This report contains the collective views of an international group of experts and does not necessarily represent the decisions or the stated policy of the United Nations Environment Programme, the International Labour Organisation, or the World Health Organization. Environmental Health Criteria 217 Microbial Pest Control Agent BACILLUS THURINGIENSIS Please note that the layout and pagination of this web version are not identical with the printed document Published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organisation, and the World Health Organization, and produced within the framework of the Inter-Organization Programme for the Sound Management of Chemicals. World Health Organization Geneva, 1999 The International Programme on Chemical Safety (IPCS), established in 1980, is a joint venture of the United Nations Environment Programme (UNEP), the International Labour Organisation (ILO), and the World Health Organization (WHO). The overall objectives of the IPCS are to establish the scientific basis for assessment of the risk to human health and the environment from exposure to chemicals, through international peer review processes, as a prerequisite for the promotion of chemical safety, and to provide technical assistance in strengthening national capacities for the sound management of chemicals. The Inter-Organization Programme for the Sound Management of Chemicals (IOMC) was established in 1995 by UNEP, ILO, the Food and Agriculture Organization of the United Nations, WHO, the United Nations Industrial Development Organization, the United Nations Institute for Training and Research, and the Organisation for Economic Co-operation and Development (Participating Organizations), following recommendations made by the 1992 UN Conference on Environment and Development to strengthen cooperation and increase coordination in the field of chemical safety. The purpose of the IOMC is to promote coordination of the policies and activities pursued by the Participating Organizations, jointly or separately, to achieve the sound management of chemicals in relation to human health and the environment. WHO Library Cataloguing-in-Publication Data Bacillus thuringiensis. (Environmental health criteria ; 217) 1.Bacillus thuringinesis – pathogenicity 2.Pest control, Biological – methods 3.Insecticides – chemistry 4.Environmental exposure 5.Occupational exposure I.Series ISBN 92 4 157217 5 (NLM Classification: QW 127.5.B2) ISSN 0250-863X The World Health Organization welcomes requests for permission to reproduce or translate its publications, in part or in full. Applications and enquiries should be addressed to the Office of Publications, World Health Organization, Geneva, Switzerland, which will be glad to provide the latest information on any changes made to the text, plans for new editions, and reprints and translations already available. ©World Health Organization 1999 Publications of the World Health Organization enjoy copyright protection in accordance with the provisions of Protocol 2 of the Universal Copyright Convention. All rights reserved. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city, or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. CONTENTS ENVIRONMENTAL HEALTH CRITERIA FOR BACILLUS THURINGIENSIS PREAMBLE vii ABBREVIATIONS xv 1. SUMMARY ............................................1 1.1 Identity, biological characteristics, and analytical methods ................................1 1.2 Mode of action on target insects ...................2 1.3 Habitats .........................................2 1.4 Commercial products, production and application .....3 1.5 Effects of Bt on non-target organisms ...............3 1.6 Exposure and effects of Bt on humans ...............4 1.7 Conclusions .....................................4 2. IDENTITY, BIOLOGICAL PROPERTIES, AND ANALYTICAL METHODS ...............................6 2.1 Identity .........................................6 2.1.1 Bacillus thuringiensis (Bt) .................6 2.1.2 Relationship between Bacillus thuringiensis and Bacillus cereus .......................6 2.1.3 Crystal composition and morphology ........7 2.1.4 Classification of Bt subspecies .............8 2.1.5 Genetics of ICP ..........................10 2.1.6 Beta-exotoxin ............................14 2.1.7 Other Bt metabolites ......................17 2.2 Bioassays ......................................18 2.2.1 Spore counts ............................18 2.2.2 International bioassay for ICPs ............18 3. MODE OF ACTION ON TARGET INSECTS ...............19 3.1 Bioactivity of field isolates ........................19 3.2 Mechanism of action of Bt formulations ............19 iii EHC 217: Bacillus thuringiensis ______________________________________________________ 3.3. Resistance of insect populations ..................21 4. NATURAL AND TREATED HABITATS ..................23 4.1 Natural occurrence of Bt ..........................23 4.1.1 Bt in insect hosts ........................23 4.1.2 Bt in soil ................................24 4.1.3 Bt on plant surfaces ......................24 4.2 Treated habitats .................................25 4.3 Environmental fate, distribution and movement ......25 4.3.1 Distribution and fate of Bt in terrestrial habitats .................................26 4.3.1.1 Fate of Bt and ICP on plant surfaces ........................26 4.3.1.2 Fate of Bt in soil .................27 4.3.2 Distribution and fate of Bt in aquatic habitats .................................29 4.3.3 Transport of Bt by non-target organisms ....30 5. COMMERCIAL PRODUCTION ..........................31 5.1 History of Bt and its commercial applications ........31 5.1.1 Production levels ........................31 5.1.2 Production processes, formulations and quality standards ........................31 5.1.3 General patterns of use ...................32 5.1.3.1 Applications in agriculture and forestry .........................32 5.1.3.2 Applications in vector control .....34 6. EFFECTS ON ANIMALS ...............................36 6.1 Mammals .......................................36 6.1.1 Oral exposure ............................37 6.1.2 Inhalation exposure ......................39 6.1.3 Dermal exposure .........................39 6.1.4 Dermal scarification exposure ..............40 6.1.5 Subcutaneous inoculation ................40 6.1.6 Ocular exposure .........................40 6.1.7 Intraperitoneal exposure ..................41 6.1.7.1 Immune-intact animals ............43 iv ______________________________________________________ 6.1.7.2 Immune-suppressed animals ......44 6.1.8 Effects of activated Bt ICP ................45 6.1.9 Studies in wild animals ....................45 6.2 Effects on birds .................................45 6.3 Effects on aquatic vertebrates .....................47 6.4 Effects on invertebrates ..........................49 6.4.1 Effects on invertebrates other than insects ..49 6.4.2 Effects on non-target insects ..............50 6.4.2.1 Aquatic insects ..................50 6.4.2.2 Terrestrial insects ................54 6.4.2.3 Honey-bees .....................59 6.4.2.4 Parasitoids ......................60 7. EXPOSURE AND EFFECTS ON HUMANS ................63 7.1 Bacillus thuringiensis ...........................63 7.1.1 Experimental exposure of humans ..........63 7.1.2 Exposure of workers during manufacture ....64 7.1.3 Exposure of workers in spraying operations . 64 7.1.4 Exposure of human populations by spraying operations over populated areas. ...........65 7.1.5 Clinical case reports ......................65 7.1.6 Dietary exposure of the general population ..66 7.2 Bacillus cereus ..................................67 8. EVALUATION OF HUMAN HEALTH RISKS AND EFFECTS ON THE ENVIRONMENT ......................69 9. CONCLUSIONS AND RECOMMENDATIONS .............70 10. PREVIOUS EVALUATIONS BY INTERNATIONAL ORGANISATIONS .....................................71 REFERENCES ..............................................72 RÉSUMÉ ..................................................94 RESUMEN ...............................................100 v NOTE TO READERS OF THE CRITERIA MONOGRAPHS Every effort has been made to present information in the criteria monographs as accurately as possible without unduly delaying their publication. In the interest of all users of the Environmental Health Criteria monographs, readers are requested to communicate any errors that may have occurred to the Director of the International Programme on Chemical Safety, World Health Organization, Geneva, Switzerland, in order that they may be included in corrigenda. * * * A detailed data profile and a legal file can be obtained from the International Register of Potentially Toxic Chemicals, Case postage 356, 1219 Châtelaine, Geneva, Switzerland (telephone no. + 41 22 – 9799111, fax no. + 41 22 – 7973460, E-mail [email protected]). * * * This publication was made possible by grant number 5 U01 ES02617-15