Mechanical Evaluation of Solvent Casted Poly(3-hydroxybutyrate) Films Derived from the Storage Polyesters Produced by Halomonas elongata DSM 2581T

Journal of Polymers and the Environment - Poly(3-hydroxybutyrate) (PHB) is a natural and biodegradable polyester which represents an alternative to replace conventional plastics in the packaging...     

Anticoagulant rodenticide exposure in raptors from Ontario,Canada

Environmental Science and Pollution Research - Anticoagulant rodenticides (ARs) are used globally to control rodent pest infestations in both urban and agricultural settings. It is well documented...     

Population monitoring for genetic damage induced by environmental physical and chemical agents

The short-term tests performed in vitro on different systems, from phage to human cells, or in vivo, on laboratory animals, allow only a qualitative estimate of the action of mutagenic agents, and the extrapolation of such experimental results to man may encounter many difficulties.Direct biomonitoring of populations exposed to chemicals could represent a more realistic approach for an evaluation of the hazards to man. Certain methods are still under development. Nevertheless, other ones can already by used routinely, e.g. the cytogenetic observations on peripheral blood lymphocytes and the Ames test for mutagenic substances in urine, and can provide useful suggestions how to set threshold limits for chemical substances encountered in the working environment.     

Local communities' participation in decision-making processes through planning and budgeting in African countries

Community participation and community based management are topical themes in current policy and discussion revolving around decision-making processes especially those dealing with natural resources management.This review shows that while governments have accepted the need to either cede or devolve control and management of natural resources to the local communities,the communities are not part and parcel of the planning and budgeting which are crucial in decisionmaking.Communities were seen to be more involved in the implementation of natural resource management programs but lacked ownership of the projects.This causes lack of commitment to the programs and at times hostile reaction from the communities.The communities are always at the receiving end when it pertains to losses in the exchange.Community participation was shown to be effective when the local population is involved not as co-operating users but as natural resource managers or owner managers.     

Ecological Status of Beaucarnea gracilis, an Endemic Species of the Semiarid Tehuacán Valley, México

We present a demographic analysis and suggestions for the conservation of Beaucarnea gracilis, a species endemic to the Tehuacán Valley, Puebla, México. The species is dioecious, it flowers every year, and the breeding system and floral display are typical of a generalist mode of pollination. The density of B. gracilis in the study plot was 16.7 individuals/ha. Distribution of trunk diameter size classes fits a normal distribution (n = 404), but the smaller sizes were not found (<0.7 m). The inflorescences were visited by 46 insect species. Over 2600 seeds are produced per inflorescence; 27–30% are damaged by parasites, and the rest germinate readily (90–100%). Survival of seeds and seedlings is very low. We found 313 seedlings in a 12-ha area, all (94.24%) of which were at the base of nurse plants; particularly Mimosa luisiana and Castela tortuosa. The ecological status of the population of Beaucarnea gracilis is relatively good for adult individuals. In addition to low recruitment, (whether natural or human influenced), past extraction of seedlings for commerce, grazing by goats, and land clearing for corn cultivation, highway construction, and urbanization, are a real threat to the survival and establishment of seeds and seedlings. Conservation of this slow-growing, long-lived species should be promoted because (1) ecologically, it is a feeding center for many insect species, an important host for many Bromeliaceae, and part of the highly rich and endemic flora of Tehuacán and (2) economically, it helps low income people in the area (seedlings raised for commerce). Protection of nurse plants, regulation of grazing by goats, a halt to illegal extraction, and conservation of areas of the Tehuacán valley will help the survival of this species in nature.     

Further 237Pu experiments with the plaice Pleuronectes platessa: Subcellular distribution of plutonium in the liver

The subcellular distribution of ²³⁷Pu in the livers of the plaice Pleuronectes platessa has been studied by differential and isopycnic gradient centrifugation. It has been shown that the ²³⁷Pu is particularly accumulated in pellets sedimenting out at 3000 and 6000 g which, by deduction from marker enzyme tests, contain a mixture of mitochondria and lysosomes. Separation of lysosomes from mitochondria was achieved by using a non-lytic detergent injected into the fish 3 d prior to removal of the livers; it was found that ²³⁷Pu was associated with the lysosomal fraction. In this respect, the metabolism of plutonium of the plaice resembles that of the rat.     

Trisomy 5 mosaicism detected prenatally with an affected liveborn

This paper reports a case of chromosomal mosaicism for trisomy 5 recovered from amniotic fluid cells and from skin fibroblasts of a liveborn dysmorphic male. Routine amniocentesis was performed at 16 weeks' gestation because of parental concern. Trisomy 5 cells were measured from 25 per cent of amniocytes from two culture vessels. No further invasive testing was performed until 32 weeks' gestation, at which time ultrasound examination showed fetus with intrauterine growth retardation. Fetal blood sampling was then performed, with only karyotypically normal cells recovered. At birth, the child was found to have multiple dysmorphic features and congenital anomalies, including an eventration of the diaphragm and ventricular septal defect, both of which required surgical correction. Chromosomal analysis of cord blood lymphocytes indicated 46,XY; however, 20 per cent of the cultured fibroblasts obtained from the chest skin at the incision site for diaphragmatic repair had a 47,XY,+5 karyotype. Trisomy 5 mosaicism may be another example of tissue-limited mosaicism. Fetal blood sampling can then be falsely reassuring. Furthermore, because some cell lines rarely appear in lymphocyte populations, cytogenetic analysis of multiple tissues warranted as part of the evaluation of individuals with developmental delay and dysmorphic features.     

The Use of Health Risk Assessment to Estimate Desirable Sampling Detection Limits

Abstract

The inclusion of non-detected chemicals in a health risk assessment may lead, in some cases, to estimated risks that exceed regulatory thresholds, because one must use the detection limit or half of the detection limit. This study presents a methodology which will allow one to estimate appropriate detection limits by conducting a health risk assessment prior to the source sampling program. The advantages and shortcomings of various levels of detail in the risk assessment to determine those detection limits are discussed. The application of the methodology is demonstrated with a case study of the potential health effects of power plant stack emissions.