Twenty years of melanoma in Victoria,Queensland, and South Australia (1997 – 2016)

BackgroundGiven the high incidence of melanoma in Australia alongside high mortality with later stage disease, we investigated the populations and locations most at risk, to optimise public health activities in areas where intervention is most needed. This study examines trends and identifies significant prognostic factors and potential disparities in incidence, mortality and survival between population groups in Victoria, Queensland and South Australia.MethodsThe analysis includes data from the population-based cancer registries of the three states over a twenty-year period (1997–2016). Age-standardized and age-specific incidence rates were calculated, and long-term trends analysed using Joinpoint Regression. Five-year relative survival estimates for the study population were calculated using the cohort method and multivariable flexible parametric survival models were applied for each jurisdiction to calculate adjusted excess mortality hazard ratios for the key characteristics.ResultsThere were more males with melanoma than females in all the three states. Over 60% of the cases occurred in the 40–74 years age group. Most melanomas had a Breslow thickness less than or equal to 1.0 mm. For males, Victoria and Queensland had a statistically significant increasing trend whereas in South Australia there was a decreasing trend. For females, the incidence rate trend was stable in Victoria but significantly decreasing in South Australia. In Queensland there was an increasing and statistically significant trend from 2006 to 2016. Across all three states there was a reducing incidence rate in the youngest cohort, stabilizing incidence in the 40–59-year-old age group, and increasing in the oldest cohorts. Five-year relative survival decreased with increasing age and with Breslow thickness across all three jurisdictions. Males had between 43%− 46% excess mortality compared to females in all the three states. There was higher risk with increasing age and Breslow thickness, with the largest risk among the 75 + age group and those with a Breslow thickness of > 4 mm.ConclusionIt is the first time that data from these three registries has been analysed together in a uniform way, covering more than half of the Australian population. This study compares the epidemiology of melanoma across three states and provides a better understanding of trends and factors affecting outcome for Australians with melanoma. While there has been some improvement in aspects of incidence and mortality, this has not been evenly achieved across Australia.     

The mercury binding activity of pectin isolated from the seagrass Zostera marina

The kinetics of mercury binding by pectin isolated from the seagrass Zostera marina was described, and its maximum mercury binding activity at pH from 2.0 up to 6.0 was determined. It was shown that mercury binding by pectin in in vitro conditions did not depend on concentration of hydrogen ions in the environment. The maximum mercury binding activity estimated from the Langmuir equation was 2.64 mmol/g of dry mass of the pectin.     

Changes in circadian LH-secretion patterns and annual gonadal cycles in the male European starling ( Sturnus vulgaris )

An analysis of the circadian and circannual patterns of luteinizing hormone (LH) secretion in male European starlings (Sturnus vulgaris) held in outdoor aviaries is presented. On the basis of six daily time points, eight calendar dates, and seven individuals per sampling unit, we present a mathematical model developed to compare the two temporal patterns of secretion, the circadian and the circannual one. The superposition of four orthonormal trigonometric base functions, plus a constant, is used to examine the daily fluctuations. The contribution of the second harmonic was not the same at each calendar date. From the subsequent regression functions, hourly estimates of LH concentration were calculated and used to construct circannual cubic splines and an LH(t,T) function over the whole year. The model features indicate strong circannual and circadian components in the data. In addition, there appear to be two daily time regions of LH secretion: morning and afternoon. In particular, the afternoon maxima occur during photorefractoriness and early gonadal development; the morning maxima at the onset of photoinduction and late gonadal development. At the peak of gonadal activity (end of April), the highest LH levels occur during the photic input phase. It appears, then, that the circadian acrophase of LH secretion in male starlings fluctuates over the annual cycle of gonadal activity in a highly predictive and biologically interpretable manner. John Dittami and Hermann Prossinger: both authors contributed equally.     

Influence of Mercury on the Green Alga Haematococcus lacustris. Inhibition Effects and Recovery of Impact

The influence of mercury ions on germination of the resting cells (aplanospores) and on cell division, cell structure, phototaxis, and photosynthesis during the flagellate stage of Hoemotococcus lacustris was investigated. Aplanospores possess a higher tolerance against mercury ions than flagellates. The reason could be seen in the thicker wall of the resting cells which possibly provide a detoxifying effect by immobilisation of Hg²⁺. This is confirmed by a normal phototactic orientation of flagellates formed from Hg ²⁺-influenced aplanospores. In contrast, a direct addition of Hg²⁺ (0.1 to 1 /*M) to the flagellate stage induced an immediate loss of the flagellates to react phototactically, but it was interesting that the inhibition was overcome with time. Obviously, these Hg²⁺ concentrations influence only the sensory transduction chain, whereas the energetic background is not injured because the velocity of movement and the percentage of motile cells were scarcely affected. This is supported by the high level of the photochemical efficiency of photosystem II, which remains unchanged at 1 uM Hg²⁺. Recovery of photosynthesis from inhibition by 10/iM Hg²⁺ suggests a connection between Hg²⁺ influence and metabolism of the D, protein in the reaction centre of photosystem II. The Hg²⁺ effect was reversed with time in light, but not in darkness, and streptomycin, an inhibitor of chloroplast protein synthesis, prevented recovery. In flagellates, showing no reactivation, exposure to 10uA/l Hg²⁺ caused cell swelling, a loss of the flagella, and a disorganisation in structure of the chloroplast and of nucleus.     

Screening Evaluation of the Ecological Risks to Terrestrial Wildlife Associated with a Coal Ash Disposal Site

Between 1955 and 1989, coal ash was deposited within an impounded watershed on the U.S. Department of Energy's Oak Ridge Reservation in Tennessee, creating the 3.6?ha Filled Coal Ash Pond (FCAP). The site has subsequently become vegetated wildlife habitat. To evaluate risks that metals in ash may pose to wildlife; ash, surface water, small mammal, and vegetation samples were collected and metal residues were determined. Metal concentrations, As and Se in particular, were elevated in ash, surface water, plant foliage, and small mammals relative to reference materials. Estimates of metal exposures were calculated for short-tailed shrews, white-footed mice, white-tailed deer, red fox, and red-tailed hawks. While shrews and mice were assumed to reside exclusively at and receive 100% exposure from the site, exposure experienced by deer, fox, and hawks was assumed to be proportional to the size of the site relative to their home range. Because deer had been observed to consume ash, presumably for its high sodium content, exposure experienced by deer consuming ash to meet sodium requirements was also estimated. Exposure estimates were compared to body-size adjusted toxicity data for each metal. These comparisons suggest that metals at the site may be detrimental to reproduction and survivorship of mice, shrews, and deer consuming ash for sodium; fox and hawks do not appear to be at risk     

Interaction of bacteria with mercuric compounds

We investigated the interaction of mercuric compounds with the bacteriaCorynebacterium ammoniagenes, Micmcoccus luteus, andMycobacterium smegmatus capable of producing hydroxy lamines (R-NOH) and 2-C-methyl-D-erythritol-2,4-cyclopvrophosphate (MECP), which are prone to form free radicals. The interaction of these substances with Hg²⁺ ions and their dynamics during the mercuric poisoning of bacteria was studied by EPR and NMR. Under stress conditions induced by lowering pH or generation of active oxygen species, the bacteria and, especially, their mutants with enhanced sensitivity to oxidative stress, were found to respond to exposure to 1–3 μ/ml HgCl₂ andp-chloromercuribenzoate by a several-fold increase in their viability. The data obtained were interpreted in terms of the involvement of the sulfhydryl groups of bacterial surface proteins in this phenomenon. The interaction of bacteria with mercuric compounds may affect the pathogenesis of tuberculosis and other diseases.     

Occurrence and transformation of mercury in formerly contaminated soils due to operation of amalgamation techniques and assessment of consequences

Abstract

Soils formerly contaminated with mercury due to the implementation of amalgamation processes at two localities in the Czech Republic were analyzed to assess the impact of such contamination on both the environment and human health. One site is an abandoned gold mine at Lib?ice, where, in the past, gold was extracted from the raw ore by the mercury amalgamation technique. The second site is the environs of a small building in Prague where dental surgery was formerly undertaken. Soils were tested for total mercury (T-Hg), elemental mercury (Hg⁰), methylmercury (MeHg⁺), phenylmercury (PhHg⁺), and gaseous elemental mercury (GEM). The T-Hg concentrations in both localities exceeded many times the maximum permissible limit for soils in the Czech Republic. The most contaminated soils were found around the dental surgery releasing GEM at concentrations of up to 1308?ng m^?3, which can represent a danger mainly for people through inhalation. Soils near the abandoned gold mine release GEM at concentrations of up to 26?ng m^?3, which indicates a long-term burden on the environment and a danger for surrounding farmland.     

Comparison of dietary mercury exposure in two sympatric top predator fishes, largemouth bass and northern pike: a bioenergetics modeling approach

Physical and ecologicalfactors, including lake temperature, fishphysiology, and diet, influence methylmercury(MeHg) exposure in fish. We employedbioenergetics modeling to compare dietary MeHgexposure in sympatric top predators, largemouthbass (Micropterus salmoides) and northernpike (Esox lucius). We comparedsimulations using field data to hypotheticalsimulations with (1) ± 25% change in meandaily lake temperature for juvenile and adultbass and pike; (2) ± 25% change inlong-term growth rate of pike; (3) adult bassdiet shift from generalist predator to strictpiscivore. Bass and pike MeHg exposures weresimilar in baseline simulations and reflectedpatterns in field tissue concentrations. Thisoccurred despite the fact that bass consumedhighly contaminated benthic invertebrates,while pike exclusively consumed lesscontaminated fish prey. Higher temperaturesincreased adult bass and pike MeHg exposures by35% and 27%, respectively. Shifting adultbass diets to 100% fish resulted in a 54%decrease in exposure, while increasing pikegrowth rates resulted in a 24% decrease. Bioenergetics modeling proved useful inunderstanding the influence of temperature,prey-base, and predator growth on differencesin Hg exposure across fish species.     

Mercury Toxicity and the Mitigating Role of Selenium

Mercury is a well-known environmental toxicant, particularly in its most common organic form, methylmercury. Consumption of fish and shellfish that contain methylmercury is a dominant source of mercury exposure in humans and piscivorous wildlife. Considerable efforts have focused on assessment of mercury and its attendant risks in the environment and food sources, including the studies reported in this issue. However, studies of mercury intoxication have frequently failed to consider the protective effects of the essential trace element, selenium. Mercury binds to selenium with extraordinarily high affinity, and high maternal exposures inhibit selenium-dependent enzyme activities in fetal brains. However, increased maternal dietary selenium intakes preserve these enzyme activities, thereby preventing the pathological effects that would otherwise arise in their absence. Recent evidence indicates that assessments of mercury exposure and tissue levels need to consider selenium intakes and tissue distributions in order to provide meaningful risk evaluations.     

Use of Indicators in Ecological Risk Assessments for Persistent,Bioaccumulative Toxicants

This paper synthesizes several presentations on the use of indicators in ecological risk assessments for persistent, bioaccumulative toxicants (PBTs). The presentations were organized around two chemical case studies: (1) mercury, and (2) compounds that exhibit an Ah-receptor based mode-of-action. Presenters summarized the current practice of ecological risk assessment for these compounds and described research on known or suspected impacts. In addition, this paper addresses three special topics that apply broadly to all PBTs: (1) the convergence of ecological assessment and ecological risk assessment, (2) integration of ecological and human health risk assessment, and (3) risk assessments for population-level effects.