Little is known about the arsenic levels of the underground aquifers which provide the only source of drinking water to many of the scattered communities beyond the areas served by public mains water supplies.
Isolated agricultural and rural dwellings have to rely on borehole or well water for human consumption and whilst these supplies are regulated by UK legislation, very few are tested for the presence of metals, relying on microbiological parameters as a measure of potability. Based on risk assessment conducted by the International Agency for Research on Cancer, arsenic exposure via ingestion has a recognised risk of several cancers and other chronic diseases.
EPHT will relate arsenic exposure events with known hazards at population level such as sources of private drinking water supplies and interventions available to address these problems. This will be an example of 'hazard tracking'.
In order to achieve this, the following 10 steps have been identified in the study:
Hazard tracking flow diagram
Approval from the Department of Health was received in mid February, following this our efforts and attention was focused on preparing for and carrying out the sampling procedure. This involved four weeks of intensive logistical planning. Initially letters were sent to all residents identified as having a private water supply; this data was provided by Cornwall council. The letter informed individuals that we will be contacting them shortly; it also provided residents with our contact details if they were interested in having their water supply tested and wanted to contact us directly.
We were overwhelmed with the number of calls and e-mails that we received by individuals wanting their private drinking water supply tested.
Routes around Cornwall had to be carefully planned in order to make best use of the time and resources available as well as taking the geology into consideration. Following planning we called the individuals that had initially contacted us to arrange specific appointments and we also called other individuals who were on our list and who had not contacted us to invite them to have their water tested.
The delivery involved a 17 day sampling programme whereby the British Geological Survey (BGS) visited approximately 260 homes and took a total of 359 water samples from kitchen taps and borehole supplies across central Cornwall, we have just completed this stage. The next stage is for BGS to analyse the samples for about 60 specific metals and minerals, the outcomes will then be reviewed and results fed back.