Polychlorobiphenyls and organochlorine pesticides in conventional and organic brands of milk: occurrence and dietary intake in the population of the Canary Islands (Spain)

The population of the Spanish archipelago of the Canary Islands has been studied in depth regarding its levels of contamination by organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs). Foodstuffs of animal origin, such as milk, are prominent contributors to the body burden of these contaminants. As this population presents one of the highest milk-intake in Spain and Europe, we evaluated the level of OCs and PCBs in 26 commercially available brands of milk (16 conventional and 10 organic brands) present in the market of these Islands, in order to estimate the relevance of milk as a source of these chemicals for the Canary population. Our findings showed that hexachlorobenzene, trans-chlordane, and PCB153 were present in almost all the samples with independence of the type of milk. For both types of milks, the concentration of OCs was very low, showing organic milks lower levels than conventional ones. As a consequence, the estimated daily intake for OCs was lower than the tolerable daily intake (TDI) established by International Agencies. The levels of PCBs in milk were also found to be very low, but, in this case, the situation was the opposite: there were higher levels of PCBs in organic than in conventional brands of milk. Unexpectedly, levels of dioxin-like PCBs (DL-PCBs) reached values higher than 25 pg WHO-TEQ g⁻¹ fat in percentile 75 for both types of milk indicating the existence of a number of brands of milk highly contaminated by these toxicants. Consequently, the population who consume the most contaminated milk brands could have estimated daily intakes well above the recommended TDI (2 pg WHO-TEQ kg⁻¹ b.w. d⁻¹) established by European Union Authorities. These results are of concern if we consider the well known adverse health effects exerted by dioxin-like compounds.     

Laboratory Scale Thermal Plasma Arc Vitrification Studies of Heavy Metal-Laden Waste

Abstract

Plasma processing has been identified as a useful tool for immobilizing heavy metal-contaminated wastes into safe, leach-resistant slag. Although much effort has gone into developing this technology on a pilot scale, not much information has been published on basic research topics. A laboratory-scale plasma arc furnace located at the University of Illinois was operated in cooperation with the U.S. Army Construction Engineering Research Laboratories in an effort to establish an understanding of the chemical and physical processes (such as metal volatilization and resultant gas evolution) that occur during thermal plasma treatment of metal-spiked samples. Experiments were conducted on nickel and chromium using a highly instrumented furnace equipped with a 75 kW transferred arc plasma torch. The volatility of nickel and chromium was examined as a function of varying oxygen partial pressures. Oxidizing conditions reduced the total dust gathered for both the nickel and chromium samples, although each dust sample was found to be metal-enriched. Plasma treating increased the leach-resistance of the slags by at least one order of magnitude when compared to unprocessed specimens. The leach- resistance of the nickel-containing slags increased in the presence of oxygen, whereas chromium samples remained relatively constant.