The Secretariat gave an update on the development of the guideline document for benzene. Members discussed the peer review comments, exposure assumptions, NSF standards, detection limits, and one-time incidents versus long term exposure. Members agreed that it would be good for the consultation document to include information on the differences in health risks between guideline values of 1 and 5 µg/L.
The draft guideline technical document will go to peer review soon. The science sections of the document have been updated since the chemical is now classified as possibly carcinogenic to humans. The guideline will likely remain at 5 µg/L.
The Secretariat updated the committee on the new chlorine guideline document. Members discussed concerns with chlorine, particularly high doses resulting from operational failures, the effectiveness of chlorine disinfection with changes to pH and temperature, and the recommended chlorine residual levels. No impact paragraphs are required from members because there is no guideline statement.
The Secretariat gave a presentation on the status of the radiological guidelines document. Members discussed the screening process recommended in the document. Nova Scotia noted major concerns with this process that will need to be addressed prior to approval.
The Secretariat gave an update on the development process for this guideline. An expert committee is looking at this guideline and will be meeting in the new year. The committee noted receipt of a letter from K.Millership through the Secretariat and reviewed and approved a proposed draft response.
The Secretariat gave a presentation on the draft chlorite/chlorate document. Members discussed whether chlorine dioxide should be included in the title.
Some forms of nitrogen have been listed as a possible human carcinogen, which could be an issue with nitrate-nitrite.
Microcystin-LR has been listed as a possible human carcinogen.
PMRA has provided information on pesticide availability and use. In some cases the data are related to drinking water.
The member from Alberta raised the issue of a small exceedence of BDCM in the province. Authorities reacted by distributing point-of-use devices to consumers because the guideline is based on single exceedence. Members discussed changing the guideline to base it on an average rather than a single exceedence and decided that what was needed was actually better risk communication tools.
Members received the draft document. Quebec noted concerns about the feasibility of implementation and suggested modifications for consideration.
The Secretariat requested monitoring data for iodinated by-products.
Consultations on the MCPA guideline will start in late November and end on January 23, 2007. The consultations for potassium and chlorate hydrate will follow.
Members discussed the use of hydrogen peroxide as a disinfectant and cleaning agent. Members noted occupational health and safety concerns with handling the chemical.