Screening assessment on MBMBP phenols: chapter 2

Introduction

Screening assessments focus on information critical to determining whether a substance meets the criteria for defining a chemical as toxic as set out in section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999) (Canada 1999). Screening assessments examine scientific information and develop conclusions by incorporating a weight-of-evidence approach and precaution.

A screening assessment was undertaken on Phenol, 2,2'-methylenebis[6-(1,1-dimethylethyl)-4- (MBMBP; CAS RN 119-47-1) on the basis that this compound was included in the Domestic Substances List (DSL) pilot project for screening assessment as a substance likely to be prioritized because it met the criteria for persistence and/or bioaccumulation and inherent toxicity to non-human organisms.

This screening assessment includes consideration of information on chemical properties, hazards, uses and exposure. Data relevant to the screening assessment of this substance were identified in original literature, review and assessment documents, stakeholder research reports, and from recent literature searches, up to January 2004 for ecological sections of the document and July 2003 for human health sections of the document. In addition, an industry survey was conducted in 2000 through a Canada Gazette notice issued under authority of section 71 of CEPA 1999. This survey collected data on the Canadian manufacture and import of the DSL pilot project substances (Canada 2001). Key studies were critically evaluated.

The approach taken in the ecological screening assessment is to examine various supporting information and develop conclusions based on a weight-of-evidence approach as required under section 76.1 of CEPA 1999. The screening assessment does not present an exhaustive or critical review of all available data. Rather, it presents the critical studies and lines of evidence pertinent to the conclusion.

Evaluation of risk to human health involves consideration of data relevant to estimation of exposure (non-occupational) of the general population, as well as information on health hazards. Decisions for human health are based on the nature of the critical effect and/or margins between conservative effect levels and estimates of exposure, taking into account confidence in the completeness of the identified databases on both exposure and effects, within a screening context. The screening assessment does not represent an exhaustive or critical review of all available data. Rather, it presents a summary of the critical information upon which the conclusion is based.

This screening assessment was prepared by staff in the Existing Substances programs at Health Canada and Environment Canada. The substance matter in this report pertaining to ecological aspects has been subjected to external review. The State of the Science Report for a Screening Health Assessment was reviewed externally by V.C. Armstrong (Consultant), P. Price (The Lifeline Group Inc), and staff of Toxicology Advice and Consulting Limited and Toxicology Excellence in Risk Assessment. While external comments were taken into consideration, the final content and outcome of the screening risk assessment remain the responsibility of Health Canada and Environment Canada. Additionally, the draft of this screening assessment was subject to a 60-day public comment period from June 23, 2007, to August 22, 2007. The State of the Science Report for a Screening Health Assessment has been posted on the Health Canada website since January 30, 2006, and the draft ecological screening assessment has been posted on the Environment Canada website since July 2006.

Information on ecological screening assessments under CEPA 1999 is available on the Evaluating Existing Substances website.

The critical information and considerations upon which the assessment is based are summarized below.