Health risks to infants from exposure to PCBs, PCDDs and PCDFs

Global contamination by a variety of anthropogenic persistent organic chemicals, such as dioxins and PCBs, has resulted in human exposure throughout all phases of development. Detectable concentrations of PCBs and dioxins have been found in amniotic fluid, placenta and foetal tissue samples while infants who are breast-fed can obtain blood levels greater than those of their mother's. In two separate food poisoning episodes where infants were exposed in utero to elevated levels of heat-degraded PCBs (PCBs, PCQs, PCDFs), a variety of adverse mental and physical developmental abnormalities have been observed. In additional human cohorts where exposure could be considered as environmental or background, more subtle effects, including lower birth weights, alterations in thyroid hormones and lymphocyte subpopulations and detriments in neurological development, have been consistently seen. In most instances, negative associations were made between in utero exposure to contaminants compared with lactational. Although the observed neurodevelopmental deficits have been described as subtle, there could be unknown consequences related to future intellectual functionality. Current regulatory efforts should focus on identification and control of environment and food chain contamination as in utero exposure is a direct consequence of the accumulated maternal body burdens.     

Persistent Organic Pollutants in Fish Oil Supplements on the Canadian Market: Polychlorinated Dibenzo-p-Dioxins, Dibenzofurans, and Polybrominated Diphenyl Ethers

ABSTRACT:  Canadians are interested in improving their diet through the consumption of fish oil food supplements, which are marketed to be rich in omega-3 fatty acids. Convenience samples of omega-3 enriched dietary supplements ( n  = 30) were collected in Vancouver, Canada, between 2005 and 2007. All of the omega-3 supplements were analyzed for polychlorinated dibenzo- p -dioxins/furans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) and, although every sample was found to contain detectable residues of PBDEs, only 24 samples were found to have PCDD/F concentrations above the level of detection. PCDD/F concentrations ranged from 0.05 pg TEQ/g lipid to 45.7 pg TEQ/g lipid in salmon and shark oils, respectively. Maximum PBDE concentrations similarly were observed in shark oil (113 μg/kg lipid), however, most supplements had concentrations below 5 μg/kg lipid. Average PCDD/F and PBDE intake estimates, based on consumption of maximum supplement dose following product label recommendations, were 4.32 pg TEQ/d and 25.1 ng/d lipid, respectively.     

Persistent Organic Pollutants in Fish Oil Supplements on the Canadian Market: Polychlorinated Biphenyls and Organochlorine Insecticides

ABSTRACT:  Fish and seal oil dietary supplements, marketed to be rich in omega-3 fatty acids, are frequently consumed by Canadians. Samples of these supplements ( n  = 30) were collected in Vancouver, Canada, between 2005 and 2007. All oil supplements were analyzed for polychlorinated biphenyls (PCBs) and organochlorine insecticides (OCs) and each sample was found to contain detectable residues. The highest ΣPCB and ΣDDT (1,1,1-trichloro-di-(4-chlorophenyl)ethane) concentrations (10400 ng/g and 3310 ng/g, respectively) were found in a shark oil sample while lowest levels were found in supplements prepared using mixed fish oils (anchovy, mackerel, and sardine) (0.711 ng ΣPCB/g and 0.189 ng ΣDDT/g). Mean ΣPCB concentrations in oil supplements were 34.5, 24.2, 25.1, 95.3, 12.0, 5260, 321, and 519 ng/g in unidentified fish, mixed fish containing no salmon, mixed fish with salmon, salmon, vegetable with mixed fish, shark, menhaden ( n  = 1), and seal ( n  = 1), respectively. Maximum concentrations of the other OCs were generally observed in the seal oil. The hexachlorinated PCB congeners were the dominant contributors to ΣPCB levels, while ΣDDT was the greatest contributor to organochlorine levels. Intake estimates were made using maximum dosages on manufacturers' labels and results varied widely due to the large difference in residue concentrations obtained. Average ΣPCB and ΣDDT intakes were calculated to be 736 ± 2840 ng/d and 304 ± 948 ng/d, respectively.     

Closure generation based on viewing lambda as epsilon plus compile

This paper describes a way of expressing λ-expressions (which produce closures) in terms of ε-expressions (λ-expressions containing only local and global variable references) and calls to an interactive compiler that compiles ε-expressions. This point of view is an interesting way of describing the semantics of λ-expressions and closure generation. It also leads to an efficient closure implementation both in time and space. A closure is uniformly represented as a piece of code instead of a compound object containing a code and environment pointer. This method can also be used to simulate closures in conventional dialects of Lisp     

Using Multilisp for solving constraint satisfaction problems: An application to nucleic acid 3D structure determination

This paper describes and evaluates a parallel program for determining the three-dimensional structure of nucleic acids. A parallel constraint satisfaction algorithm is used to search a discrete space of shapes. Using two realistic data sets, we compare a previous sequential version of the program written in Miranda to the new sequential and parallel versions written in C, Scheme, and Multilisp, and explain how these new versions were designed to attain good absolute performance. Critical issues were the performance of floating-point operations, garbage collection, load balancing, and contention for shared data. We found that speedup was dependent on the data set. For the first data set, nearly linear speedup was observed for up to 64 processors whereas for the second the speedup was limited to a factor of 16.     

Enhanced reductibility of Ni and Ni + Pd in zeolite Y: Blocking of small cages with Ca2+ or Mg2+ ions

Reducibility of zeolite encaged Ni²⁺ was found by temperature programmed reduction to increase in the following order Ni/NaY < Ni/MgY < Ni/CaY < (Pd + Ni)/NaY < (Pd + Ni)/MgY < (Pd + Ni)/CaY. In comparison with NaY supported samples, bimetallic MgY and CaY supported samples exhibited enhanced Pd²⁺ and Ni²⁺ reducibility as well as higher H_ads/Me ° ratios after reduction below 500 °C. Temperature programmed reduction (TPR) and desorption (TPD) results indicate that Mg²⁺ and Ca²⁺ ions are occupying the small cages in the zeolite thus preventing the migration of the majority of Ni²⁺ and Pd²⁺ ions to these cages.     

DOE/NETL's phase II mercury control technology field testing program: preliminary economic analysis of activated carbon injection

Based on results of field testing conducted by the U.S. Department of Energy's National Energy Technology Laboratory (DOE/NETL), this article provides preliminary costs for mercury control via conventional activated carbon injection (ACI), brominated ACI, and conventional ACI coupled with the application of a sorbent enhancement additive (SEA) to coal prior to combustion. The economic analyses are reported on a plant-specific basis in terms of the cost required to achieve low (50%), mid (70%), and high (90%) levels of mercury removal "above and beyond" the baseline mercury removal achieved by existing emission control equipment. In other words, the levels of mercury control are directly attributable to ACI. Mercury control costs via ACI have been amortized on a current dollar basis. Using a 20-year book life, levelized costs for the incremental increase in cost of electricity (COE), expressed in mills per kilowatt-hour (mills/kWh), and the incremental cost of mercury control, expressed in dollars per pound of mercury removed ($/lb Hg removed), have been calculated for each level of ACI mercury control. For this analysis, the increase in COE varied from 0.14 mills/kWh to 3.92 mills/kWh. Meanwhile, the incremental cost of mercury control ranged from $3810/lb Hg removed to $166000/lb Hg removed.