Heterotrophic plate count measurement in drinking water safety management: report of an Expert Meeting Geneva, 24-25 April 2002.

A group of microbiology and public health experts including regulatory and medical expertise was convened in Geneva, Switzerland, 25-26 April 2002 to consider the utility of heterotrophic plate count (HPC) measurements in addressing drinking water quality and safety. The group was convened following the NSF International/World Health Organization Symposium on HPC Bacteria in Drinking Water--Public Health Implications? The Expert Meeting was attended by 31 participants from Australia, Canada, France, Germany, Italy, Japan, the Netherlands, South Africa, Switzerland, UK and USA.

Safe drinking water production in rural areas: a comparison between developed and less developed countries.

At the fundamental level, there are remarkable parallels between developed and less developed countries in problems of providing safe drinking water in rural areas, but of course, they differ greatly in degree and in the opportunities for resolution. Small water supplies frequently encounter difficulty accessing sufficient quantities of drinking water for all domestic uses. If the water must be treated for safety reasons, then treatment facilities and trained operating personnel and finances are always in short supply. Ideally, each solution should be sustainable within its own cultural, political and economic context, and preferably with local personnel and financial resources. Otherwise, the water supply will be continuously dependent on outside resources and thus will not be able to control its destiny, and its future will be questionable. The history of success in this regard has been inconsistent, particularly in less developed but also in some developed countries. The traditional and ideal solution in developing countries has been central water treatment and a piped distribution network, however, results have had a mixed history primarily due to high initial costs and operation and maintenance, inadequate access to training, management and finance sufficient to support a fairly complex system for the long term. These complete systems are also slow to be implemented so waterborne disease continues in the interim. Thus, non-traditional, creative, cost-effective practical solutions that can be more rapidly implemented are needed. Some of these options could involve: small package central treatment coupled with non piped distribution, e.g. community supplied bottled water; decentralized treatment for the home using basic filtration and/or disinfection; higher levels of technology to deal with chemical contaminants e.g. natural fluoride or arsenic. These technological options coupled with training, technical support and other essential elements like community commitment provide opportunities that should be explored both for rural small communities and in rapidly growing periurban areas in developing countries.

Comparison of the up-and-down, conventional LD50, and fixed-dose acute toxicity procedures.

The up-and-down procedure (UDP), fixed-dose procedure (FDP) and conventional LD50 tests were compared to determine their consistency in chemical hazard classification for acute oral toxicity according to the European Economic Community (EEC) system. There was consistent classification for 23 out of 25 cases between the UDP and the conventional LD50 results, in 16 out of 20 cases between the FDP and the conventional LD50, and in seven out of 10 cases between the UDP and the FDP. The UDP needed only between six and 10 animals of one sex (fewer than either the LD50 or the FDP). Available literature indicates that the sexes are usually similar in their acute toxicity responses and that of females are often more sensitive than males when acute toxicity differences do exist, thus obviating the need for both sexes to be tested in most cases. Unlike the FDP, the UDP also estimates an LD50, thus providing data directly applicable to all current hazard classification systems based on acute oral toxicity.

Evaluation of reduced protocols for carcinogenicity testing of chemicals: report of a joint EPA/NIEHS workshop.

The current U.S. Environmental Protection Agency (EPA) and other national/international guidelines specify the use of two species and two sexes rodents (usually the rat and the mouse) for carcinogenicity testing of chemicals. In view of the enormous number of chemicals to be tested, the high cost of testing, and the large number of animals used in the present protocol, many academic, industrial, and government authorities are examining the possibility of using a reduced protocol (less than two species and two sexes of rodents) for carcinogenicity testing of chemicals. The use of a reduced protocol offers many advantages as well as some disadvantages. To pursue further the potential implications and impacts of using a reduced protocol for carcinogenicity testing on the processes of hazard identification and risk assessment, a workshop entitled "Evaluation of Reduced Protocols for Carcinogenicity Testing of Chemicals" was held at the Embassy Suites Hotel in Alexandria, Virginia on September 22 and 23, 1992. It was cosponsored by EPA's Office of Prevention, Pesticides and Toxic Substances (OPPTS) and the National Toxicology Program of the National Institutes of Environmental Health Sciences (NTP/NIEHS) and attended by more than 60 participants from government, industry, academia, and the general public. The Expert Consensus Panel and most of the participants supported the use of reduced protocols in carcinogenicity testing. However, it was recognized that reduced protocols may not be appropriate for the testing of all chemicals and that additional analyses/data may be needed for selection of the most appropriate reduced protocol for certain chemicals/chemical classes.

Drinking water standards and risk assessment.

The role and use of risk assessment methods in the establishment of drinking water standards are described with emphasis on recent applications. The process essentially includes an attempt to quantify human exposure from all routes including drinking water, animal toxicology, and human epidemiology, when available, to arrive at drinking water concentrations at which exposure would result in "no known or anticipated adverse effects on health, with a margin of safety." The process itself is straightforward; however, the application to decision making for substances that are considered to be potentially nonthreshold acting in their toxicity (e.g., carcinogenic) requires many policy choices beyond the scientific data and is subject to considerable controversy.

Summation from a regulatory perspective.

There is an urgent need to discuss the Office of Drinking Water's standard-setting or rulemaking process since most of the researchers whose papers are presented here directly or indirectly play a crucial role in this complex undertaking. Therefore, this paper will address the research data required to support policymaking and regulatory decisions pertaining to health effects of disinfectants and disinfection by-products.

Organic micropollutants in drinking water: an overview.

Biological contamination is still the most significant public health risk from drinking water even in industrialized countries. High potential for organic chemical transport to drinking water continues to exist even with source protection because of the multitude of chemical types and quantities. Drinking water is usually not a unique source nor the most significant contributor to total exposure from synthetic organic chemicals but it might be one of the most controllable. The major public concern with drinking water contamination has been possible contribution to cancer risks from organic micropollutants. Even though the actual risks are probably small in most cases it is clearly within the public interest to prevent adulteration of water supplies and to protect their quality for the future so that these concerns or risks can be avoided. A risk assessment/management decision model is suggested which may assist the process of making rational assessments of these contamination problems and control decisions that consciously consider all of the available data in a consistent manner.

Asbestos in drinking water: a status report.

The conference is briefly reviewed in the light of its impact on future regulatory decisions regarding the possible control of asbestos fiber in drinking water. The results of animal feeding studies indicate that asbestos fails to demonstrate toxicity in whole-animal lifetime exposures. The epidemiologic evidence of risk from ingestion of water containing asbestos fibers is not convincing, and in view of the lack of confirmation by animal studies, the existence of a risk has not been proven; however occupational gastrointestinal cancer may indicate ingestion risk. Whether or not there is a risk from asbestos in drinking water, however, common sense tells us to deal with an undesirable situation by employing means that are commonly and economically available. Well-known methods can minimize the presence of asbestos fibers in finished drinking water. In the case of natural fiber in raw water, standard or augmented filtration practices are extremely effective. If the source of asbestos fiber is asbestos-cement pipe that is being attacked by corrosive water, then, there is more than sufficient economic reason to correct the corrosivity of the water.

Health effects guidance for uranium in drinking water.

The interim regulations for radioactivity in drinking water were promulgated in 1976 (Federal Register, Friday, 9 July, 1976, p. 28402). These regulations specifically excluded uranium because of uncertainties concerning its toxicology, treatment technology and occurrence. At this time, EPA's Office of Drinking Water is considering proposing a health effects guidance level of 10 pCi/l. (0.37 Bq/l.) for uranium in drinking water. This paper describes the approach that EPAs Office of Drinking Water is considering in developing the guidance level. This value has not yet been officially determined to be EPA's formal guidance, but is presented as a working hypothesis for review and comments. Included here is a discussion of occurrence, pharmacokinetics and health effects. The calculation of doses uses the ICRP 30 model and the risk determination uses EPA's newly developed life table approach. The risk level from ingesting drinking water with a uranium content of 10 pCi/l. is estimated to be about 3 X 10(-5) excess cancers/lifetime.

EPA policies to protect the health of consumers of drinking water in the United States.

In the United States our objective is to protect drinking water at the source, during treatment and during distribution. In 1975 interim regulations for bacteria and turbidity, 10 inorganic chemicals, 6 organic chemicals and radionuclides were promulgated. In 1979 National Secondary Regulations for substances affecting the aesthetic quality of water were promulgated. In 1979 trihalomethanes were added. The United States is engaged in comprehensive revisions of the National Primary Drinking Water Regulations. The areas of our most significant concern include detection and control of contamination of ground waters by organic chemicals resulting from improper waste disposal practices, a reassessment of microbiological regulations and toxicity of disinfectant by-products and a major effort to deal with corrosion-related contamination of drinking water during distribution. We are evaluating the issue of a granular activated carbon requirement for contaminated surface waters. A program to assure the quality of direct and indirect additives to drinking water has also been initiated. Part of this activity will include determination of the contaminants and by-products associated with the use of various water treatment chemicals and pipe materials.