Transfer of pesticides to the brew during mate drinking process and their relationship with physicochemical properties

In order to evaluate the extraction of pesticide residues that are transferred to the brew during mate drinking process of P.U.1 yerba mate leaves (Ilex paraguariensis), a special device to simulate the way in which mate is drunk in Uruguay was developed. The transfer to the brew of 12 organophosphates, 5 synthethic pyrethroids and one organochlorine pesticide from spiked samples was studied. The relationship between the transfer data thus obtained and physicochemical properties like water solubility (Ws), octanol-water coefficient (Kow) and Henry's constant (H) was evaluated. The extractability of the pesticide residues from yerba mate can be correlated with log Ws and log Kow. These transfer values allowed the calculation of ARLs (acceptable residue level) for the pesticides following Food and Agriculture Organization (FAO), World Health Organizaion (WHO) guidelines. These results can help the future establishment of maximum residue levels (MRLs)     

Evaluation of landfill leachate treatment by advanced oxidative process by Fenton’s reagent combined with membrane separation system

A high content of refractory organic matter, ammonia and toxic compounds is characteristic of landfill leachate. Advanced oxidative processes (AOPs) are an attractive alternative for landfill leachate treatment. However, when applied as a unique process treatment, they do not provide a complete solution for the effluent treatment. Combining AOP with a membrane separation process (MSP) presents a number of benefits and provides an adequate solution for this problem. With this in mind, the present work aims to evaluate, using a bench scale, leachate treatability through AOP by Fenton’s reagent (AOP/Fenton) combined with microfiltration (MF) and nanofiltration (NF). A high efficient removal of COD (63%), true color (76%) and humic substances (50%) was observed during AOP/Fenton under optimized conditions (1.7 g H₂O₂/g COD_{raw leachate}; FeSO₄·7H₂O:H₂O₂ = 1:5.3; pH = 3.8; reaction conditions = 115 rpm/28 min). According to the evaluated parameters, MSP presented an efficient complementary treatment, in which the integrity of the stages was sufficient for reaching regulatory levels in the effluent (Deliberação Normativa Conjunta COPAM/CERH-MG N^o. 1, May 5, 2008).     

The role of toxicology in the evaluation of new agrochemicals

Abstract

The use of agrochemicals like crop protecting agents, veterinary disinfectants, and wood preservatives may result in (un)intentional exposure of the environment, animals and man. This paper deals with current testing strategies to assess the potential health risks for humans exposed to these chemicals during production or application or via consumption of foods containing pesticide residues.

Principles and procedures for safety assessment of pesticide residues in food as developed by WHO/FAO are described. Different types of toxicity studies in mammalian test animal species are discussed and a strategy is outlined in order to characterize the toxicity profile of a compound and the relationship between applied doses and adverse effects. Safety testing of agrochemicals should be carried out in relation to its intended use, and in particular attention will be paid to toxicity testing of residues of pesticides in food. Extrapolation of results from animal studies to humans and the use of safety factors is discussed.

Besides the use of animal protocol studies for safety testing of agrochemicals, the potential use of in‐vitro models derived from organs and tissues of animals is discussed. Data on the in‐vitro metabolism of thiabendazole, aldicarb and alachlor are discussed in order to demonstrate that such data may complement or partly substitute whole animal experimentation.

Principles and procedures for safety testing of residues of agrochemicals in food as applied during the last three decades, constitute a ‘safety‐first’ approach, providing sufficient safety margins for the consumer of foods which may contain low levels of residues of agrochemicals.     

An overview of the latest development of microencapsulation for agricultural products

Abstract

For the production of controlled‐release agricultural formulations microencapsulation technologies are now the most used. Over the past two decades enormous progress has been made in order to develop the technologies which allow us to produce formulations tailor made to reach the target and fitting our toxicological requirements. This lecture is devoted to the definition of the criteria for selection of an active ingredient for microencapsulation and to a detailed review of the various techniques used today in commerçai microencapsulated formulations.

Resources are increasingly allocated into microencapsulation research & development by many agrochemical companies. Therefore the next 20 years should continue to yield innovative ideas including significant improvement of the physico‐chemical and toxicological properties of the actual formulations on the market. Some of this new ideas are applied by our company in order to modify or improve those properties playing the key role in the intent for targeted activity:

√ Recombination during production or upon storage.

New protective colloides

Dermal toxicity (LD 50) ‐ secondary protective colloides.

√ Release rate parameters.

Modification by the change of mobility of the active ingredient from the core (solvent or fluid type) affecting transit time and therefore LD 50 values.

√ Oral toxicity (LD 50).

Graft copolymers irreversibly adsorbed to the capsule surface.     

Feasibility of mercury removal from simulated flue gas by activated chars made from poultry manures

Increased emphasis on reduction of mercury emissions from coal fired electric power plants has resulted in environmental regulations that may in the future require application of activated carbons as mercury sorbents for mercury removal. At the same time, the quantity of poultry manure generated each year is large and technologies that take advantage of the material should be explored. The purpose of the work was to obtain preliminary data to investigate if activated chars made from different poultry manures could adsorb mercury from simulated flue gas. In laboratory experiments, activated chars made from chicken cake and litter removed mercury from the gas as well as a commercial alternative. It was also found that acid-washing these chars after activation may improve pore structure but does not influence the mercury removal efficiency. Activated chars were also made from turkey cake and litter. These raw materials produced activated chars with similar pore structure as those made from chicken manure, but they did not adsorb mercury as well. Acid-washing the turkey manure-based chars improved their performance, but this step would add to the cost of production. Preliminary evaluations suggest that unwashed activated chars may cost as little as $0.95/kg to produce.     

Challenges to achieving a successful transition to a low carbon economy in South Africa: examples from poor urban communities

South Africa faces several development challenges including those linked to climate change. Energy usage in South Africa, for example, is already constrained because of a range of development challenges (the dependence on cheap coal as a heating source; energy availability; access; affordability of alternative energy sources; and a range of health impacts, including air pollution). Notwithstanding calls for a transition to a low carbon economy, there have been few, recent assessments in South Africa of the costs associated with such a transition, particularly the social and economic costs for the poor who use energy in a variety of ways. In this paper we focus on trying to unravel some of the complex energy-use behaviour including understanding what drives consumers in resource-poor areas to choose and use persistently risky energy options. Analysis of qualitative data in two township areas, Doornkop and Kwaguqa, shows that township households, whether electrified or not, continue to burn coal. In both study areas, an estimated 80% of electrified households burn coal for space heating and cooking and also make use of multiple fuel sources for a range of activities. Although the major obstacles preventing people from discontinuing domestic coal combustion are poverty, the ready availability and social acceptability of coal together with other social customs cannot be underrated. This paper therefore highlights some of the persistent challenges associated with sustainable energy transitions in South Africa including implications for improved mitigation and adaptation for the energy sector in wider climate change efforts.     

Spatial variation in soil carbon in the organic layer of managed boreal forest soil—implications for sampling design

We studied within-site spatial variation of the carbon stock in the organic layer of boreal forest soil. A total of 1,006 soil samples were taken in ten forest stands (five Scots pine stands and five Norway spruce stands). Our results indicate that the spatial autocorrelation disappears at a distance of 75-225 cm. This spatial autocorrelation should be taken into account in the sampling design by locating the sampling points at adequate intervals. With a sample size of over 20-30 samples per site, additional soil samples do not notably improve the precision of the site mean estimate. An adequate sample size is dependent on the purpose of sampling and on the site-specific soil variation. Our results on the dependence between sample size and precision of the mean estimates can be applied in designing efficient soil monitoring in boreal coniferous forests.     

Pluri-annual study of the reproduction of two Mediterranean Oscarella species (Porifera, Homoscleromorpha): cycle, sex-ratio, reproductive effort and phenology

This study presents the phenology of two common Mediterranean sponges belonging to the genus Oscarella (Porifera, Homoscleromorpha). Oscarella tuberculata and Oscarella lobularis are two sibling species, dwellers of shallow benthic communities which tend to have distinct ecological behavior, respectively, euryecious and rather stenoecious. The comparative study of their reproductive cycle showed that both Oscarella species have a seasonal reproductive cycle with a successive phase duration differing from one species to another. In both species, there is a continuous oogenesis, with new oocytes appearing in spring, whereas the spermatogenesis generally starts later with the early warming of the sea. The embryonic development and the larval release are restricted to the warmest months of the year. We also observed a shift in the period of gametogenesis and larval emission depending on species and differences in their sensitivity to changes in thermal regime. It appears that an increase in seawater temperature can affect sex determination, with mainly a shift toward males in both species. Their reproductive efforts are variable in time, and can be in some cases influenced by the temperature regime. This is especially the case of O. lobularis which seems to be the most thermosensitive, its phenology responding significantly to changes in thermal regime, whereas O. tuberculata seems to be less sensitive and/or reactive. By detecting phenological changes among sponges, this study demonstrated the relevance of such monitoring to assess the possible biological response to climate change.