Changing patterns of mortality seasonality among the western James Bay Cree

Anglican Church of Canada burial records from 1851-1964 for the Moose Factory First Nation are analysed for mortality seasonality. The 113-year study period is subdivided into three death cohorts (1851-1906, 1914-1945 and 1946-1964) that broadly reflect the late 19th century, early 20th century, and the post-WWII periods, respectively. The data are partitioned into three age groups: infants (< 1), children (1-14), and adults (15+) to determine whether the hazards of death by season varied by age. The results show a clear and statistically significant pattern of seasonal mortality in the 19th century cohort for all three age groups, with a marked peak in mortality in the summer and a smaller peak in winter deaths (chi 2 = 84.82, df = 11, p < 0.001). By the early 20th century, the seasonal pattern disappears and the risks of death are consistent throughout the annual cycle (chi 2 = 16.5, df = 11, p = 0.124). It is argued that changes in the social and economic fabric of life, associated with the decline of the fur-trade, stimulated an epidemiologic transition among the Moose Factory Cree by the early 20th century, well in advance of WWII, the event normally used to mark both the onset of the phenomenon and improved health care delivery to the region.     

Quantitative analysis of rapid pointing movements in Cree subjects exposed to mercury and in subjects with neurological deficits

To quantify rapid alternating movements (RAMs) we used a simple prototype developed in our laboratory that requires the subject to rotate two hand-held foam spheres connected to optical encoders via flexible rods. Ninety-six participants, including 30 control subjects, 36 Cree subjects exposed to methylmercury, 21 subjects with Parkinson's disease, 6 subjects with cerebellar deficits, and 3 subjects with essential tremor, were involved in the study (though data for 5 were later removed). Twelve characteristics were developed and calculated from the raw data. Conditions examined included two hands at natural cadence (NC2), right and left hands separately at fast cadence (FCl), and both hands at fast cadence (FC2). Two ratios (FC2/NC2) and (FC2/FC1) combining these conditions were also examined. Test-retest reliability was >0.80 for most characteristics but was <0.70 for some characteristics, especially in the conditions executed at normal cadence. Correlations between characteristics and numbers of outliers with respect to the control group distribution were used to reduce the set of characteristics from 12 to 7 (i.e., duration, range, maximum slope, similarity in shape, smoothness, sharpness, and coherence). ANOVAs on the three largest groups generated significant results for most characteristics in the three conditions and the two ratios for Cree subjects and subjects with Parkinson's disease. ANOVAs on 3 age-matched groups (n=6) suggest that methylmercury affects the performance of the Cree subjects with the higher exposure, especially in terms of smoothness, sharpness, and coherence. These preliminary results suggest that this test is sufficiently specific and sensitive to characterize the performance of different groups of subjects. Ratios tend to improve discrimination for Cree subjects in a few characteristics but not for patients with Parkinson's disease.     

Occupational exposure to mercury in dentistry and dentist mortality

In response to public concern, Health Canada recently conducted a review of amalgam safety and released a position statement entitled The Safety of Dental Amalgam. Essentially, the department has concluded that the levels of mercury absorbed by the body due to the release of mercury vapor from amalgam restorations, while detectable, do not approach those recognized to cause illness. It has therefore confirmed that amalgam restorations can be used safely in most patients, with some notable caveats. Despite Health Canada's position statement in support of amalgam, patient doubts about amalgam safety remain, including the tenuous hypothesized link between amalgam restorations and specific diseases. This article reviews the available studies of dentist mortality to identify possible links between mercury exposure and negative health effects. A lack of evidence to suggest a detrimental health outcome in dentists who are occupationally exposed to higher levels of mercury than their patients, and are known to have higher levels of mercury in their blood, provides an important reassurance concerning the safety of amalgam. The reviewed data indicates that the 10 leading causes of death in the United States and Canada are the same for both dentist and non dentist population groups, and that the percentage of deaths by the same cause are remarkably similar. By 1975, the year of the most recent U.S. study, the average age at death for white male dentists was about three years higher than for all adult white males. Although suicide standard mortality rates are known to be higher for dentists, suicide deaths have also been shown to be a factor in many other occupations, particularly those where there is easy access to drugs. Although updated actuarial data for dentist mortality are needed, the available data indicate no reduction in the life expectancy of practising dentists, nor any specific or disproportionate rates of disease associated with high mercury exposure. In fact, the available mortality studies are generally optimistic about the health of dentists, which should reassure patients about the safety of dental amalgam.     

Minimal immunological effects on workers with prolonged low exposure to inorganic mercury

The growth-promoting activities of interleukin 6 (IL-6) in combination with early-acting hematopoietic factors, i.e., stem cell factor (SCF) and interleukin-1 alpha (IL-1 alpha), on primitive hematopoietic and megakaryocyte progenitors (high proliferative potential colony-forming cells [HPP-CFC] and colony-forming units-megakaryocyte [CFU-Mk], respectively) from 5-fluorouracil (5-FU)-treated murine bone marrow cells (BMC) were evaluated in serum-free fibrin clot cultures. IL-6 in combination with SCF and IL-1 induced an irregular and abortive hematopoiesis characterized by a reduction in colony size of at least 50% over those stimulated by SCF + IL-1 + IL-3 and an inability to continue growth to day 12. Moreover, IL-6 in combination with the early-acting factors, SCF and IL-1, had no effect on the formation of HPP-CFC. IL-6 is synergistic with SCF + IL-1 on day 7 CFU-Mk but did not stimulate large day 12 CFU-Mk. Our results suggest that, in the absence of serum, IL-6 prevents the continued proliferation of early hematopoietic and megakaryocytic progenitors initiated by SCF + IL-1 + IL-3. Optimization of cytokine combinations for use in ex vivo expansion of marrow progenitors, either for stem cell transplants or gene therapy, must consider not only the number of colonies but their size, as well as the contributions of serum components.     

Community-acquired Legionnaires'' disease following minimal exposure to a contaminated source

Gastric antral forceps biopsies taken at gastroscopy were cultured for Helicobacter pylori and tested for anti-microbial sensitivity. Using micro-aerophilic culture, and disc testing or E-testing, there was 98-100% sensitivity to amoxycillin, tetracycline, clarithromycin and erythromycin. However, there was apparent resistance to metronidazole in 19 of 102 samples (19%). When sensitivity by E-testing was performed with preliminary anaerobic culture for 24 h only two of 94 samples (2%) showed resistance. In 37 cultures both micro-aerophilic disc testing and anaerobic then micro-aerophilic E-testing were conducted. Eight cultures showed resistance upon disc testing (MIC > 5 mg/l) but all of these organisms were sensitive on E-testing (MIC 0.003-0.5 mg/l). Metronidazole may be used with confidence in eradication regimes.     

HLA associations of seropositive rheumatoid arthritis in a Cree and Ojibway population

Eucalyptus globulus (eucalyptus) is used as a traditional treatment for diabetes. In this study, incorporation of eucalyptus in the diet (62.5 g/kg) and drinking water (2.5 g/L) reduced the hyperglycemia and associated weight loss of streptozotocin-treated mice. An aqueous extract of eucalyptus (AEE) (0.5 g/L) enhanced 2-deoxy-glucose transport by 50%, glucose oxidation by 60% and incorporation of glucose into glycogen by 90% in mouse abdominal muscle. In acute, 20 min incubations, 0.25-0.5 g AEE/L evoked a stepwise 70-160% enhancement of insulin secretion from the clonal pancreatic beta-cell line (BRIN-BD11). The stimulatory effect of 0.5 g/L AEE was unaltered by the presence of 400 micromol diazoxide/L and prior exposure to AEE did not alter subsequent insulin secretory response to L-alanine, thereby negating adetrimental effect on cell viability. The effect of AEE was not potentiated by glucose or demonstrable in cells exposed to a depolarizing concentration of KCl. Further study of the insulin-releasing effects of AEE revealed the activity to be heat stable, acetone insoluble, stable to acid, but abolished by exposure to alkali. Sequential extraction with solvents revealed activity in both methanol and water fractions, indicating the presence of more than one biologically active extract constituent. These data indicate that Eucalyptus globulus represents an effective antihyperglycemic dietary adjunct for the treatment of diabetes and a potential source for discovery of new orally active agent(s) for future therapy.     

Mercury accumulation in the squirrel monkey eye after mercury vapour exposure

Squirrel monkeys were exposed to mercury vapour at different concentrations and for different numbers of days. The calculated total mercury absorption ranged between 1.4-2.9 mg (range of daily absorption 0.02-0.04 mg). The monkeys were killed at different intervals after the end of exposure (range 1 month - 3 years) and the eyes were enucleated. Eyes from four un-exposed monkeys were used as control material. Mapping of the mercury distribution in the eye revealed that the non-myelin-containing portion of the optic disc was densely loaded with mercury deposits, which are mostly confined to the capillary walls and the glial columns. The white matter of the brain does not accumulate mercury at these exposure levels, which might suggest that the myelinization process inhibits the accumulation of mercury. The pigmented epithelium of the pars plicata of the ciliary body and of the retina contained a considerable amount of mercury. This finding indicates that mercury is trapped within the melanocytes, which keeps potentially dangerous material from reaching the neural retina. In addition, the retinal capillary walls were densely loaded with mercury deposits, even 3 years after exposure. It was also found that the inner layers of the retina accumulated mercury during a 3-year period. It is known that the biological half-time of mercury in the brain may exceed years. This seems also to be the case for the ocular tissue.     

Lactational exposure and neonatal kinetics of methylmercury and inorganic mercury in mice

The concentration of mercury in milk and the distribution pattern in the sucking pup was followed over time after administration of a single iv injection of 0.5 mg/kg body wt of 203Hg-labeled methylmercuric chloride or mercuric chloride to lactating mice on Day 10 of lactation. Mercury concentrations in milk of the dams and in whole body, blood, plasma, GI-tract, liver, kidneys, and brain of the offspring were followed up to 11 days after dosing (until lactational Day 21). Following the inorganic mercury dose to the dams, most of the mercury in milk was delivered to the pups during the first 24 h, but the maximum mercury concentration in plasma and tissues of pups was not reached until 7 days after dosing, indicating a prolonged absorption of inorganic mercury in the sucking pup. Pups of dams given methylmercury were exposed to a much lower and constant mercury concentration in milk. The estimated accumulated mercury dose via milk per pup of dams given methylmercury was less than half of that estimated after the inorganic mercury dose. When the accumulated dose via milk from methylmercury-exposed dams was compared to the amount of mercury in pup's carcass (whole body minus GI-tract including content), it was revealed that almost all mercury delivered via milk was absorbed, and that the suckling pups had a very low elimination of mercury until lactational Day 17. Lactational exposure following a maternal methylmercury or inorganic mercury dose resulted in almost similar mercury concentrations in liver, kidneys, and plasma of the suckling, but higher concentrations in brain (as most 14 times) and also twice as high mercury body burden in the methylmercury group. Thus, differences in kinetics indicate that lactational exposure of methylmercury is a greater hazard for the breast-fed infant than inorganic mercury.     

Human exposure to mercury: a critical assessment of the evidence of adverse health effects

The ubiquitous nature of mercury in the environment, its global atmospheric cycling, and its toxicity to humans at levels that are uncomfortably close to exposures experienced by a proportion of the population are some of the current concerns associated with this pollutant. The purpose of this review is to critically evaluate the scientific quality of published reports involving human exposures to mercury and associated health outcomes as an aid in the risk evaluation of this chemical. A comprehensive review of the scientific literature involving human exposures to mercury was performed and each publication evaluated using a defined set of criteria that are considered standards in epidemiologic and toxicologic research. Severe, sometimes fatal, effects of mercury exposure at high levels were primarily reported as case studies. The disasters in Minamata, Japan, in the 1950s and in Iraq in 1971-1972 clearly demonstrated neurologic effects associated with ingestion of methylmercury both in adults and in infants exposed in utero. The effects were convincingly associated with methylmercury ingestion, despite limitations of the study design. Several well-conducted studies have investigated the effects of methylmercury at levels below those in the Iraq incident but have not provided clear evidence of an effect. The lower end of the dose-response curve constructed from the Iraq data therefore still needs to be confirmed. The studies of mercury exposure in the workplace were mainly of elemental or inorganic mercury, and effects that were observed at relatively low exposure levels were primarily neurologic and renal. Several studies have investigated effects associated with dental amalgam but have been rated as inconclusive because of methodologic deficiencies. In our overall evaluation, 29 of 110 occupational studies and 20 of 54 studies where exposure occurred in the natural environment provided at least suggestive evidence of an exposure-related effect.     

Attitudes of therapists varying in community mental health ideology and democratic values.

Studied the relationship between therapists' scores on the Community Mental Health Ideology Scale and the Democratic Values Scale and their ratings of patient case histories on a number of attitudinal dimensions. 33 therapists (psychologists, psychiatrists, social workers, and nurses, aged 24-35) rated each of 8 case histories of psychiatric outpatients on likability, comfort, interest in treating, interest in friendship, and prognosis. Patients' social class, diagnosis, and insight level were systematically varied within the case histories. Results support the contention that previously reported preferences for middle-class, high-insight, and less disturbed patients are related to therapists' degree of adherence to community mental health ideology and democratic values. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Breast-feeding exposure of infants to cadmium, lead, and mercury: a public health viewpoint

The purpose of this report is to provide an overview of the public health implications of exposure via breast milk to cadmium, lead, and mercury for nursing infants and to provide health-based guidance. Daily intakes were calculated and compared with guidance values used for public health assessments at hazardous waste sites. Cadmium, lead, and mercury under normal conditions are found in breast milk at concentration ranges of < 1 microgram/L, 2-5 micrograms/L, and 1.4-1.7 micrograms/L, respectively. Women exposed environmentally or occupationally can have higher levels in their breast milk. Concentrations of about 5 micrograms/L (cadmium), 20 micrograms/L (lead), and 3.5 micrograms/L (mercury) appear to be adequate screening levels. Many factors affect both the distribution of cadmium, lead, and mercury in breast milk and the health consequences to an infant. It is not clear what additional impact low-level exposure via breast milk may have on an infant born with a body burden to one of these metals. There is sufficient evidence to make the case that contaminated breast milk is a source of potential risk to infants in certain populations. Prevention strategies that include behavior modification and proper nutrition should be communicated to women at risk. Identification and elimination of exposure pathways and a critical analysis of the benefits of breast feeding versus heavy metal exposure are needed on a site-specific or individual basis. Research is required to better understand the impact of low-level exposure to heavy metals via breast milk. Breastfeeding should be encouraged under most circumstances.     

Effects of exposure to stressors of varying predictability on adrenal function in rats.

For 5 days, rats were exposed to shocks that were signalled by a light 0, 33, 66, or 100% of the time. Basal hormone levels and responses to a light-shock pair were measured daily. Greater predictability was associated with higher basal plasma corticosterone and norepinephrine levels indicative of chronic stress. Habituation of the corticosterone response was also less in the groups with greater predictability. However, predictability did not affect plasma prolactin or epinephrine responses. Because the endocrine systems responded differently, it is unlikely that the changes were due to a unitary process. Greater predictability appeared to be more stressful in this paradigm. Both associative and nonassociative factors have major roles in determining the hormonal responses to repeated presentation of stressors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Systemic autoimmunity due to mercury vapor exposure in genetically susceptible mice: dose-response studies

Six groups of genetically mercury-susceptible female SJL/N (H-2s) mice were exposed to mercury vapor at a concentration of 0.3-1.0 mg Hg/m3 air for 0.5-19 hr/day 5 days a week for 10 weeks. The absorbed doses were calculated to be between 75 and 2365 micrograms Hg/week/kg body wt (micrograms Hg/week/kg). The correlation between the dose and the concentration of Hg in kidney, spleen, and thymus was highly significant (p < 0.0001; Spearman's rank correlation test). The lowest observed adverse effect level (LOAEL) for serum IgG antinucleolar antibodies (ANoA) was 170 micrograms Hg/week/kg, corresponding to a renal mercury concentration of 4.0 +/- 0.76 micrograms Hg/g wet wt. The correlation between the absorbed dose and the ANoA titer was highly significant (p < 0.0001; Spearman's rank correlation test), and all mice were ANoA-positive at a dose of 480 micrograms Hg/week/kg. High-titer ANoA targeted the nucleolar 34-kDa protein fibrillarin. The LOAEL for B-cell stimulation, measured as an increase in serum IgG2a and IgG1 concentrations, was 360 micrograms Hg/week/kg, but the increase was fivefold higher and also included IgE at a dose of 690 and 2365 micrograms Hg/week/kg. The serum Ig concentrations peaked after 2-4 weeks and then slowly declined but, except for IgE, remained significantly increased during the entire exposure time. Glomerular, mesangial IgG immune complex (IC) deposits, accompanied by systemic vessel wall IC deposits, were first detected at a dose of 480 micrograms Hg/week/kg. The mesangium also showed increased titers of IgM IC deposits and complement factor C3c. The correlation between the absorbed dose, and the individual titer of IgG, IgM, and C3c, was highly significant (p < 0.0001; Spearman's rank correlation test). In conclusion, mercury vapor efficiently induced an autoimmune syndrome in genetically susceptible mice, and the LOAEL for the adverse effects varied in the order ANoA < B-cell stimulation < IC deposits. Comparing the body burden of mercury in mice at the LOAEL for autoantibodies with the body burden in populations of occupationally exposed humans suggests that the safety margin may be narrow for genetically susceptible individuals.     

Development of a Dietary Exposure Potential Model for evaluating dietary exposure to chemical residues in food

The Dietary Exposure Potential Model (DEPM) is a computer-based model developed for estimating dietary exposure to chemical residues in food. The DEPM is based on food consumption data from the 1987-1988 Nationwide Food Consumption Survey (NFCS) administered by the United States Department of Agriculture (USDA) and on residue data from government-sponsored monitoring programs. Foods reported in the NFCS were categorized into exposure core foods (ECFs). A computer program for DOS-based personal computers was developed to link consumption of the ECFs with residue values observed in the foods. The data files utilized by the DEPM were designed in dBASE IV with FoxPro for Windows applications programs for queries and reporting. The program calculates exposure estimates for categories of core foods, such as grain dishes, fruits, or vegetables; for individual core foods, such as wheat and apple combination dishes; and for individual foods, such as apples or carrots. The program, residue summary databases, and core food consumption database permit the analyst to evaluate potential exposure of several population groups to various chemicals via the diet. The DEPM is not intended for risk assessments, but is a suitable tool for identifying data gaps and establishing priorities for research, and for identifying potentially significant foods for human exposure monitoring.