A contaminação ambiental é quase sempre caracterizada pela combinação de
factores de stress de várias origens (biológica, química e física).
Na agricultura, a grande diversidade de colheitas e das pestes que as
atingem, conduz à utilização de diversos tipos de tratamentos e à aplicação de
uma larga diversidade de produtos químicos. O fungicida carbendazim,
pertencente ao grupo dos benzimidazóis, e é um dos mais utilizados em todo
o mundo, enquanto que o insecticida organofosforado clorpirifos, também
globalmente utilizado, é somente o mais vendido em Portugal.
Igualmente, da actividade industrial advêm alguns dos mais frequentes
contaminantes encontrados nos nossos ecossistemas. Os metais pesados,
como o cádmio e o níquel, resultantes de actividades mineiras e metalúrgicas,
são importantes agentes de toxicidade, uma vez que induzem vários tipos de
O fenómeno das alterações climáticas, que já se faz sentir e que irá
intensificar-se nas próximas décadas, levando ao surgimento de condições
ambientais extremas durante longos períodos de tempo, será também uma
nova fonte de agentes stressores que importa ter em consideração.
A Avaliação do Risco Ecológico (ARE) tem como objectivo avaliar a
probabilidade de determinados efeitos ecológicos adversos ocorrerem como
resultado da exposição a um ou mais stressores (U.S.EPA 1992). Uma nova
abordagem baseada na avaliação dos efeitos cumulativos da toxicidade
resultante da acção de múltiplos stressores surgiu nos últimos anos...
Three hundred and one women who in their most recent pregnancy had given birth to an infant with an important congenital defect were individually matched with 301 women whose children were normal. Both cases and referents were drawn from a comprehensive survey of pregnancies in Montreal, 1982-4, and limited to women employed 30 or more hours a week until at least the 13th week of gestation. Occupational exposure to chemicals was investigated and the results classified without knowledge of case-referent status. In matched pair analysis the overall frequency of chemical exposure was higher in cases than referents (63:47), due to excesses in the cardiac and miscellaneous defect groups (ratios of 10:5 and 15:7 respectively). In analyses by nine chemical categories only exposure to aromatic solvents showed a clear excess (18:8; p approximately equal to 0.04), most evident in the urinary tract group (9:0). A comparison of cases and referents exposed to aromatic solvents showed that most of the excess was associated with toluene; the defects were varied but predominantly renal-urinary or gastrointestinal.
An examination has been made of the medical records of a group of white-skinned men, new starters in a works manufacturing dyestuffs and related chemicals. One thousand, four hundred and fifty-two such men started employment in the works in the five years 1955-59; 745 were employed as chemical process workers, 266 as chemical plant maintenance engineering workers, 335 as non-plant engineering workers, and 106 in various miscellaneous jobs. The process and plant engineering workers have considerable contact with chemicals; the non-plant engineering and miscellaneous workers have little or no chemical contact.
Various agricultural chemicals, e.g. pesticides, are known to cause different toxic effects in man and animals. Some of these produce responses involving the nervous tissue. Total of 52 such chemicals, representing organophosphates, carbamates and other miscellaneous insecticides were evaluated to determine their relative cytotoxic effects in avian dorsal root ganglia cultures. Many of these chemicals caused a slight stimulation of cellular growth at very low concentrations. At toxic concentrations, a dose-related but nonspecific inhibition of cell growth occurred. The cytotoxic changes included the decreased migration of cells from the culture implant, varicosities in and shortening of various cells and vacuolization and rounding of neuroglial cells. At high concentrations, pigmentary degeneration and complete abolition of cell growth were observed. The toxic effects were numerically scored in a random blind fashion and the concentrations of individual chemicals to produce a half maximal effect (IC50) in culture were determined from the dose-response curves. The IC50 values for various chemicals ranged from approximately 10(-6) M for compounds like methylparathion, diazinon, paraoxon and Vendex to greater than 10(-2) M for chlorpyriphos and methylchlorpyriphos. No significant correlations of nerve fiber or glial cell cytotoxicity were apparent with other toxic or physico-chemical properties such as lethal dose in animals...
A new series of 30 miscellaneous National Toxicology Program chemicals has been evaluated prospectively for carcinogenicity and overt toxicity by COMPACT (Computer Optimised Molecular Parametric Analysis for Chemical Toxicity. CYP1A and CYP2E1). Evaluations were also made by Hazardexpert, and for metal ion redox potentials; and these, together with COMPACT, were compared with results from the Ames test for mutagenicity in Salmonella, the micronucleus test, and 90-day subchronic rodent pathology. Seven of the 30 chemicals (nitromethane, chloroprene, xylenesulphonic acid, furfuryl alcohol, anthraquinone, emodin, cinnamaldehyde) were positive for potential carcinogenicity in the COMPACT evaluation; xylenesulphonic acid and furfuryl alcohol were only equivocally positive. Four of the 30 chemicals-scopolamine, D&C Yellow No. 11, citral, cinnamaldehyde-were positive by Hazardexpert; 6 of 30-D&C Yellow No. 11, 1-chloro-2-propanol, anthraquinone, emodin, sodium nitrite, cinnamaldehyde-were positive in the Ames test; 2 of 30-phenolphthalein and emodin-were positive in the in vivo cytogenetics test; and 3 of 30-molybdenum trioxide, gallium arsenide, vanadium pentoxide-were metal compounds with redox potentials of the metal/metal ion indicative of possible carcinogenicity. The overall prediction for carcinogenicity was positive for 12 of 30 chemicals: nitromethane...
OBJECTIVE—To describe the frequency, nature and location of acute chemical incidents in Wales, and the morbidity in employees, emergency responders and the general public who were exposed. DESIGN—Active multi-agency community-based surveillance system. SETTING—Wales, 1993-5. MAIN OUTCOME MEASURES—Frequency, nature and location of incidents, populations potentially exposed and with symptoms. RESULTS—Most of the 402 incidents identified were not associated with sites governed by the Control of Industrial Major Accident Hazard Regulations but with smaller industrial sites and commercial premises. About two in every thousand of the estimated 236 000 members of the public considered to be at risk from exposure reported symptoms, which were mainly nausea, headaches, and irritation of the eye, skin and respiratory tract. The most commonly reported chemicals that members of the public were exposed to were smoke toxins, miscellaneous organics, toxic gases and flammable gases. A health authority was reported to be involved in only 34 (8%) of the incidents and in only 3 of the 29 incidents where more than 100 members of the public were exposed. CONCLUSION—A geographically defined, multi-agency surveillance system can identify high risk locations and types of incidents...
OBJECTIVES—To examine trends in estimated population based incidence of occupational asthma by age, sex, occupation, geographical region, and causal agents based on 9 years of the Surveillance of Work Related and Occupational Respiratory Disease (SWORD) data. METHODS—In January 1989 the SWORD scheme for the surveillance of occupational respiratory disease was established in the United Kingdom to make good the lack of epidemiological information on the incidence of these diseases in the United Kingdom. Between 80% and 90% of chest and occupational physicians report voluntarily all new cases they see, on a monthly or random sampling basis. During the 9 years 1989-97, an estimated 25 674 new cases of occupational respiratory disease, including 7387 of occupational asthma, were reported. Suspected causal agents were classified into 44 categories and estimated annual incidences of asthma were calculated with denominators from the labour force survey. RESULTS—Overall, a third of the suspected causes of asthma were organic, a third chemical, 6% metallic, and the rest miscellaneous, or in 8%, unknown. There was evidence of an increase since 1989 in cases due to latex, and possibly glutaraldehyde, and an apparent drop since 1991 in the proportion of cases attributed to isocyanates. Incidences were higher in men than women and the disparity was especially marked in the population aged 45 years or more in which rates for men were at least twice those for women. Average annual rates per million workers for 1992-7 ranged from 7 (95% confidence interval (95% CI) 5 to 9) for the lowest risk group of professional...
Background. More than 400 agents have been documented as causing occupational asthma (OA). The list of low-molecular-weight (LMW) agents that have been identified as potential causes of OA is constantly expanding, emphasizing the need to continually update our knowledge by reviewing the literature. Objective. The objective of this paper was to identify all new LMW agents causing occupational asthma reported during the period 2000–2010. Methods. A Medline search was performed using the keywords occupational asthma, new allergens, new causes, and low-molecular-weight agents. Results. We found 39 publications describing 41 new LMW causal agents, which belonged to the following categories: drugs (n = 12), wood dust (n = 11), chemicals (n = 8), metals (n = 4), biocides (n = 3), and miscellaneous (n = 3). The diagnosis of OA was confirmed through SIC for 35 of 41 agents, peak expiratory flow monitoring for three (3) agents, and the clinical history alone for three (3) agents. Immunological tests provided evidence supporting an IgE-mediated mechanism for eight (8) (20%) of the newly described agents. Conclusion. This paper highlights the importance of being alert to the occurrence of new LMW sensitizers, which can elicit OA. The immunological mechanism is explained by a type I hypersensitivity reaction in 20% of all newly described LMW agents.
Many chemicals are present in cleaning and personal care products, which after use are washed down the drain and find their way into water bodies, where they may impact the environment. This study surveyed individuals to determine what products were used most in the home, in an attempt to prioritize which compounds may be of most concern. The survey resulted in the identification of 14 categories of products consisting of 315 specific brands. The survey estimated that individuals each discharge almost 33 L of products per year down the drain. Dishwashing liquids and hand wash gels, which accounted for 40% of this volume, were selected for identification of specific ingredients. Ingredients were classified as surfactants, preservatives, fragrances or miscellaneous, with hand wash gels having a wider range of ingredients than dishwashing liquids. A review of the literature suggested that preservatives, which are designed to be toxic, and fragrances, where data on toxicity are limited, should be prioritized. The approach undertaken has successfully estimated use and provisionally identified some classes of chemicals which may be of most concern when used in cleaning and personal care products.
En este estudio se evaluó la posibilidad de obtener pectinas a partir de los subproductos del proceso del beneficio del cacao. Los experimentos se llevaron a cabo en el laboratorio de desarrollo de productos del departamento de ingeniería de procesos de la Universidad EAFIT.; 53 p.; Contenido parcial: Cacao -- Pectina -- Materiales y equipos -- Procedimiento del desarrollo experimental -- Caracterización y comparación de las pectinas obtenidas con la pectina comercial -- Costos de materia prima.
En este trabajo se encontraron y analizaron algunas condiciones para el proceso de producción de pectina a partir de la pulpa de la Algarroba, y también, se estudiaron las semillas y la vaina de dicha fruta para detectar la existencia o no de taninos en dichas partes.
El proceso de producción de pectina a partir de la Algarroba, cuenta con una etapa crítica llamada hidrolisis, en la cual la protopectina se transforma en pectina. El ácido utilizado en esta etapa fue ácido muriático (ácido clorhídrico comercial) por su bajo costo, no carboniza la materia orgánica y es menos oxidante que el ácido nítrico.; 121 p.; Contenido parcial: La Hymenaea Courbaril -- El árbol -- La resina -- Las semillas -- Pectina -- Taninos -- Metodología para la obtención de pectina -- Metodología para la obtención de taninos -- Balance preliminar económico.
The current marine pharmacology review that covers the peer-reviewed literature during 2003 and 2004 is a sequel to the authors' 1998-2002 reviews, and highlights the preclinical pharmacology of 166 marine chemicals derived from a diverse group of marine animals, algae, fungi and bacteria. Anthelminthic, antibacterial, anticoagulant, antifungal, antimalarial, antiplatelet, antiprotozoal, antituberculosis or antiviral activities were reported for 67 marine chemicals. Additionally 45 marine compounds were shown to have significant effects on the cardiovascular, immune and nervous system as well as possessing anti-inflammatory effects. Finally, 54 marine compounds were reported to act on a variety of molecular targets and thus may potentially contribute to several pharmacological classes. Thus, during 2003-2004, research on the pharmacology of marine natural products which involved investigators from Argentina, Australia, Brazil, Belgium, Canada, China, France, Germany, India, Indonesia, Israel, Italy, Japan, Mexico, Morocco, the Netherlands, New Zealand, Norway, Panama, the Philippines, Portugal, Russia, Slovenia, South Korea, Spain, Thailand, Turkey, United Kingdom, and the United States, contributed numerous chemical leads for the continued global search for novel therapeutic agents with broad spectrum activity.