Differences In Metal Levels Research Articles

Determination of metals in different tissues of Trachurus trachurus from the Marmara Sea and evaluation of their health risks

The present study aimed to determine the differences in metal levels of Aluminum (Al), Cadmium (Cd), Chromium (Cr), Copper (Cu), İron (Fe), Manganese (Mn), Nickel (Ni), Lead (Pb) and Zinc (Zn) between muscle and liver tissues of Trachurus trachurus, the correlation of metal accumulation in tissues with fish length and weight was examined. Health risks and nutritional adequacy were evaluated based on metal levels accumulated in fish muscle. The results demonstrated that fish liver accumulated higher metal levels than muscle. The investigation revealed that the majority of metals present in the tissues of the fish did not exhibit a significant correlation with their size (p>0.05). It can be concluded that fish are not an adequate source of these nutrients because their nutrient levels are below reference values. The fish were found to be nutrient deficient, as the levels of nutrients were below reference values. The estimated daily intakes of all metals accumulated in muscle were below reference doses. The target hazard coefficient and target hazard index values were less than 1. Lifetime carcinogenic risk values were below 10-4, and total carcinogenic risk values were within the acceptable range. Pb and Cd concentrations in muscle exceeded the tolerable limit. The daily amount of fish that could be consumed without non-carcinogenic health risk was 181 grams for Cd and 295 grams for Pb. The daily amount of fish that could be consumed without carcinogenic health risk was 1.21 grams for Cd and 231 grams for Pb.

Metal Levels in Delaware Bay Horseshoe Crab Eggs from the Surface Reflect Metals in Egg Clutches Laid beneath the Sand.

Understanding variations in metal levels in biota geographically and under different environmental conditions is essential to determining risk to organisms themselves and to their predators. It is often difficult to determine food chain relationships because predators may eat several different prey types. Horseshoe crab (Limulus polyphemus) eggs form the basis for a complex food web in Delaware Bay, New Jersey, USA. Female horseshoe crabs lay thumb-sized clutches of eggs, several cm below the surface, and often dislodge previously laid eggs that are brought to the surface by wave action, where they are accessible and critical food for migrant shorebirds. This paper compares metal and metalloid (chromium [Cr], cadmium [Cd], lead [Pb], mercury [Hg], arsenic [As] and selenium [Se]) concentrations in horseshoe crab eggs collected on the surface with concentrations in eggs from clutches excavated from below the sand surface, as well as examining metals in eggs from different parts of the Bay. The eggs were all collected in May 2019, corresponding to the presence of the four main species of shorebirds migrating through Delaware Bay. These migrating birds eat almost entirely horseshoe crab eggs during their stopover in Delaware Bay, and there are differences in the levels of metals in blood of different shorebirds. These differences could be due to whether they have access to egg clutches below sand (ruddy turnstones, Arenaria interpres) or only to eggs on the surface (the threatened red knot [Calidris canutus rufa] and other species of shorebirds). Correlations between metals in clutches were also examined. Except for As and Cd, there were no significant differences between the metals in crab egg clutches and eggs on the surface that shorebirds, gulls, and other predators eat. There were significant locational differences in metal levels in horseshoe crab eggs (except for Pb), with most metals being highest in the sites on the lower portion of Delaware Bay. Most metals in crab eggs have declined since studies were conducted in the mid-1990s but were similar to levels in horseshoe crab eggs in 2012. The data continue to provide important monitoring and assessment information for a keystone species in an ecosystem that supports many species, including threatened and declining shorebird species during spring migration.

Protein Expression in the Gastrocnemius Muscle of a Rodent Shrapnel-Injury Model.

With shrapnel injuries, the metal fragment is usually left in place to reduce the risk of morbidity extensive surgery might bring. This means the individual may retain those metals for the remainder of their life. Often the long-term health effects of the embedded metal are not known, especially with respect to protein damage and perturbations of muscle repair pathways. In this study, using homogenates of rat gastrocnemius muscle implanted with pellets of military-relevant metals, we investigated expression of iNOS and eNOS, enzymes involved in nitric oxide production, as well as MMP-2 and MMP-9, matrix metalloproteinases associated with muscle repair. In addition, hydroxynonenal-modified proteins were investigated to assess metal-induced oxidative damage and metal levels in the gastrocnemius determined. Metals were implanted for up to 12 months in order to determine the long-term effects on the expression of muscle-associated proteins. With the exception of iron and cobalt at 1-month post-implantation, there were no significant differences in metal levels in the gastrocnemius in any of the cohorts. Protein expression analysis showed significant decreases in iNOS and eNOS in the 6-month and 12-month lead and depleted uranium groups. Hydroxynonenal-modified proteins were also significantly increased in the iron, copper, lead, and depleted uranium groups. These results suggest that some embedded metals can induce long-term oxidative damage, as well as affect enzyme systems involved in signal transduction.

Identifying environmental risk associated with anthropogenic activities in Zanjanrud River, Iran, using an integrated approach

The deterioration of river quality has already become a growing threat to the health of aquatic environments around the world. Hence, a sound temporal and spatial monitoring of water and sediment pollution in rivers is required for effective watershed management. The variability of water parameters (e.g., discharge, velocity, temperature, DO, pH, turbidity, phosphorus, nitrogen, etc.) and suspended sediment-associated metals (e.g., Ag, Al, Cu, Na, Pb, Mn, Mg, Fe, etc.) has been analyzed in the Zanjanrud River. The study period covered from October 2015 to March 2017 including dry and wet seasons at five sampling sites along the main stretch of the river with a bi-weekly frequency of sampling. Principal component (PCA) and cluster analysis (CA) were performed to reveal links between variables. The Geochemical Abundance Index (GAI), Accumulation Factor (AF) and Modified River Recovery Capacity (MRRC) were also calculated. The results revealed that the river is highly influenced by effluents from residential, industrial and agricultural activities. The GAI index indicated contamination by Cd, Cu, P and Zn immediately after the discharge from Zanjan city during the monitoring period. The AF showed only slight differences in metal levels in suspended sediments between the head and tail sites of the study river. The PCA results indicated linkages among several metals and sites and also pointed out to the influence of nitrogen and phosphorus inputs from residential and industrial areas on the water quality of the river. A considerable improvement of several environmental parameters along the river flow from the first discharge point to the tail site was observed. Our results suggest that efficient sewage treatment systems and a control over agricultural diffuse pollution near the polluting sites will considerably improve the water and sediment quality of the Zanjanrud.

Metal concentrations in archaeological and contemporary mussel shells (Unionidae): Reconstruction of past environmental conditions and the present state

Freshwater mussels are widely used in the monitoring of pollution because they are filter-feeding, long-lived animals that tend to accumulate metals in their shells. The temporal scale of such studies can reach thousands of years, since the composition of shells preserves them against decay. This allows us to reconstruct past environmental conditions and to compare current environmental conditions to those prevalent thousands of years ago. Here we assessed metal concentrations (Ca, Cd, Cr, Cu, Fe, Hg, Ni, Pb and Zn) in recently harvested mussel shells and mussel shells found by archaeologists, and tested the hypothesis that levels of some metals are higher in today's shells, reflecting increasing anthropogenic impact. We observed lower metal concentrations (with the exception of Cd) in shells found by archaeologists (n = 35) than in recently harvested mussel shells (n = 14) (Unio crassus, Unio pictorum, Unio tumidus) in the same water bodies. There were no significant differences in metal levels among species in shells found by archaeologists, while in recently harvested mussels almost all metals for which we tested were found in their highest levels in Unio crassus. The results suggest that metal concentrations in prehistoric times were lower than today, which probably reflects human impact, rather than changes in the geochemical structure of rocks. The results also revealed that metal transfer between mussel shells and surrounding deposits does not occur. We therefore suggest that they might be successfully used as independent bioindicators.

Oil Extraction in the Amazon Basin and Levels of Metals among Indigenous Populations

Between May and August 2016 the Peruvian Ministry of Health conducted a cross-sectional study to assess levels of exposure to metals in the local population and stablish risk factors in Corrientes, Pastaza, Marañón and Tigre river basins (Peru). 1168 people from 39 indigenous communities participated in the study. Information on socio-demographic variables and environmental exposures was collected in questionnaires. Blood and urine samples were collected from each study participant, and environmental samples were collected from each community to measure levels of metals and hydrocarbons. We used atomic absorption spectrophotometry to measure metals concentrations (Pb, As, Ba, Cd and Hg) in biological and environmental samples. We used multilevel mixed-effects linear regression models with a random effect for community and river basin, adjusted for potential confounders to study the association between socio-demographic variables and environmental exposures and levels of metals in biological samples. We used linear regression models to study the association between median concentration of metals on environmental samples and on biological samples at the community level.57% of the study population had blood lead levels above 5 µg/dL and 28%, 13%, 9% and 26% of the study population had urinary levels of As, Ba, Cd and Hg, respectively, higher than those recommended by the Peruvian Ministry of Health (20 µg Cd/g As, 6 µg Ba/g creatinine, 2 µg Cd/g creatinine and 5 µg Hg/g creatinine). There were differences in levels of metals in environmental samples according to river basin. Inhabitants of communities with higher levels of Cd in agricultural soil presented higher levels Cd urinary levels than inhabitants from other communities. The analysis of risk factors at the individual level did not yield clear results. Differences in level of exposure to metals were generally explained by ethnic group, which might reflect geographical differences in levels of exposure.

Association of metals with the risk and clinical characteristics of Parkinson's disease

IntroductionWhile metals have been implicated in the pathophysiology of Parkinson's disease (PD), the clinical evidence is scarce. Further, the contribution of metals for the risk or clinical presentation of PD remains to be explored. MethodsTo investigate the associations between the level of metals in blood serum and PD risk or clinical presentation, including sex-related differences, we studied 325 PD patients and age- and sex-matched 304 controls. We collected clinical data of the PD patients, including age at onset, PD duration, levodopa-equivalent dose (LED), Hoehn and Yahr stage (H-Y stage), presence of motor fluctuation, levodopa-induced dyskinesia (LID), freezing of gait, hallucination, and Mini-Mental State Examination (MMSE) score. Iron, copper, and zinc levels in serum were assayed by inductively coupled plasma mass spectrometry. Statistical analyses were performed to determine the sex-related differences in metal levels. ResultsAmong the three metal elements tested, serum copper levels showed significant correlations with PD risk or clinical presentation. Higher copper levels were associated with a decreased PD risk. Higher copper or lower iron levels were associated with the risk of LID in women. Serum copper levels were negatively correlated with MMSE scores in PD patients. ConclusionsThis clinical study suggests significant associations between serum metal levels and PD risk or essential clinical features, demonstrating the possible roles of metals in PD pathogenesis or symptom development.

Spatiotemporal variations in metal accumulation, RNA/DNA ratio and energy reserve in Perna viridis transplanted along a marine pollution gradient in Hong Kong

We examined spatiotemporal variations of metal levels and three growth related biomarkers, i.e., RNA/DNA ratio (RD), total energy reserve (Et) and condition index (CI), in green-lipped mussels Perna viridis transplanted into five locations along a pollution gradient in the marine environment of Hong Kong over 120days of deployment. There were significant differences in metal levels and biomarker responses among the five sites and six time points. Mussels in two clean sites displayed better CI and significantly lower levels of Ag, Cu, Pb and Zn in their tissues than the other sites. Temporal patterns of RD in P. viridis were found to be site-specific. Across all sites, Et decreased in P. viridis over the deployment period, though the rate of decrease varied significantly among the sites. Therefore, temporal variation of biomarkers should be taken to consideration in mussel-watch programs because such information can help discriminate pollution-induced change from natural variation.

Pb Uptake in Roadside Grown Wheat (Triticum aestivum L.) in the Sudan Savanna, Kano State

Cereal crops grown under irrigation in a semi-arid ecological habitat can be used to assess food quality and safety of agricultural systems at proximity to highways in the Sudan savannah of Northern Nigeria. This study focussed on the risk assessments of Pb transfer, translocation and uptake at selected growth stages (15-, 30-, 45-, 60-, 75- and 90-days representing seedling or germination, tillering, shooting/booting, earing, flowering and ripening stages respectively of two cultivars of Triticum aestivum L. The experimental (SU 1) and control (SU 2) sites were selected based on distances (345 m and 1936 m) from the Kano-Zaria Highway. Pb levels in soils and the two cultivars of Triticum aestivum L. was measured using the double-beam AAS and plant uptake factors (PUF), soil-plant transfer coefficients (TC) and translocation factors (TF) were worked out. Result reveals differences in metal levels of the cultivars of wheat according to growth stages and plant parts. Pb levels was highly significant (P=0.05 and 0.01) in the stems of Siettecerros at the control site indicating selective ability of cultivar to Pb. Pb levels were highest in both cultivars at the 30-days growth stage indicating sensitivity of tillering stage to Pb uptake. A greater than unity value indicate anthropogenic source of Pb. Siettecerros had the highest TF indicating incorporation of higher levels of Pb in the edible plant parts. A higher PUF (45), TC (6.32) and TF (7.66) for Pb in Pavon-76 and Siettecerros respectively, indicates their suitability for bioremediation particularly, phytoextraction of polluted soils from atmospheric pollutants.

Contaminant levels in Herring (Larus argentatus) and Great Black-backed Gull (Larus marinus) eggs from colonies in the New York harbor complex between 2012 and 2013.

Birds living in coastal areas are exposed to severe storms and tidal flooding during the nesting season, but also to contaminants that move up the food chain from the water column and sediment to their prey items. We examine metals in Herring Gull (Larus argentatus) and Great Black-backed Gull (Larus marinus) eggs collected from the New York/New Jersey harbor estuary in 2012 and in 2013 to determine if there were significant yearly differences in metal levels. We test the null hypothesis that there were no significant yearly differences in metal levels. We investigate whether there were consistent differences in metals from 2012 to 2013 that might suggest a storm-related effect because Superstorm Sandy landed in New Jersey in October 2012 with high winds and extensive flooding, and view this research as exploratory. Except for arsenic, there were significant inter-year variations in the mean levels for all colonies combined for Herring Gull, and for lead, mercury and selenium for Great Black-backed Gulls. All metal levels in 2013 were less than in 2012, except for lead. These differences were present for individual colonies as well. Metal levels varied significantly among islands for Herring Gulls in both years (except for cadmium in 2013). No one colony had the highest levels of all metals for Herring Gulls. A long term data set on mercury levels in Herring Gulls indicated that the differences between 2012 and 2013 were greater than usual. Several different factors could account for these differences, and these are discussed.

The status of essential elements and associations with milk yield and the occurrence of mastitis in organic and conventional dairy herds

There is a lack of detailed information on the impact of organic feeding regulation on the health and well-being of cows. This has become especially important since January 2008 when the EU required 100% organic ration for organic dairy herds. The aim of this investigation was to determine and compare the levels of essential elements in organic and conventional dairy herds, and to associate them with milk yield and the occurrence of mastitis. The field study was carried out in 10 organic and 10 conventional herds from 2005 to 2010. This period included the point in time when the ration became 100% organic in organic dairy herds. Essential element concentrations (Cu, Co, Se, Zn, Mn, Mo, I and Fe) were determined by inductively coupled plasma–mass spectrometry in 158 serum samples. Associations between concentrations of elements and milk yield and mastitis were determined with mixed linear and logistic regression models, respectively. No significant differences in metal levels between organic and conventional herds were found. No severely deficient concentrations of essential elements were observed in organic herds, either before or after the change in regulation. Cows with low serum concentrations of Se had lower somatic cell counts. Daily milk yield was significantly influenced by deficient concentrations of Cu. For the evaluation of clinical mastitis occurrence, herds were classified for each element, based on the individual values of the sampled cows. Low levels of some elements (Se, I) were associated with a reduced risk of mastitis occurrence. However, other elements indicated a protective effect against mastitis.

Interspecific and locational differences in metal levels in edible fish tissue from Saudi Arabia.

Metal levels in fish have been extensively studied, but little data currently exists for the Middle East. We examined the levels of metals and metalloids (aluminum, arsenic, copper, manganese, selenium, zinc, and mercury) in the flesh of 13 fish species collected from three fishing sites and a local fish market in Jeddah, Saudi Arabia. We tested the following null hypotheses: (1) there are no interspecific differences in metal levels, (2) there are no differences in metal levels in fishes between market and fishing sites, (3) there are no size-related differences in metal levels, and (4) there are no differences in selenium:mercury molar ratio among different fish species. There were significant interspecific differences in concentrations for all metals. There was an order of magnitude difference in the levels of aluminum, arsenic, mercury, manganese, and selenium, indicating wide variation in potential effects on the fish themselves and on their predators. Fishes from Area II, close to a large commercial port, had the highest levels of arsenic, mercury, and selenium, followed by market fishes. Mercury was positively correlated with body size in 6 of the 13 fish species examined. Mercury was correlated positively with arsenic and selenium, but negatively with aluminum, cobalt, copper, manganese, and zinc. Selenium:mercury molar ratios varied significantly among species, with Carangoides bajad, Cephalopholis argus, Variola louti, and Ephinephelus tauvina having ratios below 10:1. These findings can be used in risk assessments, design of mercury reduction plans, development of fish advisories to protect public health, and future management decision-making.

Selenium:mercury molar ratios in bullfrog and leopard frog tadpoles from the northeastern United States.

Vertebrates experience adverse effects from methylmercury, largely obtained through their food. Selenium has the potential to reduce the toxic effects of methylmercury (and vice versa). In this paper, we examine the selenium:mercury molar ratios in tadpoles (Lithobates sphenocephalus, Lithobates catesbeianus (formerly Rana), and a newly documented leopard frog species currently referred to as R. sp. nov.) and fully formed leopard frog metamorphs. There were no significant differences in metal levels between the two leopard frog species, and data were therefore combined. Selenium:mercury molar ratios varied from 19 to 38 for bullfrog tadpoles, from 16 to 330 for leopard frog tadpoles, and from 7 to 17 for leopard frog metamorphs. Leopard frog tadpoles with less than 45days exposure to field conditions had significantly higher molar ratios than other tadpoles and leopard frog metamorphs. There were significant locational differences for the molar ratios of bullfrogs, and leopard frog tadpoles with more than 45days of field exposure. At the sites where we were able to sample both leopard frog tadpoles and leopard frog metamorphs, there were significant differences between the two distinct life stages. Most of the variation in the ratio was accounted for by selenium levels, field sites, and exposure period.

Temporal trends (1989–2011) in levels of mercury and other heavy metals in feathers of fledgling great egrets nesting in Barnegat Bay, NJ

There is an abundance of data for levels of metals from a range of species, but relatively few long-term time series from the same location. In this paper I examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in feathers from fledgling great egrets (Ardea alba) collected at nesting colonies in Barnegat Bay, New Jersey from 1989 to 2011. The primary objectives were to test the null hypotheses that (1) There were no temporal differences in metal levels in feathers of fledgling great egrets, and (2) Great egrets nesting in different areas of Barnegat Bay (New Jersey) did not differ in metal levels. There were significant yearly variations in levels of all heavy metals in feathers of fledgling great egret, but levels decreased significantly from 1989 to 2011 only for lead (1470ppb to 54.3ppb), cadmium (277ppb to 30.5ppb), and manganese (only since 1996; 2669ppb to 329ppb)). Although mercury levels decreased from 2003–2008 (6430ppb to 1042ppb), there was no pattern before 2003, and levels increased after 2008 to 2610ppb in 2011. Lead, cadmium, chromium, manganese and mercury were higher in feathers from great egrets nesting in the northern part of the bay, and selenium was highest in feathers from mid-bay. The lack of a temporal decline in mercury levels in feathers of great egrets is cause for concern, since the high levels in feathers from some years (means as high as 6430ppb) are in the range associated with adverse effects (5000ppb for feathers).

Speciation of Organic Matter and Heavy Metals in Urban Wastewaters from an Emerging Country

Analytical scanning and transmission electron microscopy, sequential chemical extraction, and pyrolysis–gas chromatography on solvent-extractable organic matter are used to provide both direct and indirect speciation of heavy metals and organic matter in sewage-suspended solids and in biofilms taken from an urban sewer in an emerging country. Compared to developed countries where the domestic activities represent the main source of heavy metal pollution in wastewater, the combined sewer system of an emerging country also integrates significant contributions originating from the private drinking water supply system (Zn, Cu, Cr, and Ni), industrial discharges (Cu, Mn), and road dust transported by street washing (Pb). The relative importance of those sources changes drastically over time as evidenced by the difference in metal levels recorded between weekday and weekend effluents. Nevertheless, sewer biofilms are found to provide a good averaging of contaminant loads and they can be used as environmental archives. The speciation study reveals the predominance of neoformed minerals such as sulfides and phosphates and highlights the strong biogeochemical dynamics that takes place within the sewer system. Electron microscope observations of heavy metal-bearing phases proved to be necessary to provide a consistent interpretation of chemical extraction results. The molecular characterization of the solvent-extractable organic matter from biofilms reveals the presence of classical fingerprints of domestic activity such as fecal sterols and detergents but also confirms a major contribution of petroleum by-products consistent with a traffic-related pollution.

Gender differences for associations between circulating levels of metals and coronary risk in the elderly

Several studies have pointed out associations between various metals and cardiovascular disease. Since cardiovascular disease prevalence is different between males and females, we investigated whether circulating levels of metals related differently to coronary risk in men and women. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, coronary risk was assessed by the Framingham Risk Score together with circulating blood levels of 11 different trace and heavy metals in 1016 subjects aged 70 years. Circulating levels of cadmium, copper and manganese were significantly higher in women than in men, while mercury, zinc and lead were significantly lower following adjustment for kidney function (measured by glomerular filtration rate, GFR). No significant differences between women and men were seen regarding levels of aluminium, molybdenum, cobalt, chromium and nickel. When all 11 metals were entered as independent variables together with GFR in multiple models in the Framingham Risk Score as the dependent variable, cadmium was the major determinant of the Framingham Risk Score in women (p<0.0001, followed by zinc p=0.03), while copper was the major determinant of the Framingham Risk Score in men (p<0.0001, followed by inverse relations vs. aluminium p=0.01 and nickel p=0.01). There are gender differences in levels of metals and also regarding the association between metals and coronary risk, with cadmium levels being most important for women and copper levels for men in this elderly population.

A Trace Metal Survey of Non-Occupationally Exposed Gauteng Residents

Specific reference values for background levels of body burden of trace metals are not available for South Africa. Currently, laboratories measuring trace metal levels in workers use internationaly established values for comparison. A preliminary cross-sectional survey of 107 non-occupationally exposed volunteers of both genders and all races provided blood and urine samples. The samples were collected with consideration for possible routes of contamination. Seven metals were measured in blood and ten in urine. Reference ranges for a Gauteng population were then calculated using the central 95% of data to provide lower and upper limits, which were then compared to international limits. The trace metal levels described had both lower and higher reference ranges in blood and urine compared to international studies. This reflects the differences in the environments. Statistically significant differences in metal levels were observed by gender. The differences in detected trace metal levels in our sample as compared to other published data demonstrate the need for the establishment of local reference values for laboratories. The establishment of local 95% reference ranges would also allow South Africa to determine its exposure levels compared to those internationally. This would assist with establishing pollution control priorities.

Arsenic, Cadmium, Chromium, Lead, Mercury, and Selenium Levels in Blood of Four Species of Turtles from the Amazon in Brazil

Using blood as a method of assessing metal levels in turtles may be useful for populations that are threatened or endangered or are decreasing. In this study the levels of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and selenium (Se) in blood of four species of turtles from the tributaries of the Rio Negro in the Amazon of Brazil were examined. The turtles included the six-tubercled Amazon (river) turtle (Podocnemis sextuberculata), red-headed Amazon (river) turtle (Podocnemis erythrocephala), big-headed Amazon (river) turtle (Peltocephalus dumerilianus), and matamata turtle (Chelus fimbriatus). Blood samples were taken from the vein in the left hind leg of each turtle. There were significant interspecific differences in the sizes of the turtles from the Rio Negro, and in concentrations of Pb, Hg, and Se; the smallest species (red-headed turtles) had the highest levels of Pb in their blood, while Se levels were highest in big-headed turtles and lowest in red-headed turtles. Hg in blood was highest in matamata, intermediate in big-headed, and lowest in the other two turtles. Even though females were significantly larger than males, there were no significant differences in metal levels as a function of gender, and the only relationship of metals to size was for Cd. Variations in metal levels among species suggest that blood may be a useful bioindicator. Metal levels were not high enough to pose a health risk to the turtles or to consumers, such as humans.

Reduced Zinc and Copper in the Retinal Pigment Epithelium and Choroid in Age-related Macular Degeneration

To measure zinc and copper levels in the retinal pigment epithelium (RPE) and choroid complex and in the neural retina in subjects with and without age-related macular degeneration (AMD). Laboratory investigation. Eighty-eight donor eyes (44 subjects) were analyzed. After retinal dissection, the RPE and choroid complex was photographed. Using the Minnesota Grading System (MGS), the RPE and choroid complex was classified into 1 of 4 stages as defined by the Age-Related Eye Disease Study. Subjects without AMD were defined as both eyes having MGS stage 1; subjects with AMD were defined as both eyes having MGS stages 2 through 4. Zinc and copper levels were determined by using an inductively coupled plasma-mass spectrometer. Metal levels from two eyes of the same subject were averaged and treated as one observation. Differences in metal levels were examined by using Wilcoxon rank-sum tests. The mean RPE and choroid complex zinc level in subjects with AMD (+/- standard deviation, 223.7 +/- 94.0 microg/g; n = 15) was reduced 24% when compared with that of subjects without AMD (292.1 +/- 98.5 microg/g; n = 29; P = .01). The mean RPE and choroid complex copper level in subjects with AMD (5.1 +/- 1.1 microg/g) was reduced 23% when compared with that of subjects without AMD (6.6 +/- 1.4 microg/g; P = .002). No difference was detected in retinal zinc and copper levels in subjects with and without AMD (P > .09). Reduced RPE and choroid complex zinc and copper levels in AMD eyes combined with previous information that oral supplementation of zinc plus copper reduces the risk of progression of AMD suggests that metal homeostasis plays a role in AMD and in retinal health.

Mercury and other metals in eggs and feathers of glaucous-winged gulls (Larus glaucescens) in the Aleutians

Levels of mercury and other contaminants should be lower in birds nesting on isolated oceanic islands and at high latitudes without any local or regional sources of contamination, compared to more urban and industrialized temperate regions. We examined concentrations of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in the eggs, and the feathers of fledgling and adult glaucous-winged gulls (Larus glaucescens) nesting in breeding colonies on Adak, Amchitka, and Kiska Islands in the Aleutian Chain of Alaska in the Bering Sea/North Pacific. We tested the following null hypotheses: 1) There were no differences in metal levels among eggs and feathers of adult and fledgling glaucous-winged gulls, 2) There were no differences in metal levels among gulls nesting near the three underground nuclear test sites (Long Shot 1965, Milrow 1969, Cannikin 1971) on Amchitka, 3) There were no differences in metal levels among the three islands, and 4) There were no gender-related differences in metal levels. All four null hypotheses were rejected at the 0.05 level, although there were few differences among the three test sites on Amchitka. Eggs had the lowest levels of cadmium, lead, and mercury, and the feathers of adults had the lowest levels of selenium. Comparing only adults and fledglings, adults had higher levels of cadmium, chromium, lead and mercury, and fledglings had higher levels of arsenic, manganese and selenium. There were few consistent interisland differences, although levels were generally lower for eggs and feathers from gulls on Amchitka compared to the other islands. Arsenic was higher in both adult feathers and eggs from Amchitka compared to Adak, and chromium and lead were higher in adult feathers and eggs from Adak compared to Amchitka. Mercury and arsenic, and chromium and manganese levels were significantly correlated in the feathers of both adult and fledgling gulls. The feathers of males had significantly higher levels of chromium and manganese than did females. The levels of most metals in feathers are below those known to be associated with adverse effects in the gulls or their predators. However, levels of mercury in some gull eggs are within a range suggesting that several eggs should not be eaten in one day by sensitive humans.