Residues levels of organochlorine pesticide in cow's milk from industrial farms in Hidalgo,Mexico

A survey was carried out from 2008 to 2010 to determine the concentrations of 16 organochlorine pesticide residues (OPRs) from Tizayuca, Hidalgo, Mexico. Organochlorine residue determinations were made from milk fat, using chromatographic cleanup and analysis by gas chromatography with an electron capture detector. The OPR concentrations found were from below the detection limit (DL) to 0.91 ng g^?1 in 2008, DL to 0.38 ng g^?1 in 2009 and DL to 0.59 ng g^?1 in 2010. In general concentrations of organochlorine pesticides were higher in the wet season (3.37 ng g^?1 and 4.79 ng g^?1) than the dry season (1.92 ng g^?1 and 2.71 ng g^?1) for 2009 and 2010, due to control of pests in the pasture and sheds. According to Codex Alimentarius regulations, individual pesticides did not exceed the permissible limits, which for example were 10 μg kg^?1 for alpha hexachlorocyclohexane (HCH) and endosulfan I, 20 μg kg^?1 for p,p’-DDT, and 6 μg kg^?1 for dieldrin, endrin and heptachlor. A reduction of organochlorine pesticide concentrations in cow's milk was noted, indicating that the Mexican government has achieved reduction or elimination of some organochlorine pesticides in response to global agreements on persistent organic pollutants.     

Catalytic combustion of methane over commercial catalysts in presence of ammonia and hydrogen sulphide

The performance of different commercially available catalysts (supported Pd, Pt, Rh, bimetallic Pd-Pt, and Cr-Cu-Ti oxide catalyst) for the oxidation of methane, alone and in presence of ammonia and hydrogen sulphide is studied in this work. Catalysts performance was evaluated both in terms of activity and resistance to poisoning. The main conclusions are that supported Pd and Rh, present the highest activities for methane oxidation, both alone and in presence of ammonia, whereas they are severely poisoned in presence of H2S. Pt and Cr-Cu-Ti are less active but more sulphur resistant, but their activity is lower than the residual activity of sulphur-deactivated Pd and Rh catalysts. The Pd-Pt catalyst exhibits low activity and it is quickly deactivated in presence of hydrogen sulphide.     

Congener profiles of PCDD/Fs in soil and vegetation samples collected near to a municipal waste incinerator

Recently, we measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in soil and herbage samples collected in the vicinity of a municipal solid waste incinerator (MSWI) from Tarragona (Catalonia, Spain). Since these concentrations could be increased by the presence of other emission sources of PCDD/Fs in the same area in which the MSWI is placed, the main goal of the present study was to determine the PCDD/F congener profiles in the soil and vegetation samples collected in 1996 and again in 1997 near to the facility and to compare with those from samples collected in a close area outside of direct emissions of the plant. From an accurate inspection of the PCDD/F congener profiles, it was concluded that PCDD/F emissions from the MSWI here examined are neither the only nor the main responsible for the presence of PCDD/Fs in the samples of environmental matrices collected in the area under direct influence of the plant.     

Tail loss reduces mating success in the Iberian rock-lizard,Lacerta monticola

Summary Many lizards autotomize their tails to escape when grasped by a predator. It is hypothesized that tail loss causes a reduction in social status, thereby potentially lowering their reproductive success. We experimentally induced tail loss in Lacerta monticola in a semi-natural enclosure, and show that tail loss reduced social status and mating access in males. Tailless males increased body mass more rapidly than tailed dominant males, probably due to lower aggression costs. Also, tailless females were courted less and copulated less than tailed females, supporting the hypothesis that tail loss decreases reproduction potential.Correspondence to: J. Martin     

Modelling the influence of peri-urban trees in the air quality of Madrid region (Spain)

Tropospheric ozone (O(3)) is considered one of the most important air pollutants affecting human health. The role of peri-urban vegetation in modifying O(3) concentrations has been analyzed in the Madrid region (Spain) using the V200603par-rc1 version of the CHIMERE air quality model. The 3.7 version of the MM5 meteorological model was used to provide meteorological input data to the CHIMERE. The emissions were derived from the EMEP database for 2003. Land use data and the stomatal conductance model included in CHIMERE were modified according to the latest information available for the study area. Two cases were considered for the period April-September 2003: (1) actual land use and (2) a fictitious scenario where El Pardo peri-urban forest was converted to bare-soil. The results show that El Pardo forest constitutes a sink of O(3) since removing this green area increased O(3) levels over the modified area and over down-wind surrounding areas.     

Polychlorinated biphenyls (PCBs) residues in milk from an agroindustrial zone of Tuxpan, Veracruz, Mexico

The coasts of the Gulf of Mexico are zones exposed to the exploration and exploitation of petroleum sources, and the products generated in agricultural zones may become contaminated by persistent organic pollutants (POPs). The objective of the present study was to evaluate the presence of polychlorinated biphenyl compounds (PCBs) in milk from dairy production units near sources of environmental pollutants. It was confirmed that the seven congeners of nondioxin-like PCBs (NDL-PCBs) are present in milk where compounds PCB101, PCB118, PCB153 and PCB180 appear in 100% of the samples analyzed, the rank of concentration for the sum of the seven congeners fluctuating between 2.6 and 26 ng g⁻¹ with a median of 6 ng g⁻¹. None of the samples surpassed the provisional value established by the EU of 40 ng g⁻¹ of milk fat for the sum of the seven congeners, indicator that was not affected by the season of the year (p < 0.05), whose median of 8.6 ng g⁻¹ and 6.3 ng g⁻¹ for rain and drought respectively. The concentrations of NDL-PCBs found in milk do not represent a problem for human health; however, they alert the existence of spontaneously generated, uncontrolled sources that may represent a potential danger for human and animal health.     

Health effects from the nuclear fuel cycle and other sources in perspective

The data base for each process of the nuclear fuel cycle has been updated as a part of the Committee on Nuclear and Alternative Energy Systems (CONAES) at Brookhaven National Laboratory (BNL). The BNL Energy System Network Simulator (ESNS) was modified to accommodate the new data, and methodology was developed for estimating population dose and health effects resulting from atmosphere releases of radioactive materials from the nuclear fuel cycle.Estimates of population dose and health effects were made using these new CONAES emission data and the new model for three scenarios out to the year 2000: (1) no reprocessing; (2) reprocessing, 1-year cooling; and (3) reprocessing, 5-year cooling. Results indicate that radon emissions from mining and milling of uranium bearing ores will have greater impacts than any other component in the open nuclear fuel cycle. The estimated number of health effects will depend, to a large extent, on the lung model mechanism assumed to induce cancer; i.e., either the smeared or the unsmeared model. The smear model and the linear relationship predict for scenario 1, 630; for scenario 2, 949; and for scenario 3, 854 lung cancers, respectively, using the new CONAES data.Epidemiologic data from six United States counties were correlated using a new statistical model (described in the text) in order to test the validity of the lung model and the linear relationship. Results do not support the high lung cancer correlations expected from the unsmear model and the linear relationship; therefore, it is concluded that low-dose mechanisms may be different from those developed from high-dose data. The best place to look for effects of low-dose radiation may be the less developed countries because of a reduction in the noise level caused by chemical pollutants.     

Levels of metals in soils of Alcalá de Henares,Spain: human health risks

The concentrations of aluminium (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), vanadium (V), and zinc (Zn) were determined in soil samples collected in Alcalá de Henares (Madrid, Spain). Human health risks derived from metal inhalation and ingestion of soils were also assessed. For noncarcinogenic risks, the current levels of metals were usually lower than those considered as safe for the general population. With respect to the potentially carcinogenic elements As, Be, Cd, and Cr, the concentrations of Be, Cd, and Cr were lower than the reference values, while the average As concentration (3.4 microg/g) was higher than the safety limit for risk cancer. In general terms, the potential human health impact of ingestion/inhalation through soils of the analyzed elements seems to be rather small.     

Simulation and Evaluation of Control Strategies for Ozone Reduction in a Complex Terrain in Southwestern Spain

During the central months of the year, southwestern Spain is under strong insolation and weak synoptic forcing, promoting the development of sea breezes and mountain-induced winds and creating recirculations of pollutants. The complex topography of the Southwestern Iberia Peninsula induces the formation of vertical layers, into which the pollutants are injected and subjected to long-distance transport and compensatory subsidence. The characteristics of these highly complex flows have important effects on the pollutant dispersion. Air pollution studies in very complex terrains require high-resolution modelling for resolving the flow dynamics. This paper shows the results obtained from using the MM5-CAMx multiscale-nested air quality model to relate the sensitivity regimes for ozone, nitrogen oxides and volatile organic compounds in an area of high geographical complexity. The article assesses the impact on the hourly and eight-hourly maximum daily ozone concentrations of four reduction strategies during two ozone pollution episodes. This analysis of the ozone response has led to a preliminary evaluation of the effectiveness of the most common control strategies: traffic, industry, mixed traffic and industry, and closure of some of the largest industries (oil and petrochemical refineries). Photochemical indicators show that ozone chemistry in southwestern Spain is strongly sensitive to NO _x . However, volatile organic compound-sensitive points are found in areas with anthropogenic influence (highways, cities and industrial parks). Our results indicate that reductions in road traffic lead to ozone reductions over large areas, whereas reductions in industrial emissions, despite sometimes showing greater decreases in the maximum hourly and eight-hourly ground-level ozone levels, lead to ozone reductions in a local area only. In the control study case, with the oil refinery and the petrochemical plants closed, decreases in ozone hourly concentrations are up to 40% higher than in the other emission control scenarios studied. This analysis provides an assessment of the effectiveness of different policies for controlling precursor emissions by comparing the modelled results for different scenarios.     

Organochlorine pesticides in the ambient air of Chiapas, Mexico

Organochlorine (OC) pesticides were measured in the ambient air of Chiapas, Mexico during 2000-2001. Concentrations of some OC pesticides (DDTs, chlordanes, toxaphene) were elevated compared with levels in the Great Lakes region, while those of other pesticides were not (hexachlorocyclohexanes, dieldrin). While this suggests southern Mexico as a source region for the former group of chemicals, comparably high levels have also been reported in parts of the southern United States, where their suspected sources are soil emissions (DDTs, toxaphene) and termiticide usage (chlordane). Ratios of p,p'-DDT/p,p'-DDE and trans-chlordane/cis-chlordane/trans-nonachlor (TC/CC/TN) in Chiapas suggest a mixture of fresh and weathered sources, while congener profiles of toxaphene suggest emission of old residues from soils. This is supported by air parcel back trajectory analysis, which indicated that air masses over Chiapas at the time of sampling had previously passed over areas of continuing or recent use of some OC pesticides as well as areas of past use.