Background levels of urban land contamination

The research work reported in this thesis is concerned with the development and application of an urban scale sampling methodology for measuring and assessing background levels of heavy metal soil contamination in large and varied urban areas. The policy context of the work is broadly the environmental health problems posed by contaminated land and their implications for urban development planning. Within this wider policy context, the emphasis in the research has been placed on issues, related to the determination and application of 'guidelines' for assessing the significance of contaminated land for environmental planning. In concentrating on background levels of land contamination, the research responds to the need for additional techniques which address both the problems of measuring soil contamination at the urban scale and which are also capable of providing detailed information for use in the assessment of contaminated sites. Therefore, a key component of the work has been the development of a land-use based sampling framework for generating spatially comprehensive data on heavy metals in soil. The utility of the information output of the sampling method is demonstrated in two alternative ways. Firstly, it has been used to map the existing pattern of typical levels of heavy metals in urban soils. Secondly, it can be used to generate both generalised data in the form of 'reference levels' from which the overall significance of .background contamination may be assessed and detailed data, termed 'normal limit levels' for use in the assessment of site specific investigation data. The fieldwork was conducted in the West Midlands Metropolitan County and surface soil has been sampled and analysed for a measure of plant-available' and 'total' lead cadmium, copper and zinc. The research contrasts with much of the previous work on contaminated land which has generally concentrated on either the detailed investigation of individual sites suspected of being contaminated or the appraisal of land contamination resulting from specific point sources.

Balance ability in 7- and 10-year-old children:associations with prenatal lead and cadmium exposure and with blood lead levels in childhood in a prospective birth cohort study

OBJECTIVES: Most studies reporting evidence of adverse effects of lead and cadmium on the ability to balance have been conducted in high-exposure groups or have included adults. The effects of prenatal exposure have not been well studied, nor have the effects in children been directly studied. The aim of the study was to identify the associations of lead (in utero and in childhood) and cadmium (in utero) exposure with the ability to balance in children aged 7 and 10 years. DESIGN: Prospective birth cohort study. PARTICIPANTS: Maternal blood lead (n=4285) and cadmium (n=4286) levels were measured by inductively coupled plasma mass spectrometry in women enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) during pregnancy. Child lead levels were measured in a subsample of 582 of ALSPAC children at age 30 months. MAIN OUTCOME MEASURES: Children completed a heel-to-toe walking test at 7 years. At 10 years, the children underwent clinical tests of static and dynamic balance. Statistical analysis using SPSS V.19 included logistic regression modelling, comparing categories of ≥ 5 vs <5 µg/dL for lead, and ≥ 1 vs <1 µg/L for cadmium. RESULTS: Balance at age 7 years was not associated with elevated in utero lead or cadmium exposure (adjusted OR for balance dysfunction: Pb 1.01 (95% CI 0.95 to 1.01), n=1732; Cd 0.95 (0.77 to 1.20), n=1734), or with elevated child blood lead level at age 30 months (adjusted OR 0.98 (0.92 to 1.05), n=354). Similarly, neither measures of static nor dynamic balance at age 10 years were associated with in utero lead or cadmium exposure, or child lead level. CONCLUSIONS: These findings do not provide any evidence of an association of prenatal exposure to lead or cadmium, or lead levels in childhood, on balance ability in children. Confirmation in other cohorts is needed.