Using GIS to investigate multiple deprivation David Briggs Small Area Health Statistics Unit Imperial College, London A few thoughts and several questions

SAHSU and Environmental Injustice Socio-economic deprivation shows (often strong) associations with health outcome and exposure in most SAHSU studies Studies designed to minimise potential confounding by deprivation (small-area, case-crossover etc) Control is typically by using a (group-level) measure of socio- economic deprivation (Carstairs) in the logistic regression analysis But…. Do we over-control? Is deprivation really a confounder or effect-modifier? What is it about deprivation that affects health – and how should it be measured?

Question 1. Why are we interested in Environmental Injustice Good science Good policy Moral justice Trendy subject

Landfill site density and population density, UK

Affluent Deprived Proximity to landfill sites by socioeconomic status and urban area

Socio-economic status by distance from powerlines (km)

Odds ratios of living within 100 metres of a powerline, by socio-economic status Affluent Deprived

Exposure to black smoke and deprivation for different time periods, urban wards UK

Socio-economic deprivation and environment ExposureDirectionComment Traffic-related air pollution+Strong Industrial air pollution+Strong Road traffic noise+Strong Aircraft noise +/  Varies by country Disinfection byproducts +/  Varies by region Landfill sites+Urban/industrial Radon  Rural/upland Powerlines/EMF +/  Varies urban/rural Mobile phone masts +/  Varies urban/rural

Question 2 How do these associations develop? Imposed (via planning process) – e.g. major point emitters? Evolved (as population changes in response) – e.g. roads, airports? Geographic coincidence (i.e. shared, but independent, geography of hazard and SES) – e.g. radon, powerlines? Historical legacy (i.e. inherited from past) – e.g. landfill sites

Mortality and deprivation for four time periods: urban wards, UK

YearUnadjustedAdjusted Adjusted and unadjusted risks of respiratory mortality for a 10 ppb increase in SO 2

Outcome Mean1%99%Mean1%99% Neural tube defects Hypospadias/ epispadias Abdominal wall defects Stillbirths Low birth weight Very low birth weight Abdominal wall defects* Gastroschisis/ exomphalos* Unadjusted Adjusted Landfills: relative risks for ‘exposed’ versus ‘unexposed’

Outcome Mean1%99%Mean1%99% Neural tube defects Hypospadias/ epispadias Abdominal wall defects Stillbirths Low birth weight Very low birth weight Abdominal wall defects* Gastroschisis/ exomphalos* Before operation During/after operation * Hospital admissions Landfills: relative risks for ‘exposed’ versus ‘unexposed’

Health outcomeDirectionComment Traffic accidents+Stronger for pedestrians Lung cancer+Smoking related Asthma—Weak Cardio-vascular illness+ Pulmonary illness+ Congenital malformations+Limited evidence All-cause mortality+ Non-lung cancers—Variable Communicable diseases+ Socio-economic deprivation and health

Affluent Deprived Exposure Mortality Socio-economic confounding

Deprived Affluent Deprived Exposure Mortality Effect modification

Principle component 1 = traditional aspects of social deprivation; accounts for ca. 57% of the variation in the data and is closely associated with smoking Principle component 2 = measures relating to assets and income; accounts for ca. 15% of the variation in the data

Question 3. How does environmental injustice work? What are the mechanisms by which socio-economic status affects health? How do these combine/interact with environmental exposures to affect health? What aspects/components of SES? What aspects/components of environmental exposure Are they necessarily geographical? Is it the same everywhere (cultural determinants)? How do we study environmental injustice?

Well-being Morbidity Mortality Exposure Ambient environment Community Home Health outcome Preventive actions Remedial actions Actions Contexts Distal Proximal Less severe More severe Social conditions Economic conditions Demographic conditions causes attributable to The ME-ME Model

Questions 4+ What conceptual models do we have? What IS environmental injustice? What does it mean? For epidemiology For policy For the way we look at the world