Impact of bleached kraft mill effluents on drinking water quality.

Bleaching effluents from kraft pulp mills contain large quantities of chlorinated organic compounds, some of which are mutagenic. Mutagenic chloro-organic compounds are also formed as by-products in chlorination of drinking water. The work reported here was a combined field and laboratory study aimed at comparing the evidence of health risks from pulp mill contaminants in drinking water, with corresponding evidence from normal, chlorine disinfection by-products. The study was performed in a Swedish river basin with a large, public water works located downstream from a bleached kraft mill. Chemical analyses (gas chromatography and determination of adsorbable organic halogen) and bioassays for mutagenic activity (bacterial and mammalian cell bioassays) were performed on samples of river water, drinking water and laboratory produced drinking water. The study showed that the bleached kraft effluents caused a considerable, long-range transport of chloro-organic substances in the receiving waters, and a substantial increase in the total amount of organic chlorine in drinking water produced downstream from the mill. As regards Ames mutagenic compounds, however, chlorination of naturally occurring humic substances during the chlorine disinfection step in drinking water production, proved to be a far more important source. The contribution of volatile chloro-organic compounds from the kraft mill was also much smaller than the contribution from normal disinfection by-products. The chromosome aberration tests gave no clear evidence of a positive response for any of the samples tested.

A comparison of methods for concentrating mutagens in drinking water--recovery aspects and their implications for the chemical character of major unidentified mutagens.

A comparison of techniques for concentrating mutagenic compounds in drinking water has shown that XAD-2 adsorption and dichloromethane extraction have acceptable and almost identical enrichment properties, while purging at an elevated temperature is inappropriate in this context. Quantitatively, the most important drinking water mutagens could only be adsorbed (extracted) after acidification of the water, and even then recovery was far from complete. Recovery experiments with known mutagens from pulp mill effluents have shown that none of the major chlorination-stage mutagens identified thus far can explain the mutagenic activity of extracts from neutral or acidified chlorinated drinking water.