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The Ministers of Environment and Health have released for final publication the assessment report for the priority substance Butylbenzylphthalate. Notice concerning the assessment of this substance and a summary of its assessment report was published in the Canada Gazette, Part 1 February 5, 2000. The synopsis of the report is provided below.

A draft of this Assessment Report was made available for a 60-day public comment period (May 1, 1999 - June 29, 1999). Following consideration of the comments received, the Assessment Report was revised as appropriate. A summary of the comments and their responses may also be accessed from this page.

For paper copies of the Full Assessment Report, please contact the Inquiry Centre at Environment Canada:

To obtain an electronic version of the Assessment Report in PDF, please request a copy from the following address: ESB.DSE@ec.gc.ca<

Synopsis

Butylbenzylphthalate, also known as BBP, is used mainly as a plasticizer for polyvinyl chloride flooring and other materials. It is not manufactured in Canada, but about 4 kilotonnes are imported into the country per year. BBP is released into the environment from facilities that blend the substance with resins. Most releases of BBP appear to be to the atmosphere, but the substance has also been detected in industrial and municipal liquid effluents.

BBP is removed from the atmosphere by photooxidation and by rainwater, with a half-life of a few hours to a few days. It is not persistent in water, sediments or soil under aerobic conditions, with a half-life of a few days. Under anaerobic conditions, BBP is more persistent, with a half-life of a few months. BBP is readily metabolized by vertebrates and invertebrates. Reported bioconcentration factors are less than 1000, based on total residues, and well under 100, based on intact residues.

Monitoring data are available for BBP in Canadian air, water, sediments, soil, biota and food.

Data on acute and chronic toxicity were identified for aquatic algae, invertebrates and fish, but no information is available on the toxicity of BBP to benthic or soil organisms, terrestrial plants or wildlife. The Equilibrium Partitioning approach and data on toxicity of dibutyl phthalate were used as surrogates in this assessment when information on BBP was lacking.

Concentrations of BBP in all compartments of the Canadian environment are lower than the adverse effects thresholds estimated for sensitive organisms.

BBP is not likely to contribute significantly to depletion of stratospheric ozone, ground-level ozone formation or climate change.

Food and, to a lesser extent, indoor air appear to be the major sources of human exposure to BBP in Canada. Based upon results of a wide range of well-conducted studies in experimental animals, effects that occur at lowest concentrations in rats are increases in organ to body weight ratios, primarily for the liver and kidney, and histopathological effects on the pancreas and kidney. In studies with protocols specific for investigating reproductive toxicity, adverse effects on testes have been reported, although at dose levels higher than those that had effects on other organs, such as liver and kidney. Although results of available studies do not support the conclusion that BBP is estrogenic, the potential for other endocrine-mediated effects cannot be precluded at this time. On the basis of currently available data, the pancreas appears to be the most sensitive target for BBP-induced toxicity in laboratory animals. The estimated average daily and reasonable worst-case intakes of BBP by the general population in Canada from environmental sources are less than a Tolerable Intake derived on the basis of a benchmark dose for non-neoplastic pancreatic effects. A Tolerable Intake is the level of intake to which it is believed a person may be exposed daily over a lifetime without deleterious effect.

Based on information available, it is concluded that butylbenzylphthalate is not entering the environment in a quantity or concentration or under conditions having or that may have an immediate or long-term harmful effect on the environment, constituting or that may constitute a danger to the environment on which human life depends, constituting or that may constitute a danger in Canada to human life or health. Therefore, butylbenzylphthalate is not considered to be "toxic" as defined in Section 11 of the Canadian Environmental Protection Act (CEPA).

The evaluation of options under CEPA to reduce exposure to BBP is not considered to be a priority at this time. However, this is based upon current use patterns; thus, future releases of this compound should continue to be monitored to ensure that exposure does not increase to any significant extent. Phthalates, including butylbenzylphthalate, are also likely early candidates for testing for potential endocrine-disrupting effects when test protocols are finalized.

BBP may be emitted from building materials and is present in some consumer products. Better characterization of the significance of emissions from these sources is desirable.