studies on tractor related injuries in

8/4/2019 Studies on Tractor Related Injuries In

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PergamonAccid. Anal. and Prev., Vol. 30, No. I, pp. 53-60, 19980 1998 Elsevier Science LtdAll rights reserved. Printed in Great Britain0001.4575/98 $19.00 + 0.00

PII: S0001-4575(97)00061-4

STUDIES ON TRACTOR RELATED INJURIES INNORTHERN INDIA

ADARSH KUMAR * , DINESH MOHAN~ and PUNEET MAHAJAN~Centre for Biomedical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016,

India and Department of Applied Mechanics, Indian Institute of Technology Delhi, Hauz Khas,New Delhi 110 0 16, India(Receiced 3 February 1997)

Abstract-Epidemiological studies were conducted in two phases each of 1 year duration in nine and 30 villages,respectively, in two northern states of India. Investigations were carried out to determine the causal factors, theactivities involved and severity of injuries for farming and non-farming activities in tractor related accidents. Atotal of 76 cases involving five fatalities and 71 non-fatal injuries were recorded. The pattern of tractor relatedinjuries in India have been found to be very different compared to those reported from highly industrializedcountries. Fifty-four percent of tractor related injuries in the first phase and 49% in the second phase werebecause of non-farming activities. Of the total injuries recorded in both the phases only 1 and 6% were tractorrelated. A major cause of tractor related injuries were collisions. In the two phases 28 and 40% injured werepassengers on tractor or trailer. 8 1998 Elsevier Science Ltd. All rights reservedKeywords-Epidemiology, India, Injuries, Prevention, Tractor accidents

INTRODUCTIONSixty-seven percent of the work force (Census of India,1991) in India is dependent on agricultural occupa-tions. Agricultural production in India has increasedin the past three decades with the introduction ofhybrid varieties of grain and increased mechanization,and so have the injuries and health hazards along withthese developments. The use of tractors on Indianfarms has increased from a population of 52,000 inthe 1960s to 1,517,869 in the 1990s (Government ofIndia, 1993). The tractor is the most commonly usedpower source on farms throughout the year, unlikeother agricultural machines which have specific andoccasional use. The tractor is used in conjunction withall kinds of machinery: mounted; semi-mounted; andtrailed equipment. The use of tractor is not merelyrestricted to farms, but it is also used as the mainmode of transportation in rural areas. The tractor isalso used under stationary conditions: taking powerfrom auxiliary sources, like power take off (PTO)pulleys for threshing and tube well running.

Most of the studies done on tractor relatedinjuries have originated from highly industrializedcountries (HIC). Baker et al. (1984) have recordedthat from 1930 to 1980 the death rates due to

*Corresponding author. Tel: 00919 I I 685 8703; fax: 00919 11686 2037; e-mail: [email protected]

unintentional injuries in the United States declinedby 60% but farm machinery injuries increased by44%. The involvement of the tractor in injuries asreported in different studies of all agriculturalmachines is shown in Table 1. Tractors are reportedto be involved in 40-70% of injuries and fatalities inall studies except the one from India where theinvolvement rate was 6% (Mohan and Patel, 1992).A summary of tractor related injury studies is givenin Table 2. These studies show that the most commoncauses of injury are overturns, run-overs, falls, colli-sions and PTO injuries.

Field and Gong (1982) reported that in China670,000 regular tractors and 2,000,OOO power tillerswere in use. They estimated that in 1980 there were3000 tractor and machinery related deaths and 4000serious injuries. Of the total fatalities lo-15% wereoperators while the rest were either pedestrians orpassengers on tractors.

Juha (1992) studied the characteristics and pre-vention of tractor accidents using statistical data on403 tractor accidents in Finland in 1987. In a casestudy on 50 tractor accidents, detailed analysisshowed that 42% injuries resulted while climbing inand out of the cab and 30% while hitching andunhitching equipment.

Tractors are not only involved in overturning orfall related injuries but also cause PTO related prob-53


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54 A. KUMAR et al.

Table 1. Injuries caused by farm equipment as reported in studies from different countriesStudy*

Machinery

Young and Huston and Howell and Simpson McKnight and Cogbill and Etherton Mufti Mohan andGhrmley Smith Smith Hetzel Busch et al. et al. Pate1(1946) (1969)+ (1973) (1984) (1985)+ (1985) (1991)+ (1989) (1992)

1935543 1955567 1969 1980 1975581 1978883 1980-85 1982284 1987-88U.S. Canada Canada Canada U.S. U.S. U.S. Pakistan IndiaFodder cutter m/cThresherTractorTrolleyTillage toolsHand toolsAugerCorn-pickerCombineEngineMowerBailerSugar crusherTube wellMiscellaneousTotal

9 (5)34 (18)

29 (15)7 (4)6 (3)6 (3)

95 (52) 46 (19)186 (100) 247 (100)

2 (1)2 (1)169 (68)

10 (4)11 (4)3 (1)4 (2)2 (4)

19 (37) 18 (43) 1940 (60) 118 (52) 1523 (69)

15 (29) 7 (17)6 (12) 4 (9)4 (7)4 (7) 3 (7)

4 (8) 10 (24)52 (100) 42 ( 100)

46 (1) 61 (3)57 (26) 26 (1)93 (3) 53 (2)

42 (2)

1150 (36) 50 (22) 511 (23)3229 ( 100) 225(100) 2216(100)

6 (6)17 (16)32 (31)38 (36)

64 (11)10 (2)27 (5)8 (I)

52 (9)267 (47)

-27 (5)

-IO (2)133 (18)

576 (100)*The study is included by authors name and date of publication, the period covered by the study and the country where the study was done.+Fatality studies.*Number of victims (percent).Pesticide contact through sprayers included.

Table 2. Causes of injury in tractor related accident studiesTractor injury cause (%)

Study* Overturn Runover Fall Collision Crushed PTO or other part OthersKarlon and Noren (1979), 1961-75, Wisconsin,

U.S.. N=415 52 12 11 10 15Tupi (1988)+, 1976685, Finland, N=287 42 12 18 6 9 13Lehtola et al. (1994)+, 1988892, Iowa, U.S., N= 136 56 17 14 13Smithurst (1968), 1964-66, Australia, N= 162 53 12 17 5 3 10*The study is included by authors name and date of publication, the period covered by the study and the country where the study was done.+Fatality Studies.

lems. McElfresh and Bryan (1973) showed that PTOinjuries included traumatic amputations, multiplefractures and large skin avulsion including denuda-tion of genitalia. Kalenak et al. (1978) and Heeget al. (1986) also described PTO injuries as seriousand potentially fatal.

Most of the studies conducted from HICs showthat when tractors are either equipped with rolloverprotection devices or bars they give some protectionin tractor rollovers (Kelsey and Jenkins, 1991;MMWR, 1993).

The present study was conducted with the objec-tive of understanding the causal factors associatedwith tractor injuries experienced in northern India.The results are reported along with suggestions forcounter measures for injury control.

METHODOLOGYIn the first phase nine contiguous villages were

selected in the Sonipat District of the Haryana State.The study was conducted from 1 July 1987 to 30 June1988. The second phase of the study was extended to30 villages which included the villages from Phase I,nine from the Baraut District of Uttar Pardesh and12 from Rai Block of the Sonipat District of Haryanafor the period 1 July 1990-30 June 1991. These villageswere selected due to their high agricultural activitiesand use of modern technology. These three areaspredominantly grow wheat, sugarcane and rice. InPhase I, field workers were trained to collect injurydata from household surveys. The field workers visitedevery house once every 2 weeks and obtained informa-ion on all injury related events. In Phase II, informers


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Studies on tractor related injuries in Northern India 55

were selected in each study village to report cases ofall agriculture related injuries to us. For every injurycase reported, trained investigator visited the home ofthe victim and obtained all the injury and equipmentrelated information.

A form was prepared for collecting detailed infor-mation about each case which included event andtractor details. Follow up forms were also designed torecord details of injury recovery period. The fieldassistants visited all the victims for follow up interviewsperiodically. The severity of injuries were codedaccording to the Abbreviated Injury Scale (AmericanAssociation for Automotive Medicine, 1990).

Phase I was a base-line study and we were ableto obtain records of all injuries which disabled victimsfor > 1 day in a total population of 19,723. However,in Phase II we expected the informer to reportserious injury (AIS > 2) cases only. This study wasconducted to get a large sample of AIS > 2 injuriesto obtain a better epidemiological understanding ofthe factors involved. The population covered in PhaseII was 59,167. The first phase gives a better idea ofall injuries where as the second phase gives a biggersample of more severe injuries but is not representa-tive of all injuries.

RESULTS AND DISCUSSIONA total of 2059 and 576 injuries were reported

in Phases I and II, respectively. These included 576(28%) and 282 (49%) agricultural machinery or imple-ment related injuries, respectively. A total of 76 cases(39 and 37, respectively) of tractor related injurieswere reported in both phases (Table 3). In tractorrelated injuries 18 (46%) and 19 (51%) were due tofarming related activities and rest were associatedwith non-farming activities. We have defined farmingrelated activities as those which have some correlationwith agricultural operations and non-farming activityas that which is purely for transportation, leisure,etc. This shows that in India injuries caused by tractorare associated not only with farming activities butnon-farming activities also.

Although the total percentage of tractor relatedinjuries were very small, the corresponding percentagein severe injuries were quite large as shown in Fig. 1.All severe injuries of AIS and AIS in agricultural

Table 3. Distribution of injuries in two phasesInjuries Phase ITotal injuries 2059 (100)Agric. related 516 (28)Tractor related 39 (2)Parentheses indicates percentage.

Phase II576 (100)282 (49)

37 (6)

machinery related injuries were associated with trac-tors in Phase I and 50 and 25% in Phase II.Tractor relatedfatalities

There was a total of five fatal cases in the twophases combined. Two tractor drivers died becauseof their tractors overturning. One driver went tobring fodder from the field and on the way a suddenappearance of a buffalo in front of the tractor forcedthe driver to apply the brakes, which resulted in thetractor overturning and the driver being crushedunderneath the tractor. Another rollover occurred ina field near an irrigation channel with a high slopecausing the driver to be crushed. The third victimwas an occupant of a bullock-cart (wooden cartpulled by bullocks or buffalos), which was hit by atractor from the rear with the front wheel of thetractor subsequently crushing the victim who hadfallen on the road. Two children were runover bytractors, where in both the cases the tractor drivercould not see the children.

Figures 2(a and b) show the age distribution ofpersons involved in tractor related injuries. The 15-54age group constitutes 80 and 70% of the total tractorrelated injury cases in Phases I and II, respectively.Seven children in the O-14 age group were involvedin tractor related injuries. Of these there was onlyone involved in agricultural activities. This was acranking injury suffered by a lZyear-old child. Twochildren, aged 1 and 3 years, respectively, were run-over by tractors in Phase I. No driver of ~23 yearsof age was injured in any phase. This condition isquite different from the study by Lehtola et al. (1994)where younger operators had fatal accidents. Theolder age group (> 64 years) were injured mostly innon-farming activities in both phases.The causes of injuries

Phase I, The causes of tractor injuries is shownin Fig. 3. Injuries due to collisions were most frequentand accounted for 12 (30%) injury cases. These colli-sions occurred because tractors are frequently usedfor transporting people and are used on rural roads.Transportation is generally done with flat-bed opentrailers which are either single or double axlesattached to the tractor with a hook (Fig. 4). Seveninjuries were caused by a part of a tractor hitting thevictims. Four ( 10%) injuries were sustained whileworking with implements for hitching/unhitching oradjusting the connecting links. Three (8%) injurycases occurred while working with tractors whenfixing some auxiliary structure or putting rocks undertyres for parking etc. Two cases. respectively,


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56 A. KUMAR et al.

r-- .--Phase-l, N-576~ m Tractor m Other Machines 1

IPhase-Ii, N-282

AlS60% 25% 50% 75% 100%

Fig. 1. Percentage of tractor related injuries in two phases of the study.

occurred when repairing a tractor, while working witha PTO shaft and falling from a tractor. Cranking,climbing and playing each contributed to one injury.

Phase II. The distribution of the injuries inPhase II are different from Phase I because Phase IIdata are based on reporting by informers whereasPhase I data were obtained from regular house-holdvisits. Phase II data mainly includes AIS> injuries.Non-rollover collisions resulted in nine (24%) injurycases, including one fatal case where one passengerof a bullock cart was hit by tractor and then runover.Rollover associated injuries include a total of nine(24%) cases which included two resulting from colli-sions. Four injuries were caused while working withimplements. Three injuries were due to failure of thetrailer hook and resulting in injuries to the trailerpassengers. Two cases each were associated withclimbing up/down, falling from the tractor, crankingthe engine, repairing and playing. There were noreports of PTO related injuries in this phase.

In both the phases the injuries caused weremostly associated with transportation and werecaused because of collisions, overturning and trailerhook failure. Injuries caused while repairing fan beltsand generator/alternator of tractors were alsorecorded in four cases. No steps are provided ontrailers to help passengers to climb up or step down,which causes injury especially in single axle trailerswhich are very unstable. Fall injuries were associatedmainly with passengers sitting on the mudguard whofell because of rough terrain and got trapped betweenthe tractor and trailer. A low incidence of PTOrelated injuries were encountered because PTO oper-ated machines are rarely used.

Tractor collisionsTractor collisions are a major cause of tractor

related injuries. There were 25 cases of tractor crashes(Table 4) resulting in three fatalities. Two children wererunover in the first phase and a female on a bullockcart was hit by a tractor and then runover in thesecond phase.

The other frequent situation included the attach-ment of a modified bullock cart to a tractor in whichpassengers sat on the edge with their legs danglingoutside the cart. This was the cause of four injuriesrecorded in the second phase. Tractors were alsohit by trucks on two occasions in the second phase.The collisions resulted in the overturning of thetractor/trolley in two incidents in Phase II.

Out of all the collisions, nine collisions occurredbetween 18:00 and 06:OO hours while the rest tookplace at 06:00~18:00 hours. Truck-tractor collisionshappened in dark between 18:00 and 24:00 hours.Poor visibility and absence of bright headlights, tail-lights and reflectors on the tractors could be associ-ated factors in these collision.

Distribution of victimsPhase I. As shown in Fig. 5, 11 (28%) victims

were passengers on tractors or trailers, 12 (3 1%) wereoccupants of other vehicles and 10 (26%) were work-ing with the tractor. Only 5% of the victims weredrivers who were injured while operating the tractor.

Phase II. There were 15 (41%) victims who werepassengers on tractors or trailers. Working with trac-tors caused 10 (27%) injuries and occupants of othervehicles and drivers were involved in 5 (14%) injuries.In both the phases the injury to the passengers of


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Studies on tractor related injuries in Northern India

No of cases8r

0 Non Farm Activity6

o-4 5-14

(a)No of case8

15-24 25-34 35-44 45-54 55-64Aga,yaara

6r

1 1

IIEI~84

m Farm activity 0 Non Farm Activity

o-4 5-14 15-24 25-34 35-44 45-54 55-64 a64Age,yeara

(age of one tractor driver Is not known)@I

Fig. 2. (a) Age distribution of tractor related victims (Phase I) . (b) Age distribution of tractor related victims (Phase I I).

the tractor and trailer clearly highlighted the frequentusage of tractors for transportation. There are noproper arrangements either on the tractors or trailersfor passenger to sit, which makes them more vulnerableto injuries. As indicated in Table 4 the occupants oftractors were involved only in two collision cases buta much larger number of passengers got injured whenbeing transported either by falling from thetractor/trailer or from trailer hook failure.Severity of injury

From the analysis, tractor injuries came out tobe very severe with 21 injuries in both phases beingAIS or above. This constituted 54 and 57%, respec-

tively, of the total injuries. Compared to total agricul-tural machinery related injuries in two phase studies13 and 44% were AIS and above. Out of the totalagricultural machines, only 7 and 13% injuries werecaused by tractors and trailers. But tractors/trailerswere responsible for 25% of AIS2, 22% AIS and allof the AIS and AIS injuries in Phase I (Fig. 1). InPhase II, 17% of AIS2, 7% of AIS3, 50% of AISand 25% of AIS injuries were caused by tractorsand trailers. This clearly indicates the severity magni-tude of tractor related injuries.Recovery time

Tables 5(a and b) indicates the recovery perioddistribution in farming and non-farming activities in


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58 A. KUMAR et al.

CollisionOverturning

Imp. WorkingHit by tractor part

ReparingTractor Working

Trailer hook failureFallCrankingClimbing

PlayingPower Take Off

Runover0 2 4 6 6 10 12

No.of injured casesPhase-l. N-39 m FatalitiesPhase-II, N-37 a Fatalities

IES3 InjuriesInjuries i

Fig. 3. Mechanisms of tractor related injuries

Fig. 4. Tractor attached with loaded trailer.

both phases. In Phase I, 15 (38%) farming activityinjuries and 14 (36%) injuries related to non-farmingactivities took > 1 month to recover. Longer recoverytimes were observed with injuries caused by non-farming activities than with those from farming activi-ties in this phase. In Phase II nine (24%) farmingrelated injuries and 12 (32%) non-farming relatedinjuries took 1 month to recover. Farming activityrelated injuries took > 1 month to recover in this phase.

The average recovery time was 27 and 39 days inPhases I and II, respectively. The recovery time for

injuries caused by farming activities was 20 and 39 daysand for non-farming activities 33 and 38 days in PhasesI and II, respectively. This was because in Phase IIonly serious injuries were reported by the informers.

CONCLUSIONSTractor related injuries are not only confined to

farming activities but also resulted from non-farmingactivities. Injuries caused by using the tractor fortransportation constituted a significant percentage of


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Studies on tractor related injuries in Northern India 59

Tractor impacted by

Table 4. Details of crashes in tractor related transportation injuriesPhase I Phase II

No. of injured cases No. of injured casesTractor (%) Other object (%) Total (%) Tractor (%) Other object (%) Total (%)

CycleScooterTempoTruckBusCarTractor + cartBullock cartPedestrianTotal

4 (29)2 (14)l(7)1 (7)2 (14)*l(7)-

3 (22)14 (100)

4 (29)2 (14)1 (7)1 (7)2 (14)*1 (7)

3 (22)14 (100)

2 (8) 2 (8)1 (9) 1 (9)

2 (18) 2 (18)

4 (36) 4 (36)1 9) 1 (9)l(9) 1 (9)2 (18) 9 (82) 11 (100)*Overloaded fodder trolley injured bus passengers.

Phase-l Phase-II

N=39 N-37

DriverPlaying

Other Veh. Occup.

Passenger

Working-Tractor

525

1 5

1 0

Fig. 5. Distribution of tractor related victims

the injuries. The victims injured were passengersriding on tractors or trailers. Passengers tend to fallwhen using the tractor for transportation and alsoget hurt when the trailer hook failed. It was alsoobserved that most of the trailers were single axleand were therefore more unstable. The observations

(5)

are(1)

(2)(3)(4)

summarized as follows:Tractor related injuries were caused because ofnon-farming activities in 54 and 49% of casesin Phases I and II, respectively.No drivers ~23 years of age were involved in aninjury event.No tractors were equipped with rollover protec-tion structures (ROPS) or cabs.Out of 76 accident cases only 13% were caused

(6)

(7)

by overturning. The reasons are the flat terrain,low horse power tractors and the use of smallequipment in the study area.An extremely high percentage of victims (28 and41%) were tractor/trailer passengers in Phases Iand II, respectively. This is because tractors arecommonly used for transportation.A total of 31 and 24% of injuries were due tocollisions on the road in Phases I and II, respec-tively. The Lack of bright headlights, over loadedtrolleys and mismatched trailers were often thecause of collisions.Very few PTO related injuries, due to the non-availability of PTO operated equipment in thestudy region were observed.


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60 A. KUMARet al.

Table 5. Recovery period for different activities: (a) Phase 1 and agricultural trauma. Journal of Emergency Medicine 3,(b) Phase 11 205-210.Recovery time(days)(a) Phase IO-10Ill2021-3031-6061-9091-150151-200Total (%)(b) Phase IIO-101 -2021-3031-6061-9091-150151-200Total (%)

Farmactivity

951111018 (46)3246220

19 (51)

Non-farmactivity

852122

21 f54)264401

18 f49)

Total(%)

17 (43)10 (25)3 (8)2 (5)3 (8)3 (8)l(3)39 (100)5 (14)8 (22)8 (22)10 (27)2 (5)1 (2)1 (2)

37 (100)

Etherton, J. R., Myers, J. R., Jensen, R. C., Russell, J. C.and Braddee, R. W. (1991) Agricultural machinesrelated deaths. American Journal of Public Health 81,766-768.

Field, W. E. and Gong, S. F. (1982) Agricultural MachinerySafety in China. Paper presented at the 1982 SummerMeeting, ASAE, Paper No. 82-5007, 1982. AmericanSociety of Agricultural Engineers, St. Joseph, Michigan.Government of India (1993) Motor Transport Statistics ofIndia 1991-93. Transport Research Wing, Ministry ofSurface Transport, Government of India, New Delhi,India.Heeg, M., Duis ten, H. J. and Klasen, H. J. (1986) Powertake-off injuries. Injury 17, 28-30.Howell, J. M. and Smith, E. S. 0. (1973) An agriculturalaccident survey in Alberta. Canadian Journal of PublicHealth 64, 36-43.Huston, A. F. and Smith, C. (1969) Farm accidents inSaskatchwen. Canadian Medical Association Journal100, 764-769.

(8) Maintenance injuries were also prevalent, occur-ring mainly while repairing fan belts and thegenerator/alternators of tractors.The following suggestions are made based on

observations gathered during the two phases of thestudy:

Juha. S. (1992) Tractor accidents and their prevention.International Journal of Industrial Ergonomics 10,321-329.Kalenak, A., Gordon, S. L., Miller, S. H., Greer, R. B. andGraham, W. P. ( 1978) Power take-off injuries. Journalof Trauma 13, 775-782.Karlon, T. and Noren, J. (1979) Farm tractor related fatali-ties: the failure of voluntary safety standards. AmericanJournal of Public Health 69, 146-149.Kelsey, T. W. and Jenkins, P. L. (1991) Farm tractors andmandatory roll-over protection retrofits: potential costsof the policy in New York. American Journal of PublicHealth 81, 921-923.

(1)(2)(3)

(4)(5)(6)

Redesigning the tractors/trailers so as to makepassenger transport safer.Redesigning the hitching arrangement for thetrailer and implements to make hitching andunhitching safer.The tractors should be made more conspicuousby providing better headlights, sidelights andreflectors.Provision of safety structures and ROPS.Training of drivers in safer methods of mainte-nance and use of tractor trailers on roads.Training of drivers regarding the conditions oftractors and tractor-trailer rollovers.

Acknowledgements-The field work was supported by CAPART,Ministry of Rural Development and Ministry of Social Welfare.The study was assisted by Rajesh Pate1 and data entry done byMahesh K. Gaur. S. J. Shah and H. Kumar helped in data collection.

REFERENCESThe Abbreviated Injury Scale (1990) American Associationfor Automotive Medicine, Arlington Heights, IL.Baker, S. P., ONeill, B. and Karpf, R. S. (1984) The Injury

Fact Book. D.C. Health and Company, Lexington, MA.Census of India (1991) Series I, Paper 2 of 1991. RegionalGeneral and Census Commissioner, India.Cogbill, T. H. and Busch, H. M. (1985) The spectrum of

Lehtola, C. J., Marley, S. J. and Melvin, S. W. (1994) Astudy of five years of tractor related fatalities in Iowa.Applied Engineering in Agriculture 10, 6277632.McElfresh, E. C. and Bryan, R. S. (1973) Power take-offinjuries. Journal of Trauma 13, 775-782.McKnight, R. H. and Hetzel, G. H. (1985) Trends in farmmachinery fatalities. Agaric Engineering 66, 5, 15- 17.

MMWR 42(3), 57-59 (1993).Mohan, D. and Patel, R. (1992) Design of safer agriculturalequipments: application of ergonomics and epidemiol-ogy. International Journal of Industrial Ergonomics 10,301-309.Mufti, A. I., Ahmad, S. I. and Majid, A. (1989) Farmaccidents in Pakistan. Agricultural Mechanisation inAsia, Africa and Latin America 20, 73-75.Simpson, S. G. (1984) Farm machinery injuries. Journal ofTrauma 24, 150-152.Smithurst, B. A. (1968) An epidemiological study of 162tractor accidents in Australia, 1962 to 1966. MedicalJournal of Australia 1, 5 l-54.Tupi, K. (1988) Fatal occupational accidents with tractorin Finnish agriculture in 1976685. International Confer-ence on Agricultural Engineering, Paris, pp. 62-63.National Centre for farm machinery, agricultural engi-neering, water and forestry, Montpellier, France.Young, H. H. and Ghrmley, R. K. (1946) Accidents on thefarm. Journal of the American Medical Association 132,768-77 1.

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