Chronic exposure to sour gas emissions: meeting a community concern with epidemiologic evidence.

For 25 years residents of a rural area in southwestern Alberta have complained of health problems attributed to sour gas emissions from nearby natural gas refineries. We undertook a large epidemiologic study of the current health status and the selected morbidity rates among 2152 people in the exposed area. We established two comparison groups: one was a demographically similar unexposed population and the other a demographically different group also exposed to sour gas emissions in another region. The methods included a cross-sectional survey of current residents and separate historical cohort studies involving registry linkage to investigate cancer incidence and all-cause mortality. The cross-sectional survey involved a comprehensive health questionnaire, standardized clinical examinations by physicians blinded to the subjects'' symptoms and concerns, and several laboratory tests. We were able to contact just under 60% of the people who we knew had moved from each area since 1958 and found no evidence of selective migration for health reasons. Although the residents of the exposed area reported an excess number of symptoms and health problems there were no significant differences in the mortality rate, incidence of cancer, reproductive problems, major ailments, hair levels of arsenic and certain metals or respiratory function between the groups.     

Hemlock woolly adelgid invasion affects microhabitat characteristics and small mammal communities

Hemlock woolly adelgid (HWA) invasion and preemptive logging practices alter the habitat structure of New England forests and may indirectly affect associated small mammal communities. Microhabitat structure was measured and small mammals were censused in eight large experimental plots to quantify these effects. The Harvard Forest long-term ecological research experiment is a replicated two-block design that includes four ~ 0.81-ha canopy treatments: (1) hemlock control, (2) hardwood control, (3) girdled Treatment, in which hemlock trees were killed by girdling in 2005 and left standing to simulate HWA invasion, and (4) logged treatment, in which trees were removed to simulate preemptive logging management practices. Nine microhabitat characteristics were measured from plot photos revealing differences among ground and canopy microhabitat structure. Small mammals were censused during high (2012) and low (2013) abundant years. Populations of common species were estimated with mark-recapture analysis. Peromyscus spp. were not affected by treatment in either year, but southern red-backed vole populations were greatest in the girdled treatments in 2012 and rarely captured in 2013. Between 6 and 9 mammal species were recorded in all treatments and species composition varied slightly. Estimated species richness was greater in girdled treatments than hemlock controls, but did not differ between girdled and logged treatments, which suggests preemptive logging is as detrimental to some small mammal species as HWA invasion. Overall, there is little evidence of a major shift in small mammal community structure in response to HWA invasion, with only minor changes in relative abundance both years.     

The very hungry amphipod: the invasive <Emphasis Type="Italic">Dikerogammarus villosus</Emphasis> shows high consumption rates for two food sources and independent of predator cues

The invasion of the Ponto–Caspian amphipod Dikerogammarus villosus in European rivers is assumed to reduce macroinvertebrate diversity and to alter ecosystem functions. D. villosus shows an extraordinarily flexible feeding behavior including the ability to use various food sources. On the other hand, its response to predation risk seems to depend on environmental factors. To evaluate the ecological function of D. villosus, we estimated the daily food consumption for different food sources and analyzed potential effects of predator avoidance behavior on feeding. D. villosus consumption of willow leaves or chironomid larvae was quantified in 24-h laboratory experiments with and without kairomones of the European bullhead (Cottus gobio). Consumption rates were estimated based on gut content and gut evacuation rate under semi-natural laboratory conditions enabling the animals to feed over the whole time of the evacuation rate experiment. We observed very high evacuation rates and consequently high consumption rates up to 89% of body weight per day. Consumption rates differed significantly between food sources: D. villosus ingested more leaves than chironomid larvae. In contrast, predator cues did not affect the feeding of D. villosus. This might be explained by its strong refuge affinity and probably benefits its successful invasion. A comparison of the estimated consumption rates with results of an own consumption experiment (and other studies) under more artificial conditions indicated that more natural conditions result in higher consumption rates. Consequently, feeding rates from highly artificial experiments should be used with great caution to assess the ecosystem function of D. villosus.     

Returning home after fire: how fire may help us manage the persistence of scrub-steppe specialist bird populations

Semi-natural open habitats have drastically changed in the last few decades due to agricultural intensification and rural depopulation. Steppe-birds, and especially those adapted to primary stages of vegetation succession, are threatened by an increase in scrub cover, and management actions are being applied to reverse scrub encroachment and restore habitat suitability in semi-natural open habitats. In this paper we evaluated for the first time, the long-term effects of a wildfire on habitat structure, vegetation productivity, and the associated response of an endangered scrub-steppe specialist bird, the Dupont’s Lark Chersophilus duponti. Wildfire occurred in a Mediterranean steppe of central Spain dominated by permanent community of dwarf cushions scrubs. Bird abundance was evaluated by line transects in the burnt and unburnt areas 3 years prior to the fire and 4 and 7 years after the fire. We quantified changes in habitat structure at fine scale level through vegetation sampling points and in vegetation productivity by estimating the Normalized Difference Vegetation Index (NDVI). Fire had strong effects for at least up to 4 years after the fire, when lower NDVI values, less scrub cover and fewer, but not significant, number of males were detected in the burnt area with respect to the pre-fire conditions. Seven years after fire most vegetation variables measured did not differ between areas, number of males detected within the burnt area was recovered and NDVI values in burnt area were slightly recovered but were significantly lower than in control area. Slow regeneration of the scrub cover after fire explained the unsuccessful occupation of the burnt area by the Dupont’s Lark up to several years after fire. The more dispersed and shorter habitat created by fire 7 years after the fire seems to be more suitable for the species than that in control areas. The large number of males around the burnt area may have played a role in the recolonization process. In sum, vegetation recovery and the presence of a low scrub-steppe specialist, as the Dupont’s lark, suggests that fire management could be integrated into conservation plans to effectively manage scrub encroachment processes in Mediterranean scrub-steppes.     

Insufficient Milk Supply and Breast Cancer Risk: A Systematic Review

Background

An association between insufficient milk supply, the inability of a mother''s breast milk to provide sufficiently for her infant, and breast cancer has been suggested by observations in animal models. To determine if an association has been reported in epidemiological studies of human breast cancer, a systematic review of the literature has been conducted. We also sought to identify the methodological limitations of existing studies to guide the design of any future prospective studies in this field.

Methodology/Principal Findings

PubMed, EMBASE, Web of Science, BIOSIS, and CAB abstracts were searched. We selected any study that (1) assessed breast cancer in association with breastfeeding history and (2) examined the relationship between insufficient milk supply with breast cancer. Seven relevant studies were identified that met both criteria. There was statistically significant heterogeneity among the results which likely reflects clinically significant differences in definitions of insufficient milk supply and reference groups that were used. Among premenopausal women who had experienced insufficient milk supply, odds ratios (ORs) for breast cancer risk ranged from 0.9 to 16.3. Among postmenopausal women, ORs ranged from 0.6 to 6.7. Based on the range of odds ratios obtained in the studies reported in this review, it remains unclear if there is a true association between insufficient milk supply and breast cancer.

Conclusions/Significance

Although some studies have shown a strong positive association, there is no consistent evidence for an effect of insufficient milk supply on breast cancer risk. Exposure definitions are in need of improvement in order to focus on primary insufficient milk supply. Reference groups consisting of women who have successfully breastfed may also introduce positive bias (inflation of the odds ratio) into study results because of the protective effect of prolonged breastfeeding in the control group.