Abstract of PhD Thesis

General health, blood lead levels and their environmental predictors, in the vicinity of abandoned mines, Silvermines, Co. Tipperary

Karmel-Carrie Garavan MPH RGN Dip. (GIS), University of Limerick (2005)

The toxic effects of lead (Pb) on adult and, in particular, on children’s development has been well documented and include neurological deficits and behaviour disorders. Blood Pb levels (BPb) have been associated with soil and dust Pb levels in former mining areas. The Silvermines area, North Tipperary, has a long history of mining dating from the 10th century until 1994.

Following the deaths of cattle in the Silvermines from Pb toxicity in 1999, coupled with concerns of the local community regarding possible risks to human health from certain former mine sites, a cross sectional exposure study was initiated. The study objective was to determine the extent to which environmental, behavioural and other risk factors contributed to Pb exposure in individuals, particularly young children living in the community. Questionnaires regarding possible exposure to Pb and an individual’s general health were completed. Pre-school and primary school children were targeted. A total of 723 individuals provided blood samples for BPb screening, of which 439 were children (3 months and 17.7 years). Soil samples (n = 119), internal dust samples (n = 118) and handwipes (n = 168) were analysed for Pb content. A Geographical Information System (GIS) was used to produce maps of heavy metal distribution within the study area.

The geometric mean BPb in 1999 for adults and for children was 2.7µg/dl, and this declined ten per cent per year for children for the following two years. No significant difference was found between the state of health of the Silvermines’ population when compared to comparative data from other studies. Elevated soil Pb levels were found in gardens within the Silvermines village. Multiple regression indicated that three variables (soil Pb, age in years, handwipe Pb) were the best predictors of BPb in children.

Overall the study suggests that the elevated environmental Pb levels are not being transferred to humans, particularly children, currently. However, recent research undertaken in former mining areas in other countries suggests that mine waste, with or without smelting waste, is related to elevated BPb and consequently, safeguards must be taken to lessen exposure to this Pb source.