Factors influencing mercury exposure in Arctic-breeding shorebirds.

Mercury (Hg) pollution remains a concern to Arctic ecosystems, due to long-range transport from southern industrial regions and melting permafrost and glaciers. The objective of this study was to identify intrinsic, extrinsic, and temporal factors influencing Hg concentrations in Arctic-breeding shorebirds and highlight regions and species at greatest risk of Hg exposure. We analyzed 1094 blood and 1384 feather samples from 12 shorebird species breeding at nine sites across the North American Arctic during 2012 and 2013. Blood Hg concentrations, which reflect Hg exposure in the local area in individual shorebirds: 1) ranged from 0.01-3.52 µg/g ww, with an overall mean of 0.30 ± 0.27 µg/g ww; 2) were influenced by species and study site, but not sampling year, with birds sampled near Utqiagvik, AK, having the highest concentrations; and 3) were influenced by foraging habitat at some sites. Feather Hg concentrations, which reflected Hg exposure from the wintering grounds: 1) ranged from 0.07-12.14 µg/g fw in individuals, with an overall mean of 1.14 ± 1.18 µg/g fw; and 2) were influenced by species and year. Most Arctic-breeding shorebirds had blood and feather Hg concentrations at levels where no adverse effects of exposure were predicted, though some individuals sampled near Utqiagvik had Hg levels that would be considered of concern. Overall, these data increase our understanding of how Hg is distributed in the various shorebird breeding areas of the Arctic, what factors predispose Arctic-breeding shorebirds to Hg exposure, and lay the foundation for future monitoring efforts.

Continuous exposure to mercury during embryogenesis and chick development affects later survival and reproduction of zebra finch (Taeniopygia guttata).

Methylmercury (MeHg) is a global environmental contaminant that bioaccumulates and has multiple toxic modes of action. Aquatic species have traditionally been the focus of wildlife toxicological research on mercury, but terrestrial organisms, including passerine birds, can be exposed to similarly elevated levels of MeHg. In this study we exposed a model passerine, the zebra finch (Taeniopygia guttata), to MeHg in ovo, as chicks only, or with a combined 'in ovo + chick' treatment. We isolated exposure to specific developmental stages through the use of egg injections (3.2 µg Hg/g egg) and controlled oral dosing of chicks (0.24 µg Hg/g bw/day from day 1 to day 30). In ovo exposure to MeHg reduced hatching success, but there was no effect of MeHg on chick growth. We found that in ovo only or chick only exposure did not have long-term effects, but there was some evidence for longer-term effects of combined 'in ovo + chick' exposure on post-fledging survival and potentially sex-biased survival which resulted in very few 'in ovo + chick' exposed females surviving to breed. These females also had lower overall breeding productivity that was mainly due to lower hatching success of their offspring, not lower chick-rearing success. We found no effect of treatment on clutch size or latency to laying among females that did lay eggs. Our study suggests that combined embryonic and nestling MeHg exposure has compounding latent effects on productivity, likely through a mechanism that influences the ability of females to lay fertile eggs that hatch.

Ultraviolet-assisted oiling assessment improves detection of oiled birds experiencing clinical signs of hemolytic anemia after exposure to the Deepwater Horizon oil spill.

While large-scale oil spills can cause acute mortality events in birds, there is increasing evidence that sublethal oil exposure can trigger physiological changes that have implications for individual performance and survival. Therefore, improved methods for identifying small amounts of oil on birds are needed. Because ultraviolet (UV) light can be used to identify thin crude oil films in water and on substrate that are not visually apparent under normal lighting conditions, we hypothesized that UV light could be useful for detecting small amounts of oil present on the plumage of birds. We evaluated black skimmers (Rynchops niger), brown pelicans (Pelecanus occidentalis), clapper rails (Rallus crepitans), great egrets (Ardea alba), and seaside sparrows (Ammodramus maritimus) exposed to areas affected by the Deepwater Horizon oil spill in the Gulf of Mexico as well as from reference areas from 20 June, 2010 to 23 February, 2011. When visually assessed without UV light, 19.6% of birds evaluated from areas affected by the spill were determined to be oiled (previously published data), whereas when examined under UV light, 56.3% of the same birds were determined to have oil exposure. Of 705 individuals examined in areas potentially impacted by the spill, we found that fluorescence under UV light assessment identified 259 oiled birds that appeared to be oil-free on visual exam, supporting its utility as a simple tool for improving detection of modestly oiled birds in the field. Further, UV assessment revealed an increase in qualitative severity of oiling (approximate % of body surface oiled) in 40% of birds compared to what was determined on visual exam. Additionally, black skimmers, brown pelicans, and great egrets exposed to oil as determined using UV light experienced oxidative injury to erythrocytes, had decreased numbers of circulating erythrocytes, and showed evidence of a regenerative hematological response in the form of increased reticulocytes. This evidence of adverse effects was similar to changes identified in birds with oil exposure as determined by visual examination without UV light, and is consistent with hemolytic anemia likely caused by oil exposure. Thus, UV assessment proved useful for enhancing detection of birds exposed to oil, but did not increase detection of birds experiencing clinical signs of anemia compared to standard visual oiling assessment. We conclude that UV light evaluation can help identify oil exposure in many birds that would otherwise be identified visually as unexposed during oil spill events.

Historical patterns in mercury exposure for North American songbirds.

Methylmercury (MeHg) is a global environmental contaminant that poses significant risks to the health of humans, wildlife, and ecosystems. Assessing MeHg exposure in biota across the landscape and over time is vital for monitoring MeHg pollution and gauging the effectiveness of regulations intended to reduce new mercury (Hg) releases. We used MeHg concentrations measured in museum specimen feathers (collected between 1869 and 2014) and total Hg concentrations (as a proxy for MeHg) of feathers sampled from wild birds (collected between 2008 and 2017) to investigate temporal patterns in exposure over approximately 150 years for North American songbirds. For individual species, we found greater concentrations for samples collected post-2000 compared to those collected during historic times (pre-1900) for six of seven songbird species. Mean feather concentrations measured in samples collected post-2000 ranged between 1.9 and 17 times (mean 6.6) greater than historic specimens. The proportion of individual songbirds with feather concentrations that exceeded modeled toxicity benchmarks increased in samples collected after 1940. Only 2% of individual songbirds collected prior to 1940 had feather concentrations greater than 2.4 µg/g (a toxicity benchmark related to a 10% decrease in nest success) compared to 35% of individuals collected post-1940. Many species included in this study have a vulnerable or near-threatened conservation status, suggesting recovery actions are needed to address mercury pollution.

Development and application of a novel method to characterize methylmercury exposure in newborns using dried blood spots.

BACKGROUND: Methylmercury (MeHg) is a pollutant of global concern. While there is a need to gauge early-life exposures, there remain outstanding ethical, financial, and practical challenges with using the preferred biomarker, whole blood, notably in pregnant women, infants, toddlers, and children. Dried bloodspots (DBS) may help overcome some of these challenges. Notably DBS are collected from newborns in many jurisdictions offering an institutionalized platform to efficiently characterize exposures. OBJECTIVE: To develop, validate, and apply a new method to measure MeHg levels in DBS with a specific aim to use this method to increase understanding of newborn exposures. METHODS: Method development and validation was pursued by consulting U.S. EPA Method 1630 and other resources. The method was applied to measure MeHg levels in DBS from newborns (n = 675) from the Michigan BioTrust for Health program. RESULTS: The assay's detection limit (0.3µg/L), accuracy (96-115% of expected), precision, linearity, and range met performance criteria guidelines. In the newborn DBS samples, the mean (SD) and geometric mean values of MeHg were 1.46 (0.90) and 1.25µg/L respectively, and ranged from 0.09 to 9.97µg/L. The values we report here are similar to cord blood mercury values reported elsewhere. CONCLUSIONS: This is the first characterization of MeHg exposure in newborns, and thus fills an important data gap as prior studies have focused on pregnant women, cord blood, or toddlers. This method helps overcome technical challenges associated with other proposed approaches, and moving ahead there is great promise for applying this DBS-based method for population-level surveillance, particularly in resource-limited settings and for children's health.

Dried blood spots for estimating mercury exposure in birds.

Mercury (Hg) is a pervasive environmental contaminant that can impair avian health, consequently there is a need to gauge exposures. Bird blood provides a measure of recent dietary exposure to Hg, but blood collection and storage can be complex and costly. Dried blood spots (DBS) may help overcome challenges of whole blood analyses, therefore, this study aimed to develop and validate a novel method to assess Hg exposure in birds using DBS. First, accuracy and precision of blood Hg concentrations for entire DBS and DBS punches were determined for white leghorn chicken (Gallus gallus domesticus) dosed with methylmercury (MeHg) via egg injection. Next, we investigated Hg stability in chicken DBS subjected to time, temperature, and humidity treatments. Lastly, we applied the method to DBS created using standard field methods from zebra finch (Taeniopygia guttatato) in the laboratory and American golden-plover (Pluvalis dominica) sampled in the field. All samples were analyzed for total Hg (THg) using direct Hg analysis. Accuracy was determined by comparing DBS concentrations with those of corresponding whole blood and reported as percent recovery. Accuracy for entire chicken DBS was 101.8 ±â€¯5.4%, while DBS punches revealed lower recovery (87.7 ±â€¯4.0 to 92.4 ±â€¯4.1%). There was little effect of time, temperature, and humidity storage treatments on Hg concentrations of DBS, with mean DBS THg concentrations within ±8% of whole blood (n = 10 treatments). For zebra finch, DBS punches were more accurate (93.7 ±â€¯9.7%) compared to entire DBS (126.8 ±â€¯19.4%). While for American golden-plover, entire DBS resulted in the most accurate THg concentrations (111.5 ±â€¯7.6%) compared to DBS punches (edge: 115.4 ±â€¯18.9%, interior: 131.4 ±â€¯16.1%). Overall, results indicate that DBS analysis using direct Hg analysis can accurately evaluate Hg exposure in birds.

Mercury speciation and subcellular distribution in experimentally dosed and wild birds.

Many bird species are exposed to methylmercury (MeHg) at levels shown to cause sublethal effects. Although MeHg sensitivity and assimilation can vary among species and developmental stages, the underlying reasons (such as MeHg toxicokinetics) are poorly understood. We investigated Hg distribution at the tissue and cellular levels in birds by examining Hg speciation in blood, brain, and liver and Hg subcellular distribution in liver. We used MeHg egg injection of white leghorn chicken (Gallus gallus domesticus), sampled at 3 early developmental stages, and embryonic ring-billed gulls (Larus delawarensis) exposed to maternally deposited MeHg. The percentage of MeHg (relative to total Hg [THg]) in blood, brain, and liver ranged from 94 to 121%, indicating little MeHg demethylation. A liver subcellular partitioning procedure was used to determine how THg was distributed between potentially sensitive and detoxified compartments. The distributions of THg among subcellular fractions were similar among chicken time points, and between embryonic chicken and ring-billed gulls. A greater proportion of THg was associated with metal-sensitive fractions than detoxified fractions. Within the sensitive compartment, THg was found predominately in heat-denatured proteins (∼42-46%), followed by mitochondria (∼15-18%). A low rate of MeHg demethylation and high proportion of THg in metal-sensitive subcellular fractions further indicates that embryonic and hatchling time points are Hg-sensitive developmental stages, although further work is needed across a range of additional species and life stages. Environ Toxicol Chem 2017;36:3289-3298. © 2017 SETAC.

Multiple elemental exposures amongst workers at the Agbogbloshie electronic waste (e-waste) site in Ghana.

Electronic waste (e-waste) recycling is growing worldwide and raising a number of environmental health concerns. One of the largest e-waste sites is Agbogbloshie (Ghana). While several toxic elements have been reported in Agbogbloshie's environment, there is limited knowledge of human exposures there. The objectives of this study were to characterize exposures to several essential (copper, iron, manganese, selenium, zinc) and toxic (arsenic, cadmium, cobalt, chromium, mercury, nickel, lead) elements in the urine and blood of male workers (n = 58) at Agbogbloshie, as well as females (n = 11) working in activities that serve the site, and to relate these exposures to sociodemographic and occupational characteristics. The median number of years worked at the site was 5, and the average worker indicated being active in 6.8 tasks (of 9 key e-waste job categories). Additionally, we categorized four main e-waste activities (in brackets % of population self-reported main activity): dealing (22.4%), sorting (24.1%), dismantling (50%), and burning (3.4%) e-waste materials. Many blood and urinary elements (including essential ones) were within biomonitoring reference ranges. However, blood cadmium (1.2 µg/L median) and lead (6.4 µg/dl; 67% above U.S. CDC/NIOSH reference level), and urinary arsenic (38.3 µg/L; 39% above U.S. ATSDR value) levels were elevated compared to background populations elsewhere. Workers who burned e-waste tended to have the highest biomarker levels. The findings of this study contribute to a growing body of work at Agbogbloshie (and elsewhere) to document that individuals working within e-waste sites are exposed to a number of toxic elements, some at potentially concerning levels.