Food Chain

This paper discusses both occupational health risks to workers and environmental health risks to residents and workers. The report presents an overview of the available health literature for causes of diseases, injuries, and accidents from solid waste management collection, treatment, and disposal technologies. Illnesses discussed include infectious diseases, allergies, respiratory damage, and cancers. Some diseases are derived from direct ingestion of infectious micro-organisms, others involve infection through contamination of the food chain, whereby animals or other vectors have ingested infectious micro-organisms. Injuries include joint and spinal damage, fractures, puncture wounds, damage to eyes and ears. Accidents include slides from unstable disposal piles, cave-ins of disposal site surfaces, fires, explosions, being caught in processing equipment, and being run over by mobile equipment. As the next steps toward improving occupational and environmental health and safety in s...

Contamination of land and water caused by heavy metal mercury (Hg) poses a serious threat to biota worldwide. The seriousness of toxicity of this neurotoxin is characterized by its ability to augment in food chains and bind to thiol groups in living tissue. Therefore, different remediation approaches have been implemented to rehabilitate Hg-contaminated sites. Bioremediation is considered as cheaper and greener technology than the conventional physico-chemical means. Large-scale use of Hg-volatilizing bacteria are used to clean up Hg-contaminated waters, but there is no such approach to remediate Hg-contaminated soils. This review focuses on recent uses of Hg-resistant bacteria in bioremediation of mercury-contaminated sites, limitation and advantages of this approach, and identifies the gaps in existing research.

Ecotoxicological risks of sediment contamination in floodplains are supposed to be highest in the regularly flooded parts. Therefore, in risk assessments, the non-flooded parts are neglected or considered to be reference areas. We investigated the metal extractability and levels in important food sources for vertebrates, viz. grass shoots and earthworms, in flooded as well as non-flooded parts and compared these

Network analyses of plant-animal interactions hold valuable biological information. They are often used to quantify the degree of specialization between partners, but usually based on qualitative indices such as 'connectance' or number of links. These measures ignore interaction frequencies or sampling intensity, and strongly depend on network size. Here we introduce two quantitative indices using interaction frequencies to describe the degree of specialization, based on information theory. The first measure (d') describes the degree of interaction specialization at the species level, while the second measure (H2') characterizes the degree of specialization or partitioning among two parties in the entire network. Both indices are mathematically related and derived from Shannon entropy. The species-level index d' can be used to analyze variation within networks, while H2' as a network-level index is useful for comparisons across different interaction webs. Ana...

Polychlorinated biphenyls (PCBs) were quantified in bulk seawater (3.1 ± 1.0 ngl−1, N = 3) in 1976, in plankton (2.9 ± 3.3 ng g−1 wet weight, N = 176) in 1976 and 1977 and in fish (155 ± 194 ng g−1 wet weight, N = 135) in 1977 collected from St. Georges Bay in the southern Gulf of St. Lawrence. PCB concentrations in the plankton of the entire water column varied seasonally by ten times, with the highest values occurring in spring, lowest during summer and variable levels in late fall. The lower PCB levels in the total summer community coincide with a reduced biomass in certain size fractions in the Bay rather than a decrease in PCB concentration of the plankton. PCBs were concentrated in the middle-sized fractions of the planktonic community and this is attributed to the greater biomass present in these categories. PCB concentrations in plankton were most highly correlated with their lipid content at the time of sampling. Seasonal reductions of lipid in the plankton per m3 resulted in a higher concentration of PCB per unit lipid in the remaining community. Planktonic PCB concentrations, expressed on a lipid basis, are found to be correlated with cumulative rainfall 21 d before sampling for both years combined.Adult fish were more contaminated by PCBs than either their egg or juvenile stages. Mature gaspereau, herring and smelt had higher concentrations of PCB contamination than mackerel, capelin, white hake and silversides. No difference was found between PCB contamination of the sexes of fish species analyzed. PCBs were transferred from mother to offspring in fish, but at lower levels than the level present in the parent; and the maximum accumulation from the environment occurred between immature and adult fish. The best predictors of PCB contamination in fish in St. Georges Bay are lipid content followed by size and age.PCB concentrations in plankton, normalized to lipid content, did not increase with size or trophic level. PCB concentrations in fish increased with size and on average were ten times the levels found in plankton. Marine mammals collected by other researchers in the region during the 1970s had accumulated up to several orders-of-magnitude higher concentrations than those found in fish, with a more gradual increase with size of organism. Lipid content and age or exposure period appear to be the main factors which determine PCB concentrations in the marine food chain in the southern Gulf of St. Lawrence.