title: Is environmental radon gas associated with the incidence of neurodegenerative conditions? A retrospective study of multiple sclerosis in radon affected areas in England and Wales.
abstract: To test whether an association exists between radon gas concentration in the home and increased multiple sclerosis (MS) incidence, a retrospective study was undertaken of MS incidence in known areas of raised domestic radon concentration in England and Wales, using The Health Improvement Network (THIN) clinical research database. The study population comprised 20,140,498 person-years of clinical monitoring (males: 10,056,628: 49.93%; females: 10,083,870: 50.07%), representing a mean annual population of 2.5 million individuals. To allow for the possible latency of MS initiation following exposure, data extraction was limited to patients with at least five years registration history with the same GP practice before first diagnosis. Patient records were allocated to one of nine radon concentration bands depending on the average radon level in their postcode sector. MS incidence was analysed by searching for patients with first MS diagnosis over the eight calendar years 2005-2012 inclusive. 1512 new MS cases were diagnosed, 1070 females, 442 males, equivalent to raw incidence rates of 7.51, 10.61 and 4.40 per 10(5) person-years respectively, comparable to previously reported results. Of these new cases, 115 could be allocated to one of the radon bands representing high radon areas. Standardising to the UK 2010 population, excess relative risk (ERR) figures for MS were calculated for each radon band. Linear regression of ERR against mean band radon concentration shows a positive gradient of 0.22 per 100 Bq·m(-3) (R(2) = 0.25, p = 0.0961) when forced through the origin to represent a linear-no-threshold response. The null hypothesis falls inside the 95% confidence interval for the linear fit and therefore this fit is not statistically significant. We conclude that, despite THIN sampling around 5% of the population, insufficient data was available to confirm or refute the hypothesised association between MS incidence and radon concentration.
authors.affiliation: Department of Environmental & Geographical Sciences, School of Science and Technology, University of Northampton, St. Georges Avenue, Northampton NN2 6JD, UK. Electronic address: chris.groves-kirkby@northampton.ac.uk.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Groves-Kirkby
authors.affiliation: Department of Environmental & Geographical Sciences, School of Science and Technology, University of Northampton, St. Georges Avenue, Northampton NN2 6JD, UK. Electronic address: tony.denman@northampton.ac.uk.
authors.forename: Antony R
authors.initials: AR
authors.lastname: Denman
authors.affiliation: Institute of Health & Wellbeing, School of Health, University of Northampton, Boughton Green Road, Northampton NN2 7AL, UK. Electronic address: jackie.campbell@northampton.ac.uk.
authors.forename: Jackie
authors.initials: J
authors.lastname: Campbell
authors.affiliation: Department of Environmental & Geographical Sciences, School of Science and Technology, University of Northampton, St. Georges Avenue, Northampton NN2 6JD, UK. Electronic address: robin.crockett@northampton.ac.uk.
authors.forename: Robin G M
authors.initials: RG
authors.lastname: Crockett
authors.affiliation: Department of Environmental & Geographical Sciences, School of Science and Technology, University of Northampton, St. Georges Avenue, Northampton NN2 6JD, UK. Electronic address: pauls.phillips@icloud.com.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Phillips
authors.affiliation: Institute of Health & Wellbeing, School of Health, University of Northampton, Boughton Green Road, Northampton NN2 7AL, UK; Public Health Department, Northamptonshire County Council, Guildhall Road, Northampton NN1 1DN, UK. Electronic address: sr232@leicester.ac.uk.
authors.forename: Stephen
authors.initials: S
authors.lastname: Rogers
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000396:Air Pollutants, Radioactive / Q000009:adverse effects*; D016902:Air Pollution, Indoor / Q000009:adverse effects*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000139:chemically induced / Q000453:epidemiology*; D011886:Radon / Q000009:adverse effects*; D012189:Retrospective Studies; D014852:Wales / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000396:Air Pollutants, Radioactive; D011886:Radon
keywords: Clinical extraction database; Multiple sclerosis; Radon; Retrospective population-based study