The Canadian Environmental Protection Act (CEPA) authorizes the Ministers of the Environment and of Health in Canada to investigate a wide variety of substances that may contaminate the environment and cause adverse effects on the environment and/or on human health. Under the Act, assessments have been completed for 44 environmental contaminants on the first Priority Substances List, including four metals and their compounds. The principles developed for the assessment of risk to human health for priority substances under CEPA are outlined, with specific emphasis on the metals. These include general aspects such as estimation of total exposure from all media, the development of exposure potency indices for carcinogens in lieu of low-dose risk estimates, and incorporation of toxicokinetic and toxicodynamic data, where available, to modify traditionally adopted uncertainty factors for development of tolerable intakes, or concentrations, for nonneoplastic effects. Aspects of the approach to human health risk assessment more specific to the metals considered under CEPA (i.e., arsenic, cadmium, chromium, and nickel) and implications for the subsequent strategic options process are also addressed, including the extent to which various chemical forms could be assessed (i.e., speciation) and essentiality.
Native Hawaiian women in Hawai'i suffer the highest breast cancer incidence and death rates among women from Hawai'i's five major ethnic groups. Native Hawaiian women have the third highest breast cancer mortality rate in the nation, following African American and Native American/Alaska Native women. While overall cancer mortality rates in other U.S. populations have improved, epidemiological research shows mortality rates among Native Hawaiians has dramatically increased since 1976. Several barriers prevent Native Hawaiian entry into health care. Frequently cited barriers are: a history of oppression; high prevalence of behavioral risk factors; ineffective screening, prevention and treatment efforts; poor utilization of existing services; poor financial and geographical access to care; an absence of culturally appropriate programs, and few Native Hawaiian health professionals. To address poor health service utilization and to sensitize the health care system in Hawai'i, the Native Hawaiian Breast Cancer Sub-Committee (NHBCSC) of the American Cancer Society Hawai'i Pacific, developed and implemented a culturally based training for health professionals. The training is designed to meet continuing medical and professional education requirements. Professional in-service training began in 2001, with over 300 of Hawai'i's health care professionals participating, to date (March 2004). This training provides a model for other cultural and ethnic groups.
Postoperative length of stay (LOS) may be affected by more intensive physical therapy following surgery. This study was designed to assess whether LOS could be affected by weekend physical therapy following surgery in patients who had undergone total hip arthroplasty (THA) or total knee arthroplasty (TKA). Weekend coverage for these patients was made possible by increased staffing in the Physical Therapy Department. The study group consisted of 84 patients who had undergone THA or TKA and had physical therapy treatment the weekend following surgery. The Control group consisted of 53 patients who had undergone THA or TKA prior to the implementation of the weekend intervention program. A retrospective chart audit was used to obtain pertinent information about control group patients. In the total sample mean LOS following weekend therapy (10.84 days) was significantly different (p
A precedent setting legislative mandate under the Canadian Environmental Protection Act 1999 to establish priorities for assessment based on systematic consideration of all of the approximately 23,000 Existing Chemicals in Canada required the development and refinement of methodology in a number of important areas. This included development of simple and complex exposure and hazard tools for priority setting which draw maximally and efficiently on available data to systematically identify substances that are highest priorities in relation to their potential to cause adverse effects on the general population. The hierarchical approach in the simple and complex hazard tools described here efficiently and effectively sets substances aside as non-priorities, or prioritizes them for consideration additionally in assessment. The hazard tools efficiently incorporate previous work, contributing to consistency internationally, and involve hierarchical consideration of sources of information based on their relative weighting. They are health protective, based on their incorporated degree of conservatism, and provide direction for additional assessment for substances deemed to be priorities. Although designed for prioritization of Existing Substances in Canada, these tools have potential for broader application in other national and international programs to provide focus and increase efficiency in human health risk assessment.
1,3-Butadiene was included in the second list of Priority Substances to be assessed under the Canadian Environmental Protection Act. Potential hazards to human health were characterized on the basis of critical examination of available data on health effects in experimental animals and occupationally exposed human populations, as well as information on mode of action. Based on consideration of all relevant data identified as of April 1998, butadiene was considered highly likely to be carcinogenic to humans, and likely to be a somatic and germ cell genotoxicant in humans. In addition, butadiene may also be a reproductive toxicant in humans. Estimates of the potency of butadiene to induce these effects have been derived on the basis of quantitation of observed exposure-response relationships for the purposes of characterization of risk to the general population in Canada exposed to butadiene in the ambient environment.
1,3-Butadiene has been assessed as a Priority Substance under the Canadian Environmental Protection Act. The general population in Canada is exposed to 1,3-butadiene primarily through ambient air. Inhaled 1,3-butadiene is carcinogenic in both mice and rats, inducing tumors at multiple sites at all concentrations tested in all identified studies. In addition, 1,3-butadiene is genotoxic in both somatic and germ cells of rodents. It also induces adverse effects in the reproductive organs of female mice at relatively low concentrations. The greater sensitivity in mice than in rats to induction of these effects by 1,3-butadiene is likely related to species differences in metabolism to active epoxide metabolites. Exposure to 1,3-butadiene in the occupational environment has been associated with the induction of leukemia; there is also some limited evidence that 1,3-butadiene is genotoxic in exposed workers. Therefore, in view of the weight of evidence of available epidemiological and toxicological data, 1,3-butadiene is considered highly likely to be carcinogenic, and likely to be genotoxic, in humans. Estimates of the potency of butadiene to induce cancer have been derived on the basis of both epidemiological investigation and bioassays in mice and rats. Potencies to induce ovarian effects have been estimated on the basis of studies in mice. Uncertainties have been delineated, and, while there are clear species differences in metabolism, estimates of potency to induce effects are considered justifiably conservative in view of the likely variability in metabolism across the population related to genetic polymorphism for enzymes for the critical metabolic pathway.
Because metals occur in various forms in the environment, speciation is an issue which must be addressed in regulatory health risk assessment programs. The manner in which speciation was addressed in a federal program in Canada is discussed in this article. Under the Canadian Environmental Protection Act, four metals, including arsenic, cadmium, chromium, and nickel, and their compounds were assessed as priority substances to determine the risk to human health associated with exposure to levels present in the general environment in Canada. The extent to which the speciation of these metals could be considered in these assessments was largely determined by the nature of available data. Very few data were identified on speciation in environmental media to which humans are exposed. Based on available data on health effects, it was possible to conduct assessments on only one form each of arsenic and cadmium (i.e., inorganic arsenic and inorganic cadmium), two forms of chromium (trivalent and hexavalent), and four forms of inorganic nickel (oxidic, sulfidic, soluble, and metallic.
To review and assess published findings from relevant cancer research studies in Native Hawaiians and other Pacific Islanders and to develop strategies for designing and implementing successful cancer research studies in the future.
Data were collected primarily from MEDLINE and BIOSIS Preview searches of the English literature during a 30-year period for published reports of cancer surveillance studies and epidemiological and clinical cancer studies in the Native Hawaiian and Pacific Islander populations. The cancer burden was critically assessed in the retrieved citations for each of the indigenous groups from Hawai'i, American Samoa, Guam, Commonwealth of the Northern Mariana Islands, Federated States of Micronesia, Republic of Palau, and the Republic of the Marshall Islands.
A review of the published literature revealed a lack of systematic data collection on cancer incidence and mortality in Pacific Islanders. Wide variations were found regarding the status of cancer research among ethnic groups. It is estimated that Native Hawaiians represent 0.1% of subjects accrued to cancer prevention trials, and that Pacific Islanders represent 0.5% of subjects in a large cancer screening trial.
The paucity of cancer data and clinical cancer research supports the need for increased attention to these indigenous populations to improve the quality of cancer care in Native Hawaiian and Pacific Island communities.
We analyzed tree rings in wood samples collected from some of the few surviving trees found close to the epicenter (within 4-5 km) of the Tunguska event that occurred on the last day of June 1908. Tree-ring growth shows a depression starting in the year after the event and continuing during a 4-5-year period. The most remarkable traces of the event were found in the rings' anatomical structure: (1) formation of "light" rings and a reduction of maximum density in 1908; (2) non-thickened tracheids (the cells that make up most of the wood volume) in the transition and latewood zones (the middle and last-formed parts of the ring, respectively); and (3) deformed tracheids, which are located on the 1908 annual ring outer boundary. In the majority of samples, normal earlywood and latewood tracheids were formed in all annual rings after 1908. The observed anomalies in wood anatomy suggest two main impacts of the Tunguska event on surviving trees--(1) defoliation and (2) direct mechanical stress on active xylem tissue. The mechanical stress needed to fell trees is less than the stress needed to cause the deformation of differentiating tracheids observed in trees close to the epicenter. In order to resolve this apparent contradiction, work is suggested on possible topographic modification of the overpressure experienced by these trees, as is an experimental test of the effects of such stresses on precisely analogous growing trees.
Migration has become a profound global phenomenon in this century. In Canada, uncoordinated policies, including those related to immigration, resettlement, employment, and government funding for health and social services, present barriers to immigrant women caregivers. The purpose of this paper is to share relevant insights from individual and group interviews with immigrant women family caregivers, service providers and policy influencers, and discuss these in relation to immigration, health and social policy, and programme trends in Canada. The present authors conducted individual interviews with immigrant women family caregivers (n = 29) in phase 1, followed by two group interviews with women family caregivers (n = 7), and two group interviews with service providers and policy-makers (n = 15) in phase 2. Using an inductive approach, the authors employed thematic content data analysis. Immigrant women experienced barriers to health and social services similar to Canadian-born family caregivers, particularly those who have low incomes, jobs with limited flexibility and heavy caregiving demands. These immigrant women family caregivers avoided certain formal services for a variety of reasons, including lack of cultural sensitivity. However, their challenges were compounded by language, immigration and separation from family in the home country. The identified barriers to support reinforce the importance of modifying and expanding policies and programmes affecting immigrant women's ability to care for family members with illnesses or disabilities within the context of Canadian society. Participants recommended changes to policies and programmes to deal with information, transportation, language, attitudinal and network barriers. The various barriers to services and programmes which were experienced by immigrant women caregivers underscore the importance of reviewing policies affecting immigration, caregiving, and access to health and social services. Intersectoral collaboration among agencies is essential to reduce the barriers identified in the present study, and to establish services which are linguistically and culturally appropriate.