Permitted chemicals
· Drinking water safety is
taken very seriously in the
· All substances added to
public water supplies must be on a list of approved substances issued by the
Drinking Water Inspectorate under Regulation 31 of the Water Supply (Water
Quality) Regulations 2000, and approved by the Secretary of State who is
ultimately responsible. Under the legal
authorisation of the Water Quality
Regulations1, the Drinking Water Inspectorate actively enforces
the standards by undertaking regular checks
· Only two compounds of
fluoride are permitted for artificial fluoridation in the UK2:
hexafluorosilicic acid (H2SiF6), and sodium
hexafluorosilicate (Na2SiF6). These compounds are included on the Drinking Water
Inspectorate’s list of approved substances.
They achieve the desired concentration of fluoride (1 part per million)
reliably and safely, and must meet Department of Environment purity
specifications3.
· A national body of experts,
the Committee on Products and Processes for Use in Public Water Supply (CPP),
assesses all chemicals that come into contact with drinking water or water for
swimming pools.
· The
chemicals used for water fluoridation are specifically manufactured to exacting quality
standards, and, as stated above, must meet Department of Environment purity
specifications. The chemicals are
important co-products of the manufacture of
phosphate fertilisers. Part of
the manufacturing process involves `capturing’ gases using product recovery units.
These units are technically similar to pollution scrubbers. However the important difference is that, in
the process of the manufacture of fluoride chemicals, the end result is a
valuable and useful resource, not a waste product.
· In
Fluoride in water
·
Fluoride is the ionic form of the element fluorine. Fluorine is a highly reactive gas, and is
never found in a
·
At 1ppm in water fluoride is fully ionised. It is this ionic fluoride – free fluoride
ions in solution – that we are talking about when we talk of fluoride in water.
·
Fluoride occurs naturally in all water, and is
present as a result of having been dissolved out of the rocks over which the
water has travelled.
·
Fluoride ions in water are identical irrespective of whether naturally
occurring or added.
· Fluoride for water fluoridation is a co-product of the manufacture of phosphate fertilisers. (It would be equally valid to describe phosphate fertilisers as a co-product of the manufacture of fluoridation compounds since both are valuable products.)
·
In fact fluoridation makes no measurable contribution to the
concentration of arsenic in water supplies.
·
Trace elements such as lead and arsenic are present in minute quantities in fluoride compounds, BUT,
because of the very high dilution factor, fluoridation makes no measurable
contribution to the concentration of these substances in the water supplies.
·
The current standard for arsenic in water in the
·
The 1998 European Water Quality Directive lowered the level from 50 ppb
to 10ppb. In the
·
Maximum levels of trace elements - including arsenic (and lead) - in
water treatment chemicals used for fluoridation are laid down in product
standards4 and details are incorporated in the product
specifications.
·
These levels are immeasurable when diluted thousands of times to
achieve 1ppm fluoride content in water.
It is not possible for example to measure arsenic in water at concentrations
lower than about 1ppb.
1 Her
Majesty’s Government (2000): The Water
Supply (Water Quality) Regulations 2000. Statutory Instruments 2000 No
3184.
2 Her
Majesty’s Government (1991): Water
Industry Act 1991.
3 Drinking
Water Inspectorate (2005): Code of
Practice on Technical Aspects of Fluoridation of Water Supplies 2005.
4 In the