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DWI
Regulation 31 Test Protocol
The tests needed to show compliance with Regulation
31 are determined, on
a product-to-product basis, by the Drinking Water Inspectorate Committee on
Products and Processes for Use in Public Water Supply (DWI CPP) on behalf of the
Secretary of State for the Environment, Food & Rural Affairs.
This independent expert committee considers the full formulation of a product, together with its method of manufacture or application, and then specifies what testing, if any, will be
needed to meet the requirements of Regulation 31.
Since the interest in leaching is concerned with compounds present in water at levels in excess of 1µg/l, highly sensitive
methods of analysis are
often required, and in many cases methods have to be specifically
researched and developed.
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[GCMS chromatogram] |
Leachate
Preparation
Initially, extracts are prepared in the test laboratory using a much more severe surface area to volume ratio than in BS 6920 tests.
This test ratio is specified normally at 1cm2 in 1 cm3
(compared with 0.15 cm2 in 1 cm3 used in BS 6920 testing) to ensure that the concentrations of any leachates are sufficiently high to make analysis of them practical. Although the Committee publishes a general procedure for preparing extracts from a product for testing, they
retain the right to vary this based upon the nature and use of the product.
Interpretation
of the Results
There are no pass/fail criteria for these tests. The results from each product are considered on the basis of the following factors
1.
The proposed application. Allowance will be made for products with a small surface area used in contact with large volumes of water, and for issues such as water flow rates etc.
2.The toxicity of the substances found in the leachates, including consideration of long-term exposure, general toxicity, tetragenicity and the presence of any substance thought or known to be an endocrine disruptor.
On the basis of the initial test results the Committee may ask for further work to be done on leachates from the product, or even require further toxicological studies to be carried out on specific leachates.
Regulation 31
Approval
Products which satisfy the Committee are listed in a Directory published by the Drinking Water Inspectorate and this information is also posted on the Internet.
LINK -
[Approved Products List]
Future
Developments
Several European countries currently have “positive” lists of ingredients which can be used for food contact purposes. Attempts are now being made to develop a harmonised positive list of ingredients (perhaps based upon
Synoptic document - “Provisional lists of monomers and additives notified to European Commission as substances which may be used in the Manufacture of Plastics Intended to come into contact with foodstuffs”).
You can download a copy of this Synoptic document
here:
LINK - [Synoptic Document]
Further Information
You can get further information about these tests from the Secretariat to the DWI
CPP:
Drinking
Water Inspectorate
Room G01
55 Whitehall
LONDON,
SW1A 2EY.
Tel : + 44 (0) 20 7082 8015
Fax : + 44 (0) 20 7082 8028
E-mail : cpp@defra.gsi.gov.uk |
