Soil lead levels in parks and playgrounds: an environmental risk assessment in Newcastle.

In June 1993 the National Health and Medical Research Council set a national goal for blood lead of below 10 micrograms/dl. There is a need to know if the lead contamination of the urban environment is so high as to put community health at risk. Decisions, including whether soil should be removed and replaced, will have to be made. During the second half of 1993, an environmental assessment of lead contamination of soil within the City of Newcastle was conducted. Samples, 108 from surface soil and 10 from subsurface soil, were taken from public parks and playgrounds in the city area and analysed for lead content. The proportion within and the proportion above the guidelines for soil contamination were reported. Lead concentrations ranged from 25 to 2400 parts per million (ppm); 21 per cent of samples had concentrations higher than the 300 ppm action level, and the geometric mean was 134 ppm. Both the range and the average lead levels were typically no more than, or were even less than, soil lead levels documented for other cities in Australia, the United States and United Kingdom. Although each sampling site was noted, it was not our intention to focus in on individual sites. Indeed, to draw health-risk implications from any one result may be misleading and inaccurate. The results indicated moderate lead contamination of soil that could be controlled by regular top-dressing of soils, the use of bark chip on playground surfaces and by government initiatives aimed at lowering lead levels in petrol.

A cluster of brain tumours in a New South Wales colliery: a problem in interpretation.

Following the reporting of a cluster of cases of brain tumour in the workforce of an underground coal mine (Mine A) in the Newcastle coalfield, a study was carried out to determine whether this phenomenon was due to chance alone or whether an environmental cause could be postulated. The study design was a historical cohort study over 15 years comparing the incidence of brain tumour (ICD9 191 and 192) in the index mine with that in two control mines (Mines B and C) in the same area and with that in the general Australian population. We compared environmental exposures (ionising and nonionizing radiation and chemical exposure) in the three mines. With Australian brain tumour incidence rates as reference, the standardised incidence ratio for brain tumour in Mine A was 5.3 (95 per cent confidence interval (CI) 1.08 to 14.04) and in Mines B and C combined was 1.23 (CI 0.02 to 3.80). On most environmental assessments the three mines were similar but Mine A used larger volumes of solvents than the other mines. This study poses two questions: was the increase in cases of brain tumour in Mine A 'real' and if so, was it related to the use of solvents? Data, from an investigation of a cluster such as this, are unlikely to be conclusive. Nevertheless, such answers are demanded not only by those at risk but also by the mine management, which is responsible for a safe working environment. Some of the difficulties involved with this judgment are discussed.