Drinking-water priority chemicals

As discussed above, for risk management purposes, priority should be assigned to specific chemicals on the basis of site-specific assessments. However, it is also important to pay particular attention to chemicals that have been found in many locations worldwide to present serious human health hazards due to exposure through drinking-water. These chemicals are mentioned below and are discussed in greater detail in the WHO Guidelines for Drinking-water Quality (WHO, 2004 WHO, 2006). 

The RMBC assessed its regional public-health priorities and developed the following nine demonstration projects on the basis of the needs of the community possible correlation of exposure to arsenic in drinking water and type 2 diabetes, a spot blood metals-analysis feasibility study, health-clinic samples for chemical-terrorism baselines, of relationship between urine arsenic and metal concentrations and drinking-water exposure, assessment of exposure to VOCs from subsurface volatilization, cotinine concentrations associated with environmental tobacco smoke, assessment of exposure to mercury from ingestion of fish, analysis of radionuclides in urine, and biomonitoring of organophosphorus pesticides in urine (Utah Department of Health 2006). 

The objective of this publication is to help users at national or local level to establish which chemicals in a particular setting should be given priority in developing strategies for risk management and monitoring of chemicals in drinking-water, The document will be useful to public... 

Limiting the number of chemicals to be managed on the basis of available resources for monitoring or control, without consideration of the potential for health effects associated with particular chemicals, could result in unacceptably high levels of hazardous chemicals in drinking-water. A more rational way to set priorities is needed. The present document is intended to meet this need by providing a simple, rapid and rational basis for assigning priority to specific chemicals, which can complement administrative practices at local or national level. 

Identifying chemicals of concern to public health in drinking-water is based on the hazard to health of those chemicals and the probability of exposure. In many parts of developing countries, and in rural areas of some developed countries, water quality data are limited or nonexistent, making it difficult to determine priorities for risk management based on both criteria. In such cases, the priority for risk management must be determined on the probability of exposure alone,... 

Identifying priority chemicals in a drinking-water supply... 

Once priority chemicals within a particular drinking-water system have been identified, a management policy should be established and implemented to provide a framework for the prevention and reduction of these chemicals. Appropriate monitoring programmes should be established to ensure that the chemical quality of drinking-water remains within appropriate national standards. 

The facilities and resources available may be sufficient to allow a comprehensive analytical assessment of the inorganic constituents in a source.1 However, such an assessment is often not possible in which case, the following sections and Table 4.1 indicate the naturally occurring chemicals that should be considered in setting priorities for chemicals in drinking-water sources. 

Fluoride, arsenic, selenium and, in certain circumstances, nitrate should be given high priority. As noted in Chapter 2, the presence of these chemicals in drinking-water has been shown to cause health effects. The natural occurrence of these chemicals is relatively common in water supplies around the world in both developing and developed countries therefore, they should be assumed to be potentially present, and consideration should be given as to whether they are actually present in concentrations of concern. 

X Potential source of chemical in drinking water, To be taken into consideration as part of the assessment of priority chemicals,... 

Chemical safety of drinking-water Assessing priorities for risk management... 

Drilling, pumping, and transporting of crude oil invariably results in some spills of petroleum. These spills result in the introduction of aliphatic hydrocarbons, aromatic hydrocarbons, and PAHs into surface and ground-waters. Many of the chemicals listed on the EPA s list of 129 priority water pollutants (see Section 8.8) enter drinking water sources. 

Monitoring surface water, ground water, seawater, effluents and drinking water for toxic compounds is traditionally carried out by discrete (spot) sampling that is followed by chemical analysis in the laboratory. This provides qualitative and quantitative information on specific analytes, in Europe often focused on the priority substances defined by the EC Water Framework Directive, WFD (European Commission, 2000). Although... 

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