Human health risk estimates for sites with contaminated soils are often based on the assumption that the outdoor soil sieved to In vitro bioaccessibility tests are also increasingly used to "improve ingestion exposure predictions of contaminants at different sites. However, when considered in terms of factors that influence desorption of contaminants from particles and uptake into humans, available studies indicate that current "standards of practice with respect to assays of oral bioaccessibility have a number of significant shortcomings, at least in Canada. These shortcomings are discussed and various factors that influence the assessment of bioaccessibility of contaminants in soils are examined. We finish with proposing some minimum data submission requirements to support the application and relevance of bioaccessibility assays at contaminated sites.

Human health risk estimates for sites with contaminated soils are often based on the assumption that the bulk concentration of substances in outdoor soil samples is a reasonable predictor of exposures via incidental soil ingestion, soil particle inhalation, and dermal absorption. Most underlying conceptual models are grossly simplistic, however, when considered in light of (i) biases in the distribution of contaminants across soil particle sizes, (ii) the size range of particles in soils and dusts that is environmentally available, and (iii) factors that influence desorption from particles and uptake into humans. The available studies indicate that contaminant distribution across soil particle size fractions varies widely between different soil types and contaminant delivery mechanisms, and it cannot be assumed that higher masses of contaminants per unit mass of soil are correlated with smaller particles sizes. Soil data gathered in support of detailed human health risk assessments, therefore, should allow for the examination of distribution across particle sizes of contaminants of concern, and consider those size fractions most critical to human exposure. Soil evaluations for health risk assessments of metals/metalloids should also consider mineralogical characterization.

This study examines the potential for environmental risks due to organic contaminants at sewage sludge application sites, and documents metals and various potential organic contaminants (volatile organics, chlorinated pesticides, PCBs, dioxins/furans, extractable petroleum hydrocarbons, PAHs, phenols, and others) in current production biosolids from five wastewater treatment plants (WWTPs) within the Greater Vancouver Regional District (GVRD). There has been greater focus in Europe, North America and elsewhere on metals accumulation in biosolids-amended soil than on organic substances, with the exception of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. Another objective, therefore, was to evaluate the extent to which management of biosolids re-use based on metal/metalloid levels coincidentally minimizes environmental risks from organic contaminants. Historical-use contaminants Such as chlorophenols, PCBs, and chlorinated pesticides were not detected at environmentally relevant concentrations in any of the 36 fresh biosolids samples, and appear to have virtually eliminated from sanitary collection system inputs. The few organic contaminants found in freshly produced biosolids samples that exhibited high concentrations relative to British Columbia and Canadian soil quality benchmarks included p-cresol, phenol, phenanthrene, pyrene, naphthalene, and heavy extractable petroleum hydrocarbons (HEPHs-nCl9-C34 effective carbon chain length). It was concluded that, with the exception of these petroleum hydrocarbon constituents or their microbial metabolites, the mixing of biosolids with uncontaminated soils during land application and based on the known metal concentrations in biosolids from the Greater Vancouver WWTPs investigated provides adequate protection against the environmental risks associated with organic substances such as dioxins and furans, phthalate esters. or volatile organics. Unlike many other organic contaminants, the concentrations of petroleum hydrocarbon derived substances in biosolids has not decreased within the last decade or more in the WWTPs studied, and-unlike persistent chlorinated compounds-the associated PAHs and other hydrocarbon constituents merit careful consideration, especially in the context of repeated land-application of biosolids.

A scientific review was conducted of studies published since 1993 to assess the ecological risks associated with final effluents from pulp mills using 100% ClO2 in bleaching processes. AU available data indicate that chlorinated compounds in effluents from pulp mills that employ 100% ClO2 bleaching are of very limited persistence and not strongly bioaccumulative. Chlorinated compound concentrations in final effluent (following secondary treatment) comprise a negligible risk to aquatic organisms in comparison with the known toxicological thresholds.

Multivariate pattern analysis techniques, principal components analysis, and polytopic vector analysis (PVA) were used to apportion sources of dioxins and furans to Howe Sound and the lower Strait of Georgia marine ecosystem, British Columbia, Canada, based on deposition in recent sediments. In sediment cores collected in 1990, differences between congeners in the depth of maximum concentration suggested the influence over time of several different sources. Those with a predominance of hexachlorinated dibenzodioxins and 2,3,7,8-tetrachlorodibenzofuran comprised one of the major contributions to the sediment core samples and surficial samples collected from Howe Sound, consistent with past inputs of pulpmill effluent. For most sediment samples, however, over 50% of the composition was attributable to a separate source with octachlorodibenzo-p-dioxin (OCDD) as the dominant congener, followed by heptachlorodibenzo-p-dioxins with small amounts of heprachlorodibenzofuran and octachlorodibenzofuran (OCDF). This source signature is consistent with the composition of dioxins/furans in formulations of pentachlorophenol-based wood preservatives, which were used extensively in British Columbia, Canada prior to the mid-1980s. This major input signature to the greater Strait of Georgia cannot be unequivocally ascribed to PCP use and disposal, however, since several other dioxin/furan sources also exhibit a highly similar composition, one dominated by OCDD. For example, source signatures similar to PCP formulations include those from diesel emissions, coal combustion, municipal solid waste, or other incineration stack emissions (fly ash, in particular), chimney soot from oil central heating, black-liquor recovery furnace flue gas, and scrap wire and car incineration. Further research is required to discriminate among the OCDD-containing sources and, hence, provide for improved future source management.

PCB and PCDD/F analysis carried out during assessments of abandoned military sites in the Canadian North allowed an opportunity to test the utility of multivariate statistical techniques in the assignment of source signatures to contaminated soil samples. A combination of principal component analysis (PCA) and polytopic vector analysis (PVA) was used to assess the inputs of PCDD/Fs to soils along with source signatures obtained from the literature. The composition of background samples obtained at least 20 km from any local source contamination showed a clear correlation with combustion sources. Soil samples taken in the vicinity of the military sites showed evidence of PCDD/F contamination associated with the extensive use and spillage of PCBs in transformer fluids and the use of chlorophenols as wood preservatives. There was evidence that significant changes in signature occur with distance from the source. The results of the statistical analysis in assigning source signatures agreed well with field observations.

A series of subArctic lakes near Yellowknife, Northwest Territories, Canada, are contaminated with arsenic released from a gold mine. The high environmental arsenic levels afforded an opportunity to identify factors that control methylarsenical production in freshwater sediments. A large variety of methylated arsenicals were observed in most pore water and water column samples from lakes contaminated by aqueous or atmospheric arsenic inputs, albeit at low concentrations relative to inorganic arsenic (generally less than 10% of the total dissolved arsenic concentration). Biologically-mediated methylation/demethylation reactions, therefore, may influence the local arsenic cycle. Water column samples exhibited a consistent methylarsenic composition in which the dominant form was dimethylarsonic acid, followed by monomethylarsinic acid. A much broader range of mono-, di- and trimethylated arsenicals was found in sediment pore water, and the composition of methylarsenic species was highly variable both within and between cores. We provide indirect evidence that many samples contained mono-, di-, and trimethylated arsenic(III)thiols, of the form (CH3)nAsIII(SR)3−n (n = 1, 2, 3), the existence of which has been predicted but not previously demonstrated in the environment. The total dissolved methylarsenic concentration in cores consistently exhibited a subsurface maxima between 5 and 15 cm depth, which suggests—in conjunction with the presence of other metabolites in pore water —that methylation may be enhanced by sulfate-reducing bacteria. The role of sulfate-reducers in the production of methylarsenicals observed in sediment pore water is also supported by co-variations with depth between the concentration of methylarsenic species and iron dissolution or other chemical distributions attributed to metabolism by heterotrophic bacteria across different redox zones. Many samples contained appreciable concentrations of arsenicals the specific identity of which are presently unknown, and some of which are ‘hidden’ to conventional hydride-generation analyses. At least one unidentified arsenical found in lake water and sediment pore water appears to have been produced directly or indirectly from atmospheric emissions from the gold mine. The occurrence of methylated arsenicals and hidden arsenic at concentrations that comprise a substantial portion of the total arsenic budget in some aquatic systems suggests that current models of lacustrine arsenic cycling that incorporate only inorganic arsenicals need to be revisited.

The results of a PCB weathering experiment (i.e., losses from soil and changes in PCB composition from soil over time) at Cambridge Bay, Northwest Territories, in the Canadian Arctic are presented. Nine plots representing three different general substrate types (dry barren, dry moss, and wet grass) were treated with three different PCB Aroclor formulations (1254, 1260, and a 1:1 mixture). Soil and plant samples were collected annually over a 5-year period and analyzed for individual PCB congeners. The results showed a high degree of variability between treatments that was ascribed to the presence of vegetation as well as non-homogenous PCB application and/or soil heterogeneity (e.g., biomass, organic carbon, and moisture content) within individual plots. Where readily interpretable data were available, the first-order rate constant for the loss of PCBs from the substrate was calculated to be approximately 0.5 yr(-1) (t(1/2) = 1.1 yr) (range = 0.3-1.0 yr(-1) for individual congeners). For the dry barren area, the rate of loss from soil of individual congeners was negatively correlated with the planar total surface area of the congener (or positively correlated with vapor pressure). For a wet grass area or a dry moss area, the rate of loss was not correlated with any of the standard physical constants, suggesting that live and detrital vegetation may play a key role in the release and retention of PCBs. The estimated loss rates for the three plots may or may not be applicable to PCB-contaminated soils in general, where PCB volatility may be reduced by the presence of hydrocarbon-based carriers or influenced by other factors not considered in this study.

Elevated concentrations of organochlorines in the tissues of large marine predators in the Canadian Arctic are well documented. This paper presents some of the first data on the composition and distribution of chlorinated organic compounds in some arctic coastal animals found at lower levels of the marine food chain. Organisms include bottom-dwelling invertebrates: clams (Mya truncata), mussels (Mytilus edulis), sea urchins (Strongylocentrotus droebachiensis) and fish: sculpins (Myoxocephalus quadricornis). The majority of samples were collected in the vicinity of Cambridge Bay, Northwest Territories (NWT), Canada; however, samples were also collected near another inhabited area (Hall Beach, NWT) and at a reference site (Wellington Bay, NWT). PCBs and other organochlorines typically originate in more industrialized parts of the northern hemisphere, enter the Arctic, and are subsequently biomagnified. In this study, differences in the PCB congener compositions and concentrations, as well as the relative concentrations of a larger suite of organochlorines in biota, allowed the discrimination between local and distant PCB sources. Terrestrial runoff from southern Victoria Island, NWT, has resulted in localized elevation of PCBs and chlorinated pesticides in marine sediment and bottom-dwelling animals. The major inputs of PCBs to coastal waters within Cambridge Bay were derived from local sources (the hamlet dump and DEW Line site). In addition, transport from more distant sources via riverine input accounts for locally elevated concentrations of other organochlorines in upper Cambridge Bay. This process may also account for concentrations of all measured organochlorines that are higher in Wellington Bay than in Queen Maud Gulf. The high PCB concentrations in the whole tissue (excluding liver) or livers of four-horned sculpins in Cambridge Bay (up to 220 ng/g and 1950 ng/g, respectively) and, to a lesser extent, Wellington Bay (3.8 ng/g and 47 ng/g, respectively) reflect a strong tendency for biomagnification of PCBs in coastal benthic communities.

The Distant Early Warning (DEW) Line, a series of radar stations spanning the Canadian Arctic, is closing. In order to determine the environmental status of these installations, the Canadian Department of National Defence has sponsored an assessment of soil contamination, the partial results of which are presented here. A comparison of PCB concentrations in background samples taken from pristine areas near the radar sites and samples taken in remote locations (> 20 km distant) provides evidence for short-range redistribution of PCBs. Principal component analysis, which was used to highlight differences in congener composition, provided confirmation of this observation. The PCB congener signatures for background samples taken at the radar sites correlated well with PCB signatures from contaminated locations at the radar sites. In contrast, the congener signature attributed to long-range transport, contained a relatively higher proportion of more volatile congeners, which can be attributed to the increased atmospheric residence time.

Arsenic concentrations in freshwater macrophytes were examined in relation to arsenic loadings in sediments (solid phase and pore water) and surface waters for a group of lakes contaminated by the discharge of mine tailings near Yellowknife, N.W.T. Lakes closest to the current discharge were highly contaminated with arsenic (up to 18 650 μg g−1 in sediments) compared with other areas. Macrophytes tended to bioconcentrate arsenic relative to sediment concentrations (up to a factor of ten), with submerged species containing much higher levels of arsenic than emergents. Differences in levels between the most common submerged (Potamogeton pectinatus L.) and emergent species (Typha latifolia L.) were attributed to differences in growth form and possible differences in the ability to exclude arsenic with increasing sediment concentrations. High environmental arsenic concentrations appeared to have negative effects on Typha latifolia, as suggested by decreased stand height, necrosis of leaf tips and reduced micro-nutrient concentrations in root tissues of copper, managanese, and zinc. Phytotoxic symptoms in Typha were generally observed at sediment and water concentrations exceeding 300 μg g−1 and 400 μg l−1, respectively. The lack of relationships between tissue concentrations of arsenic and environmental concentrations of phosphorus (as pore water PO−34, particulate total extractable P, or As:P ratios) did not support the hypothesis that arsenic bioavailability (as arsenate) and toxicity is related to its competition for uptake with phosphate.

The composition of 47 ortho- and seven non-ortho-substituted PCBs in sediment, water, invertebrates, and fish collected from Cambridge Bay, Northwest Territories, Canada, is presented. The congener composition in sea urchins (Strongylocentrotus droebachiensis) was attributed to differences in the log K-ow of individual congeners during uptake from ingested sediment and aqueous solubility during secondary uptake from the water column. Four-horn and short-horn sculpins exhibited selective bioaccumulation of the recalcitrant congeners: those lacking two non-chlorinated carbons in adjacent meta and para positions on the biphenyl ring. The presence of methyl sulfone PCBs in four-horn sculpin liver provided direct evidence for metabolism. The percent composition of total PCB levels in four-horn sculpin livers, contributed by non-ortho-substituted PCBs 77 and 126 (those with potential for dioxin-like toxicity), was relatively constant regardless of total PCB concentration, suggesting that for a given species increased exposure to PCBs does not lead to increased relative concentrations of non-ortho-substituted congeners. Limited data on congeners 77 and 126 in sediment, sea urchins, or four-horn sculpins suggests that, with increasing trophic status, these congeners were diminished rather than enriched relative to the total PCB concentration.

Anaerobic enrichment cultures, isolated from arsenic-contaminated lake sediment in the Canadian sub-arctic and grown in five selective media, methylated arsenate/arsenite to produce mono-, di- and tri-methyl arsenicals. The extent of methylation and methylarsenic species produced varied with the type of enrichment. Iron-reducing, manganese-reducing, sulfate-reducing and broad-spectrum anaerobic heterotrophic mixed cultures all produced methylarsenicals. Sulfate-reducing cultures produced higher concentrations of methylarsenicals (especially trimethyl species) than iron-or manganese-reducers. There is evidence that several of the methylarsenicals, which were hydride-reactive at pH 6, were methylarsenic(III) thiols. The organoarsenicals produced by enrichment cultures were the same as those detected in the porewater of the lake sediments used to initiate the enrichment cultures. Overall, this study demonstrates that microbes from anaerobic lake sediments can methylate (and demethylate) arsenic, a capability shared by manganese-, iron-, and sulfate-reducing microbial consortia.

Throughout the years many functional organophosphorus compounds have been prepared for incorporation into polymer systems. In order to prevent loss of these phosphorus-containing additives from the polymer, either through migration or vaporization, one approach has been to provide the phosphorus-containing additive with functional groups which allow it to become chemically bound into the polymer system. Also, modifications of the additives were often required to prevent the phosphorus-containing additive from either interfering with the polymer-forming reactions or destabilizing the polymer. This paper describes some of the approaches recently taken at this laboratory to address these requirements. Also reported is a novel use of elemental phosphorus as a reducing agent.

Imposex, the manifestation of male morphological sex characters in females of functionally dioecious neogastropod taxa, is an abnormal response to tri-n-butyltin (TBT) contamination introduced to the marine environment in antifouling paints. Since the phenomenon has been thoroughly described only in Atlantic species, a comparative survey of field populations from British Columbia was undertaken, and field studies were carried out to assess the relative value as bioindicators of species in the genus Nucella from the Pacific coast. The majority of neogastropods studied to date have demonstrable signs of imposex, although this leads to sterilization of females in only a few species, depending on differences in the development in females of a palliai vas deferens. Within the Nucella species complex, N. lamellosa, N. canaliculata, and N. emarginata show promise as TBT bioindicators. Only the response of N. emarginata, however, was related to TBT bioaccumulation, based on measurements of a limited number of samples. This is attributed to the apparent irreversibility of imposex, the temporal variability of both environmental levels and tissue burdens of TBT, and the considerably shorter life-span of N. emarginata relative to that of N. lamellosa and N. canaliculata. The geographic distribution of imposex in Nucella spp. suggests that water-borne concentrations of TBT sufficiently high to induce imposex occur over large areas within British Columbia where exchange with oceanic water is limited.

A series of thieno[3,4-d]-, thieno[3,2-d]-, and thieno[2,3-d]pyrimidine-2,4-diones with (phenylpiperazinyl)alkyl substitution at N-3 have been synthesized and evaluated for antihypertensive effects in spontaneously hypertensive rats (SHR). These 49 compounds were compared to the vasodilator standards prazosin and the isosteric quinazoline-2,4-dione SGB 1534. Substitution at the 2-, 3-, or 4-position of the phenyl ring was examined, with that at the 2-position more potent than 4-substitution while the isomeric 3-substituted compounds were least potent. Neither alkylation nor acylation at the N-1 position improved the antihypertensive effects as compared to hydrogen. The three thienopyrimidine-2,4-diones (3-5) that contain a [(2-methoxyphenyl)piperazinyl]ethyl moiety at N-3 and hydrogen at N-1 were found to be potent oral antihypertensive agents in the SHR with doses (mg/kg, po) for reducing systolic blood pressure (SBP) by 50 mmHg (ED-50SBP) of 0.21, 0.19, and 1.0, respectively. The compounds 1-5 were further evaluated for alpha blocking potency by measuring the iv doses necessary to antagonize the phenylephrine pressor response by 50% (ED50) in the SHR. The ED50 values (micrograms/kg) are 10.4, 3.3, 1.7, 2.1, and 15.4, respectively. These results clearly show that all three thiophene systems have potent activity as antihypertensive agents and that 3 and 4 are more potent than 1 or 2 as alpha 1-antagonists in vivo.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSyntheses of .alpha.-phenylneopentyl chloride enantiomers: (S)-(-)-1-chloro-1-phenyl-2,2-dimethylpropane from (R)-(+)-1-phenyl-2,2-dimethyl-1-propanol via the reaction of tri-n-butylphosphine in carbon tetrachloride and (R)-(+)-1-chloro-1-phenyl-2,2-dimethylpropane from anthranilic acidHerman E. Zieger, Danielle Angrand Bright, and H. HaubenstockCite this: J. Org. Chem. 1986, 51, 8, 1180–1184Publication Date (Print):April 1, 1986Publication History Published online1 May 2002Published inissue 1 April 1986https://pubs.acs.org/doi/10.1021/jo00358a005https://doi.org/10.1021/jo00358a005research-articleACS PublicationsRequest reuse permissionsArticle Views358Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts