Impact of age and gender on postural stress of dairy workers

Postural stress was measured by assessing time spent in different body postures, frequency of adopting various body postures and angle of body deviations in lumber region of dairy workers during milking. Findings of study suggested that squatting posture was adopted for the longest period of time along with standing posture as a frequently adopted posture by all dairy workers. Further, time spent in different posture was maximum in females of the higher age group and minimum in males of lower age group. However, frequency of adopting different posture was same for all dairy workers. Angle of body deviation was observed with the help of flexi curve by dividing whole process of milking operation into five parts-lifting of empty bucket (p1), placing of bucket on ground (p2), milking (p3), lifting of bucket containing milk (p4), carrying of bucket containing milk (p5), angle of body deviation was maximum during milking operation (p3) with maximum value in females of the higher age groups.


INTRODUCTION
India is one of the world's largest agriculture economies and has the second largest agricultural work force with two hundred and sixty million workers.The number of person/hour expended in crop production in India is measured in billions.India's human population has approached one billion marks and is rising at a compound growth rate of about 2.1%.It is expected to reach 1.5 billion marks in the next twenty-five years (Anonymous, 2003(Anonymous, -2004)).Rapidly increasing population of India is continuously decreasing the land available for farm operations.Except it, urbanization, industrialization and land fragmentation is also responsible for decreased land holding.The average size has decreased from 2.28 ha in 1977 to 1.55 ha in 1990-1991(Chowdhary, 2005)).
In these conditions, dairy farming has emerged as an important source of income to rural people especially to small and landless farmers.In a study carried out in Karnal district of Haryana, Patel and Mehta (1988) evaluated that, landless women spent more number of hours in dairying than men and their per hour earning from dairying was 4 times than that of agriculture.
Livestock is the fastest growing source of productive employment as compared to any other sector of Indian economy (Alagh, 2000).Within India, the livestock sector supports the livelihood of nearly two hundred million poor (Ahuja et al., 2000).Evidence showed that contribution has increased with decrease in land holding under mixed farming system prevalent in our country.
However, unlike developed country, dairy farming requires manual material handling with heavy lifting, pushing and pulling.All these have been recognized as risks factors for occupational health by NIOSH.More than 1 million workers annually sustain severe injuries enough to result in lost time from work due to overexertion or repetitive motion (Anonymous, 1999).There is a clear relationship between back disorders and physical load with the main physical risks factors being manual material handling (MMH), load moment, frequent bending and twisting during work awkward postures of stooping, squatting and kneeling (Anonymous, 2001).Manual material handling (MMH) has been recognized as a major cause of industrial accident, acute overexertion injury and chronic repetitive strain injury.Osteoarthritis of hip and upper limb complaints and hand arm syndrome are the occupational disease and hazards associated with work related risks factors prevalent in dairy farming activities.Gustafsson et al. (1994) investigated the presence of musculo-skeletal symptoms in Swedish dairy farmers and observed that 82% of males and 86% of females were bearing musculo-skeletal symptoms.Guo et al. (1994) investigated the prevalence of work related to back pain for gender in agricultural production crops and reported the prevalence for males was 16.7 and 10.8 for females.For male workers, an average of 14.9 (SE = 9.4) work days was lost per back incident case.Another study was related to prevalence rate (29.5) among the males for Dutch trades and professionals (Hildebrandt et al., 1995b).Dairy farmers perceived frequent symptoms in the shoulders, elbows, lower back, hips and knees.In addition, female dairy farmers reported severe hand and wrist problems.As compared to women, men reported more back and knee problems.Women reported more symptoms in the neck, upper back and upper extremities than men.This statement was similar to the findings by Hildebrandt et al. (1995b) in which 75% of farm workers reported experiencing musculo-skeletal symptoms during the previous 12 months.Myers et al. (1995) found many risk factors associated with the development of musculo-skeletal disorders in agricultural tasks.Occupational risk factors included static positioning, forward bending, heavy lifting, carrying, kneeling and vibration.Further, work force of dairy sector in India is heterogeneous, that is, females and males of various age groups are engaged in dairy sector.There was no single operation of dairy farming which was exclusively performed by men whereas cleaning of cattle shed, preparation of cow dung cakes and 'ghee' making Chauhan 385 were found to be the exclusive domains of women in the Hisar district of Haryana (Jain and Verma, 1995).Women constitute seventy-one percent of labour force in livestock sector (GOI, 2004).In dairy sector, there is an estimated seventy-five million women as compared to fifteen million men (Padmanabhan, 2001).Data on gender division of labour in livestock rearing show that the total mean working hours of women was significantly higher than that of men (Upadhyay, 2003).
Women who work in dairy farming may be at special risk for occupational injury (Nordstrom et al., 1995) because women have anatomical and physiological differences with men that may place them at risk for work related injuries (Engberg, 1993).On an average, upper body strength is 40.75% less in females than in males while lower body strength is 5.30% less in females (Falkel et al., 1986).Female's internal organs are more vulnerable to infections, external trauma and environmental irritants (Abbot, 2003).Whole body vibration affects women more than men because of anatomical and physiological characteristics.Fifty-two percent of the injuries occurred among women.Many injuries were reported to have occurred in bones, or while carrying out tasks such as feeding and milking (Boyle et al., 1997).Women who work in dairy farming may be at special risk for occupational injury.Nordstrom et al. (1995) reported that dairy farmers were 2.5 times more likely to be injured than residents of other types of farms.Nordstrom et al. (1996) observed that although crude rate for falls was higher for men, the rate based on hours worked was higher for women.Among a case series of 154 injured farm women, 26% of injuries resulted from falls (McCoy, 2000).A study among farm women in Texas and Louisiana (U.S.A.) found falls to be the second leading cause of external injury (Carruth et al., 2001).In a case study of dairy farmers, Boyle et al. (1997) found that milking and feeding caused most injuries among the women.Many injuries were reported to have occurred in burns, or while carrying out tasks such as feeding and milking (Nordstorn et al., 1995;Pickett et al., 1995;Reed et al., 1999;Boyle et al., 1997;Stueland et al., 1997).
In a Swedish study, female milkers had a greater risk of developing hand and wrist MSDs as compared to agricultural workers that were non milkers (Stal et al., 1996).In the same study, symptoms of numbness and white finger related to vibration exposure were also reported.Triple burden of child rearing, farm work with dairy farming activities and household has fallen on the women.Economic pressure and third shift phenomenon result in long hours without rest and increased hours of exposure to potential injury producing agents.As we know that males and females have different body capacity to perform the work and as the age of workers increases, various physiological changes take place in human bodies which reduce worker's working capacity.
Thus, age and sex of dairy workers are contributing factors in developing occupational diseases.As with many developing and even developed countries, India has a dearth of accurate statistics on the incidences and prevalence of occupational health hazards exposure.The problem of work related risk factors specifically stooped and squatting posture of greater magnitude in developing countries as in India.Milking is a very common practice performed by dairy workers in squatting posture.In present study, an attempt has been made to find out postural stress among males and females of lower and higher age groups during milking and to find out impact of age and sex on postural stress caused during milking.Findings of the study will be useful in improving the working conditions of the dairy sector and enhancing work and health status of the workers through developing appropriate tools and techniques for milking operations while keeping age and sex factors of the workers in consideration.

Research design
Experimental research design was planned for the study.In experimental research design, researcher tests the hypothesis of casual relationship between variables.Experimental research designs require procedures that will not only reduce bias and increase reliability but will permit drawing inferences about casualty.

Sampling design
Multistage random cum purposive sampling design was used to select the study area and respondents.The following stages were included for selection of locale, block, villages and respondents.
Selection of locale: District Kanpur (U.P.) was selected purposively for the present study with the assumption that the rural population of district was intensively engaged in dairy farming activities.Selection of block: District Kanpur was covered by 10 developmental blocks.Out of 10 blocks, Kalyanpur was selected randomly.The total population of Kalyanpur block was 140, 285 lakh comprised of 75, 666 lakh males and 64,619 lakh females.Selection villages: Three villages namely Hirdayapur, Ishwariganj and Dharampur were selected randomly from the list of villages of Kalyanpur block (Lottery or chit system).Selection of respondents: Forty male and thirty female respondents of two age groups (30 to 40 years and 40 to 50 years) were selected purposively on the basis of physical fitness.Thirty male and twenty-two female respondents of 30 to 40 years and ten male and eight female respondents of 40 to 50 years were found physically fit from the selected samples of Phase -1.Heart rate : 70-90 beats/min.

METHOD OF DATA COLLECTION
Postural stress was measured by assessing time spent in different body postures, frequency of adopting various body postures and angle of body deviation in lumber region of dairy workers during milking.Time spent in different body postures by dairy workers was recorded with the help of stop watch and frequency of adopting various body postures by dairy workers was observed by simple count and record method from start to end of work without splitting up the whole activity into its various parts and without giving rest inbetween stages of the activity.Angle of body deviation in lumber region of dairy workers was analyzed with the help of flexi curve.
The shape adopted by flexi curve was immediately drawn on paper and angle of deviation of normal curve and deviated curve were measured with the help of protractor.

ANALYSIS OF DATA
The collected data were tabulated and analyzed with the help of tabulation, subjective frequency, arithmetic mean, standard deviation, paired 't' test one way classification, ANOVA, Adjusted ANOVA (Snedecor and Cocharan, 1967).Before analyzing data related to angle of body deviation were transformed on the basis of their size and unit given by Federor (1955).

RESULTS AND DISSCUSSION
Time spent in different body postures by female and male dairy workers of lower and higher age groups during milking In milking, F-values for group means of time spent by dairy workers in different body postures (S 1 B 1 , S 3 ) were highly significant at 0.1% level of significance for all male and female dairy workers of lower and higher age group ).Further, it is also evident from that during milking, maximum time spent by dairy workers of all the four groups was in squatting postures followed by standing and bending posture (Table 2).
In complete cycle of milking, 't' values for the difference of means for time spent by dairy workers in different body postures (S 1 , S 2 , B 1 ) were significant for each two groups of dairy workers taken at a time (Table 3).It is also evident from the Table 4 that in complete cycle of milking,   main effect age (A) and sex (B) of dairy workers on time spent in different body postures was significant while their interaction effect (A×B) was  non-significant.Non-significant interaction effect (A×B) infers that effect of sex on time spent in different body postures of dairy workers has not varied along with age of dairy workers.Moreover, mean value (adjusted) of time spent in different body postures was maximum in females (B 1 ) and minimum in males (B 2 ) [for complete cycle of milking (Table 5).Except that, among dairy workers of higher age group (A 2 ), mean value (adjusted) of time spent in different body posture in milking was significantly higher than that dairy workers of lower age group (A 1 ).Further, it was also significantly higher in females (B 1 ) than that of males (B 2 ) in complete cycle of time spent in milking (Table 6).Thus, on the basis of above analysis, it can be said that age (A) and sex (B) of dairy workers have a significant impact on time spent in different body postures during milking and age of dairy worker has similar effect on time spent by dairy workers of both sex.Female dairy workers of higher age group had taken more time to complete the work; hence their time duration on different body posture was greater than dairy workers of other groups.Among all the body posture, squatting posture was adopted for longest period by dairy workers of all the four groups.

Frequency of adopting various body postures by female and male dairy workers of lower and higher age group during milking
From Table 7, it is clear that frequency of adopting different body posture during milking was the same for both female and male dairy workers of lower and higher age group.Furthermore, frequency of adopting standing posture was  maximum whereas frequency of adopting squatting posture during whole work period was minimum which points out that during Stage-2 (milking), squatting postures was adopted for longer period by all dairy workers without any change in their body position.

Angle of body deviation in lumber region of female and male dairy workers during selected dairy farming activities
In milking, the following activities were studied to assess the postural stress caused by body deviation from normal body curve: lifting of empty bucket in bend posture (P 1 ), placing bucket on ground in bend posture (P 2 ), milking in squatting posture (P 3 ), lifting of bucket containing milk in bend posture (P 4 ), carrying bucket containing milk in bend postures (P 5 ).Further, it is evident from Table 8 that, F-values of the angle of body bend in lumber region were highly significant for the dairy workers of all the four groups, during all activities of milking, that is, lifting empty bucket (P 1 ), placing bucket on ground (P 2 ), milking (P 3 ) lifting bucket containing milk (P 4 ) and carrying bucket containing milk (P 5 ).Furthermore, Table z9 explicit that average values for the angle of body deviation in lumber region was found maximum in females of higher age group (A 2 B 1 ) and minimum in males of lower age group (A 1 B 2 ) during all the working postures (P 1 , P 2 , P 3 , P 4 and P 5 ) in complete cycle of cleaning of cattle shed.Furthermore, it is also observed that average value of angle body deviation was maximum during milking, (P 3 ) followed by lifting bucket containing milk (P 4 ) by workers of four groups (A 1 B 1 , A 1 B 2 , A 2 B 1 and A 2 B 2 ).On the other hand, Table 10 highlights that difference of the mean of angle of body bend in lumber region of dairy workers was significantly different for each of the  two groups of dairy workers taken at a time in all the activities adopted by dairy workers during milking.Moreover, from the findings of Table 11, it is observed that main effect of age (A) and sex (B) of dairy workers on angle of body deviation in lumber region was significant and their interaction effect was non-significant for all the activities of milking.Non-significant interaction effect implies that impact of sex of dairy workers on angle of body deviation in lumber region during different activities has not changed along with the age of dairy workers.Except that, mean value (adjusted) of angle of body deviation in lumber region in different activities (P 1 , P 2 , P 3 , P 4 and P 5 ) of milking was maximum in female (B 1 ) and minimum in males (B 2 ) (Table 12).
Table 13 shows that mean value (adjusted) of angle of body deviation in lumber region in the activities of milking was significantly higher in dairy workers of higher age group (A 2 ) than the dairy workers of lower age group (A 1 ) as well as, also significantly higher in female dairy workers (B 1 ) as compared to male dairy workers (B 2 ).
In nutshell, it can be said that all the work posture of milking requires deviation of backbone from its natural alignment.Except, the maximum angle of body deviation in all the activities was Physical fitness was assessed through body mass index, body temperature, body pressure and heart rate.

Table 1 .
ANOVA for the group means of time spent (min) in different body postures by diary workers in milking (complete cycle).

Table 2 .
Mean values of time spent by dairy workers in different body postures of milking (complete cycle).

Table 3 .
Comparison of groups of dairy workers on the basis of time spent in different body posture during milking (complete cycle).

Time spent (min.) in different body postures (Milking)
G 1 = A 1 B 1 (Females of lower age group), G 2 = A 1 B 2 (Males of lower age group), G 3 = A 2 B 1 (Females of higher age group), G 4 = A 2 B 2 (Males of higher age group).

Table 4 .
Adjusted ANOVA for the age (a) and sex (A) of dairy workers and their interaction (A × B) effect on adjusted means of time spent in different body postures of milking (complete cycle).

Table 5 .
Adjusted means of groups of dairy workers for time spent in different body postures during milking (complete cycle).

Table 6 .
Comparison of groups of dairy workers on the basis of time spent in different body postures during milking (complete cycle).

Table 7 .
Mean values of frequency of adopting different body postures by dairy workers during milking (complete cycle).No statistical test was applied for the above table because of same data for all the male and female dairy workers was recorded during milking.A 1 B 1 = Females of lower age group, A 1 B 2 = Male of lower age group, A 2 B 1 = Female of Higher age group and A 2 B 2 = Male of the Higher age group.

Table 11 .
Adjusted ANOVA for age (A) and sex (B) of dairy workers and their interaction effect (A×B) on adjusted means of angle of body deviation in lumber region during different activities of milking (complete cycle).Lifting of empty bucket, P 2 = Placing of bucket on ground, P 3 = Milking, P 4 = Lifting of bucket containing milk and P 5 = Carrying bucket containing milk.

Table 12 .
Adjusted means of groups of dairy workers for angle of body deviation in lumber region during different activities of milking (complete cycle).Lifting of empty bucket, P 2 = Placing of bucket on ground, P 3 = Milking, P 4 = Lifting of bucket containing milk, P 5 = Carrying bucket containing milk, A 1 = Lower age group (30-40), A 2 = Higher age group (40-50), B 1 = Female and B 2 = Male.