Canadian mercury inventories: the missing pieces.

Research was conducted to determine the significance of the deliberate use of mercury in products in Canada and the associated releases from these sources. Through a combination of literature review and new calculations, the reservoir, flux, and releases of mercury from eight product sources were calculated, and these results compared to historical Canadian inventories. Mercury contributions from the waste sector were also assessed and compared to total Canadian mercury releases and to mercury releases from coal-fired generating stations. Results suggest the use and release of mercury associated with release of mercury associated with its use in products is 4.5 times what previous inventories indicate. Including dental amalgam and sewage sludge, the total releases of mercury to all environmental compartments in Canada totals 20 tonnes per year. This accounts for less than one-half of the 44 tonnes per year of mercury released from mercury waste disposal each year in Canada. Waste mercury contributions from hazardous waste imports, unknown product sources, and incomplete information on the use of mercury in known products may account for this discrepancy. Waste-related mercury releases and transfers for disposal and recycling are 11 times greater than that of electricity generation in Canada. Results indicate that Canadian inventories have underestimated the significance of mercury use and release associated with products, calling into question the current priorities for mercury management. This paper was developed as part of a panel session at the International Joint Commission "Mercury in the Ecosystem" workshop, February 26-27, 2003, Windsor, ON, Canada, as a complement to the information on Canadian Inventories presented by Luke Trip (Senes Consulting, Ottawa, ON, Canada).

Experience with electron microscopy in the differential diagnosis of smallpox.

The usefulness of negative-contrast electron microscopy in the rapid differential diagnosis of poxvirus and herpesvirus exanthems is described in this study of 301 specimens from patients with vesicular exanthematous diseases. Specimens from patients with smallpox, various forms of vaccination complications, varicella, zoster (shingles), and herpes simplex are included in this evaluation. Electron microscopy, when applied to the study of lesion material, was found to be more sensitive than the classical techniques of virus isolation in the diagnosis of both poxvirus and herpes/varicella virus infections. However, since specific identification of a virus within a group cannot be made morphologically by electron microscopy, it is recommended that both electron microscopy and virus isolation methods be employed for the routine differential diagnosis of vesicular exanthematous diseases in the reference diagnostic laboratory.

Isolation of poxvirus from an African Rodent.

A poxvirus was isolated from a wild gerbil (Tatera kempii) caught in northern Dahomey, Africa at the time of an epidemic of human smallpox. Electron microscopic appearance and serologic reactions placed it in the vaccinia subgroup of poxviruses. The isolate differed from ectromelia, rabbitpox, vaccinia, monkeypox, and cowpox viruses in pock morphology on chorioallantoic membrane, ceiling temperature, relative innocuity for mice, and cytopathic effect in tissue culture. Like variola minor virus, it had a ceiling temperature of 38 C, produced small hypertrophic foci in tissue culture, and failed to grow in rabbit skin. Inoculated into a rhesus monkey, it caused fever but no skin eruption and produced seroconversion and protection from subsequent challenge with monkeypox virus. The growing list of animal viruses that differ only slightly from smallpox virus suggests the hypothesis that long-term survival of variola virus may be based on inapparent infection in animals as well as virulent spread among humans.

Evaluation of two kinds of smallpox vaccine: CVI-78 and calf lymph vaccine. I. Clinical and serologic response to primary vaccination.

A comparative study of two smallpox vaccines, standard calf lymph vaccine, and an attenuated vaccine, CVI-78, was performed in 95 children. Primary vaccination with CVI-78 resulted in a more attenuated response than primary vaccination with standard vaccine. Sixty-one percent of those vaccinated with CVI-78 and 96 percent of those vaccinated with standard vaccine developed a major dermal reaction; 16 percent of those vaccinated with CVI-78 and 89 percent of those vaccinated with standard vaccine developed post-vaccination neutralizing antibodies. Twenty-seven percent of the children vaccinated with CVI-78 demonstrated neither a dermal nor serologic postvaccination response, whereas only 2 percent of those vaccinated with standard vaccination demonstrated no postvaccination response.

Evaluation of two kinds of smallpox vaccine: CVI-78 and calf lymph vaccine. II. Clinical and serologic observations of response to revaccination with calf lymph vaccine.

Revaccination with standard calf lymph vaccine was performed on 26 children who had received a primary vaccination with an attenuated smallpox vaccine, CVI-78, and 22 children who had received primary vaccination with standard calf lymph. Revaccination resulted in a vesicular reaction in 96 percent of those who had been vaccinated previously with CVI-78 and 73 percent of those vaccinated previously with standard calf lymph. All children had a positive hemagglutination-inhibition (HI) antibody titer either after primary vaccination or revaccination. Only 65 percent of those initially vaccinated with CVI-78 vaccine had positive neutralizing antibodies after revaccination. All children who received primary vaccination with standard calf lymph had postrevaccination neutralizing antibodies. The children who had neither a dermal nor a serologic response after primary vaccination responded as primary vaccinees on challenge with standard calf lymph.

Human infection with monkeypox virus: laboratory investigation of six cases in West Africa.

Between September 1970 and May 1971 six cases of human infection with monkeypox virus were identified in three West African countries-Liberia, Sierra Leone, and Nigeria. Four of the cases were confirmed by viral isolation, and two were diagnosed on epidemiological and serological evidence. Poxvirus strains isolated from the four cases were indistinguishable from reference monkeypox strains (Copenhagen and Utrecht), and all were easily differentiated from variola and vaccinia viruses. The isolated strains produced small necrotic haemorrhagic pocks on CAM, grew well at 39.0 degrees C, formed large plaques in Vero cell cultures, showed markedly more virulence for chick embryos and mice than do variola strains, and produced large necrotic haemorrhagic local lesions with generalized illness and florid secondary exanthem when inoculated into rabbit skin.The finding of smallpox-like illness in humans resulting from infection with a poxvirus of lower animal origin serves to emphasize the importance of thorough epidemiological and laboratory evaluation of all suspect smallpox cases occurring in areas where smallpox has been or is about to be eradicated.

Simultaneous administration of smallpox, measles, yellow fever, and diphtheria-pertussis-tetanus antigens to Nigerian children.

Children receiving smallpox, measles, and yellow fever vaccines simultaneously at separate sites responded adequately to all three vaccines. In those children, 9 months of age and older, who received these three vaccines in addition to diphtheria-pertussis-tetanus vaccine, there was a decrease in measles seroconversion rates from 89% to 70%. Possible interactions between live and killed vaccines should be considered when the administration of multiple antigens is planned.

Human monkeypox.

Between October 1970 and May 1971, six cases of human infection with monkeypox virus were identified in Liberia, Nigeria, and Sierra Leone. Four of the cases were confirmed by virus isolation and two were diagnosed on the basis of epidemiological and serological investigations. All the cases occurred in unvaccinated individuals.Post-infection serological studies showed high haemagglutination-inhibition and neutralizing titres to pox group virus in four of the cases. Repeated challenge vaccination of all cases with potent smallpox vaccine resulted in equivocal reactions.In all, 24 susceptible household contacts were exposed to the infected cases, but none developed disease. All the contacts subsequently responded to vaccination with a primary reaction, thus confirming their susceptibility and ruling out asymptomatic infection.