View of Farmers’ exposure to dusts and gases in modern Finnish cubicle cow houses

Farmers’ exposure ^{to dusts and} gases in ^modern Finnish cubicle cow houses

KyöstiLouhelainen, JuhaniKangas, MarjutReiman

Kuopio Regional Institute ofOccupational Health,POBox93,FIN-70701 Kuopio, Finland, e-mail:kyosli.louhelainen^@occuphealth.fi

Pentti Kalliokoski

UniversityofKuopio, DepartmentofEnvironmental Sciences, PO Box 1627,FIN-70211 Kuopio,^Finland

The occurrenceof airborne dust, gases,microbes, endotoxin and bovine epithelial antigens^(BEA, BDA2O)wasstudiedin 26 modern,mainly cubicle,cowhouses.Airsamplesof totaldust,total spores,

endotoxinand bovineepithelial allergens ^{werecollectedon}membrane filters withportable orpiston pumps andanalyzedwith appropriate methods. Concentrations ofgases(ammonia, carbondioxide, hydrogen sulfide)were measured withdiffusiontubes. Airborneviablesporeswerecollected witha cascade impactoronfiveselectiveculture media for the identification ofxerophilic, mesophilic and thermotolerant fungiand thermophilic actinomycetes.

The geometric mean concentrations of total dust, BEAand BDA2O were 0.2-1.9 mg/m³, 5.2- 9.7 pg/m³and50-260 ng/m^3,respectively. Themeanconcentrations of ammonia and carbon dioxide were^{between 2.8-15ppm and2200-3200ppm,}respectively. Thegeometricmeanof endotoxins was

19 ng/m³and the concentrations offungi wereatthe lO'-IO^{3cfu/m3level.}

Ingeneral,the variation in concentrations of total dust,viablefungiand endotoxinwas^large.The concentrations of total dust andfungi werelower than inearlier studies. Thusnew cubicle houses provideabetterworkingenvironment withregardtoairborne hazards than the traditionalcowhouses.

Keywords: agriculture,airborne healthhazards, allergens, micro-organisms

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Introduction

(Malmberg 1990,Terho etal. 1987, Tammilehto etal. 1994, Donham 1993).Symptoms ofchronic bronchitis and farmer’s lungare still the _most common respiratory complaints among dairy farmers (Tammilehto et al. 1994). In^Finland, duringrecent years the dominant etiologic fac-

torfor occupational respiratory diseases among Farm workersareexposed toavariety ofagents

thatcan cause injury by inhalation. Epidemio- logical studies indicate_ahigh prevalence of_res- piratory symptoms or diseases among farmers

©Agricultural and Food ScienceinFinland ManuscriptreceivedJune 1997

Louhelainen, K. etal. Farmers^’exposuretodusts andgasesin cubicles farmers has beencow dander,but microbialex-

posure also has caused hundreds of cases of farmer’s lung (Karjalainen et al. 1996, 1997, Kauppinen ^etai. 1994, 1995).

Themean levels of total dust in cow houses have been low (range from 0.7 to 1.5 mg/m³⁾ (Louhelainen etai. 1987

a,

Virtanenetal. 1986, Virtanen et ai. 1988) related to swineries (Louhelainen et ai. 1987^b, Gustafsson 1988, Donham etai. 1995).Thus other factors which are constituents of dust explain the etiology of respiratory diseases in the farming population.

The airborne concentrations and serological studies of bovine epithelial antigen (BEA) and 20 kD bovine dander antigen (BDA2O) have been reported mainly by Finnish researchers(Virtanen etal. 1986, Virtanen_etai. 1988. Virtanenetai.

1992, Ylönen etai. 1990, Ylönen_etai. 1994).

Several studies have concluded that the main sourcesof microbial dust in agriculturearehay, strawand grain (Kotimaa etal. 1987, Kotimaa 1990, Kotimaa ^etai. 1991).Straw samples lib- eratesignificantly larger numbers of spores than hay and grain do(Kotimaa 1990). Thermoactin- omyces vulgaris has been the predominant mi- crobe from strawand Aspergillus umbrosus from

hay and grain. On farms where fodder_wasdried artificially the concentration of thermophilic actinomycetes was lower than_on farms with_a traditionalstorage system(Dalphin etal. 1991).

Malmberg and coworkers concluded that aller- gic alveolitiswasassociated with high levels of exposure ^tomold sporeson ^mostweekdays for weeks at a time and that ODTS (organic dust toxic syndrome) was associated withextreme exposureon asingle day (Malmbergetal. 1993).

In agriculture, endotoxinscanbe found in vari- ous materials and environments (Olenchock et al. ^1990,Liesivuori^etal. 1994).

Ammonia is themost harmful of the gases causing respiratorysymptoms normally found in animal houses (Kangas ^et al. 1987, Donham 1991, Donham ^etal. 1995). In cow houses, the lowest concentrations of airborne ammonia have been found in facilities equipped witha lowex-

haustsystemof ventilation through the manure

channels (Gustafsson 1988, Linnainmaa et al.

1993).

The objective of this studywas^toinvestigate airborne health hazards during the working pe- riod in 26modern,mainly cubicle, cow houses.

The factors measured were total dust, bovine epithelial and dander allergens, microbialdust, endotoxins, ammonia,carbon dioxide and hydro- gen sulfide.

Material and methods

A total of 26 farmswere included in this study.

They were chosen among about 80 farms pro- vided by agricultural extension services. The main criteria for including a farm in the study were that the cow houses had to be new, the number of milking cowshigh (20-30) and it had

tobeafamily farm. Thecow houses were ^new, less than five years old; the mean year ofcon- struction_orcomplete renovationwas 1991,range

1989-93. Each farmwas runby^twopersons and themeannumber of milkingcows was 22 (range 17-40).Twenty-three farms had cubicle houses (loose-housing barns), two had traditional tie stall barns andone hadacold cubicle barn. The cold cubicle(coldloose-housing barn) is the lat- estmethod of barnconstruction,but notyet com- mon in Finland. Thecow department is uninsu- lated and equipped with wooden walls and roof.

The ventilation is natural with openings in the roof. The milking parlor isa separate warm and insulated_roombeside the cold barn. All warm barns had _a mechanical system ofventilation, but onlyonefarm had_adetailed design forven- tilation. The farmswere situated in middle and southern Finland.

Allexcepttwo of the barns hadanautomatic feeding systemfor milkingcows,but the heifers had to be fed manually. The normal working tasks included cleaning the feeding table anu feeding the cows with forage, fodder grain and dry hay. Hay for fodderwas used on 23 of the

26farms;strawwasused for beddingon6farms, wood shavings on 13 farms;and seven of the farms didnot usebedding atall.

Measurements weremade during winter and early autumn between 1994-1995 in each cow house. The indoortemperatures and relative hu- midity measured in the barn varied from7 to

17°C(mean 12.7°C)and55^to95%^(mean87%), respectively. At the time ofmeasurementthetem- perature in the cold loose barn was -6°C. The outdoortemperature was from+2to -20°C dur- ing farm visits.

The total dustwas sampled gravimetrically according _to the Finnish standard method (SFS 3860). For results below the limit of detection (0.1 mg/m¹for areasampling and 0.5 mg/m⁵for breathingzone sampling according^to the stand- ard)half of the limit of detection has been used for interpreting the results (CEN 1995). Dust samples were collected on membrane filters (Millipore,USA) mounted in open-faced three- piece_cassettes(Millipore,USA).Personalsam- pling was doneatair flowrates of2-2.5 L/min (SKC, USA) and stationary sampling _at flow rates of 20-25 L/min (Piston pump, ^Finland).

Sampleswere taken during the whole working period, and therefore the sampling time varied from 1.5to3.5 hours. The sampling sites forsta- tionary sampling in cubicle houses werelocated in the milking parlor and in the feeding aisle, and in tied barns theywerelocated in the feed- ing and manure aisles. The purpose of thesta- tionary sampleswastoevaluate spreading of the dust. For personal sampling 1-2 samples were taken. The pumps wereweekly calibrated with a calibrator (Gilian, ^USA) and the pumps were checked visually during themeasurements.

Samples for bovine epithelial antigen and specific bovine dander antigen _werecollected in the same way as samples for total dust. After sampling the filters were frozen at-20°C until analyzed. The samples _were analyzed for BEA by aimmunochemical method described by Vir- tanen etal. (1992) and for BDA2O with two-site

immunometric assay described in detail by Ylönenetal.(1994).

Viable fungal sporesweresampled withasix- stage Andersen impactor ^(Model 10-800, An- dersen Inc., USA). Sampling volume_was 50to

100 liters. The culture media and incubationtem- peratures and times for analysis of viable spores were;xerophilic fungionNaCl maltextract agar or on Dichloran Glycerol 18 (DG18) agarat +2O°C for7 days, mesophilic fungi on Hagem agar at+2O°C for 7 days, thermotolerant fungi on Hagem agar at +4O°C for 3-5 days, ther- mophilic actinomycetes on half-strength nutri-

ent agar at +55°C for3 days. Xerophilic fungi arelow-moisture fungi found for example in hay.

The optimumtemperaturerange for mesophilic fungi is20-25°C, whereas thermotolerant fungi are heat-tolerant up to 45°C and thermophilic fungi _cangrow^attemperatures up^to 60°C(Dix

&Webster 1995). Viable sporecountswerecal-

culated ascolony forming units per cubicmeter of air (cfu/m^3), and the fungalorbacterial group was identified with a light microscope. Three types of samples were taken, one background sampleone hour beforework, oneduring milk- ing when hay, forage and fodder grainwerealso deliveredtocows and heifers, and the thirdone twohours after the workwasfinished. The concen- trations of total sporesweredeterminedby the CAM- NEA method describedby Palmgren etal. (1986).

Endotoxin sampling and analysis is described in detailby Laitinenetal. (1994). One nanogram of endotoxin standard from Esherichia coli 01 11 :B4 corresponds to

12

endotoxin units.

Concentrations of airborne ammonia,carbon dioxide,and occasionally also hydrogen sulfide weremeasured with passive diffusion tubes^(am- monia20/a-D, carbon dioxide500/a-D,hydro- gen sulfide 10/a-D,Draeger, Germany) from feeding aisles orin thecasein tied barns inma- nureaisle and in milking parlor. Sampling time for gaseswas the whole working period of the farmers, 1.5to3.5 h.

When the results _were interpreted, the milk- ing parlors were divided into 1) open-parlors opentothebarn, separated only by_afence about 2 m high and 4-5 m long and 2)closed parlors totally separated from therestof the barn.

Louhelainen^,K. etal. Farmers’exposure todusts andgasesin cubicles

Data analysis

Most of the statistical analyses wereperformed with log-transformeddata,because the data_was notnormally distributed. When the GM (geomet- ric mean) valueswere calculated for fungi and actinomycetes, 1 was added to each result be- cause the results included zero values. The _sta- tistical significance of differences between mi- crobial concentrations measured in threeconsec- utive periods (before work, during milking and 2 h after milking)^weretested by repeated meas- ures analysis of variance (ANOVA) for normal distribution and Friedman rank ANOVA fornon-

normal distribution. The differences in thecon- centrations of totaldust, endotoxin,bovine epi- thelial antigens, and gases between the milking parlors and stationary and personal sampling sites were examined with thet-test for normal distribution _or Mann-Whitney U-test for _non-

normal distribution. The correlations between the variablesweretested with Pearson productmo- ment correlation coefficientor with Spearman production momentregression.

Results

The geometricmeanconcentrations of total dust did notexceed the OFF (Occupational Exposure Level) of 5 mg/m³for organic dust (Työminis- teriö 1996).Seven samples from atotal52sam- ples inareameasurementsand 15 samples from a total45 personal samples were under the re- spective detection limits. Therewere nostatisti- cal differences in the total dust concentrations between sampling sitesorbetween persons do- ing feeding and milking work (Table 1).The personal concentrations of total dustwere2 ^to3 times higher than theareaconcentrations(t-test, p<0.001). The highest personal total dust con- centration (14.5 mg/m^{3 )} was measured during feed delivery in abarn where the farmer had to take feedtothe calves fromasilo withashowel.

The GM concentrations of BEAwere atthe same level inarea sites and breathing zones in both tied houses and cubicle houses (Table 2).

Concentrations of BDA2O antigen were 2 to 3 times higher in the breathingzonesamples than in the area site samples in cubicles (t-test, p<0.001) (Table 2). However, no correlations werefound between concentrations of total dust and BEAorBDA2O in open-orclosed-type par- lors either in the breathing zone samples orat stationary site samples.

In all 26 barns the GM of endotoxinconcen- trationwas 19 ng/m^3. The endotoxinconcentra- tion _was 5.5 ng /m³ in the cold cow barn, and in other barns the GMs varied from 16 to 27 ng/m^{3 .}

The concentrations of viable fungi varied strongly during different sampling periods (Ta- ble 3). For every group of microorganisms, in the closed parlors, the concentrationswere2-3 times higher during milking than during other measurementperiods, but in the open parlors, in only with thermophilic actinomycetes. In addi- tion,the concentrations of microorganisms in the cold barn parlor wereatabout thesamelevelas in other parlors. Statistical differences (ANO- VAorFriedman rankANOVA,p<0.05) between measuring periods were found with both xerophilic (NaCl-Malt and DG18), mesophilic fungi and thermophilic actinomycetes in closed -typeparlors, butnotwithany groupof fungior actinomycetes in open-type parlors. In the tied barns during milking, the geometric means of all microorganisms exceptthermophilic actino- mycetes were about tentimes higher thancon- centrations measured from all other cow hous- es. This difference was not noticed for before work orafter workmeasurements.

The meantotal spore countduring milking was 1.2 x I0⁵ spores/m³ (Table 3). The viable fungal spores of xerophilic, mesophilic, thermo- tolerant fungi and thermophilic actinomycetes consisted of about 1-77% of the total spores measured during milking. Therewas nocorrela- tion between the concentration of viable spores from any group of fungi and the total sporecount.

The prevalence of viable fungal groupsor gen-

Table 1.Concentrationsof total dustduringindoor farmwork,mg/m3 .(n⁼number ofsamples, AM⁼arithmetic mean, GM⁼geometric^mean,s=stationary sampling site,bz⁼breathingzonesampling)

Feeding aisle,s Milking parlor,s Milking,bz Feeding,bz

nAMGM range nAM GM range nAMGM range nAM GM range

cold bam I 0.7 I 0.1 I 0.3 1 1.8

tied bam 2 0.2 0.2 0.2 ^- 0.3 2 0.2 0.2 0.2 -0.3 2 1.0 0.8 0.25-1.8 2 0.3 0.3 0.25-0.3 cubicle 23 0.8 0.3 0.05-11.7 23 0.3 0.2 0.05-1.2 17 1.1 0.6 0.25-4.5 23 1.9 0.8 0.25^1.5 closed 12 1.2 0.3 0.05-11.7 12 0.4 0.2 0.05-1.2 9 1.3 0.7 0.25-1.5 12 2.5 0.9 0.25^1.5 open 11 0.4 0.2 0.05- 1.3 11 0.2 0.1 0.05-0.4 8 0.8 0.5 ll 0.8 0.7 0.25-2.2

Table 2. Concentrations of BEA (bovine epithelial antigen) and BDA2O (bovine danderantigen) in cow houses, (n⁼number ofsamples, AM⁼arithmetic mean, GM⁼geometricmean,s⁼stationary sampling site,bz⁼breathing zone sampling)

Feeding aisle,s Milking parlor,s Milking,bz Feeding, bz

nAMGM range nAM GM range nAMGM range nAM GM range

HEA. Hg/m³

cold bam I 2.8 1 1.3 1 0.9 1 10.0

tied bam 2 10.6 7.3 2.9-18.3 2 5.4 5.2 3.8- 7.0 2 6.5 4.6 1.1-18.4 223.4 9.7 2.1-44.8 cubicle 23 9.2 6.1 1.3-35.5 22 8.0 5.3 1.4-25.8 18 8.6 5.6 1.4-28.4 21 12.9 8.6 1.7-43.2 BDA2O. ng/m’

cold bam I 40 1 44 1 90 I 310

tied bam 2 50 50 43-62 2 25 25 24-26 2 210 200 140-270 2 210 200 150-270

cubicle 23 124 85 12-320 22 99 76 21-450 18 240 200 63-550 21 320 260 60-700

era is presented in Table4. Themostprevalent fungus wasAspergillus, followed by Cladospo- rium, Paecilomyces, Penicillium,and Wallemia sebi. The most abundant species of thermoac- tinomycetes wereThermoactinomyces Candidas and T vulgaris. In ^addition, many yeasts were foundonmesophilic media andonboth_typesof

xerophilic culture media.

Hydrogen sulfide_was notdetected in^anyof thecowhouses. Intwotiedbarns,themean con- centration of ammoniawas7 ppm in the feeding aisle and 11 ppm in themanureaisle. In the cold loose barn, the concentration of ammonia _was under the limit of detection atboth sampling

sites. The concentrations of ammonia measured in all 26cowhouses weresignificantly lower in milking parlors _oraisles than in feeding aisles (Mann-WhitneyU-test,p<o.osj. Themean con- centrations of ammonia also differed between

openand closed parlors in cubicle houses(Mann- WhitneyU-test, p<0.05) (Table 5). The _ammo- nia concentrationwassignificantly lower(t-test, p<0.001) in closed parlors than in open parlors.

The_presentOEL of25 ppmwasexceeded in only one cow house.

In all 26cowhouses themeanconcentrations of carbon dioxide in feeding aisles and milking parlorsoraisles were2970 ppm and 2630 ppm,

Louhelainen,K. ^etal. Farmers^’exposure todusts andgasesin cubicles

Table3.Concentrationsof viable and totalfungi incowhouses.

Sampling phase/

fungalgroup

Sporeconcentration (cfu/m³,spores/m³⁾ Number of

samples

CM Range

Before^work

Xerophilic, ^NaCl-Malt 26 1.5 10’ ^110-7.7I0⁴

Xerophilic,^DG18 26 2.5 10’ 220-1.1 10'

Mesophilic 26 1.4 10’ 80-1.2 10'

Thermotolerant 26 1.2 101 ^{1-1.1 10s}

Thermophilic 26 9.3 10° 1-4.010’

During milking

Xerophilic, NaCl-Malt 26 4.110’ ^{310-9.5 104}

Xerophilic,^DG18 26 6.0 10’ 160-9.9 10⁴

Mesophilic 26 3.8 10’ 77-1.5 10'

Thermotolerant 26 2.7 101 ^1-9.5 10’

Thermophilic 26 2.4 101 ^1-1.8I04

CAMNEA, total spore count 12 1.2 10' ^{2.5 lo'}

2 hafter^work

Xerophilic, ^NaCl-Malt 26 1.810’ ^31-1.2 10'

Xerophilic,^DG18 26 3.4 10’ 100-1.2 10'

Mesophilic 26 1.8 10’ ^{20-1.3 10'}

Thermotolerant 26 1.8 101 ^{1-3.0 104}

Thermophilic 26 8,4 10° 1-8.6 10’

GM⁼Geometricmean

respectively. Incubicles,carbon dioxideconcen- trations did^notdiffer significantly between sites (t-test,p<o.l) (Table 5). In tied barns the mean concentration of carbon dioxidewas 5700 ppm in the feeding aisle and 4600 ppm in themanure

aisle.Furthermore, the maximum value reached 6100 ppm. Duetothe nearly outdoorconditions, in the cold cubicle barn the carbon dioxidecon- centrationwas only 900 ppm in the animal de- partment and 1600 ppm in the milking parlor.

Table4.Prevalence offungiandactinomycetes inairsamples^(%) collected fromcowhouses Xerophilic

fungi,^(NaCl)

Xerophilic fungi,^(DG-18)

Mesophilic fungi Thermotolerant fungi

Thermophilic actinomycetes Aspergillus100%

Cladosporium38%

Paecilomyces 22%

Penicillium26%

Wallemia sebi2%

yeasts60%

sterile9%

Aspergillus 100%

Cladosporium 39%

Paecilomyces 43%

Penicillium85%

Wallemia sebi57%

Scopulariopsis2%

yeasts 69%

sterile 14%

Aspergillus 98%

Cladosporium 16%

Paecilomyces28%

Penicillium68%

Rhizopus 6%

Hyalodendron 3%

Trichoderma 2%

Monilla 1%

yeasts66%

sterile 10%

Aspergillus 53%

Acremonium 1%

Paecilomyces5%

Penicillium7%

Trichoderma2%

Thermoascus6%

yeasts 11%

sterile 1%

Th.candidus 24%

Th.vulgaris 32%

Table5.Concentrationsof ammonia and carbon dioxideincubiclehouses,ppm.

Gas^/ Milking parlor

type ofmilking n mean S.D. range parlor

Feedingaisle mean S.D. range

Ammonia

closed 12 ^2,8 2.9 0-7 9,4 3.3 3-14

open II 11 5.3 3-19 15 10 2-38

allbuildings 23 6.4 5.5 0-19 12 7.5 2-38

Carbondioxide

closed 12 2200 490 1400-2900 2700 750 1800-4000

open II 2800 700 1800-4100 3200 820 2200-4800

allbuildings 23 ^{2500 640 1400-4100 2900 790 1800-4800}

S.D,⁼standard deviation

Discussion

The farmers’ exposuretothe airborne dust incow houses have decreased compared toour previ- ous studies(Louhelainen ^etai. 1987

a,

Virtanen etal. 1986, Virtanenetal. 1988),where the total dust levels ranged from 0.7to 1.5 mg/m³ in the feeding aisles. Obviouslyoneofreasonsfor this decrease is the development of feeding tech- niques in agriculture, in particular, the change from manual feeding ofcowstototally automatic feedingsystems.The farmers in thepresent study had _to do _some manual feeding especially for calves andheifers,andontwooccasions also for cows. However, the manual feeding didnot ef- fect _to the concentrations of total dust in the breathing zone of the farmers on those farms.

The threshold value of2.8 mg/m³proposed by Donham(1995)asthe _amountof total dust that will produce adverse respiratory effectswas rare- ly exceeded.

The range of concentration of BEA varied from 1.1. ^to 44.8 |4g/m³ atdifferent sampling sites. However, the concentration of BEA was similar atstationary sites and in the breathing zone. The BEA concentrations of the present studywere^atsamelevel asthose measured pre- viously (Virtanen _etal. 1988)when arithmetic mean concentrations varied from5 to 23 |4g/m³ in the breathing zoneand from5 ^to 13 pg/m^3at

stationary sites in fivecowhouses. Theconcen- trations of BDA2O were from one third ^to half lower atthe stationary sites than in the breath- ing zones of farmers. The range ofconcentra- tions of BDA2O between measuring siteswas as large as with BEA. In this study in stationary sites the arithmetic means of concentrations of BDA2O were lower than in the previous study (Ylönen ^et al. 1994), where concentrations ranged from 266 to 295 ng/m^{3 .} Somewhat sur- prisingly, however,therewas nocorrelation be- tweenBEA and BDA2O. The exposure of farm- erstobovine antigens isatthesamelevel in^new cubicle houses _as in older _cow houses. A few probable reasons canbe suggested; mechanical ventilation usually decreases the relative humid- ity and thereafter increases the secondary dust emission from surfaces,and secondly, although the distance between the cow and the milker is greater in _a milking parlor, the allergen parti- cles are small in diameter and areemitted easi- ly. In addition, the larger number of cow and heifers may produce more airborne allergenic material thanafewcows in smallercowhouses.

Most of the cases of occupational asthma and rhinitis in Finland are caused by cow dander in agricultural work. The concentrations of cow danderareconsistent in differentstudies,and it canbe speculated that thepresent levels of bo- vine allergenscan induce adverse health effects for the farming population.

Louhelainen, K. etal. Farmers’ exposuretodusts andgasesin cubicles The geometric meansof endotoxinconcen-

trations ranged from 17to27 ng/m^3. Ononefarm the endotoxin concentration wasveryhigh, 4830 ng/m^{3 .} On that farm the concentrations of microbial dustwerealso elevated. Even exclud- ing the highest concentration,the results of this study _are still about twice_ashigh _asthose in an earlier study (16 ng/m³ of endotoxins) of dairy farms (Liesivuori etal. 1994).However, these concentrationswerelow compared toother ag- riculturalenvironments, e.g. swineriesor poul- try yards (Olenchock etal. 1990, Liesivuori et al. 1994).

The concentrations of viable airborne fungi and actinomycetes measuredwere at the order of lO'-lO³ cfu/m³which is lower than those in previous Finnish studies (Kotimaaetal. 1984, 1987, Pasanenetal. 1989, Hanhela_etal. 1995).

The concentrations of different microbes were higher, but_not in all _cases significantly higher, during milking than before workor 2 hours af-

ter work. In open parlors, however,the concen- trations rose further and the highest levels of microbes were found2 hours after work. The concentrations ofalltypesof microbes measured were significantly lower in the closed-type milk- ing parlor than in the open-typeparlor. The ob- viousreasonfor this is the closed space, which preventsair from thecowbarn from entering the parlor. The prevalences of the predominant fun- gi ⁽Aspergillus, Penicillium, Wallemia sebi, Cladosporium andyeasts)weresimilartothose found in earlier Finnish study(Hanhela et al.

1995). In ^addition, in this study Paecilomyces was found_morefrequently. Thermophilic actin- omycetes, which have been considered tobe causative_agentsof farmer’s lung,werefound on only_a few occasions and in low concentrations compared with earlier findingsonFinnish farms (Kotimaa etal. 1984).No correlationwasfound between microbial concentrations and the type of methods used to dry and storehay (data not shown).These results may be duetomodern farm practices in which there is littleuse of hay for feed, littleuse ofstrawfor bedding, or no bed- dingatall. Theworstsourcesof airborne spores are thus eliminatedortheir role is clearly less-

ened(Pasanen ^etal. ^1989,Kotimaa 1990, Koti- maaetai. 1991, Dalphin ^etai. 1991).

Concentrations of ammonia were lower in closed-type parlors than inopen-typeparlors. In addition,ammonia concentrationswerelower in milking parlors than in the feeding aisles, and this difference_waslargeronfarms with closed- type parlors. The concentrations of ammonia equaledourprevious results (Kangasetal. 1987, Linnainmaa etai. 1993) which ranged from 0.2

to 35 ppm. The correlations between ammonia levels in milking parlors and in feeding aisles were significant _on all 26 farms,in all cubicle houses and open-type houses (Pearson coeffi- cients between r= 0.69-0.74, p<0.01), but in closed-type parlors no such correlation was found. Visual investigation with smoke revealed that in several cubicles the ventilation did not remove airborne gases effectively. Forex- ample, the inlet air went directly to the outlet channels without mixing, the heat exchangers were blocked by dust, and the outlet fans were insufficienttoremove indoor air. Concentration of ammonia is a function of ventilation effi- ciency but other factors, such as the shape of inlets andoutlets, arealso involved(Gustafsson 1998, Linnainmaaetal. 1993). The lowestcon- centrations of ammoniawerefound in cowhouses from which air was removed only through the manurechannels. The correlation of ventilation ratewith the concentration of ammonia has been foundto be low (Linnainmaa etal. 1993). The lower concentrations of ammonia in milking parlors compared to feeding aisles can be ex- plained by better ventilation of milking parlors, and in particular, by closed space in the closed type parlors. According to Donham et al.

(1995),ammonia in swineries is anenvironmen- tal predictor of decrease in pulmonary function, namely decreasedFEVj ^(forced expiratory vol- ume in one second) at the level of7.5 ppm or more. That threshold is only one-fourth of the present OEL (25 ppm) of ammonia. However, this finding is difficultto apply to cow houses because of different exposure_patterns, e.g. low concentrations of dust compared to the swiner-

ies.

All concentrations ofcarbondioxide, except one, were lower than the OEL of5000 ppm.

However, the limit recommended by the Minis- try of Agriculture and Forestry (3000 ppm)was occasionally exceeded in feeding aisles and also in _open-typemilking parlors in cubicles. Inour previous studies themeanlevels of carbon diox- ide in tie stalls have been about 1500 ppm and 3100 ppm (Kangas et al. 1987, Linnainmaa ^et ai. 1993). The correlation between carbon diox- ide levels in milking parlors and in feeding aisles was significant in all houses and also in open- and closed-type parlors ^(Pearsoncoefficient be- tween r=o.Bo-0.86, p<0.01). Donham (1991) proposed that carbon dioxide would be a good substitute indicator of the relative amounts of ammonia, bacteria, endotoxins, and total mi- crobes in swineries. In this studyno suchcorre- lationswere foundexceptbetween carbon diox- ide and ammonia in all 23 cubicle houses and in open-type barns. The correlation betweencar- bon dioxide and ammonia in feeding aisles was less significant^(Pearson coefficient r= 0.44, p<0.05) in allcow houses than in cubicle barns (Pearson coefficient r=0.55, p<0.01). ^Inmilking parlors oraisles therewas nocorrelation between carbon dioxide and ammonia in all barns meas- ured,but in cubicle barns the correlationwassig- nificant (Pearson coefficient r=0.60, pcO.Ol).

Airborne exposure especially togases was low in the_one cold cubicle studied. However, there might be otherfactors,suchaslowtemperatures, slipperiness and ergonomics in cold,which have an adverse effect onfarmers.

The occupational exposure of farmerstogases and dusts in cubicle barns has been rarely re- ported previously in the literature. The results show that the exposuretoseveral hazards is lower than inolder, tiedcow houses, but gas exposure have remainedat thesame level. The mainrea- sons for the decreasearethe automatic feeding systemsforcows,the automatic ventilation sys- temsand minoruse of material containing or- ganic dusts. Occupational respiratory diseases are, however, common among farmers and fur- ther research is neededtostudy the relationship between exposure and diseases. To improve the environmental conditions in thecowhouses stud- ied, emphasis should be placed on design of the buildings ^- especially the ventilation. Only one farm had aproperdesign for ventilation. Venti- lation affects many environmental exposures, namely ammonia, carbondioxide, temperature, relative humidity andtoasmallextentalso dust.

Another measure for improvement is provision of additionalheat,which is needed incowhous- es during wintertime. Warming the supply air increases the_rate of ventilation and reduces air impurities and relative humidity. Although work- ing conditions have become more comfortable and organic and biological exposures have de- creased, there are still exposures that threaten farmers’ health.

Acknowledgements.Thisstudy^wassupported bythe grant from Fanners’ Social InsuranceInstitution,Espoo,Finland.

We wish to thank Ms. MinnaKallionpää, Mr.Heikki Kal- lunki andMr.Kari Ojanenfor theirparticipation indata collection andMr.Pentti Mäkelä for statistical advice.

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SELOSTUS

Maanviljelijöiden altistuminen pölyille ja kaasuille nykyaikaisissa ^navetoissa

Kyösti Louhelainen,JuhaniKangas, MarjutReimanjaPentti Kalliokoski Kuopio aluetyöterveyslaitos ja Kuopion yliopisto

Tutkimuksessa selvitettiin viljelijöiden altistumista kaasuille ja pölyille nykyaikaisissa pihattonavetois-

sa.Tutkimuksessa oli mukana23 pihattoa, yksi kyl- mäpihatto jakaksiparsinavettaa. Navetoissa oli kes- kimäärin 22 lypsylehmää.Tutkittavat ilmanepäpuh- taudet olivatkokonaispöly, lehmänkarva-jahilseal- lergeeni, mikrobit, endotoksiinitsekä kaasuista am- moniakki, hiilidioksidija rikkivety. Mittaukset teh- tiin sisäruokintakaudella lehmienruokinta-ja lypsy- töiden aikana.

Tutkituissa navetoissa kokonaispölypitoisuudet olivat keskimäärinpieniä, alle 2 mg/m^3,kuntyösuoje- luviranomaisten antama suositusarvo on 5 mg/m3.

Tämä on mm.kehittyneiden työmenetelmien ansio- ta. Esimerkiksi automaattisten ruokintalaitteiden käyttövähentääpölylle altistumista.Vähentynytkui- vaheinänkäyttövähentää ilmanepäpuhtauksia ja vai-

kuttaa osaltaanmyös kokonaispölypitoisuuteen. Re- hun otto siilostaja jakelu vasikoille oli syynä satun- naisiin suuriin pölypitoisuuksiin.

Lehmän karva- ja hilseallergeenipitoisuuksia on mitattu vähän navetoissa. Hilsepöly ^aiheuttaa vilje- lijöille vuosittain satoja ammattitautejakutennuhaa, astmaajaihottumia. Tutkimuksessa mitattiin kahta allergeenia, joiden pitoisuudet olivat erittäin pieniä kokonaispölymäärään verrattuna.Allergeenipölyä oli viljelijöiden hengitysvyöhykkeellä, ruokintapöydällä ja lypsyasemalla, joten viljelijä altistuutällepölylle kaikkialla navetassa.

Tutkimuksessa mitattiin viidenerityyppisen mik- robiryhmän pitoisuuksia. Kaikkien mikrobienpitoi- suudet olivatpienempiäkuin aiemmissa suomalaisis- sa^navetoissatehdyissätutkimuksissa. Ruokinnanai-

kainen homeitiöpitoisuusoli keskimäärin4000-6000

itiötä /m³, kun suurimmat pitoisuudet olivat noin 150 000itiötä/m^3.Mikrobien lähteinä olivatkuivaheinä, rehu jaolkikuivike. Endotoksiinia on tiettyjen bak- teerien soluseinässä. Koska lehmätiloilla käytetään bakteerejasisältäviämateriaaleja,navetanilmassaon myösendotoksiinia.Senpitoisuutta on mitattuaiem- min vainyhdessätutkimuksessa Suomessa. Kummas- sakin tutkimuksessa keskimääräinen pitoisuus oli

suurinpiirtein sama. Suurinyksittäinen pitoisuus oli erittäin suuri verrattuna suositeltuunraja-arvoon.

Ammoniakkipitoisuudet olivat pienimpiä sulje- tuilla lypsyasemilla. Ruokintakäytävältä mitatutpi- toisuudet olivatyhtäsuuria kuin vanhemmistanave- toista mitatut. Nykyaikaisten navettojenkeskimääräi- nen hiilidioksidipitoisuusei ole pienentynyt vanhem- piin tuotantorakennuksiinverrattuna. Rikkivetyäei

osoitettu mittauksissa.

Ilmanvaihto vaikuttaa mm. kaasupitoisuuksiin.

Kaasupitoisuuksistavoidaan päätellä, ettäilmanvaih- tojärjestelmät eivätolleet riittävän tehokkaitapois- tamaankaasuja.Lisäksinavettojen suhteellinen kos- teus oli keskimäärin yli 85 ^%.Tutkituista navetoista

vainyhdessäoli yksityiskohtainen ilmanvaihtosuun- nitelma.

Yhteenvetona voidaan todeta, että viljelijöiden altistuminen ilman epäpuhtauksille on vähäisempää uusissa navetoissa kuin vanhoissa parsinavetoissa.

Kaasu-ja mikrobipitoisuudet olivatsuljetuilla lypsy- asemillapienempiäkuin avonaisilla. Kuitenkin vil- jelijätaltistuvatepäpuhtauksille satunnaisestijauu- detkaan navetat eivät takaa viljelijöiden terveyttä.

Tulevaisuudessa erityisesti ilmanvaihtoon tuleepa- nostaavoimakkaasti navetoita suunniteltaessa.