Trends In Contaminant Levels Research Articles

Blood mercury and plasma polychlorinated biphenyls concentrations in pregnant Inuit women from Nunavik: Temporal trends, 1992–2017

The Inuit of Nunavik (Northern Quebec, Canada) are exposed to polychlorinated biphenyls (PCBs) and mercury (Hg) through their consumption of marine country foods. A temporal trend study was initiated in 1992 to monitor circulating levels of PCBs and Hg in pregnant Inuit women, since the fetus is most at risk of adverse health effects. We set out (1) to describe temporal trends of PCBs and Hg levels in pregnant Nunavik women between 1992 and 2017; (2) to determine the prevalence of participants exceeding the guidance values in 2017; (3) to investigate relations between marine country food intake and contaminant levels over the study period. A total of 559 pregnant women provided a blood sample for contaminant analysis from 1992 to 2017. PCB congeners were quantified in plasma (serum) by gas chromatography (GC) coupled to electron capture detection or mass spectrometry (MS). We determined whole blood mercury concentration by cold vapor atomic absorption or inductively-coupled plasma MS. We performed multilevel modeling to assess temporal trends in contaminant levels and relations with marine country food consumption. Concentrations of total PCBs and Hg decreased by 84% and 65% between 1992 and 2017, respectively. Nevertheless, 10% and 22% of women in 2017 exceeded guidance values for PCBs and Hg, respectively. While the decline in marine country food intake is the only factor associated with decreasing Hg levels, other factors may explain the decline in PCB levels. Despite the significant decline in PCBs and Hg levels from 1992 to 2017, exposure to these contaminants is still quite prevalent among pregnant Nunavik women. Most of the decline in Hg exposure is likely due to a shift away from marine country foods to store-bought foods, which is a concern given the cultural and nutritional importance of country foods and the high food insecurity that prevails in Nunavik.

The hydrological regime of a large Mediterranean river influences the availability of pollutants to mussels at the adjacent marine coastal area: Implications for temporal and spatial trends

The present study reports the levels and trends (1993–2013) of DDTs, PCBs and metals in mussels collected at two coastal sites influenced by the River Ebro discharges. Results showed that levels of PCBs, DDTs, Cd and Hg were related to water inputs from the river, while these did not seem to be the main source for the Pb, Zn, Cu and As levels observed. Significant relationships were observed between PCBs and DDTs levels and the river flowrate in the fast-flowing months, suggesting that overflow periods promoted the mobilization of contaminants from sediments, and their subsequent discharge and spreading across the sea. Results indicated that PCBs were effectively southwestern transported, probably in relation to their soluble behavior in stream waters, while DDTs were limitedly spread in seawater, likely due to their particulate behavior. Significant declining trends observed for some metals, PCBs and p,p’ DDE may reflect the reduction of pollutants inputs along the river basin. However, the results also showed significant relationships between the river's flowrate in the fast-flowing months and PCBs and DDTs levels, and significant decreases on the river flowrate in some fast-flowing months during the long-term series studies. Both facts suggested that the reduction on overflow periods influenced the decreasing pollutants trends observed in mussels. The present study advises that decreasing trends in contaminant levels in Mediterranean estuarine coastal areas may be related not only to successful remediation works/policies, but also to the fluctuations on the hydrological regime of the rivers, which are directly linked to current climatic trends.

Spatial patterns of polybrominated diphenyl ethers (PBDEs) in mosses, herbivores and a carnivore from the Norwegian terrestrial biota

The widespread occurrence of polybrominated diphenyl ethers (PBDEs) in the environment has attracted considerable attention, leading to concerns about the extent and magnitude of wildlife and human exposure. In this work, we focus on the occurrence and fate of PBDEs in a Norwegian air–plant–herbivore–carnivore system. Specifically, we have analysed for PBDEs in moss, livers from various terrestrial herbivores (moose, grouse, and European roe deer) and, for the first time, livers from the top predator lynx. The samples were collected from different sites and time periods (1990–2004) to identify possible spatial and temporal trends in contaminant levels and patterns. The general finding was that PBDEs were found in all (biotic) samples, although at lower concentrations than previously observed in mammals from the marine environment. The PBDE levels in the herbivores ranged from less than 0.5 ng/g lipid weight to 9.4 ng/g lipid weight as the highest. The median PBDE concentration in lynx was approximately one order of magnitude higher than in the herbivores. In the lynx samples there was a predominance of BDE-153 whereas BDE-47 and 99 dominated in the herbivores. This probably reflects different bioaccumulation properties or metabolic transformation processes of the BDE-congeners, and food choice. Levels of PBDEs in both moss and herbivores showed a general decline towards the northern parts of Norway. No clear temporal trends were observed. The PBDE levels observed in this study were low and are probably of limited toxicological significance.

The potential impact of climate on human exposure to contaminants in the Arctic

Many northern indigenous populations are exposed to elevated concentrations of contaminants through traditional food and many of these contaminants come from regions exterior to the Arctic. Global contaminant pathways include the atmosphere, ocean currents, and river outflow, all of which are affected by climate. In addition to these pathways, precipitation, animal availability, UV radiation, cryosphere degradation and human industrial activities in the North are also affected by climate change. The processes governing contaminant behaviour in both the physical and biological environment are complex and therefore, in order to understand how climate change will affect the exposure of northern people to contaminants, we must have a better understanding of the processes that influence how contaminants behave in the Arctic environment. Furthermore, to predict changes in contaminant levels, we need to first have a good understanding of current contaminant levels in the Arctic environment, biota and human populations. For this reason, it is critical that both spatial and temporal trends in contaminant levels are monitored in the environment, biota and human populations from all the Arctic regions. (Int J Circumpolar Health 2005; 64(5):498–508)

Trace element distribution during the reproductive cycle of female and male spiny and Pacific scallops, with implications for biomonitoring

Trace element concentrations and contents in gills, gonad, kidneys, mantle, muscle and remainder during the reproductive cycle of female and male spiny and Pacific scallops, from the Strait of Georgia, BC, Canada, were quantified by using ICPMS. The elements investigated were chromium, manganese, iron, cobalt, nickel, selenium, molybdenum, cadmium, tin and mercury. For all ten elements, the tissue distribution was to some extent influenced by species, sex and reproductive status. The implications of the present study in relation to the design of biomonitoring programmes are: (1) care should be taken to ensure an equal/constant sex composition when making interannual comparisons of pooled samples. Preferably the sexes should be monitored separately. (2) the practice of obtaining pooled samples in the interspawn phase is applicable only to monitoring long-term trends in contaminant levels, while the reproductive status should be heeded when studying short-term changes. (3) the present study confirms that direct temporal or spatial comparisons of absolute accumulated element concentrations are only valid intraspecifically.

Metal levels in eggs of common terns ( Sterna hirundo) in New Jersey: temporal trends from 1971 to 2002

Managers and public policy makers require information on the status of and trends in contaminant levels in organisms to assess ecosystem health. Seabirds are excellent bioindicators because they are long-lived, feed at different trophic levels, and are at the top of the food chain, and many are abundant and widely distributed. They can reveal spatial or temporal trends in contaminant levels. In this paper, we examine temporal trends in the levels of cadmium, chromium, lead, manganese, mercury, and selenium in eggs from common terns ( Sterna hirundo) nesting on several salt marsh islands in Barnegat Bay, New Jersey. We test the null hypothesis that there are no temporal differences in levels of cadmium, lead, and mercury from 1971 to 2002 and in chromium, manganese, and selenium from 1992 to 2002. Arsenic was also analyzed in recent years. Levels were highest for manganese, followed by selenium, mercury, arsenic, lead, chromium, and cadmium. The eggs of Barnegat Bay common terns show a decline in levels of cadmium, chromium, and lead. Mercury declined from 1971 to 1982, increased dramatically in 1999, and declined thereafter. Manganese, an essential element, showed a decline (except for 2001), and selenium declined initially, but then remained stable. The data indicate that common terns can serve as useful bioindicators of temporal trends in exposure and that some of the metals of concern in estuarine environments (lead, cadmium) have declined over the past 30 years, although mercury levels are higher than in the early 1980s. The spike in 1999 is unexplained.

The use of zero‐valent iron injection to remediate groundwater: Results of a pilot test at the Marshall Space Flight Center

AbstractIn situ treatability studies are being conducted to evaluate various in situ technologies to manage groundwater contamination at the NASA Marshall Space Flight Center in Huntsville, Alabama. The focus of these studies is to evaluate remediation options for contaminated (mostly aerobic) groundwater occurring within the basal portion of a clayey residuum called the rubble zone. The tension‐saturated media and unsaturated media lying above the rubble zone are also being treated where they make up a significant component of the contaminant mass. An in situ chemical reduction field pilot test was implemented (following bench‐scale tests) during July and August 2000. The test involved the injection of zero‐valent iron powder in slurry form, using the FeroxSM process patented by ARS Technologies, Inc. The pilot test focused on trichloroethene (TCE)‐contaminated groundwater within the rubble zone. Maximum pre‐injection concentrations of about 72,800 micrograms per liter (μg/l) were observed and no secondary sources are believed to exist beneath the area. The potential presence of unexploded ordnance forced an implementation strategy where source area injections were completed, as feasible, followed by overlapping injections in a down gradient alignment to create a permeable reactive zone for groundwater migration. Eight post‐injection rounds of groundwater performance monitoring were completed. The results are encouraging, in terms of predicted responses and decreasing trends in contaminant levels. © 2003 Wiley Periodicals, Inc.

Environmental Contaminants in Colonial Waterbirds from Great Slave Lake, NWT: Spatial, Temporal and Food-chain Considerations

Great Slave Lake in the Northwest Territories, Canada, differs regionally in trophic status and local and regional inputs of contaminants. Spatial and temporal trends in contaminant levels in bioindicator species such as colonial waterbirds could offer insights into the potential for contaminant bioaccumulation in Great Slave Lake. Persistent chlorinated hydrocarbon contaminants, mercury (Hg), and selenium (Se) were examined in herring gull ( Larus argentatus ) eggs and livers collected from various locations on Great Slave Lake in 1995. Eggs were collected in May and June, and livers in May and August. Also, the relationship between contaminants and trophic level, as inferred from stable-nitrogen isotope analysis (delta 15N), was examined in four colonial waterbird species: herring gull, mew gull ( L. canus ), Caspian tern (Sterna caspia ), and black tern ( Chlidonias niger ). Finally, the co-accumulation of mercury and selenium was examined in eggs of these birds. There were no differences in chlorinated hydrocarbon concentrations among four sampling sites (colonies). Concentrations did not differ between herring gull adults collected in early May and those collected in early August. Chlorinated hydrocarbon concentrations in eggs of herring gull, mew gull, Caspian tern, and black tern were related to their trophic positions as inferred from their delta 15N values in their lipid-free egg yolks. Concentrations in these colonial waterbirds were much higher than those in fish from Great Slave Lake, but lower than those in their conspecifics from the Great Lakes. It is probable that a relatively large proportion of the chlorinated hydrocarbon contaminant load in colonial waterbird eggs on Great Slave Lake results from exposure to and storage of such contaminants at more heavily contaminated wintering and staging areas. This possibility limits the usefulness of colonial waterbirds as indicators of chlorinated hydrocarbon bioaccumulation in Great Slave Lake. Selenium and mercury concentrations in herring gull eggs differed significantly among the four breeding colonies, and concentrations in adults declined between May and August. Selenium and mercury were positively correlated in eggs of all species. Key words: black tern, Caspian tern, Great Slave Lake, herring gull, mew gull, mercury, organochlorines, selenium

Organochlorine levels in cetaceans from South Africa: A review

Publications on levels of organochlorines in cetaceans from South Africa are reviewed. Organochlorine contamination in cetaceans off South Africa is similar to those in Australian waters, but generally low compared to the Northern Hemisphere. An exception is the coastal dolphins inhabiting the South African east coast waters. In these animals levels are similar to Northern Hemisphere coastal cetaceans. Levels are generally higher in coastal dolphins, compared to dolphins living in deeper waters. It is suggested that these differences are directly related to the levels of industrialisation and cultivation of the surrounding area. Too few samples of either baleen whales or toothed whales are available to investigate the differences in Organochlorine levels between these two groups. Similarly, even for species with the highest sample sizes — common and bottlenose dolphins — the data are insufficient to investigate trends in contaminant levels.

Equilibrium Lipid Partitioning Concentrations as a Multi-Media Synoptic Indicator of Contaminant Levels and Trends in Aquatic Ecosystems

Large quantities of monitoring data have been gathered over many years for the Great Lakes basin in the form of contaminant concentrations in a variety of media including air, water, suspended and bottom sediments, wildlife (especially fish, birds, and birds’ eggs), soils, vegetation, foodstuffs, and human tissues. The quantity of data and the diversity of units used to report the concentrations are such that it is difficult to gain a comprehensive, ecosystem-wide, interpretation of contaminant levels and trends. It is suggested that the problems arising from the use of a diversity of units can be addressed, at least for an organic contaminant, by expressing all concentrations on a common equilibrium partitioning basis. The equilibrium lipid partitioning (ELP) concentration is suggested as being most appropriate for this purpose. It is shown that expressing monitoring data as ELP concentrations permits a more reliable determination of time trends in contaminant levels in multi-media systems, facilitates comparison between ecosystems, and contributes to an improved understanding of contaminant sources and fate. An “adjusted” ELP concentration may be deduced to compensate for differences in equilibrium status between media, thus consolidating all multi-media contaminant levels in a single, ecosystem-wide, synoptic indicator of trends in contaminant status. The approach is illustrated for polychlorinated biphenyls (PCBs) in the Lake Ontario and Lake Superior ecosystems showing a definite decrease in concentrations over the period 1977 to 1993 with estimated decay half-lives of 8.1 and 11.4 years, respectively.

Environmental contaminants in wild mink in the Northwest Territories, Canada

As a top trophic level species that readily bioaccumulates environmental pollutants, the mink (Mustela vison) is considered to be a sensitive indicator of ecosystem health. Here we report on the first 2 years of a 4-year program established to examine organochlorine and heavy metal residues in wild mink from western Northwest Territories (NWT), Canada. Tissue samples taken from up to 24 mink harvested from each of five sites in 1991-92 and 1992-93 were analyzed for residues of a suite of 63 organochlorines in fat and liver samples, including 43 polychlorinated biphenyl (PCB) congeners and 20 pesticides, and residues of 10 heavy metals in liver and kidney samples. Overall, contaminant levels were low in comparison with level in other mink studied in North America. ΣPCB residues (sum of 43 congeners) ranged from a mean of 5.32 ng/g wet weight in the livers of Inuvik mink (the most northerly collection site) to 27.67 ng/g in mink from Fort Smith (the most southerly collection site). There appeared to be no differences in organochlorine burden between sexes. Heavy metal residues were also comparatively low, with the exception of total mercury, which was at moderate levels (community means of 1.16-3.30 μg/g wet wt. in liver samples). There was a distinct trend of decreasing organochlorine contaminant burdens with increasing latitude, but no trend in heavy metal burdens was evident. There was a doubling of mean ΣPCB levels in Inuvik mink from 5.32 ng/g wet weight in 1991-92 to 10.69 ng/g in 1992-93. Population indices derived from age and sex ratios of the harvest, coupled with comparatively low levels of contaminants, suggest little or no effects on mink reproduction or population health as a result of these contaminants. Long-range atmospheric transport is probably the major source of most of the contaminants. Additional collections will further elucidate spatial and temporal trends in contaminant levels in NWT mink.

Trend analysis using a multivariate procedure for data with unequal residual covariance and regression coefficient matrices: Application to Canadian Atlantic cod contaminant data

Conventional univariate and multivariate analysis of covariance (ANCOVA and MANCOVA) are commonly used to investigate time trends in contaminant levels in fish tissues. Both procedures require that years do not differ in their residual variances, covariances, and regression parameters. These requirements were not met in many data sets. A multivariate procedure that does not have these requirements was used to reanalyse contaminant concentration trends in Canadian cod data collected between 1977 and 1985.

A Multivariate Procedure for Linear Comparisons of Mean Vectors when Residual Covariance and Regression Coefficient Matrices are Unequal

AbstractA multivariate procedure for testing linear comparisons of vectors of adjusted group means of response (dependent) variables when groups differ in residual covariance and regression coefficient matrices is presented. Such disparities have been observed in investigations of trends in contaminant levels in fish. Application of the procedure is illustrated with data on Atlantic cod (Gadus morhua). The procedure is quite general and can be employed to test any linear comparisons.

A weighted procedure of analysing for time trends in contaminant levels in CMP data: application to cod and flounder data of the Belgian coast (1978-1985)

A weighted procedure of analysing for time trends in contaminant levels in CMP data: application to cod and flounder data of the Belgian coast (1978-1985)

Time trends of chemical contaminant levels in Canadian Atlantic cod with several biological variables

Investigation of time trends in contaminant levels has been one of the highest priority tasks within the International Council for the Exploration of the Sea (ICES). Univariate procedures of analysing for temporal variations (provided in the ICES guidelines) are of severely restricted scope. Additional problems, which arise due to multicollinearity when two or more covariates are used, are identified. A procedure which has a more extended scope than the univariate one and which overcomes the multicollinearity situation is presented. Canadian Atlantic cod ( Gadus morhua) data of the eight-year period, 1977–1985, are analysed for time trends by this procedure. Whereas the true mathematical form of temporal variations was not identifiable and will require additional time points, linear trends were significant and provided an effective description of these variations.