Due to the inherent limitations of the analytical methods of measurement, environmental exposure data often present observations described as below a certain detection limit, also called left-censored data. Censored data directly interferes in almost all types of statistical analyzes, including descriptive parameters, hypothesis testing, confidence intervals, correlations and regressions. In this work, we investigated the performance of the main classes of methods from major publications available in the literature, considering their advantages and limitations. Some criteria for selecting the best method of dealing with censored data are presented.

Um estudo foi realizado no município de Manhuaçu, Minas Gerais, objetivando estudar os efeitos dos agrotóxicos utilizados nas culturas de café em águas superficiais e subterrâneas. Manhuaçu está localizada em uma região brasileira importante em termos de produção agrícola. Além disso, a cidade possui vários mananciais destinados ao abastecimento público e 13 pontos de captação de águas superficiais e subterrâneas. Houve várias ocorrências de câncer na população local. Um levantamento realizado em municípios de Minas Gerais identificou 122 cidades com altas ocorrências de câncer na população, entre essas constava Manhuaçu. As propriedades físico-químicas e as massas aplicadas de cada ingrediente ativo dos agrotóxicos estudados foram levantadas. Os algoritmos de Goss e GUS foram utilizados para se estimar o risco de contaminação de águas superficiais e subterrâneas, respectivamente. Alguns dos agrotóxicos utilizados na região, cujos potenciais de contaminação foram estimados como sendo altos, foram detectados em águas superficiais por CL/EM-EM. Este estudo pode auxiliar agricultores e organizações ambientais oficiais na seleção e controle de produtos, respectivamente.

A study was conducted in Manhuaçu city, Minas Gerais, aiming to study the effects of pesticides used in coffee crops on surface and ground waters. Manhuaçu is located in an important Brazilian region of agricultural production. Moreover, the city possesses many different water sources directed to the public water supply, and 13 points of surface and groundwater pumping. There have also been several occurrences of cancer in the local population. A survey conducted among cities of Minas Gerais identified 122 cities with high occurrences of death due to cancer, among which was Manhuaçu. The physico-chemical properties and applied mass of the active ingredients of each pesticide studied were surveyed. Goss and GUS algorithms were applied to estimate the risk of surface and ground water contamination, respectively. Some of the most widely used pesticides in the region, whose contamination potential was estimated as high, were later detected in surface waters through LC/MS-MS. This study can help agriculturists and officials of environmental organizations select and control, respectively, less harmful products to the water.

From the environmental point of view, the textile sector is outstanding for the generation of large amounts of biorecalcitrant effluents. In this paper the textile effluent biodegradability, both before and after its treatment with Fenton's Reagent, were compared by means of biologic tests. These tests showed that the Fenton treatment lowered the biodegradabilty of practically all tested effluents, except one specific effluent from a scouring bath of polyester fibers, which achieved a 93% COD removal. This removal was due to a significant phase separation (oil/water).