EXCESS MORTALITY IN THE HUNTER REGION OF AUSTRALIA A. J. DORSON.* R. W. GIRRERD* and S. R. LEEDERt Faculties of Mathematics* and MedIcmet, Umversity of Newcastle, Australia Abstract-The Hunter region of New South Wales has experienced higher death rates than expected durmg the past two decades To try to explam this phenomenon the excess mortality was analysed by sex, age, cause of death and local governmental area within the region. Apart from unusually high mortality from motor vehicle accidents amongst young males. the excess deaths were confined to the age groups 35-74 years in both sexes, occurred m the predommantly industrial and mining areas and were largely attributable to lschaemic heart disease and stroke (with deaths from cancers occurring at normal rates). These findings emphaslse that any prevention programme aimed at reducing mortality should focus on vascular diseases and be directed towards those sectIons of the community Identified at greatest potential risk. Comparing mortality rates from different geographi- cal areas may lead to the identification of environ- mental factors or population characteristics that are associated with abnormally high or low mortality. Historically, this method was used to study the aetio- logy of infectious diseases. such as cholera and measles, and the association between cholera and a water pump in Soho in 1894 is the classical example of identifying an environmental risk factor from the study of disease excess [l]. Recently, significant re- gional differences in death rates from various chronic, non-infective diseases such as heart disease and cancer have been documented. The association between smoking and lung cancer, for example, has been strengthened by a geographIca comparison between lung cancer rates in 19 different countries and the number of cigarettes smoked per adult per year 30 years previously [?I. In most cases, however, the causes of observed differences in death rates between areas are not known. although it is assumed that they are attributable, at least in part, to social and environmental differences. In this study a specific region m Australia which had experienced consistently somewhat high mor- tahty was considered and the following questions were asked. (1) Which causes of death, which age-groups and sex. and which areas are responsible for the excess mortahty? (II) Are any of the excess deaths feasibly preventible by medical intervention. by changes in the physical environment. or by changes in life-style of the popula- tlon’l Thus this study extends the medical geographer’s concern for spatial differences and asks how, on the basis of current knowledge of diseases and risk factors. further excess deaths might be prevented. THE STCDI- REGIOK The region under. study is the Hunter Statistical Dl\lsion (S.D.1 located on the eastern coast of Austra- ha. approximately 150 km north of Sydney (Fig. 1). The population at the last census was 429,250, or 9’:, of the New South Wales (N.S.W.) population. The region is rich in natural resources, especially coal and agricultural land, and displays considerable physical variation. For the purposes of this study the Hunter region is composed of the following areas. (a) The Local Government Area (LGA) of New- castle is the main commercial, industrial and adminis- trative centre of the region containing 36:; of the population and 51% of the employment. It is a major port and manufacturing centre for steel and heavy engineering products and ranks as the sixth urban centre in Australia. (b) Surrounding Newcastle are four urban LGA’s. The largest, Lake Macquarie, consists of dormitory surburbs to Newcastle, with the usual attributes of these areas: newer housing, younger population and higher population growth. Maitland, which began as a river port and centre for trade and agriculture. is increasingly providing dormitory suburbs for New- castle. The Cessnock LGA is sufficiently separated from Newcastle that it can be regarded as an indepen- dent urban area containing several mining towns based on the Cessnock coalfields which commenced production around 1900. Today 267: of the male workforce of Cessnock is still associated with mming although several manufacturing industries have also been established. The fourth urban LGA is Port Ste- phens which is unique in that its rapid population growth is due to people retiring to the coastal resort centres, as well as growth in the air-force base. (c) Surrounding the urban areas is a rural area which for the purpose of this study has been divided mto three subregions. All three contain towns which are basically centres providing services to the sur- rounding rural areas. Subregion 1 is being increasingly used for coal extraction and power generation, while subregion 3 contains coastal resort centres. similar to those in the Port Stephens LGA. THE ANALYSIS Pubhshed data have shown that the study region has had about 5”, higher mortahty rates than N.S.W. 169