweineställen, aus arbeitsmedizinischer Sicht. Dtsch. tierärztl. Wschr. 1998, 105, 225-234. Radon, K., Monso, E., Weber, C., Danuser, B., Iversen, M., Opravil, U., Donham, K., Hartung, J., Pedersen, S., Garz, S., Blainey, D., Rabe, U., Nowak, D.: Prevalence and risk factors for airway diseases in farmers – summary of results of the European farmers´ project. Ann Agric Environ Med 2002, 9, 207-213. Saleh, Maher (2006): Untersuchungen zur Luftqualität in verschiedenen Systemen der Geflügelhaltung mit besonderer Berücksichtigung von Staub und Luftkeimen. PhD-These, Tierärztliche Hochschule Hannover
Saleh, M., Seedorf, J., Hartung, J. (2003): Zum Umfang des allgemeinen Luftkeimgehaltes in drei verschiedenen Legehennenhaltungsssystemen.[Total count of bacteria in the air of different laying hen housing systems.] Dtsch. tierärztl. Wschr., 110, 349-400 Saleh, M., Seedorf, J., Hartung, J. (2004): Inhalable and respirable dust in work place atmospheres of layind hen houses. In: Madec, F., Clement, G. (eds.): Proceedings In-Between Congress of The ISAH (Int. Society for Animal Hygiene) Animal Production in Europe: The way forward in a changing world. Vol. 1, Saint-Malo, France, 11.-13.10.04, 211-212 Seedorf, J.:An emission inventory of livestock-related bioaerosols for Lower Saxony, Germany. Atmospheric Environment 2004, 38, 6565-6581 Seedorf, J.: Die integrierte tier- und umwelthygienische Erfassung und Bewertung von Bioaerosolen in der Nutztierhaltung unter Einsatz eines mobilen Messkonzeptes Habilitationsschrift, Tierärztliche Hochschule Hannover, 2003 5
Seedorf, J., Hartung, J. (2002): Stäube und Mikroorganismen in der Tierhaltung. KTBL-Schrift 393, Landwirtschaftsverlag GmbH, Münster, 166 Seiten Seedorf, J., Hartung, J., Schröder, M., Linkert, K.H., Phillips, V.R., Holden, M.R., Sneath, R.W., Short J.L, White, R.P., Pedersen, S., Takai, T., Johnsen, J.O., Metz, J.H.M., Groot Koerkamp, P.W.G., Uenk, G.H., Wathes, C.M.: Concentrations and Emissions of airborne Endotoxins and Microorganisms in Livestock Buildings in Northern Europe. In: Journal of Agricultural Engineering Research, 1998, 70, 97-109. Takai, H., Pedersen, S., Johnsen, J. O., Metz, J. H. M., Groot Koerkamp, P. W. G., Uenk, G.H., Phillips, V.R., Holden, M.R., Sneath, R.W., Short, J.L., White, R.P., Hartung, J., Seedorf, J., Schröder, M., Linkert, K. H., Wathes, C. M.: Concentrations and Emissions of Airborne Dust in Livestock Buildings in Northern Europe. Journal of Agricultural Engineering Research, 1998, 70, 59-77.
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Tab. 1: Micro-organisms, dust and endotoxin concentrations in the air of different laying housing systems. MW = average value, min = minimum, max = maximum, ET = endotoxin (after Saleh 2006) Compound
Unit
Conventional cage MW min
max.
Furnished cage MW Min
Max
Aviary MW min max
Total bacteria count Fungi
cfu/m³ 5.1 105 cfu/m³ 1177
0.2
22
1.7
0.09
4.1
25
5.1
81
90
7226
1490
140
20395
2455
142
10885
Inhalable dust fraction Respirable dust fraction ET inhalable dust fraction ET respirable dust fraction
mg/m³ 1.22
0.24
2.27
1.5
0.44
3.48
3.69
1.3
9.5
mg/m³ 0.34
0.01
1.3
0.24
0.01
0.99
1.67
0.2
4.4
EU/m³ 373
47
1222
865
50
3303
1992
237
3623
EU/m³ 328
9
759
80
5
243
971
18
1827
7
Tab. 2: Micro-organisms, dust and endotoxin concentrations in the air of a broiler, turkey and Moscovy duck house. MW = average value, min = minimum, max = maximum, ET = endotoxin (after Saleh 2006)
Compounds
Unit
Broiler
Turkey
Moscovy duck
MW min Max
MW min max
MW Min max
Total bacteria Count
cfu/m³ 69 106
0.6
140
7.5
0.03 44
3.3
0.8 8.3
Fungi
cfu/m³ 24 103 mg/m³ 6
0.7
137
98
0.5
293
0.8
0.5 2.2
2.1
10.4
2.5
0.5
6
1.0
0.8 2.5
1.7
0.2
0.1 0.5
Inhalable dust fraction
Respirable dust mg/m³ 0.6 0.17 1.7 0.7 0.1 fraction ET in inhalable EU/m³ 4925 648 13930 4100 67 dust fraction ET in respirable EU/m³ 791 295 1626 786 6 dust fraction
11581 1997 343 6763 1490
100
12
283
8
7,00 6,42
6,00
mg/m_
5,00
a
4,00
3,80
3,00
b
2,00 0,06 c 0,04 0,00
1,00 0,00
outside
1,78
b 1,05
d 0,50
1,00
0,78 0,51 enriched cage
1,35
0,27 0,00
0,36 conventional cage
aviary
scratching area
Keeping system
Fig. 1: Inhalable dust (mg/m³) in the air of three different laying hen systems, in an outdoor scratching area and in the ambient air close to the building. 24 h samplings per month during one year in each place (n = 12). Different letters indicate significant differences. p = 0.05. (Saleh et al. 2004)
4,00
Respirable dust
3,50
3,37
3,00
a
mg/ 2,50 m3 2,00
1,93
1,50 1,00 0,50
0,44
b
b
0,33
Furnished cage
0,90
0,66 0,23
0,23
0,00
1,06
Conv. cage
Aviary
Keeping system
Fig. 2: Respirable dust (mg/m³) in the air of three different laying hen systems. 24 h samplings per month during one year in each house (n = 12). Different letters indicate significant differences. p = 0.05. (Saleh et al. 2004)
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