Optimization of laccase-alginate-chitosan-based matrix toward 17 α-ethinylestradiol removal.

Laccase extract (LE) from Pycnoporus sanguineus was immobilized on calcium and copper alginate-chitosan beads and applied for the removal of 17α-ethinylestradiol (EE2). Effects of immobilization conditions such as: sodium alginate (SA) concentration; LE/SA ratio and chitosan/ion (Ca+2 or Cu+2) ratio on the immobilization yield were investigated. Immobilized LE on Ca-beads and Cu-beads was then used to degrade an EE2 solution. The optimal conditions for LE immobilization on Ca-beads were: 1.5% (w/v) SA, 1:5 (v/v) LE/SA and 3:7 (v/v) chitosan/ion (Ca+2). The optimal conditions for immobilization on Cu-beads were 2.0% (w/v) SA, 0.5:5 (v/v) LE/SA and 3:7 (v/v) chitosan/ion (Cu+2). The best result was obtained for immobilized LE on Ca-beads in buffer-absent medium. Furthermore, the immobilized enzyme was reused in five cycles for EE2 removal. The formation of EE2 dimers by LE treatment has been demonstrated by electrospray ionization coupled to time of flight mass spectrometer (ESI-TOF-MS). The results evidenced that immobilized LE in alginate-chitosan-divalent cation bead is an effective alternative for EE2 removal.

Polished silver solid amalgam electrode and cationic surfactant as tool in electroanalytical determination of methomyl pesticide.

The polished silver solid amalgam electrode (p-AgSAE) combined with square wave voltammetry (SWV) was used in the development of an analytical procedure to Methomyl determination in natural water samples. The experimental and voltammetric parameters were optimized and the use of cationic surfactant cetyltrimethyl ammonium bromide promoted a considerable change in the kinetic and mechanism of the Methomyl reaction. Was observed the presence one-single reduction peak, related to a totally irreversible two-electrons transfer, followed by chemical reaction involving two protons. Analytical parameters (linearity range, analytical curve equations, correlation coefficient, detection and quantification limits, recovery efficiency, and relative standard deviation for intraday and interday experiments) were evaluated indicating that the proposed voltammetric procedure is suitable for determination of Methomyl. The application of the proposed procedure in natural water analysis indicated high robustness with only simple filtration, without pre-concentration steps, good stability and suitable sensitivity to determination of Methomyl in natural water samples.

Public health and chronic low chlordecone exposure in Guadeloupe, Part 1: hazards, exposure-response functions, and exposures.

BACKGROUND: Inhabitants of Guadeloupe are chronically exposed to low dose of chlordecone via local food. The corresponding health impacts have not been quantified. Nevertheless the public authority implemented an exposure reduction program in 2003. We develop methods for quantifying the health impacts of chlordecone and present the results in 2 articles: 1. hazard identification, exposure-response functions (ERF) and exposure in Guadeloupe, 2. Health impacts and benefits of exposure reduction. Here is the first article. METHODS: Relevant data are extracted from publications searched in Medline and Toxline. Available knowledges on mode of action and key-event hazards of chlordecone are used to identify effects of chlordecone that could occur at low dose. Then a linear ERF is derived for each possible effect. From epidemiological data, ERF is the delta relative risk (RR-1) divided by the corresponding delta exposure. From animal studies, ERF is the benchmark response (10 %) divided by the best benchmark dose modeled with BMDS2.4.0. Our goal is to obtain central values for the ERF slopes, applicable to typical human populations, rather than lower or upper bounds in the most sensitive species or sex. RESULTS: We derive ERFs for 3 possible effects at chronic low chlordecone dose: cancers, developmental impairment, and hepatotoxicity. Neurotoxicity in adults is also a possible effect at low dose but we lack quantitative data for the ERF derivation. A renal toxicity ERF is derived for comparison purpose. Two ERFs are based on epidemiological studies: prostate cancer in men aged >44y (0.0019 per µg/Lblood) and altered neurodevelopment in boys (-0.32 QIpoint per µg/Lcord-blood). Two are based on animal studies: liver cancer (2.69 per mg/kg/d), and renal dysfunction in women (0.0022 per mg/kg/d). CONCLUSION: The methodological framework developed here yields ERFs for central risk estimates for non-genotoxic effects of chemicals; it is robust with regard to models used. This framework can be used generally to derive ERFs suitable for risk assessment and for cost-benefit analysis of public health decisions.

Public health and chronic low chlordecone exposures in Guadeloupe; Part 2: Health impacts, and benefits of prevention.

BACKGROUND: Inhabitants of Guadeloupe are chronically exposed to low doses of chlordecone via local food due to its past use in banana plantations. The corresponding health impacts have not been quantified. We develop a quantitative method and present the results in two articles: 1. Hazard identification, exposure-response functions, and exposure, 2. Health impacts, and benefits of a program to reduce the exposure of the population. Here is the second article. METHODS: The exposure-response functions derived in Part 1 (for liver and prostate cancer, renal dysfunction and cognitive development) are combined with the exposure data to calculate the impacts. The corresponding costs are calculated via DALY's and VOLY. A no-effect threshold is included via the marginal fraction of the collective exposure above the reference dose. The health benefits are the impacts in 2002 (before the exposure reduction program) minus the impacts in 2006 (since the program). They are compared to the costs, namely the public annual expenditures for reducing the population exposure. RESULTS: Without threshold, estimated annual cases of liver cancer, prostate cancer and renal dysfunction are respectively 5.4, 2.8, 0.10 in 2002; and 2.0, 1.0, 0.04 in 2006. Annual IQ points lost (cognitive development) are respectively: 1 173 and 1 003. The annual cost of total impacts is 38.3 Million Euros (M€) in 2002 and 23.7 M€ in 2006. Comparing the benefit of 14.6 M€ with the 3.25 M€ spent for prevention, the program appears well justified. With threshold, the costs of the impacts are lower, respectively: 26.5 M€ in 2002 and 12.8 M€ in 2006, but the benefit is not very different: 13.7 M€. CONCLUSION: This is the first study that quantified chronic non genotoxic effects of chlordecone exposures in Guadeloupe. According to our results, preventive actions should be focused on pregnant women because of the high social cost of development impairment and also because their exposures decreased less rapidly than others. Prevention effort should be sustained as long as chlordecone remains in soils. Additional toxicological and epidemiological research would also be required for health endpoints that could not be taken into account (neurotoxicity of adults, autoimmune diseases and other developmental effects).

Contaminación, disruptores endocrinos y cáncer / Contamination, endocrine disruptors and cancer

Desde mediados del siglo XX numerosas especies, muy diferentes entre sí y ubicadas en todas las áreas y rincones del planeta, comenzaron a presentar diversas alteraciones, muchas de las cuales sugerían estar relacionadas con trastornos del sistema endocrino. Las investigaciones demostraron que tales alteraciones eran producidas por la exposición a diferentes sustancias químicas contaminantes, las cuales podían alterar la salud y producir graves enfermedades. Dentro de ellas destacó un grupo heterogéneo de compuestos con estructuras químicas muy diferentes, capaces de actuar a dosis muy bajas, mostrar distintos mecanismos de acción y ser capaces de alterar el equilibrio hormonal, por lo que se les denominó “disruptores endocrinos químicos”. Estas sustancias, al ser liberadas al medioambiente o formar parte de objetos, alimentos o medicinas, constituyen un gran riesgo para los seres humanos y toda la vida del planeta, produciendo no solo disfunciones endocrinas sino también diferentes tipos de cáncer, destacando los más frecuentes. A pesar de la trascendencia y significado del impacto de estos compuestos, ellos no son suficientemente conocidos ni entendidos, por lo que el objetivo de esta revisión es mostrar su origen e impacto en la salud humana, resaltando su papel como inductores de cáncer, lo cual ha motivado múltiples investigaciones clínicas y biológicas.

Since the mid-twentieth century, many species, very different from each other and located in all areas and corners of the planet, began presenting various alterations, many of which suggested to be related to endocrine disorders. Research has shown that such alterations were caused by exposure to various chemical contaminants that could affect the health and cause serious illnesses. Among them stands a diverse and large group of compounds, with very different chemical structures, capable of altering the hormonal balance, act at very low doses and with different mechanisms of action, that are called “endocrine disrupting chemicals”. When released into the environment or as part of objects, food or medicines, constitute a major risk to animals and humans, which produces not only endocrine dysfunctions but also different cancers, which include the most common types. Despite the importance and significance of the impact of these compounds, they are not sufficiently known or understood, so the aim of this review is to show their origin and impact in the field of human health, highlighting their role as inducers of cancer, which has led to multiple clinical and biological investigations.

Evaluation of the reproductive toxicity of fungicide propiconazole in male rats.

The propiconazole (Prop) is a fungicide extensively used in agriculture. There are evidences that this compound may cause endocrine disrupting effects. In vitro studies have demonstrated that Prop inhibits the activity of CYP 19 (aromatase), responsible for converting androgens into estrogens and also is an androgen and estrogen receptor antagonist. Therefore, this study evaluated the reproductive toxicity of Prop treatment in male rats. The Wistar rats were divided in three groups and were treated daily, by gavage, with corn oil (control group), propiconazole 4 mg/kg (Prop 4) and 20 mg/kg (Prop 20), from post-natal day 50 to 120. The following were observed: the body weight gain, sexual behavior, testosterone and estradiol plasmatic levels, organs weight, sperm count and morphology and testicular histomorphology. There was an increase in abnormal tail morphology sperm, seminal vesicle and vas deferens weight, and a decrease in estradiol levels in Prop 4 group. Sexual behavior was affected only in the Prop 20 group. These results suggest that Prop treatment induced alterations in some reproductive parameters, what could be related with an endocrine disruption.