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Effluents from Pulp Mills using Bleaching - PSL1

Section 3 Scope of the Investigation of Effluents from Pulp Mills Using Bleaching

The risk assessment process involves searching chemical, biological, medical, legal, technological, and environmental literature and supplementing this information, where possible, with actual testing, monitoring, and research. Information of particular importance includes environmental effects and human toxicity data, as well as data dealing with the routes, levels and effects of short- and long-term exposure. Additional information, in this instance, was acquired through a CEPA Section 18 notice requiring bleached pulp mills to submit specific information about their operations and discharges.

Chlorinated organic constituents of effluents from bleached pulp mills are the primary focal point of this assessment report, as recommended by the Ministers' Priority Substances Advisory Panel⁽³⁾. Chlorinated "dioxins" and "furans" (also found in bleached pulp mill effluents) were evaluated in a previous assessment report⁽⁶⁾.The effects of Total Suspended Solids (TSS) and Biochemical Oxygen Demand (BOD) (characteristic of pulp mill effluents) were not evaluated as they are regulated under the Fisheries Act.

The toxic effects of bleached pulp mill effluents on human health have not been widely studied. The toxicity of dioxins and furans, as well as their potential to harm human health, has been well established and they were the first substances on the Priority Substances List (PSL) to be declared "toxic" under CEPA. Insufficient data were found in a preliminary review on other organochlorine components of bleached pulp mill effluents to be able to judge their effects on the quality of fish for human consumption or on drinking water. This assessment therefore focused on the environmental impacts of pulp mill effluents.

Similarly, no information was found which suggested that any of the constituents of bleached pulp mill effluents affected the environment on which human health depends. "Toxic" effects as defined by Paragraphs 11(b) and 11(c) of the Act, therefore, are beyond the scope of this assessment. This does not preclude future use of CEPA in these areas should new information arise.

This investigation of effluents from pulp mills employing bleaching included the following activities:

1. The technology of bleached pulp manufacture was studied to provide a basis for evaluating biological information.
   
   
2. The physical and chemical properties of selected chlorinated organic compounds in bleached pulp mill effluents were reviewed. Particular emphasis was placed on those properties that influence chemical analysis, environmental persistence and distribution, and aquatic toxicity.
   
   
3. The complexity of bleached pulp mill effluents was explored and available information on generic and specific releases from bleached pulp mills to the aquatic environment was evaluated.
   
   
4. Analytical methods employed to measure organochlorine concentrations in bleached pulp mill effluents were examined. Particular emphasis was placed on surrogate measurements, such as Adsorbable Organic Halogen (AOX), for the estimation of the organochlorine Content in effluents and receiving waters.
   
   
5. Existing and proposed guidelines, regulations, and legislation relating to the control of organochlorine pollution of the aquatic environment by bleached pulp mills were reviewed and compared for Canada, the United States, Scandinavia, and Europe.
   
   
6. Canadian statistics on quantities of chlorine consumed, effluents discharged, and bleached pulp produced were collected and analyzed, and an estimate of the chlorinated matter released was made.
   
   
7. The environmental distribution and fate of chlorinated substances released in bleached pulp mill effluents were investigated. Particular emphasis was placed on the manner in which bleached pulp mill effluent constituents are partitioned among various environmental compartments (water, sediments, and biological tissues), how long they persist in these compartments, the potential for physical and biological degradation and the transformation, and the degree to which they are bioaccumulated in the aquatic environment.
   
   
8. Canadian levels of chlorinated organic compounds detected in bleached pulp mill effluents, receiving waters, sediments, and aquatic organisms were reviewed and compared when possible with the levels found in Scandinavia. This information was examined for organochlorine concentration gradients in the aquatic environment to determine if the exposure levels involved in extensive Scandinavian studies are comparable to those found in Canada.
   
   
9. The acute and chronic toxicities to aquatic organisms associated with whole bleached pulp mill effluent and its known organochlorine constituents were reviewed for both field and laboratory conditions. Emphasis was given to relating, where possible, the levels of these compounds measured in water, sediments, and biota to the levels required to induce acute or chronic effects in exposed aquatic life. Comparable data on exposure and effects from other countries were included, when available.