Arsenic: are we exposed?

Sampling private water supplies in South West England

This page is to provide additional information to participants of a biomonitoring study associated with a private water supply (PWS) survey in Cornwall.

Between March 2011 and March 2013, commissioned by the UK Health Protection Agency (now part of Public Health England (PHE)), BGS undertook a sampling campaign of 512 properties in Cornwall served by private water supplies (PWS).

Results from the study showed that five per cent of drinking water samples collected exceeded the 10 μg/L prescribed concentration or value (PCV) for arsenic.

Exposure assessment

However, these results alone don't tell the full story of population exposure to arsenic in the region and to go a step further in assessing exposure, a biomonitoring study is being carried out. The new study is a collaboration between BGS and PHE, with the addition of the University of Manchester, through a jointly funded PhD studentship.

This study will explore the use of human biomarkers (urine, toenails and hair) to determine how much arsenic (if any) is being taken up by the local population.

The study will also include environmental monitoring of household dust, garden soil and rice. Study participants will be interviewed, to gather data for an assessment questionnaire, in an attempt to quantify the importance of a range of potential exposure routes.

Focus on Cornwall

Cornwall is a region known for high environmental arsenic due to its highly mineralised geology.

There are believed to be upwards of 3 500 private water supplies in Cornwall, serving an estimated 9 000 people (DWI, 2013).

Although the problem is likely of lesser concern in the UK, arsenic is a documented carcinogen known to be the cause of a number of internal cancers in countries where heavily contaminated groundwater is utilised for human consumption.

Previous studies in the region have focused their attention on other exposure routes (mostly soil) and the consumption of groundwater is an area warranting further research.

Progress update March 2016

Households were visited by BGS teams in November 2013, following an invite to take part in the biomonitoring study through direct mailing and followup calls. More than 120 households and more than 200 volunteers from across Cornwall participated. Since then, the samples collected have undergone a series of measurements for each of the sample types. The measurements for water data were reported in June 2014 to the households. Biological data was reported in March 2015, with soil sample data to be reported in March 2016 in consultation with Cornwall Council.

Communicating the results from the analysis of the soil samples to householders

Participants will shortly receive the results of the analysis on their soil samples. This completes the feedback of all their available results. Participants will be sent the results of their soil samples by means of a letter. Participants will receive the individual concentrations of all of the soil samples collected from their garden for arsenic, cadmium, and lead. This is because these were the elements where a C4SL exists and some exceedances occurred.

Participants will be able to compare their results with the appropriate C4SL for their sample. Participants with levels of chemicals in their soil above a C4SL are informed and they are provided with general public health advice. They are also provided with the phone number for Cornwall Council, as the regulator, the Council are happy to provide individual advice to householders. For further information on the C4SL guidance value for Arsenic, Cadmium and Lead, additional documents can be found at the DEFRA (Department for Environment, Food and Rural Affairs) website providing extensive explanation of how the guidelines were developed (in Appendix C, F and H).

Why has it taken so long?

A substantial number of checks during the analyses were undertaken to ensure the quality and reliability of the measurements and when matching the measurements with the volunteer records. All data is anonymised and secure in accordance with ethical guidelines.

A range of sample types were collected and required bespoke measurements.

Advisory documents have been prepared by PHE for households where measurements in all sample types exceed recommended levels. This process is extremely complex, particularly where there is a lack of information in the scientific literature and so great care was required in providing any recommendations to households.

Publications from this project

An overview of the water chemistry has recently been published, the paper is titled: "Variability in the chemistry of private drinking water supplies and the impact of domestic treatment systems on water quality".

Frequently asked questions

Please read the FAQs: Measuring biological levels of Arsenic in the population of Cornwall 118 KB pdf if you have any questions about the study.

See also the private water supply (PWS) advice sheets 461 KB pdf.


DWI.  2013.  Drinking Water 2012, Private water supplies in England.   A report by the Chief Inspector of Drinking Water, July 2013.


If you have any further concerns about the project please feel free to call PHE helpline on 01235 825042 or email