Environmental health sciences center task force review on halogenated organics in drinking water

Abstract

The disinfection of drinking water by chlorination has in recent years come under closer scrutiny because of the potential hazards associated with the production of stable chlorinated organic chemicals. Organic chemical contaminants are common to all water supplies and it is now well-established that chlorinated by-products are obtained under conditions of disinfection, or during tertiary treatment of sewage whose products can ultimately find their way into drinking water supplies. Naturally occurring humic substances which are invariably present in drinking waters are probably the source of chloroform and other halogenated methanes, and chloroform has shown up in every water supply investigated thus far. The Environmental Protection Agency is charged with the responsibility of assessing the public health effects resulting from the consumption of contaminated drinking water. It has specifically undertaken the task of determining whether organic contaminants or their chlorinated derivatives have a special impact, and if so, what alternatives there are to protect the consumer against bacterial and viral diseases that are transmitted through infected drinking waters. The impetus to look at these chemicals is not entirely without some prima facie evidence of potential trouble. Epidemiological studies suggested a higher incidence of cancer along the lower Mississippi River where the contamination from organic chemicals is particularly high. The conclusions from these studies have, to be sure, not gone unchallenged. The task of assessing the effects of chemicals in the drinking water is a difficult one. It includes many variables, including differences in water supplies and the temporal relationship between contamination and consumption of the finished product. It must also take into account the relative importance of the effects from these chemicals in comparison to those from occupational exposure, ingestion of contaminated foods, inhalation of polluted air, and many others. The susceptibility of different age, genetic, and ethnic groups within the population must also be carefully considered. The present review discusses: the reasons for disinfection; the general occurrence of chlorinated organics in drinking water; the chemistry in the synthesis of chlorinated organics under aqueous conditions; and alternatives to chlorine for disinfection.

Mutagenicity studies in salmonella: Residues of ozonated and/or chlorinated water fulvic acids

“…Drinking water supplies are known to contain trace amounts of many chemicals, many of which arise during disinfection processes [Deinzer et al, 1978;Coleman et al, 1980;Williams et al, 19821. Although the potential health effects that these contaminants may cause cannot be measured directly, they are not considered to be of concern because their levels fall within accepted standards for drinking water in the vast majority of cases [Guidelines, 1978, 19841.…”

“…The production of chlorination by-products through chlorine disinfection of drinking water has been well documented [Deinzer et al, 1978;Loper, 19801. Organic precursors for these chemicals are thought to include fulvic acids [Rook, 19771, a heterogeneous group of compounds probably arising through the oxidative coupling of phenolic and aliphatic residues derived from the degradation of biological materials [Schnitzer and Khan, 19721.…”

Influence of nitrogen source on NDMA formation during chlorination of diuron

“…1 with an equilibrium constant of 6.7 × 10 5 at 25°C (Deinzer et al 1978; Schreiber and Mitch 2005). Stock NHCl 2 solution was prepared by lowering the pH of stock NH 2 Cl solution to 3.7 and aging for 1 hour.…”

Differential display identified changes in mRNA levels in regenerating livers from chloroform-treated mice

“…Chloroform (CHCl 3 ) is a trace contaminant generated as a by-product of drinking water and swimming pool chlorination [1,2] and of some paper-bleaching processes [3,4]. Chloroform induces cancer in rodents by a nongenotoxic-cytotoxic mode of action [5].…”