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World Health Organization Publication : Year 2003 ; Issue 9241530499: Concise International Chemical Assessment Document 49 ; Thiourea

By K. Ziegler-Skylakakis

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Book Id: WPLBN0000170951
Format Type: PDF eBook
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Reproduction Date: 2005
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Title: World Health Organization Publication : Year 2003 ; Issue 9241530499: Concise International Chemical Assessment Document 49 ; Thiourea  
Author: K. Ziegler-Skylakakis
Volume:
Language: English
Subject: Health., Public health, Wellness programs
Collections: Medical Library Collection, World Health Collection
Historic
Publication Date:
Publisher: World Health Organization

Description
Medical Reference Publication

Excerpt
1. EXECUTIVE SUMMARY This CICAD on thiourea was prepared jointly by the German Chemical Society (GDCh) Advisory Committee on Existing Chemicals of Environmental Relevance (BUA) and the Fraunhofer Institute of Toxicology and Aerosol Research, Germany. It is based on the BUA (1995) report on thiourea and the German MAK Commission (MAK, 1988, 1997) documentation. A comprehensive literature search of relevant databases was conducted in November 2001 to identify any relevant references published subsequent to those incorporated in these reports. Information on the preparation and peer review of the source documents is presented in Appendix 1. Information on the peer review of this CICAD is presented in Appendix 2. This CICAD was approved as an international assessment at a meeting of the Final Review Board, held in Monks Wood, United Kingdom, on 16–19 September 2002. Participants at the Final Review Board meeting are listed in Appendix 3. The International Chemical Safety Card for thiourea (ICSC 0680), produced by the International Programme on Chemical Safety (IPCS, 2000), has also been reproduced in this document. Thiourea (CAS No. 62-56-6) is a white crystalline solid. It is soluble in water (137 g/litre at 20 °C), soluble in polar protic and aprotic organic solvents, and insoluble in non-polar solvents. It is analysed mainly by highperformance liquid chromatography (HPLC) with subsequent ultraviolet (UV) detection. In 1993, the global annual production of thiourea was about 10 000 tonnes. A more recent global production figure is not available. Thiourea has a wide range of uses; for example, it is used in the production and modification of textile and dyeing auxiliaries, in the leaching of ores, in the production of pharmaceuticals and pesticides, as a vulcanization accelerator, and as an auxiliary agent in diazo paper. Based on thiourea’s use pattern, the hydrosphere is expected to be its main environmental target compartment. Measured concentrations of the chemical in surface waters are not available. Thiourea is not expected to evaporate from water. It is resistant to hydrolysis in water and direct photolysis in water and air, and it undergoes photochemical oxidation by hydroxyl radicals in the atmosphere (calculated half-life 2.4 h). Thiourea will be biodegraded by an adapted microflora only after extended acclimation periods. Thus, under conditions not favouring biotic or abiotic removal, thiourea may be present in surface waters and sediments over longer periods. Adsorption to sediment particles, however, is not to be expected, as indicated by low soil sorption coefficients. Leaching of thiourea from soil to groundwater seems possible, particularly under

Table of Contents
TABLE OF CONTENTS FOREWORD................................................................................................................................................. 1 1. EXECUTIVE SUMMARY ............................................................................................................................ 4 2. IDENTITY AND PHYSICAL/CHEMICAL PROPERTIES ......................................................................... 5 3. ANALYTICAL METHODS .......................................................................................................................... 6 4. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE.............................................................. 6 4.1 Natural sources ................................................................................................................................... 6 4.2 Anthropogenic sources........................................................................................................................ 6 4.3 Uses..................................................................................................................................................... 6 4.4 Estimated global releases ..................................................................................................................... 7 5. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION................................ 7 5.1 Transport and distribution between media ........................................................................................... 7 5.2 Transformation ................................................................................................................................... 8 5.3 Accumulation ...................................................................................................................................... 9 6. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE....................................................................... 9 6.1 Environmental levels........................................................................................................................... 9 6.2 Human exposure.................................................................................................................................. 9 6.2.1 Workplace exposure .................................................................................................................. 9 6.2.2 Consumer exposure ................................................................................................................. 10 7. COMPARATIVE KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS.................................................................................................................................................... 10 8. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS..................................... 11 8.1 Single exposure ................................................................................................................................. 11 8.2 Irritation and sensitization.................................................................................................................. 12 8.3 Short-term exposure ........................................................................................................................... 12 8.4 Medium-term exposure ...................................................................................................................... 12 8.5 Long-term exposure and carcinogenicity ........................................................................................... 13 8.5.1 Initiation–promotion studies.................................................................................................... 13 8.6 Genotoxicity and related end-points................................................................................................... 15 8.6.1

 

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