Biomedical subjects

Bondi Gevao

Publications and source records attributed to Bondi Gevao.

6 recordsLinked to original sources

PubMed2006

House dust as a source of human exposure to polybrominated diphenyl ethers in Kuwait.

This study reports concentrations of polybrominated diphenyl ethers (PBDEs) in dust samples collected from 17 homes in Kuwait. PBDEs were measured in all homes investigated with mean summation operatorPBDEs concentration ranging from 1 to 393 ng g(-1), with a geometric mean of 76 ng g(-1). The dominant congener in all samples was BDE 209 constituting ca. 85% of the summationPBDEs followed by BDE 99 (5%), BDE 47 (4.5%), and BDE 183 (2%). The congener mixture in dust is dominated by those in deca and penta formulations. Using the measured concentrations and estimates of dust ingestion rates for children and adults, estimated human non-dietary exposure based on mean PBDE levels were 14.8 and 1.5 ng day(-1) for children and adults, respectively. The 10-fold difference in exposure estimates between children and adults in this study supports previous reports that children are at greater risk from pollutants that accumulate indoors. The ubiquitous distribution of these chemicals as noted in this study highlights the fact that we are continuously exposed to low doses of chemicals in the indoor environment.

Air Pollution, Indoor↗

PubMed2006

Passive sampler-derived air concentrations for polybrominated diphenyl ethers and polycyclic aromatic hydrocarbons in Kuwait.

The present study presents, to our knowledge, the first ambient air data for a range of polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) in Kuwait. This was achieved by concurrently deploying polyurethane foam-disk passive samplers at 14 sites over a six-week period. Calculated mean sigma5PBDE concentrations (sum of brominated diphenyl ethers [BDEs] 47, 99, 100, 153, and 154) ranged from 2.5 to 32 pg/m3 of air, with BDE 47 contributing between 39 and 65% of the sigmaPBDEs detected. Differences in relative concentrations were observed between sites, with higher concentrations measured close to suspected sources. Calculated sigmaPAH concentrations ranged from 5 to 13 ng/m3 (mean, 8.3 ng/m3). The compound distribution was dominated by three- and four-ring compounds, which constituted approximately 90% of the sigmaPAHs, with phenanthrene contributing approximately 35%. However, the proportion of five- and six-ring PAHs increased around the "oil lakes," which were formed by the torching of oil wells during the 1991 Gulf War. The oil lakes are a reservoir of PAHs that will continue feeding the atmosphere as long as they remain untreated.

Air Pollutants↗

PubMed2005

Spatial distribution of polychlorinated biphenyls in coastal marine sediments receiving industrial effluents in Kuwait.

The concentrations of polychlorinated biphenyls (PCBs) were measured in surficial sediments receiving industrial and municipal effluents in Kuwait. The SigmaPCB concentrations varied by two orders of magnitude ranging from 0.4 to 84 microg kg(-1) dw. The homologue distribution in the study favored the more chlorinated congeners and generally followed the order: penta-PCBs > hexa-PCBs > tetra-PCBs approximately hepta-PCBs, with the dominant congeners being 138, 101, 110, 180, 153, 132, 149, and 118. The spatial distribution revealed significant intersite difference in concentration, with high levels encountered close to a harbor and several wastewater outlets suggesting that point source input is the primary delivery mechanism of PCBs to the sediment. This study suggests that atmospheric deposition of PCBs may not be a significant delivery mechanism to sediments in Kuwait possibly due to low annual precipitation and high annual temperatures that are experienced in the Arabian Gulf. The implication of this observation is that PCBs in air are likely to remain in the gas phase long enough to be subject to long-range atmospheric transport to other regions.

Carbon↗

PubMed2005

Spatial distribution of polybrominated diphenyl ethers in coastal marine sediments receiving industrial and municipal effluents in Kuwait.

Polybrominated diphenyl ether (PBDE) concentrations were measured in surficial sediments from coastal sediments receiving industrial and municipal effluents in Kuwait. The summation PBDE concentrations varied by two orders of magnitude ranging from 80 to 3800 pg g(-1)dw. The congener distribution was dominated by BDE 183, with minor contributions from BDEs 154 and 153. The similarity between the congener profile to that of the technical octa formulation (Bromkal 79-8DE) suggests a source of this product in Kuwait. The observed gradient in concentration distribution, with high summation PBDE concentrations near the shore and an exponential decrease seaward, indicates that wastewater discharge from industrial activities in the study area is the primary source of these compounds in the sediments.

Environmental Monitoring↗

PubMed2005

Formation and release of non-extractable 14C-Dicamba residues in soil under sterile and non-sterile regimes.

The role of native soil microorganisms in the formation and release of non-extractable (14)C-residues, previously treated with (14)C-Dicamba, was investigated to examine their significance to the longer-term environmental effects on non-extractable pesticide residues. A 90 d study compared the fate of Dicamba under sterile and non-sterile regimes. In addition, soils were aged for 30 d and repeatedly extracted with a 0.01 M CaCl(2) solution, to an extraction end point, to produce non-extractable residues. The extracted soil containing non-extractable residues was mixed with clean soil that had been freshly spiked with non-labeled Dicamba at 0.2 mg kg(-1) to increase the bulk volume of the soil and stimulate microbial activity. Sub-samples were then introduced into microcosms to compare the extent of microbially facilitated release and mineralisation with release rates in sterile microcosms. The results show that microorganisms play a significant role in the formation and release of non-extractable Dicamba residues. The release of (14)C-activity in sterile microcosms was linked to physical mixing of the extracted soil with field soil prior to the beginning of the incubations. The released (14)C-activity may be further mineralized, reincorporated into humus, or taken up by plants or other soil inhabiting biota.

Biodegradation, Environmental↗

PubMed2005

Formation of non-extractable pesticide residues: observations on compound differences, measurement and regulatory issues.

Six major use pesticides (Atrazine, Dicamba, Isoproturon, Lindane, Paraquat and Trifluralin) with differing physico-chemical properties were evaluated for the significance of 'bound' or non extractable residue formation. Investigations were carried out in purpose-built microcosms where mineralization, volatilisation, 'soil water' extractable and organic solvent extractable residues could be quantified. Extractable residues were defined as those accessible by sequential extraction where the solvent used became increasingly non-polar. Dichloromethane was the 'harshest' solvent used at the end of the sequential extraction procedure. (14)C-labelled volatilised and (14)CO(2) fractions were trapped on exit from the microcosm. The pesticides were categorised into 3 classes based on their behaviour. (i) Type A (Atrazine, Lindane and Trifluralin) in which ring degradation was limited as was the formation of non-extractable residues; the remainder of the (14)C-activity was found in the extractable fraction. (ii) Type B (Dicamba and Isoproturon) in which approximately 25% of the (14)C-activity was mineralised and a large portion was found in the non-extractable fraction after 91 days. Finally, Type C (Paraquat) in which almost all of the (14)C-activity was quickly incorporated into the non-extractable fraction. The implications of the data are discussed, with respect to the variability and significance of regulatory aspects of non-extractable residues.

Atrazine↗