RR829 - Current control standards for tasks with …

1 Executive Health and Safety Current control standards for tasks with high exposure to grain dust Prepared by the Institute of Occupational Medicine for the Health and Safety Executive 2010 RR829 Research Report Executive Health and Safety Current control standards for tasks with high exposure to grain dust Sally Spankie & John W Cherrie Institute of Occupational Medicine Research Avenue North Riccarton Edinburgh EH14 4AP Six sectors of the British grain industry were investigated to try to identify and characterise exposure-significant tasks in terms of the inhalable dust, microorganism, endotoxin and mycotoxin exposures associated with these tasks .

2 Information was collected from stakeholders in the industry by telephone interviews and during visits to company premises. In addition, the available scientific literature was reviewed to identify relevant exposure data. It was judged that some cleaning activities and certain process tasks may create airborne inhalable dust levels in excess of the British Workplace Exposure Limit (WEL) of 10 mg m-3. Long-term average levels are probably generally less than about 3 mg m-3, with perhaps 15 to 20% of individual exposures above the WEL.

3 Endotoxin levels were judged likely to be less than 104 EU m-3 throughout the industry provided inhalable dust levels are less than 10 mg m-3. There is no published exposure data on mycotoxin, respirable crystalline silica and mite contamination but these are not considered to present widespread problems in the British industry. Further improvements in control technology and the use of respiratory protection are needed in some sectors of the industry. This report and the work it describes were funded by the Health and Safety Executive (HSE).

4 Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. HSE Books Crown copyright 2010 First published 2010 You may reuse this information (not including logos) free of charge in any format or medium, under the terms of the Open Government Licence. To view the licence visit , write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email Some images and illustrations may not be owned by the Crown so cannot be reproduced without permission of the copyright owner.

5 Enquiries should be sent to ii CONTENTS EXECUTIVE SUMMARY V GLOSSARY VII 1 INTRODUCTION TO THE INDUSTRY, PROCESSES AND tasks 1 2 SCOPE AND AIMS 3 3 RESEARCH METHODOLOGY 5 Introduction 5 Data collection by literature review 5 Data collection by industrial survey 6 4 RESULTS FROM LITERATURE REVIEW 9 Introduction 9 Status of microorganism exposure monitoring of grain dust components

6 9 Past exposure to grain dust in Great Britain 11 Subsequent studies carried out in Great Britain 12 Other studies relevant to Great Britain 14 5 RESULTS FROM INDUSTRY SURVEYS 25 Introduction 25 Grain import/export (Port Services) 25 Farms 30 Intake 37 Commercial Grain Storage 42 Milling 45 Malting

7 48 Animal feed milling 52 Outloading 54 6 DUST MONITORING DATA 57 Farms 57 Milling 58 Malting 58 Animal feed milling 58 7 tasks AND EXPOSURE 61 tasks generating airborne dust information from the present project 61 tasks generating airborne dust information from the published literature 65 Estimation of exposure in the British grain industry 71 8 DISCUSSION 77

8 9 REFERENCES 79 iii APPENDIX 1 CHECKLIST FOR STAKEHOLDER ENGAGEMENT 83 APPENDIX 2 TYPICAL control MEASURES AND EXPOSURE RATING FOR tasks IN THE GRAIN INDUSTRY 93 APPENDIX 3 - HOT AIR GRAIN DRYING TECHNIQUES 97 APPENDIX 4 - MILLING 101 APPENDIX 5 - MALTING 107 iv EXECUTIVE SUMMARY Airborne grain dust is a complex mixture of fragments of organic material from grain, plus possible fungal, bacterial or insect contamination or their toxic products such as endotoxin, and mineral matter from soil.

9 In the 1990s grain workers in Britain were frequently exposed to inhalable dust above 10 mg m-3 (8-hr), with particularly high exposures being found at terminals where grain was imported or exported and in drying operations (personal exposure typically about 20 mg m-3). Since then the industry has made substantial progress in improving the control of airborne dust through better-designed processes, increased automation and an improved focus on product quality. We have used information from the published scientific literature and a small survey of industry representatives to estimate Current exposure levels, both long-term average and task-specific exposures.

10 Workers are most highly exposed to grain dust during manual tasks such as cleaning plant and premises and maintenance. These, like farming tasks carried out in the yard, were of short duration but had potentially high exposures if respiratory protection or other controls were not used. The high level of automation in the import/export, commercial grain storage, milling and malting sectors has led to many fewer operators routinely manning the plant compared to the past. The plant is now largely enclosed, often under negative pressure and there is considerable use of remote operating from control rooms.