A Review of Skin Irritation and Tap Water Quality WRc Ref: DWI8375.01 March 2011 A Review of Skin Irritation and Tap Water Quality Report No.: DWI8375.01 Date: March 2011 Authors: Annette Ewence, Paul Rumsby, Leon Rockett, Andrew Davey WRc, Hywel Williams, University of Nottingham, Simon Danby, Michael Cork, University of Sheffield Medical School Project Manager: Annette Ewence Project No.: 15491-0 Client: Drinking Water Inspectorate Client Manager: Jeni Colbourne RESTRICTION: This report has the following limited distribution: External: Drinking Water Inspectorate © WRc plc 2011 The contents of this document are subject to copyright and all rights are reserved. No part of this document may be reproduced, stored in a retrieval system or transmitted, in any form or by any means electronic, mechanical, photocopying, recording or otherwise, without the prior written consent of WRc plc. This document has been produced by WRc plc. Any enquiries relating to this report should be referred to the Project Manager at the following address: WRc plc, Telephone: + 44 (0) 1793 865000 Frankland Road, Blagrove, Fax: + 44 (0) 1793 865001 Swindon, Wiltshire, SN5 8YF Website: www.wrcplc.co.uk Acknowledgement The research was funded by the Department for Environment, Food & Rural Affairs (Defra) under project DWI70/2/257. The views expressed here are those of the authors and not necessarily those of the Department. We would like to thank the following for providing information: Dr Susan Richardson of the US Environmental Protection Agency, Denise Kula of Citizens Concerned About Chloramination and Manouchehr Boozarpour of the San Francisco Public Utilities Commission. Contents Acknowledgement .................................................................................................................... iii Summary .................................................................................................................................. 1 Glossary ................................................................................................................................... 3 1. Introduction .................................................................................................................. 5 1.1 Background ................................................................................................................. 5 1.2 Current thinking ........................................................................................................... 5 2. Skin Disease ............................................................................................................... 7 2.1 How common is skin disease in the UK? .................................................................... 7 2.2 Causes of skin diseases ............................................................................................. 7 2.3 How does skin disease affect people? ........................................................................ 7 2.4 The skin barrier ........................................................................................................... 9 2.5 The skin barrier and skin disease ............................................................................. 15 2.6 Assessment of skin barrier structure and function .................................................... 21 2.7 Aquagenic pruritus .................................................................................................... 22 3. Chemical Parameters and Properties of Interest ...................................................... 25 3.1 Parameters of water .................................................................................................. 30 4. Comparison of Occupational Exposure Limits and Drinking Water Levels ........................................................................................................................ 33 4.1 Workplace Exposure Limits (WELs) .......................................................................... 33 5. Intrinsic Irritating Properties of Chemicals/Parameters Including Animal Data ........................................................................................................................... 39 6. Human Data .............................................................................................................. 51 6.1 Water hardness and alkalinity ................................................................................... 51 6.2 Other chemical properties of tap water ..................................................................... 58 7. Review of Possible Associations and Causalities of Experimental and Human Studies .......................................................................................................... 71 7.1 Animal data ............................................................................................................... 71 7.2 Human data ............................................................................................................... 71 7.3 Conclusion ................................................................................................................. 76 7.4 Future avenues of research ...................................................................................... 78 8. Assessment of How Drinking Water Quality Data of Customer Skin- related Health Concerns May be Used to Analyse Skin Irritation Effects of Drinking Water ....................................................................................................... 81 8.1 Outline of requirement to collect data ....................................................................... 81 8.2 Available data ............................................................................................................ 82 8.3 Type of data .............................................................................................................. 82 8.4 The possibility of use of data ..................................................................................... 83 8.5 Recommendations for data to be collected ............................................................... 84 8.6 Potential study ........................................................................................................... 85 References ............................................................................................................................. 87 Appendices Appendix A Toxicity Data Search ............................................................................. 105 Appendix B Human Data Search .............................................................................. 109 Appendix C Primary Chemical and Parameter Screen ............................................. 115 List of Tables Table 3.1 Prioritised list of chemical parameters and properties of interest ..................................................................................................... 27 Table 4.1 UK Workplace Exposure Limits (WELS) ................................................. 35 Table 5.1 Parameters of water in dog cross-over study (Ohmori et al., 2010) ....................................................................................................... 45 Table 7.1 Future avenues of research .................................................................... 79 Table B.1 Chemical parameters in UK tap/drinking water to be included in the review .......................................................................................... 109 Table B.1 Data collection form ............................................................................... 114 Table C.1 Table of chemicals that have either English and Welsh, US, Canadian and WHO drinking water standards/guidelines and information on their irritancy potential created as part of the development of a priority chemicals list ................................................ 115 List of Figures Figure 2.1 The epidermis (Cork et al., 2009) .............................................................. 9 Figure 2.2 The brick wall analogy of the skin barrier (Elias, 1983; Cork et al., 2006) .............................................................................................. 10 Figure 2.3 Thickness of stratum corneum (Cork et al., 2009) .................................. 12 Figure 2.4 The serine protease-PAR2 axis (Ohman and Vahlquist, 1994; Schade and Marchionini, 1928; Hanson et al., 2002) ................... 14 Figure 2.5 A visual representation of the skin barrier (Cork et al., 2010) ................. 16 Figure 2.6 A visual representation of the skin barrier in this condition (Cork et al., 2010) .................................................................................... 17 Figure 2.7 The course of Atopic Dermatitis. Adapted from Proactive Medicine, Danby and Cork, 2010 ............................................................ 18 Drinking Water Inspectorate Summary i Reasons There have been regular unsubstantiated reports in the literature attributing the occurrence of skin disease to tap water exposure. Some consumers attribute their skin complaints to tap water, therefore water companies and the drinking water regulators have identied the need for more information in order to respond appropriately to these consumer concerns. There is a cost to water companies investigating consumer water quality complaints and any protocol needs to be based on sound science and beneficial to the public. ii Objectives To conduct a wide ranging review of the evidence for a possible link between