Exposure of Canadian aboriginal peoples to methylmercury

Aboriginal peoples living a traditional lifestyle are potentially exposed to contaminants, such as methylmercury (MeHg), which bioaccumulate in aquatic ecosystems. A preliminary analysis of testing of Canadian indigenous people for MeHg from 1970 to 1992 is outlined. By December 1992,71,842 tests of 38,571 individuals had been carried out in 514 native communities across Canada. Of these, 8,847 individuals (23%) had blood, or blood equivalent, MeHg levels greater than 20 μg/l and 608 (1.6%) had levels over 100 μg/l. Clinical examinations were offered to all with levels greater than 100 μg/l in blood, but were unable to produce a definitive diagnosis. In an attempt to ascertain fetal exposure, 2,405 umbilical cord blood samples were taken. In about half of these cases the samples were paired with maternal levels. Of the cord samples 523 (21.8%) were found to have levels greater than 20 μg/l, and the highest level was 224 μg/l. The highest maternal level found was 86 μg/l. A discussion of the assessment of risk from exposure to MeHg in this population is presented as are the initial results of the 20 year retrospective analysis including seasonal exposure patterns and trends in exposure levels. Probable future intiatives based on this analysis are noted.     

广州市典型食用鱼类甲基汞含量及风险评估

通过分析广州市区居民消费量较大的7种淡水鱼和5种海水鱼肌肉中甲基汞（MeHg）含量,评估人体通过食鱼摄入MeHg的暴露风险。结果显示,广州市鱼体肌肉中MeHg含量范围为2.39～349μg·kg-1,平均含量为43.4μg·kg-1。不同食性鱼类MeHg含量水平依次为：肉食性〉杂食性〉草食性,处于食物链不同环节解释了这种含量差异。从生长环境来看,海水鱼肌肉的MeHg含量总体上高于淡水鱼。所有鱼中MeHg含量均低于国内外相关标准限值。与国内其他地区商品鱼相比,广州市商品鱼中MeHg含量相当,但明显低于野生鱼。居民通过食鱼摄入的MeHg范围为0.035～0.087μg·kg-1·d-（1bw）,均值为0.050μg·kg-1·d-（1bw）,远低于美国EPA规定的MeHg暴露参考剂量（RfD）值（1.1μg·kg-·1d-1）,也低于WHO和FAO制定的临时性周可承受摄入量（PTWI）（1.6μg·kg-1）。研究结果表明,广州居民食鱼MeHg暴露风险较小,但儿童等敏感人群食用特定鱼类的量和频次要引起一定注意。     

Geographic variation of strontium concentrations in orange leaves

Abstract

Very high (>7,000 μg g^‐1 d.w.) strontium (Sr) concentrations in orange leaves from a site in southwestern Florida raised the question of how common were these higher than previously reported levels. Five leaf samples each of which had been collected for nutritional diagnosis at the optimum sampling time at 22 locations in Florida and one each in Texas, Arizona, Mexico, Nicaragua, Brazil, and Argentina, were analyzed for Sr, calcium (Ca), and magnesium (Mg). High Sr levels in the leaves were limited to three sites in a narrow band across Florida between latitudes 27°00’ and 27°30’ N. Levels in the more northern locations tended to be lower (<100 μg g^‐1 d.w.) than at the southern sites. The out‐of‐state and foreign samples contained Sr in the 100 to 400 ug g^‐1 d.w. range reported from California.     

The role of dissolved organic carbon in the chemistry and bioavailability of mercury in remote Adirondack lakes

A number of recent studies have documented elevated concentrations of mercury (Hg) in fish caught in remote lakes and a pattern of increased concentrations of Hg in fish tissue with decreasing water column pH. Because of the potential linkage between fish Hg and surface water acidification, factors regulating water column concentrations and bioavailability of Hg were investigated in Adirondack lakes through a field study and application of the Mercury Cycling Model (MCM). Concentrations of total Hg and total MeHg were highly variable, with concentrations of total MeHg about 10% of total Hg in lakes which did not show anoxic conditions. In lakes exhibiting anoxic conditions in the hypolimnion during summer stratification, concentrations of total MeHg were elevated. Concentrations of total Hg and total MeHg increased with decreasing pH in remote Adirondack lakes. However, more importantly, concentrations of total Hg and total MeHg increased with increasing concentrations of dissolved organic carbon (DOC) and percent near-shore wetlands in the drainage basin. Mercury concentrations in muscle tissue of yellow perch from Adirondack lakes were elevated above the U.S. FDA action level (1 μg/g Hg) in 7% of the fish sampled or in one or more individual fish from 9 of the 16 lakes sampled. Fish Hg concentrations generally increased with increasing fish length, weight and age. Patterns of increasing Hg concentration with age likely reflect shifts in prey of yellow perch and the bioconcentration of Hg along the food chain. For age 3 to 5 perch, concentrations of Hg increased with increasing concentrations of DOC and percent near-shore wetlands in the drainage basin. However, for a lake with very high DOC concentrations, fish concentrations of Hg declined. Calculations with the MCM also show that concentrations of Hg species increase with increasing DOC due to complexation reactions. Increases in DOC result in increasing concentrations of Hg in biota but decreases in the bioconcentration factor of Hg in fish tissue. This research suggests that DOC is important in the transport of Hg to lake systems. High concentrations of DOC may complex MeHg, diminishing its bioavailability. At high concentrations of monomeric Al, the complexation of MeHg with DOC apparently decreases, enhancing the bioavailability of MeHg.     

Concentrations and amounts of methylmercury in water and fish in the limed and acid basins of a small lake

Three months after neutralization concentrations of methylmercury (MeHg) were higher in the water of the limed than in the control basin of a small lake. After two years, the concentrations in the limed basin were somewhat lower than in the control (0.056–2.19 ng L^?1 and 0.129–2.65 ng L^?1, respectively). The highest concentrations were found in the anoxic hypolimnia. The total amount of MeHg in the water mass of the lake varied from 19 to 68 mg, showing a drop after spring and autumn overturns and a maximum during stratification periods. The total Hg concentrations of fish in L. Iso Valkjärvi varied from 0.06 to 0.14 μg g^?1 (ww) in whitefish to 0.1 to 0.7 μg g^?1 in perch and to 0.2 to 1.4 μg g^?1 in pike. The total amount of MeHg bound in the fish of the lake was quite similar to that in the water column, 43 to 59 mg in 1990–1993, 33 to 47 mg of which was in the perch population.     

Mercury in zooplankton of Northern Wisconsin Lakes: taxonomic and site-specific trends

Mercury content and speciation were determined in freshwater zooplankton from twelve northern Wisconsin (USA) lakes that spanned gradients of dissolved organic carbon (DOC, 1.6 to 20.9 mg/L) and pH (4.6 to 7.2). MeHg in crustacean taxa ranged from 1 to 479 ng/g dry weight, and from 2 to 45 ng/g in the invertebrate predators. Total Hg in the predators ranged from 20 to 153 ng/g. Although the highest MeHg values were found in the herbivores from high DOC lakes (and the experimentally acidified basin of Little Rock Lake), we observed considerable variation in the relationship between MeHg content of zooplankton and lakewater DOC. Bioconcentration factors (BCF) for both MeHg (3.5 to 7.1 log units) and Hg (3.7 to 5.4 log units) decreased with increasing lake DOC, while pH effects were not as apparent. Bioconcentration of MeHg was higher than Hg indicating that MeHg increases while non-methyl Hg declines in progressively higher trophic levels. Biomagnification factors (BMF) for Hg and MeHg were low relative to BCF. The BMF for crustaceans averaged 0.4 log units for MeHg and ?0.5 log units for Hg, indicating that MeHg increased 2.5-fold from seston to crustacean herbivores, while non-MeHg concentrations declined. Unlike BCF, BMF were not related to DOC or pH. In contrast to studies of vertebrate predators, both BCF and BMF in the invertebrate predatorChaoborus, were lower than those in presumed prey. These observations point toward several complexities in the transport of Hg species in the lower levels of aquatic foodwebs.     

广州市兽用抗生素的环境残留研究

畜禽废物中的抗生素可造成土壤及水体的抗生素污染,利用高效液相色谱及高效液相色谱-串联质谱分析了广州市代表性养殖场畜禽废物、施用畜禽粪土壤和鱼塘水中尼卡巴嗪、喹乙醇、四环素类、磺胺类、喹诺酮类、氯霉素类抗生素的含量。结果发现：猪粪、鸡粪中抗生素含量最高的均为四环素类,分别为123.76、14.59 mg.kg-1;含量最低的均为氯霉素类,分别为2.35μg.kg-1、0.08 mg.kg-1;小猪猪粪中抗生素的含量明显高于大猪。鱼塘水中抗生素含量较高的是四环素（5.16μg.L-1）与磺胺对甲氧嘧啶（4.78μg.L-1）,土霉素在所有样点中均未被检出。施用禽畜粪土壤中四环素类、喹诺酮类含量较高,分别为70.40、49.77μg.kg-1;磺胺甲基嘧啶、磺胺对甲氧嘧啶、磺胺甲噁唑、甲砜霉素、氯霉素、喹乙醇均未被检出。粪样中的抗生素可导致土壤和水体的抗生素污染,TCs、QNs和NCZ可能对生态环境和人类健康安全的威胁更大。     

Seasonal space-use estimates of basking sharks in relation to protection and political-economic zones in the North-east Atlantic

The basking shark Cetorhinus maximus is listed as Vulnerable (A1a,d, + 2d) worldwide, and Endangered (EN A1a,d) in the north-east Atlantic in the IUCN Red List. However, protection for this species is limited in European waters and varies spatially. Without information on the amount of time individuals spend in different areas, any potential risks to population levels from incidental capture, possible future exploitation and climate change will be difficult to assess. To quantify the annual space-use patterns within political-economic zones in the north-east Atlantic we used geolocation data from seven transmitter-tagged basking sharks tracked for 964 days (16,754 km). Basking sharks tagged within the UK protection zone off south-west England and north-west Scotland spent subsequently only about 22% (range, 2.4-47.7%) of time at liberty within this zone, and a further 30% in the UK fishing zone. Although only about 6% of time was spent in the territorial waters of Ireland and France, basking sharks remained in UK, Irish and French fishing and EEZ zones for over 71% of track time (range, 51.4-89.2%). Sharks did not occupy International waters away from the European shelf at any time. These results indicate basking sharks move between different economic zones and were not afforded statutory protection for the major part of the time (78%) they spent within preferred habitat on the European shelf. This demonstrates the limited capacity of the British protection zone for encompassing the greater part of shark space utilisation. Tracked basking sharks regularly crossed national zone boundaries suggesting that conservation measures for this species need to be framed on a European, rather than national, basis. This study highlights the need for better information about the movements and habitat use by marine animals if conservation strategies are to be truly effective.     

Mercury speciation in Lake Baikal

Research on mercury (Hg) distribution and speciation was carried out in Lake Baikal, a large, strong-oligotrophic freshwater reservoir in Siberia, Russia, during June 1992 and march 1993. In summer, total Hg in the water column ranged from 0.14 to 0.77 ng Hg/L, with the highest concentrations observed in the central basin of the lake in surface water samples. Labile inorganic Hg was found to be 7 to 20 % of the total Hg content. Highest total Hg concentrations were found in river waters: up to 2 ng Hg/L. Labile methylmercury (MeHg) concentrations ranged from 2 to 38 pg Hg/L in the water column, with the higher concentrations in the central part of the lake, and showing a slight increase in near bottom waters. Labile MeHg makes up 1 to 15 % of the total Hg content in the water column, with larger fractions in deep waters. The slight increase of the MeHg gradient with depth corresponds with the O₂ minimum region. Highest MeHg concentrations were observed in river waters (up to 145 pg Hg/L) and in some bays of the lake (up to 160 pg Hg/L). In these high temperature- and phytoplankton-rich water masses, the MeHg-fraction increased up to 35 % of total Hg. Labile MeHg concentrations in water samples taken in winter in the southern basin (under the ice cover), showed slightly higher concentrations than in summer, possibly due to an early spring bloom. In rainwater, total Hg ranged from 3 to 20 ng Hg/L and MeHg from 0.1 to 0.25 ng Hg/L. In snow, a large fraction of total Hg is bound to particulate matter; concentrations of total Hg ranged from 8 to 60 ng Hg/L and labile MeHg from 0.1 to 0.25 ng Hg/L. Atmospheric Hg was found to be 0.73 to 2.31 ng/m³ as gaseous Hg and 0.005 to 0.02 ng/m³ in its particulate form. Spatial distribution patterns of atmospheric Hg show slightly higher concentrations over the central part of the lake and the Selenga river delta. In winter, atmospheric Hg values (measured in the southern region), ranged from 1.2 to 6.1 ng/m³ as total gaseous Hg and 0.02 to 0.09 ng/m³ as total particulate Hg, and are higher than in summer, probably influenced by coal burning and traffic by the local population. MeHg contents in fish ranged from 20 ng Hg/g dry weight in small Cottocomephorus to 300 ng Hg/g dry weight in pike and trout species, which were caught in organic-rich waters.     

Trace Elements in Fish Overlying Subaqueous Tailings in the Tropical West Pacific

From 1972–1989, Bougainville Copper Limited (BCL) dischargedmine tailings into Empress Augusta Bay on the west coast ofBougainville Island, Papua New Guinea. For a decade(1977–1987), trace elements (Cu, Pb, Zn, Cd, Hg and As) weremeasured in muscle tissue and organs of 8 species of tropicalmarine fish common to both the east and west coasts of theIsland. Metal concentrations were not elevated in muscle tissueof west fish compared with those from the east coast.Concentrations of Cu, Pb, Zn and Cd in fish muscle from bothcoasts ranged from 10–15% of recommended maximum residuelimits (MRLs), whereas concentrations of Hg in muscle wereslightly higher, ranging up to 80% of the MRL (0.5 mgkg^-1 Hg wet wt.). Maximum total As concentrations (3.6 mgkg^-1 wet wt.) were recorded in the shark (Rhizoprionodon acutus), while highest Hg values (0.76 mgkg^-1 wet wt.) were found in hammerhead sharks (Sphyrnalewini) from both coasts. Despite significant temporalvariations in Hg and As concentrations in muscle tissue of somewest coast fish populations (p < 0.05), there was no evidencefor bioaccumulation or biomagnification of any of these metalsduring the 10 yr period, even in the soft organs (liver andkidney) of fish. Several site specific factors contributing toabsence of metals uptake from tailings are discussed.     

天津污灌区水稻土壤汞形态特征及其食品安全评估

选择天津污水灌溉区作为研究区域,该文的主要研究目的是分析土壤不同形态汞对水稻不同组织中总（THg）和甲基汞MeHg富集的影响以及评估污灌区稻米食用汞暴露风险,并对污灌区土壤溶解与可交换态汞安全阀值进行了初步分析。结果表明,北塘、大沽和北京污灌区稻田土壤THg和MeHg浓度显著高于对照区海河土壤THg浓度。大沽、北京河污灌区和海河土壤汞的形态为残渣态浓度最高,而北塘污灌区为有机结合态浓度最高。由于水稻地上组织中THg浓度受到大气汞浓度影响,各组织中汞浓度在不同污灌区分布规律不同。水稻籽粒的 MeHg 富集系数为1.63～3.70,通过人体每天摄入MeHg量的安全值计算得出土壤溶解与可交换态汞质量分数应低于9.19 ng/g。污灌区食用稻米MeHg暴露对居民健康存在较大风险,人体MeHg每天摄入量超标率达到20.83%。因此,可以对超标土壤进行治理或改变耕作方式来降低土壤污染对人体MeHg暴露造成的影响。     

Lead, cadmium, and fluoride levels in market milk and infant formulas in Canada

Lead, cadmium, and fluoride were determined in 68 samples of market milk and about 115 infant formulas. Mean and median levels (ranges) in ng/g found for cow milk were as follows: lead, 1.12, 1.19 (0.01-2.48); cadmium, 0.10, 0.039 (0.005-0.74); and fluoride, 41, 40 (7-86). In canned, ready-to-use formulas, lead, cadmium, and fluoride levels averaged 37.3, 1.50, and 840 ng/g, respectively. In concentrated liquid formulas, the respective levels were 21, 3.54, and 600 ng/g. In powder formula concentrates, respective levels were 73.7, 6.78, and 1130 ng/g. On the basis of this study and literature data, lead levels in market milk exceeding 5 ng/g appeared to signify contamination of the milk either directly or via the cow. For formulas considered on an as-consumed basis, lead levels exceeding about 10-15 ng/g were attributed to contamination from either the can used to store the formula or the formula ingredients. Infant formulas in lead-free cans contained about 1.7 ng/g of lead on a ready-to-use basis. Milk-based formulas contained about 0.26 ng/g of cadmium on a ready-to-use basis. Soy-based or milk-free formulas contained about 8-15 times more cadmium than did milk-based formulas. Canadian and U.S. ready-to-use formulas contained 900 and 230 ng/g fluoride, respectively, and this difference was attributed to the level of fluoride in the processing water used by the manufacturers.     

Observations on metal concentrations in three species of shark (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstoni) from southeastern Australian waters

Deep sea dog sharks (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstonii) were captured from the waters off western Victoria, Australia, in April and May 1998. The elements As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, Sr, and Zn were detected in the muscle tissue. The concentrations of Al, Ba, Be, Cr, Mo, Ni, Pb, and V were below the detection limits of the instrumental techniques employed (ICP-ES and GF-AAS). However, significant concentration differences between species were detected for As, Cd, Hg, and Zn. C. owstoni contained the highest concentrations of each of these elements. The concentrations of Cu, Pb, and Zn in each species were below the maximum levels permitted in food by the Australian Food Standards Code. The maximum permitted concentrations of As and Hg were exceeded in all species, and weekly consumption of 400 g of any of these sharks would result in intake of more than the FAO's provisional tolerable weekly intake. Although C. crepidator and D. calcea have strong relationships between length and mercury concentration, C. owstoni does not. Placing C. crepidator and C. owstoni in the same genus, therefore, is worth re-examination as the mechanisms for controlling mercury in C. owstoni appear to differ from that used by both C. crepidator and D. calcea.     

Human exposure to mercury due to goldmining in the Tapajos River basin,Amazon, Brazil: Speciation of mercury in human hair,blood and urine

To obtain the basic information on human exposure to mercury (Hg) due to gold mining activities in Amazon, total mercury (T-Hg) and methylmercury (MeI Ig) were determined for human hair, blood and/or urine samples collected from populations living in gold mining area and fishing villages upstream of the Tapajos River basin. Abnormally high levels of T-Hg were observed in hair and blood from all fishing villages investigated and more than 90% of T-Hg was in the form of MeHg in both samples, whereas in goldrnining area the value were much lower and the %MeHg values varied widely (20–100%) with individuals even in blood samples. Urine from gold shop workers contained Hg mostly in inorganic form at 165μg/g creatinine on the average, with the range of 20 to 450μg/g creatinine. A good correlation between Hg in hair and blood was found in fishing villages and the ratios of hair Hg to blood Hg were very close to 250, generally established for MeHg. T-Hg and inorganic Hg levels in urine from gold shop workers were also significantly correlated with inorganic Hg in blood.     

Mercury exposure in humans through food consumption from the Everglades of Florida

In March 1989, The Florida Department of Health and Rehabilitative Services (HRS) issued a Health Advisory recommending the limited consumption of several fish species caught from the Everglades region of South Florida due to elevated methylmercury (MeHg) levels (average 2–3 ppm in fish meat). There were no reports of clinical MeHg poisoning in humans in Florida, although deaths of Florida panthers were attributed to mercury (Hg). poisoning. This study evaluated the extent of MeHg exposure in persons eating contaminated fish in the Everglades region. Populations at risk were identified including sport fishermen, Everglades Residents and subsistence fishermen. Over 1700 individuals were approached; those who had eaten fish or wildlife from the contaminated areas at least once/month for the prior three months were asked to participate. Three hundred and fifty (350) participants completed a brief questionnaire and provided a hair sample for Hg analysis. In 119 (36%) of individuals with levels above the limits of detection, the mean total Hg in hair was 3.62±3.0μg/g [± standard deviation] with a range of 1.28 – 15.57. The most at risk populations identified with respect to Hg levels were Blacks and men. Although the majority of the participants had fished in the Everglades for many years (>15 years), they reported relatively low intake of fish and had low hair Hg levels compared with similar populations in prior studies of other populations at risk. Although 71% of participants knew of the State Health Advisories concerning ingestion of Hg contaminated fish from the Everglades, this did not change their consumption habits. In addition, Blacks, individuals of lower income and of lower education levels were less likely to know about the Health Advisories. Given recent studies of neurologic effects from relatively low in utero MeHg exposure, the continuation of the Mercury Health Advisories and wildlife monitoring in the Everglades are warranted, especially for women of childbearing age and children. However, public education must be targeted for the populations at risk identified in this study in order to reach these populations more effectively.     

Survey of mycotoxins in U.S. distiller's dried grains with solubles from 2009 to 2011

Distiller's dried grains with solubles (DDGS) is a major coproduct of the fuel-ethanol industry and is becoming a popular low-cost ingredient for animal feed. Uncertainties regarding the risk factors in DDGS, such as level of mycotoxins, could limit its application in the animal feed industry. To provide a scientifically sound assessment of the prevalence and levels of mycotoxins in U.S. DDGS, we measured aflatoxins, deoxynivalenol, fumonisins, T-2 toxin, and zearalenone in 67 DDGS samples collected from 8 ethanol plants in the midwestern United States from 2009 to 2011. Among the five mycotoxins, deoxynivalenol was the main focus of the study because the crop year of 2009 was favorable for deoxynivalenol occurrence in corn. We learned that no more than 12% of the samples contained deoxynivalenol levels higher than the minimum advisory level for use in animal feed provided by the U.S. FDA, and the deoxynivalenol levels in all DDGS collected in 2011 were <2 mg/kg. Besides, intensive study showed that the enrichment of deoxynivalenol from contaminated corn to DDGS was about 3.5 times. With regard to the other mycotoxins in DDGS, the study suggested that (1) almost none of the DDGS samples produced in 2010 contained detectable aflatoxins and the highest level of aflatoxins in DDGS was 5.7 μg/kg; (2) no more than 6% of the samples contained fumonisin levels higher than the guidance level for feeding equids and rabbits provided by the U.S. FDA; (3) none of the samples contained T-2 higher than the detection limit; (4) most samples contained zearalenone levels between 100 and 300 μg/kg. This study was based on representative DDGS samples from the U.S. ethanol industry, and the data were collected using state-of-the-art analytical methodology. This study provided a comprehensive and scientifically sound assessment of the occurrence and levels of mycotoxins in DDGS produced from 2009 to early 2011 by the U.S. ethanol industry.     

Soil lead concentrations in residential Minnesota as measured by ICP-AES

A total of 2454 samples were collected to evaluate the degree, extent, and distribution of Pb contaminated soil in Minnesota. Samples were collected primarily at locations where susceptible populations were concentrated. Soil Pb concentrations in chilldren's play areas, urban gardens, and at open sites were generally below 100 μg g ^?1 when Pb painted structures were absent. Street side and yard soils typically had Pb concentrations between 10 to 300 μg g^?1, with samples collected near major highways or Pb painted structures exhibiting greater values. The most severely contaminated soils were found in localized areas around the foundations of private residences, where concentrations up to 20 136 μg g^?1 were detected. Exterior Pb based house paint is the major Pb source in these soils, and its presence greatly influences the distribution of contaminated soil in individual yards. Contamination attributable to autoemissions is less concentrated but more widespread than contamination from paint. A higher proportion of soils exceeding 1000 wg g^?1 Pb was found in large cities than elsewhere. However, a sufficient number were detected in small cities and rural areas to confirm that high soil Pb levels are not exclusively an urban phenomenon. By examining the degree, extent, and distribution of Pb contaminated soils in Minnesota, this study provides information useful in guiding response actions to reduce children's exposure to Pb by this pathway.     

Multielement concentrations in liver and kidney tissues from five species of Canadian slaughter animals

The present paper describes results of a national survey conducted between 1982 and 1989 to determine residues of arsenic, cadmium, copper, mercury, lead, selenium, and zinc in Canadian slaughter animals. Liver and kidney tissues from cattle, swine, poultry, horses, calves, and sheep were tested. Arsenic was found in most avian and porcine samples, and their respective means of 0.36 and 0.26 micrograms/g in liver were 7 to 12 times higher than mean concentrations found in the other species. Cadmium was found in the tissues of all species; however, levels were consistently highest in equine samples with mean values of 3.09 and 27.7 micrograms/g in liver and kidney, respectively. Copper levels greater than 150 micrograms/g were found predominantly in liver from calves and sheep, with values considerably lower in the remaining species. Mercury levels were low or not detected in all species except horses. Ninety % of equine kidneys and 54% of equine livers had mercury concentrations greater than 0.01 microgram/g, with mean values of 0.18 and 0.06 microgram/g, respectively. Lead was found in tissues of all species; however, values greater than 2 micrograms/g were found only in 2 kidneys from adult cattle and 1 kidney from a horse. Selenium, tested only in cattle, was found at mean concentrations of 0.28 microgram/g in liver, and 0.92 microgram/g in kidney. Relatively high zinc levels were found in livers of horses, pigs, and calves, with respective mean concentrations of 67.3, 65.6, and 70.2 micrograms/g.     

Decline in whale shark size and abundance at Ningaloo Reef over the past decade: The world’s largest fish is getting smaller

Over-exploitation of whale sharks threatens the future of these wide-ranging pelagic fish. A long-term continuous record (4436 sightings) from a large aggregation (300-500 resident individuals) of whale sharks at Ningaloo Reef, Western Australia shows that mean shark length declined linearly by nearly 2.0 m and relative abundance measured from ecotourism sightings (corrected for variation in search effort and environmental stochasticity) has fallen by approximately 40% over the last decade. This population-level result confirms previous predictions of population decline based on projection models parameterised using mark-recapture estimates of survival. The majority of these changes are driven by reductions in the number of large individuals in the population. Phenomenological time series models support a deterministic (extrinsic) decline in large females, although there was some evidence for density dependence in large males. These reductions have occurred despite the total protection of whale sharks in Australian waters. As this species is highly migratory, the rapid change in population composition over a decade (<1 whale shark generation) supports the hypothesis of unsustainable mortality in other parts of their range (e.g., overfishing), rather than the alternative of long-term abiotic or biotic shifts in the environment. As such, effective conservation of whale sharks will require international protection, and collaborative tagging studies to identify and monitor migratory pathways.     

Distribution of Fusarium Molds and Fumonisins in Dry-Milled Corn Fractions

The distribution of Fusarium molds and fumonisins was determined in commercial and experimental dry-milled corn fractions. Fusarium infection of the commercial whole corn samples ranged from 10 to 28%; F. moniliforme was the predominant species. Fusarium counts in corn fractions were <100 colony-forming units (CFU)/g in flaking grits, <100 - 6.4 × 10⁴ CFU/g in bran, <100 − 1.6 × 10⁴ CFU/g in germ, and <100 − 2.7 × 10³ CFU/g in flour. Fumonisin concentrations were ≤0.1 μg/g in flaking grits, 0.2–1.1 μg/g in flour, 0.1–2.0 μg/g in germ, and 1.5–3.2 μg/g in bran. Yellow, blue, and white dent corns naturally contaminated with varying levels of fumonisins (25.4, 3.9, and 0.3 μg of fumonisin B₁ per gram) and Fusarium molds (3.9 × 10⁶, 8.0 × 10⁵, and 2.6 × 10⁴ CFU/g) were experimentally dry milled with a horizontal drum degermer. Number 5 grits contained significantly lower Fusarium counts and fumonisin concentrations than the whole kernel corn. Fusarium counts and fumonisins increased as grit size decreased, and high Fusarium counts and fumonisin concentrations were found in germ, bran, and fines.