Priority Substances List Assessment Report- 1,3-Butadiene

Environment Canada
Health Canada
2000
ISBN: 0-662-29014-3
Cat. No.: En 40-215/52E

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(720K)

Canadian Environmental Protection Act 1999

Table of Contents

• List of Acronyms and Abbreviations
• Synopsis
• 1.0 Introduction
• 2.0 Summary of Information Critical to Assessment of "Toxic" Under CEPA 1999
  • 2.1 Identity and Physical/Chemical Properties
  • 2.2 Entry Characterization
    • 2.2.1 Production and Uses
    • 2.2.2 Sources and Releases
      • 2.2.2.1 Natural Sources
      • 2.2.2.2 Anthropogenic Sources
  • 2.3 Exposure Characterization
    • 2.3.1 Environmental Fate
      • 2.3.1.1 Air
      • 2.3.1.2 Water
      • 2.3.1.3 Sediment
      • 2.3.1.4 Soil
      • 2.3.1.5 Biota
      • 2.3.1.6 Environmental Distribution
    • 2.3.2 Environmental Concentrations
      • 2.3.2.1 Ambient Air
      • 2.3.2.2 Indoor Air
      • 2.3.2.3 Surface Water
      • 2.3.2.4 Groundwater
      • 2.3.2.5 Drinking Water
      • 2.3.2.6 Soil and Sediment
      • 2.3.2.7 Food
      • 2.3.2.8 Consumer Products
  • 2.4 Effects Characterization
    • 2.4.1 Ecotoxicology
    • 2.4.2 Toxicokinetics and Metabolism
    • 2.4.3 Experimental Mammals and in vitro
      • 2.4.3.1 Acute Toxicity
      • 2.4.3.2 Short-term and SubchronicToxicity
      • 2.4.3.3 Chronic Toxicity and carcinogenicity
      • 2.4.3.4 Genotoxicity
      • 2.4.3.5 Reproductive and Developmental Toxicity
      • 2.4.3.6 Immunotoxicity
    • 2.4.4 Humans
      • 2.4.4.1 Clinical Studies
      • 2.4.4.2 Carcinogenicity
      • 2.4.4.3 Non-neoplastic Effects
      • 2.4.4.4 Genotoxicity
    • 2.4.5 Abiotic Atmospheric Effects
• 3.0 Assessment Of "Toxic" Under CEPA 1999
  • 3.1 CEPA 1999 64(a): Environment
    • 3.1.1 Assessment and Measurement Endpoints
      • 3.1.1.1 Aquatic
      • 3.1.1.2 Terrestrial
    • 3.1.2 Environmental Risk Characterization
      • 3.1.2.1 Aquatic Effects
      • 3.1.2.2 Terrestrial Effects
        • 3.1.2.2.1 Plants
        • 3.1.2.2.2 Soil Invertebrates
        • 3.1.2.2.3 Mammalian Wildlife
      • 3.1.2.3 Discussion of Uncertainty
  • 3.2 CEPA 1999 64(b): Environment Upon which Life Depends
  • 3.3 CEPA 1999 64(c): Human Health
    • 3.3.1 Estimated Population Exposure
    • 3.3.2 Hazard Characterization
      • 3.3.2.1 Weight of Evidence for Carcinogenicity and Genotoxicity
      • 3.3.2.2 Weight of Evidence for Non-neoplastic Effects
    • 3.3.3 Exposure-Response Analyses
      • 3.3.3.1 Carcinogenicity
        • 3.3.3.1.1 Estimated Potency Based on Epidemiological Data
        • 3.3.3.1.2 Estimated Potency Based on Data from Studies in Experimental Animals
      • 3.3.3.2 Non-neoplastic Effects
    • 3.3.4 Human Health Risk Characterization
    • 3.3.5 Uncertainties and Degree of Confidence in Human Health Risk Characterization
  • 3.4 Conclusions
  • 3.5 Considerations for Follow-up (Further Action)
• 4.0 References
• Appendix A Search Strategies Employed for Identification of Relevant Data

List Of Tables

• Table 1 - Chemical and Physical Properties of Butadiene
• Table 2 - Acute and Chronic Environmental Toxicity Values for Butadiene
• Table 3 - Incidences of Neoplastic Lesions in Critical Carcinogenicity Bioassays for Butadiene in Experimental Mammals
• Table 4 - Overview of Genotoxicity of Butadiene and its Metabolites in Rodents
• Table 5 Summary of Measures of Risk for Cancers of the Lymphohematopoietic System in Populations Occupationally Exposed to Butadiene
• Table 6 Summary of Risk Quotients for Environmental Assessment of Butadiene
• Table 7 Stratification Variables for Exposure-response Modelling of Epidemiological Data from Delzell et al. (1995)
• Table 8 Parameter Estimates and Model Deviances for each of Four Models Fitted to Mean Cumulative Exposure per Person-year for Delzell et al. (1995) Study and Comparison to Parameter Estimates from Delzell et al. analyses
• Table 9 Carcinogenic Potency Estimates (TC₀₁s) for Models Fitted to Mean Cumulative Exposure per Person-year Based on Delzell et al. (1995) Study and Comparison to Estimates from Delzell et al. Analyses
• Table 10 Parameter Estimates and Model Deviances for each of Four Lagged-Exposure Models Fitted to Median Cumulative Exposure per Person-year
• Table 11 Model Validation P-values for Delzell et al. (1995) study
• Table 12 Carcinogenic Potency Estimates (TC₀₅s) of Butadiene Based on Results of Bioassays in Experimental Animals
• Table 13 Incidence and Severity of Ovarian Atrophy Observed in 2-year Bioassay in Mice
• Table 14 Benchmark Concentrations for Ovarian Atrophy

List Of Figures

• Figure 1 - Proposed Metabolism of Butadiene in Mammals
• Figure 2 - Observed Rate Ratios and Fitted Curves for Leukemia in Delzell et al. (1995) Study
• Figure 3 - Exposure-response Analysis for Butadiene-induced Tumours in Mice
• Figure 4 - Exposure-response Analysis for Butadiene-induced Tumours in Rats
• Figure 5 - Exposure-response Analysis for Ovarian Atrophy in Mice
• Figure 6 - Exposure-response Analysis for Ovarian Atrophy in Mice, Excluding Two Highest Dose Groups
• Figure 7 - Exposure-response Analysis for Moderate/marked Ovarian Atrophy
• Figure 8 - Exposure-response Analysis for Moderate/marked Ovarian Atrophy, Excluding High-dose Group