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 Organization, or the World Health Organization. Environmental Health Criteria 231 BENTONITE, KAOLIN, AND SELECTED CLAY MINERALS First draft prepared by Dr Zoltán Adamis, József Fodor National Center for Public Health, National Institute of Chemical Safety, Budapest, Hungary; and Dr Richard B. Williams, US Environmental Protection Agency, Washington, DC, and Regional Office for the Americas of the World Health Organization The layout and pagination of this pdf file and of the printed EHC are not identical Published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organization, 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, 2005 The International Programme on Chemical Safety (IPCS), established in 1980, is a joint venture of the United Nations Environment Programme (UNEP), the International Labour Organization (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 Bentonite, kaolin, and selected clay minerals. (Environmental health criteria ; 231) 1.Bentonite - toxicity 2.Kaolin - toxicity 3.Aluminum silicates - toxicity 4.Environmental exposure 5.Risk assessment I.International Programme for Chemical Safety II.Series ISBN 92 4 157231 0 (LC/NLM classification: QV 65) ISSN 0250-863X ©World Health Organization 2005 All rights reserved. Publications of the World Health Organization can be obtained from Marketing and Dissemination, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel: +41 22 791 2476; fax: +41 22 791 4857; email: [email protected]). Requests for permission to reproduce or translate WHO publications — whether for sale or for noncommercial distribution — should be addressed to Marketing and Dissemination, at the above address (fax: +41 22 791 4806; email: [email protected]). 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 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. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. 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. All reasonable precautions have been taken by WHO to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either express or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall the World Health Organization be liable for damages arising from its use. This document was technically and linguistically edited by Marla Sheffer, Ottawa, Canada, and printed by Wissenchaftliche Verlagsgesellschaft mbH, Stuttgart, Germany. CONTENTS ENVIRONMENTAL HEALTH CRITERIA FOR BENTONITE, KAOLIN, AND SELECTED CLAY MINERALS PREAMBLE viii ACRONYMS AND ABBREVIATIONS xvi 1. SUMMARY 1 1.1 Identity, physical and chemical properties, and analytical methods 1 1.2 Sources of human and environmental exposure 2 1.3 Environmental levels and human exposure 2 1.4 Kinetics and metabolism in laboratory animals and humans 3 1.5 Effects on laboratory mammals and in vitro test systems 4 1.6 Effects on humans 5 1.7 Effects on other organisms in the laboratory and field 6 1.8 Evaluation of human health risks and effects on the environment 6 2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, AND ANALYTICAL METHODS 8 2.1 Introduction 8 2.2 Identity 9 2.2.1 Bentonite 9 2.2.2 Kaolin 11 2.2.3 Other clays 12 2.3 Physical and chemical properties 14 2.3.1 Bentonite 14 2.3.2 Kaolin 15 2.3.3 Other clays 15 2.3.4 Surface chemistry 17 2.3.5 Trace elements in clays 18 2.4 Analytical methods 19 2.4.1 Quantitative measurement of dust 19 2.4.2 Identification of phyllosilicates 20 iii EHC 231: Bentonite, Kaolin, and Selected Clay Minerals 3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE 23 3.1 Natural occurrence 23 3.1.1 Bentonite 23 3.1.2 Kaolin 23 3.1.3 Other clays 24 3.2 Anthropogenic sources 25 3.2.1 Production levels and sources 25 3.2.1.1 Bentonite 25 3.2.1.2 Kaolin 27 3.2.1.3 Other clays 30 3.2.2 Uses 31 3.2.2.1 Bentonite 31 3.2.2.2 Kaolin 34 3.2.2.3 Other clays 37 4. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE 40 4.1 General population exposure 40 4.1.1 Bentonite 40 4.1.2 Kaolin and other clays 40 4.2 Occupational exposure 42 4.2.1 Bentonite 42 4.2.2 Kaolin 45 4.2.3 Other clays 54 5. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS 56 6. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS 59 6.1 Single exposure 59 6.1.1 Bentonite 59 6.1.2 Kaolin 70 6.1.2.1 Intratracheal administration 70 6.1.2.2 Parenteral administration 77 6.1.3 Other clays 77 6.2 Repeated exposure 78 iv 6.2.1 Bentonite 78 6.2.2 Kaolin 82 6.3 Genotoxicity 83 6.4 Reproductive effects 83 6.5 Administration with other agents 84 6.5.1 Kaolin and microbes and microbe-derived factors 84 6.5.2 Kaolin and quartz 85 6.6 In vitro test systems 85 6.6.1 Bentonite 85 6.6.2 Kaolin 97 6.6.2.1 Haemolysis 97 6.6.2.2 Macrophage studies 108 6.6.2.3 Other tissue cultures and in vitro systems 109 6.6.3 Other clays 110 6.6.4 Relationships between in vivo and in vitro studies 110 6.7 Summary of the effects of quartz 110 7. EFFECTS ON HUMANS 112 7.1 General population 112 7.2 Occupational exposure 112 7.2.1 Bentonite 112 7.2.2 Kaolin 118 7.2.2.1 Kaolin workers, United Kingdom 119 7.2.2.2 Kaolin workers, USA 128 7.2.2.3 Kaolin workers, other countries 130 7.2.2.4 Brick and tile workers and others 130 7.3 Summary of the effects of quartz 131 8. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD 133 9. EVALUATION OF HUMAN HEALTH RISKS AND EFFECTS ON THE ENVIRONMENT 135 9.1 Evaluation of human health risks 135 9.2 Evaluation of effects on the environment 137 v EHC 231: Bentonite, Kaolin, and Selected Clay Minerals 10. CONCLUSIONS AND RECOMMENDATIONS FOR PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT 138 11. FURTHER RESEARCH 139 12. PREVIOUS EVALUATIONS BY INTERNATIONAL BODIES 140 REFERENCES 141 RESUME 160 RESUMEN 168 vi 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. vii Environmental Health Criteria PREAMBLE Objectives In 1973 the WHO Environmental Health Criteria Programme was initiated with the following objectives: (i) to assess information on the relationship between exposure to environmental pollutants and human health, and to provide guidelines for setting exposure limits; (ii) to identify new or potential pollutants; (iii) to identify gaps in knowledge concerning the health effects of pollutants; (iv) to promote the harmonization of toxicological and epidemio- logical methods in order to have internationally comparable results. The first Environmental Health Criteria (EHC) monograph, on mercury, was published in 1976, and since that time an ever-increasing number of assessments of chemicals and of physical effects have been produced. In addition, many EHC monographs have been devoted to evaluating toxicological methodology, e.g., for genetic, neurotoxic, teratogenic and nephrotoxic effects. Other publications have been concerned with epidemiological guidelines, evaluation of short-term tests for carcinogens, biomarkers, effects on the elderly and so forth. Since its inauguration the EHC Programme has widened its scope, and the importance of environmental effects, in addition to health effects, has been increasingly emphasized in the total evaluation of chemicals.