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Vertical and temporal variations of acid-volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediment can control biological impacts of metals. To assess the significance of these variations in field sediments, sediments spiked with cadmium, copper, lead, nickel, and zinc were deployed in Narragansett Bay for four months and recolonization by benthic organisms investigated. In surface sediments, concentrations of AVS decreased with time whenever AVS exceeded SEM but remained unchanged when AVS was less than SEM; in subsurface sediments, concentrations increased slightly. Concentrations of total SEM decreased with time only in surface sediments in which SEM exceeded AVS. Metals were not detected in interstitial waters of sediments where AVS exceeded SEM but were significant when SEM exceeded AVS and followed the order of solubilities of their sulfides. Concentrations in interstitial waters decreased with time, but exceeded U.S. Environmental Protection Agency chronic water quality criteria for 56 to 119 d. After 119 d, faunal assemblages in all treatments were similar to controls. Lack of biological response was related to vertical distributions of AVS and SEM. Biological exposure took place in near-surface sediments, where AVS exceeded SEM in even the highest treatments. Therefore, concentrations of metals in interstitial waters were low and consequently biological impacts were undetectable.

The Canadian Cancer Incidence Atlas is among recent national atlases using incidence rather than mortality data. Methods used to assess the significance and spatial correlation of the age-standardized rates (ASIRs) for the 290 census divisions are described. The expected number of cases by area was used to determine cancer sites with sufficient cases to be mapped. ASIR significance was assessed using a simulation based on a Poisson distribution. The consistency of the observed case distributions with the Poisson distribution was examined. The bootstrap confidence interval (CI) for the ASIR developed by Swift was used in the atlas. Spatial correlation was assessed with Moran's I/I(max) and the significance determined by a simulation in order to allow for area population variation. Data quality indicators typically used for cancer registries were presented, supplemented by a registry questionnaire., (Copyright 2000 John Wiley & Sons, Ltd.)

Accurate and complete registries are an important source of knowledge about cancer. The concordance of the recording of neoplasms in the Saskatchewan cancer registry with that in hospital charts and death registrations was evaluated for 368 patients. The agreement between registry and hospital charts or death registrations was excellent (kappa: 0.93; 95% confidence interval: 0.89, 0.97), with 91.3% of those with cancer having the same neoplasm recorded in their chart or death registration as in the registry. There was only one patient whose hospital chart indicated cancer who was not in the registry and one apparent major discrepancy relating to the cancer site, which was due to the recording of the primary site in the registry and a secondary in the hospital chart. Although based on a relatively small number of patients, these results suggest a high degree of consistency between cancer registry, hospital charts and death registrations in Saskatchewan.

The in vitro V79/metabolic cooperation assay measures the extent of gap-junctional transfer of metabolites from wild-type to mutant V79 cells. The assay is currently being explored as a short-term test to screen for tumor promoting chemicals, many of which inhibit metabolic cooperation. In this study, the assay was used to determine whether chemical interactions affect detection of tumor promoters in mixtures and to investigate types of interactions that may occur between chemicals. Several two-chemical mixtures were examined. The effects of phorbol-12-myristate-13-acetate (PMA) and phorbol-12,13-dibutyrate, two inhibitors of metabolic cooperation that operate through the same receptor-mediated pathway, were additive at concentrations below the maximally effective concentrations of either. A summation effect was observed in mixtures of two other inhibitors of metabolic cooperation, the pesticide aldrin and the principal metabolite of sodium cyclamate, cyclohexylamine. Synergistic effects were noted when PMA was combined with either aldrin or cyclohexylamine, demonstrating that chemicals in a mixture may yield a much stronger response than expected based on individual chemical exposures. Interactions were also examined between PMA, aldrin, cyclohexylamine and 2,4-diaminotoluene, a chemical that appears to enhance metabolic cooperation. 2,4-Diaminotoluene reversed effects of all inhibiting chemicals to some extent, although the pattern of response was different for each combination. In the most dramatic case, the powerful tumor promoter PMA was completely masked by 2,4-diaminotoluene. These results suggest that the V79/metabolic cooperation assay must be applied with caution in mixture testing because detection of tumor promoting chemicals can depend on other chemicals present.

The amount of pituitary PRL detected by RIA in extracts of tissue and of secretory granules was augmented by thiols or EDTA in the extractant, and diminished by divalent cations or cysteamine. GH was affected by thiols and cations similarly, but to a lesser extent, and was not influenced by EDTA or cysteamine. For full immunologic detection of tissue PRL and GH, thiol-dependent mechanisms appear to be required to unmask immunoreactive sites from the poorly immunoreactive oligomeric granule storage forms. Interpretation of studies which rely on measurement of tissue PRL and GH content by RIA, immunoprecipitation, or electrophoretic detection should be reassessed in light of these observations.