Proposal for the investigation of the association
between cases of skin irritation and exposure to pools disinfected with
Until 1999, DWI provided the support services for the voluntary approval system for chemicals used in swimming pool treatment. Following the decision to terminate the voluntary approval system, this study was commissioned in response to unresolved concerns about the conditions of approval for products based on the organobromine compound BCDMH.
Bromine-based disinfectants were introduced during the 1970's and early 1980's for use in recreational pools following the government's recommendation for the discontinuation of the use of chlorine gas. At the time, the perceived benefits of bromine were the improved bactericidal efficiency of bromination over chlorination (due to the greater biological activity of bromamines over chloramines, produced by the combination of the halogen with nitrogenous pollution - ie. urine), and the reduced scale of pH correction required, although it was recognized that elemental bromine is hazardous and capsulated dosing systems were recommended (Humphrey, 1978). By 1983 proprietary products with the active constituent 1-bromo-3-chloro-5,5-dimethyl-hydantion (BCDMH) were being marketed in the UK under the name DiHalo, now marketed as Aquabrome. Other bromine-based chemicals are also marketed in the UK include BCDMH in combination with DCDMH/DCEMH (Bromasin, a disinfectant) and sodium bromide (Poolcure, a disinfectant additive).
Current usage figures, and information about the location and operation of 12 pools using Aquabrome, have been made available, and it appears that in the UK bromine-based products are used to provide disinfection to smaller scale pools such as school swimming pools and hydrotherapy pools. This may be because Aquabrome is not cost effective for large pools, but it is relatively easy to use and sold as an easy dosing system. Six of the 12 pools using Aquabrome reported that skin rash complaints had been received.
Reports of dermatoses have appeared in the medical literature associating the condition with brominated pools, including some from the UK. Rycroft and Penny (1983) reported 48 cases of swimming pool-associated dermatoses, and circumstantial evidence gathered at swimming pools for an association between swimming in brominated pools and having dermatoses. They presented two case reports. One was of a 32 year old male life-guard who suffered itchy red papules and subsequent eczema on contact with a brominated pool (Di-Halo/Aquabrome disinfectant) but not with a chlorinated pool. A 40 year old female swimming instructor also suffered similar symptoms on contact with a pool brominated with Di-Halo/Aquabrome. A postal survey was conducted by Penny (1991) of people in Somerset who had skin rashes they believed to be attributed to exposure to pools. Invitation to participate was by means of the local press. The survey showed the incidence of skin rash was 1 per 715 annual swims in brominated pools compared with 1 per 865000 annual swims in chlorinated pools. There is evidence that the complex chemistry of bromination results in reduced efficacy of bromine disinfectants compared with chlorine, and consequently some dermatoses associated with poor disinfection may have an infectious aetiolgy. Pseudomonas folliculitis was reported among users of two spa pools disinfected with BCDMH and bromide salt in Alberta, Canada. Pseudonomas aeruginosa was found to persist in the pools despite recorded bromide residuals of up to 5mg/l and with apparently effective disinfection as measured by coliform and plate counts (Shaw, 1984). Shaw concluded, through microbiological investigations of different spas and supportive evidence from other researchers (citing Nelson and Vazopolos, 1980) that P. aeruginosa is more resistant to bromine than to chlorine on an equimolar basis. He pointed out that the major confounding variables of the study were pool design, loading and operator effectiveness.
In order to provide data on the association between dermatitis and exposure to Aquabrome as a pool disinfectant, a number of approaches could be taken, since there are a number of problems with surveillance and epidemiological studies for skin reactions following bathing in brominated waters:
To investigate how these problems might be addressed or circumvented in any proposed studies, a meeting was convened by RC and took place on 5th April 2000 at the National Focus for Work on Response to Chemical Incidents and Surveillance of Exposure to Environmental Chemicals ("National Focus"), Cardiff, attended by:
|Rachel Chalmers||PHLS Cryptosporidium Unit|
|Malcolm Dubber||National Focus|
|Jody Foster||National Focus|
|Yo Fung||National Focus|
|John Lee||PHLS Water and Environmental Microbiology Research Unit|
|Gordon Nichols||PHLS Communicable Disease Surveillance Centre|
|Daniel Thomas||National Focus|
Paul Hunter (Chair, PHLS Advisory Committee on Water and the Environment) and Hilary Fielder (University of Wales College of Medicine) gave apologies but provided comments. The outcomes of the meeting were the following proposal aims/objectives. These vary in the potential costs and levels of evidence they will provide.Copies of this report may be available as an Acrobat pdf download under the 'Post 2000 Reports' heading on the DWI website.