Identifying the Cause of Toxicity of a Saline Mine Water

Elevated major ions (or salinity) are recognised as being a key contributor to the toxicity of many mine waste waters but the complex interactions between the major ions and large inter-species variability in response to salinity, make it difficult to relate toxicity to causal factors. This study aimed to determine if the toxicity of a typical saline seepage water was solely due to its major ion constituents; and determine which major ions were the leading contributors to the toxicity. Standardised toxicity tests using two tropical freshwater species Chlorella sp. (alga) and Moinodaphnia macleayi (cladoceran) were used to compare the toxicity of 1) mine and synthetic seepage water; 2) key major ions (e.g. Na, Cl, SO4 and HCO3); 3) synthetic seepage water that were modified by excluding key major ions. For Chlorella sp., the toxicity of the seepage water was not solely due to its major ion concentrations because there were differences in effects caused by the mine seepage and synthetic seepage. However, for M. macleayi this hypothesis was supported because similar effects caused by mine seepage and synthetic seepage. Sulfate was identified as a major ion that could predict the toxicity of the synthetic waters, which might be expected as it was the dominant major ion in the seepage water. However, sulfate was not the primary cause of toxicity in the seepage water and electrical conductivity was a better predictor of effects. Ultimately, the results show that specific major ions do not clearly drive the toxicity of saline seepage waters and the effects are probably due to the electrical conductivity of the mine waste waters

Oral health of Indigenous adult public dental patients in Australia

The definitive version can be found at www.blackwell-synergy.comBackground: Indigenous Australians have been reported in a range of studies to have worse health than non-Indigenous Australians. Among health care card holders, a financially disadvantaged group eligible for public-funded dental care, oral health may also be worse among Indigenous persons. The aims of this study were to examine the oral health of Indigenous compared to non-Indigenous adult public dental patients in terms of caries experience and periodontal status, controlling for age and gender of patient, type of care and geographic location. Methods: Patients were sampled randomly by state/territory dental services in 2001–2002. Dentists recorded oral health status at the initial visit of a course of care using written instructions. The samples were weighted in proportion to the numbers of public-funded dental patients for each state/territory. Results: Multivariate logistic regression showed that the presence of periodontal pockets of 6+ mm was higher (P < 0.05) among Indigenous compared to non-Indigenous patients (OR=2.24, 1.34–3.76), after controlling for age and gender of patients, type of care and geographic location. Multivariate negative binomial regression analysis (RR: rate ratio) controlling for age and gender of patients, type of care and geographic location indicated that Indigenous patients had higher numbers of decayed teeth (RR=1.42) and missing teeth (RR=1.44) but lower numbers of filled teeth (RR=0.51) compared to non-Indigenous patients (P < 0.05). There was no significant difference in the DMFT index, indicating similar cumulative past and present experience of dental caries for Indigenous and non-Indigenous patients. Conclusions: Indigenous adult public dental patients had worse oral health status than non-Indigenous patients, with a higher percentage of Indigenous patients having periodontal pockets 6+ mm, and Indigenous patients having more decayed and missing teeth. Indigenous patients lack both timely and appropriate preventive and treatment services.DS Brennan, KF Roberts-Thomson, AJ Spence