Worker Exposure to Dusts and Bioaerosols in the Sheep Shearing Industry in Eastern NSW. by Ryan Kift BAppSc (Hons) (Occupational Health and Environment) BAppSc (Environmental Health) A thesis presented in fulfillment of the requirement for the degree of Doctor of Philosophy March 2007 CERTIFICATE OF ORIGINALITY The text of this thesis contains no material which has been accepted as part of the requirements for another degree or diploma in any University, or material previously published or written by another author unless due reference to this material has been made. Ryan Kift 2 March 2007 ii ACKNOWLEDGEMENTS Thank you to my family, supervisors, friends and colleagues that helped and supported me throughout this study. Thank you to the University of Western Sydney for their financial, academic and resource support. Thank you to all of the people involved in the sheep shearing industry that participated in this study. Without the help and support of all of these people this study would not have been possible. iii ABSTRACT The air found in a sheep shearing environment is normally contaminated with many different airborne substances. These contaminants include dust (predominantly organic), bioaerosols (fungi and bacteria) and gases (ammonia and carbon monoxide). Respiratory disorders, such as Hypersensitivity Pneumonitis, chronic bronchitis and asthma, have been associated with exposure to the types of airborne contaminants found in a normal sheep shearing environment. The majority of Australian and international research in the livestock handling industries that has investigated dust exposure has focused on the poultry and pig industries. Some worldwide studies have been undertaken on feedlot cattle. Research in the sheep shearing industry in relation to worker exposure data for airborne contaminants has been identified as a major need as no documented studies have been undertaken anywhere in the world. Many of the past studies have focused on investigating the health of the animals exposed to these environments rather than that of the workers. Twenty nine sheep shearing sheds in the state of New South Wales in Eastern Australia were sampled for concentrations of airborne contaminants. These contaminants include inspirable and respirable dust (that was sampled both personally and statically) and bioaerosols (bacteria and fungi). The dust was collected using gravimetric means and the bioaerosols were collected using an Andersen Instruments 2-Stage bioaerosol sampler. The use of this equipment allowed only static samples to be collected while shearing was being undertaken in each shed. This study found that in relation to dusts the mean concentrations for each farm and the majority of most individual concentrations were below either the 3 mg m-3 recommended standard for respirable dust or the 10 mg m-3 recommended standard for inhalable dusts. A major issue is whether the current exposure standards for dusts (not otherwise classified) should be used in agricultural animal handling environments, including shearing sheds. This debate centres on the exposure to organic dusts which can contain high concentrations of microorganisms and their constituents. The current literature suggests that current exposure standards should be reduced. iv Bacteria concentrations recorded in this study ranged from 35 to 57,224 cfu m-3 and fungi from 0 to17,173 cfu m-3. There are no current exposure standards adopted for bioaerosol exposure anywhere in the world making it hard to determine if a potential health risk from bioaerosol exposure exists in these sheds. Some bioaerosol concentration limits have been suggested in the past. One suggested exposure limit was 103 cfu m-3 and if this limit was adopted in Australia then 83% of farms sampled exceeded it for bacteria concentration. In the case of fungi the number of sheds exceeding this concentration is lower with only 65% of concentrations for fungi exceeding 103 cfu m-3. The collected concentrations for both dusts and bioaerosols were analysed against the important variables that can exist in the shearing environment. The variables analysed were: the type of job completed by workers; the position of the static sampling equipment; the different geographical region that the samples were collected from; the indoor air temperature of the shed when the samples were collected; the number of sheep shorn during each sampling session and the shearing session (time of the day) in which the samples were collected. The concentration of respirable dust (both static and personal) was found to be most influenced by the concentration of inspirable dust that is present at the time of sampling. Inspirable dust was found to have a statistically significant relationship (=0.492, and p= 0.000) with the number of sheep shorn during the session, the indoor air temperature of the shed(r=0.249, p=0.014 for static samples, r=0.213, p=0.019 for personal samples) and the region in which the shed is located. The concentration of bacteria was found to be influenced by the shearing region where the samples were collected but was not found to be significantly related to any other variables. The concentration of fungi was found to have a statistically significant relationship with the indoor air temperature of the shed(r=0.228, p= 0.044), the region the shed was in (F(94, 493)=17.213, p<0.001) and the concentrations of both inspirable dust(r=0.351, p=0.013) and bacteria (r=0.466, p<0.001) present during sampling. Based on the results of the study the following recommendations are made for the shearing industry: under the current dust and bioaerosol exposure standards there is no requirement to instigate mechanical ventilation to reduce airborne contaminants and there is no need for respiratory protection in any of the monitored sheds. v However, it is recommended that if a person has a known predisposition to respiratory illness/stress they should be closely monitored while working in a shearing shed. However if bioaerosol standards are implemented in Australia (such as 103 cfu m-3) then respiratory protection and new ventilation strategies may need to be introduced to reduce concentrations. If lower dust exposure standards are implemented then additional recommendations would include: reducing dust at the source, rotating shearing and wool handling positions within the shed and respiratory protection may need to be used. There are issues raised in this thesis that require further research including the need for an epidemiological study on the health of people working in shearing sheds in relation to their respiratory health. The monitoring of shearing sheds in other regions in Australia needs to be undertaken and based on available literature similar studies are needed in other livestock industries in Australia. vi TABLE OF CONTENTS TITLE PAGE i CERTIFICATE OF ORIGINALITY ii ACKNOWLEDGEMENTS iii ABSTRACT iv TABLE OF CONTENTS vii LIST OF APPENDICES xiii LIST OF TABLES xv LIST OF FIGURES xvi LIST OF PLATES xviii GLOSSARY OF TERMS xix Chapter 1 Introduction 1 1.1 Aim and Objectives 4 Chapter 2 Literature Review 5 2.1. Overview of agriculture 5 2.1.1 Different work done on farms 5 2.1.2 Confinement housing 6 2.1.3 Sheep 8 2.2 Airborne Contaminants 8 2.2.1 Dusts 9 2.2.2 Bioaerosols 12 vii 2.2.3 Gases 23 2.3 Health Impacts 24 2.3.1 Respiratory System 27 2.3.2 Respiratory Diseases 31 2.3.3 Other diseases 40 2.4 Positive effects of exposure 46 2.5 Assessment of Airborne Contaminants 47 2.5.1 Dust Monitoring 48 2.5.2 Bioaerosol Monitoring 50 2.5.3 Endotoxin 57 2.5.4 Alternative sampling methods 58 2.5.5 Identification of bioaerosols 59 2.5.6 Sampling Statistics 60 2.6 Sampling variables that impact on airborne contaminants 61 2.6.1 Season 62 2.6.2 Indoor temperature 63 2.6.3. Outside concentrations of airborne contaminants 63 2.6.4 Type of flooring in animal shed 64 2.6.5 Ventilation rates 65 2.6.6 Animal diet and living area (grasses and soil type) 66 2.6.7 Number, activity and species of animals 67 2.6.8 Sampling collection methods 68 viii 2.7 Standards 69 2.7.1 Dusts 69 2.7.2 Bioaerosols 70 2.7.3 Endotoxin 71 2.7.4 Standards for Agriculture 72 2.8 Methods of Controlling Exposures 73 2.8.1 Elimination 73 2.8.2 Substitution 74 2.8.3 Engineering 74 2.8.4 Administrative controls 78 2.8.5 Personal Protective Equipment (PPE) 80 2.8.6 Problems with control measures 81 2.8.7 Costs 81 2.9 Exposure in agriculture 82 2.9.1 Factors that may affect agricultural exposures 82 2.9.2 Relevant exposure studies from the literature 86 Chapter 3 Methods 90 3.1 Dust Monitoring and Analysis 92 3.1.1 Sampling for respirable dust 93 3.1.2 Inspirable dust 94 3.1.3 Calculations used to determine concentration of dust 96 3.2 Bioaerosol monitoring and analysis 97 ix 3.2.1 Bioaerosol Sampling method 98 3.2.2 Bioaerosol Analysis 99 3.3 Additional parameters monitored 99 3.4 Ethical approval 100 3.5 Statistical analysis of data 100 Chapter 4 Results and Discussion 102 4.1 Introduction to Sampling Variables 102 4.2 Data analysed by the job type and static sampling position 104 4.2.1 Introduction 104 4.2.2 Mean personal respirable and inspirable dust concentrations for the different jobs undertaken 106 4.2.3 Mean static respirable and inspirable dust concentrations for sample location110 4.2.4 Conclusion of effects of job undertaken or sample location on mean airborne dust concentration 114 4.3 Data analysed by the region of NSW in which the data was collected 114 4.3.1 Introduction 114 4.3.2 Mean personal and static respirable and inspirable dust concentrations for each region sampled 118 4.3.3 Mean bacteria and fungi concentrations for sample region 122 4.3.4 Conclusion of effects of region on airborne concentration 125 4.4 Data analysed by taking into account the indoor temperature on the day that dust and bioaerosol samples were collected 125 4.4.1 Introduction 125 x 4.4.2 Mean personal respirable concentrations for each temperature range 127 4.4.3 Mean personal inspirable concentrations for each temperature range 129 4.4.4.