Accumulation levels and characteristics of some pesticides in human adipose tissue samples from Southeast China

This paper presents a comprehensive study of pesticide levels and bio-accumulation characteristics in human adipose tissues among residents of Southeast China. A large number of adipose samples (n = 633) were selected for 58 pesticides and were analyzed by high sensitive Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS). The results showed that POPs pesticides were frequently detected, including 2,4′-DDD, 2,4′-DDE, 2,4′-DDT, 4,4′-DDD, 4,4′-DDE, 4,4′-DDT, α-HCH, β-HCH, γ-HCH, δ-HCH, hexachlorobenzene (HCB), and mirex. Other detected pesticide species were dicofol, methamidophos and chlordimeform, which have rarely been reported. Comparing to different countries, the concentrations of total DDT and HCH in these three Chinese southeastern sites were in the middle range, whereas the HCB and mirex were in the lower end. A significant correlation was observed between region as well as age and POPs pesticide levels. Some pesticide residue levels were also found significantly correlated to occupation. However, there was no significant correlation between gender and pesticides. Meanwhile, it is interesting to find that mortality of malignant tumors tends to associate with the pesticides levels in human adipose tissue. More importantly, the measured data presented in this study provide realistic information which is useful for assessing human exposure to pesticides in the general population of Southeast China.     

Effects of salinity, DOM and metals on the fate and microbial toxicology of propetamphos formulations in river and estuarine sediment

Toxicity studies tend to use pure pesticides with single organisms. However, natural systems are complex and biological communities diverse. The organophosphate pesticide propetamphos (PPT) has been found exceeding regulatory limits (100 ng L⁻¹) in rivers. We address whether solution properties affect the fate of Analar (Analar-PPT) or industrial PPT (PPT-Ind) propetamphos formulations and whether propetamphos and metal toxicant effects are additive, antagonistic or synergistic? The sorption, desorption, biodegradation and microbial toxicology of Analar-PPT and PPT-Ind were investigated in Conwy River and estuary sediment. Results showed elevated salinity enhanced PPT sorption, while higher salinities increased PPT-Ind retention. Higher dissolved organic matter (DOM) and low salinity slowed Analar-PPT biodegradation (1.9 × 10⁻³ h⁻¹). Analar-PPT and PPT-Ind biodegradation was further reduced by low salinity, high DOM and dissolved Zn and Pb (6.3 × 10⁻⁴ h⁻¹, 1100 h t_½ for Analar-PPT; 7.5 × 10⁻⁴ h⁻¹, 924 h t_½ for PPT-Ind). Toxicity effects of PPT, Zn and Pb in equitoxic ratio were higher for PPT-Ind (4.7 μg PPT-Ind g⁻¹; 581 μg Zn g⁻¹; 395 μg Pb g⁻¹) than for Analar-PPT (34.6 μg PPT g⁻¹; 312 μg Zn g⁻¹; 212 μg Pb g⁻¹) whilst a toxicant ratio 1:100:10 suggested small quantities of Analar-PPT (EC₁₀ = 0.06 μg g⁻¹) affected microbial communities. The combined toxicity effect was more than additive. Thus, industrial formulations and pollutant mixtures should be considered when assessing environmental toxicity.     

Response of diazotrophic cyanobacterium Nostoc carneum under pesticide and UV-B stress

A study was under taken, under controlled laboratory conditions, to investigate the influence of non-ionizing radiation (UV-B) and an organochlorine pesticide on the growth, photosynthetic pigments, protein content and DCPIP photoreduction of a cyanobacterium Nostoc carneum. Test algae was isolated from rice field soils of Sambalpur, Western Orissa, India and grown in nitrogen free BG 11 culture medium. Culture of algae from log phase of growth was treated with 5 ppm of the insecticide, Endodhan and UV-B (20 mW m⁻²) for 2 h daily, separately and in combination of insecticide and UV-B radiation. Algal samples treated with UV-B and pesticide separately showed distinct inhibitory effects on growth, pigments, protein content and DCPIP reduction of the test samples. However, when pesticide treated samples were subjected to UV-B exposure, the effect showed additive as well as synergetic effect. Experiment conducted to check the ability of the organism to recover from the stress, exposed for various time periods, suggest their ability to partially recover from the stress.     

Evaluation of the field dissipation of fungicides and insecticides used on fruit bearing trees in northern Italy

The dissipation of the fungicides captan, cyprodinil, fludioxonil, dithianon, and tebuconazole and of the insecticides chlorpyrifos, fenitrothion, and malathion was studied, following a single treatment of different cultivars of pears, apples, and peaches. The study was conducted in northern Italy, over two successive growing seasons (2004 and 2005). The treatments were performed by the farmers involved, in line with their usual practice. At various time intervals from treatment to harvest, representative samples of fruit were collected and analyzed for pesticide residues. In some cases, concentrations lower than the maximum residue levels (MRLs) were found immediately after treatment. In all trials a rapid decline in pesticide concentrations was observed leading to residues at harvest greatly below the MRLs.     

Controlled release and retarded leaching of pesticides by encapsulating in carboxymethyl chitosan /bentonite composite gel

A novel composite gel composed of carboxymethyl-chitosan (CM-chit) and bentonite (H-bent) was used as the carrier for encapsulating atrazine and imidacloprid to control their release in water and retard their leaching in soil. Strong interactions between CM-chit and H-bent in the composite were confirmed by FT-IR, and good dispersion of pesticides in the carrier was observed by SEM. According to the results of release experiments in water, the CM-chit/H-bent composite carrier showed double advantages of both encapsulation by the polymer and sorption by the bentonite. The time taken for 50 % of active ingredients to be released, t ₅₀, was prolonged to 572 h for atrazine and 24 h for imidacloprid, respectively. The difference between the two pesticides on release behavior was related to their hydrophobicity and water solubility. Leaching experiments through a soil layer showed that this novel carrier reduced the amount of pesticides available for leaching, and would be useful for diminishing the environmental pollution of pesticides.     

Pesticide distribution in an agricultural environment in Argentina

An assessment of the off-site migration of pesticides from agricultural activity into the environment in the Neuquen River Valley was performed. The aim of this study was to evaluate the distribution of pesticides in several compartments of a small agricultural sub-catchment. Soil, surface water, shallow groundwater and drift deposition were analyzed for pesticide residues. Results showed the presence of some pesticide residues in soil, surface water and shallow groundwater compartments. The highest detection frequencies in water (surface and subsurface) were found for azinphos-methyl and chlorpyrifos (>70%). In terms of concentration, the highest levels were observed in shallow groundwater for azinphos methyl (22.5 μg/L) and carbaryl (45.7 μg/L). In the soil, even before the application period had started, accumulation of residues was present. These residues increased during the period studied. Spray drift during pesticide application was found to be a significant pathway for the migration of pesticide residues in surface water, while leaching and preferential flows were the main transport routes contributing to subsurface contamination.     

Review of advances in the thin layer chromatography of pesticides: 2008–2010

Techniques and applications of thin layer chromatography (planar chromatography) for the separation, detection, qualitative and quantitative determination, and preparative isolation of pesticides and their metabolites and other related compounds are reviewed for the period from November 1, 2008 to November 1, 2010. Analyses are described for a variety of samples types and pesticide classes. In addition to references on residue analysis, studies such as pesticide structure-retention relationships, identification and characterization of plant pesticides and synthesized pesticides, metabolism, degradation, mobility, identification of biomarkers for detection of herbicide effects in plants, and lipophilicity are covered.     

Urinary dialkyl phosphate levels before and after first season chlorpyrifos spraying amongst farm workers in the Western Cape,South Africa

The study investigated urinary levels of dialkyl phosphates resulting from pesticide exposure amongst 40 farm workers. Workers were tested (urinary dialkyl phosphate levels, anthropometry, short exposure questionnaire) before and after the first day of seasonal chlorpyrifos spraying. Median baseline urinary dialkyl phosphates was high amongst both non-applicators (1587.5 μg/g creatinine, n = 8) and applicators (365.6 μg/g creatinine, n = 9). There was not much evidence of an increase in post-spray dialkyl phosphates levels from pre-spray levels amongst both applicators and non-applicators. Hours mixing, spraying, driving a tractor and hours worked by non-applicators were not significantly associated with an increase in post-spray dialkyl phosphate levels, adjusting for age, height, weight, gender, use of empty pesticide containers and self-reported kidney problems. Past applicator status was weakly positively associated with pre-spray dialkyl phosphate levels adjusting for age, height, weight, and gender, self-reported kidney problems, smoking and alcohol (β= 1019.5, p = 0.307, R²= 0.28). The high dialkyl phosphate levels call for an epidemiological investigation into the health effects of organophosphorous pesticides.     

Degradation of ethylenethiourea pesticide metabolite from water by photocatalytic processes

In this study, photocatalytic (photo-Fenton and H₂O₂/UV) and dark Fenton processes were used to remove ethylenethiourea (ETU) from water. The experiments were conducted in a photo-reactor with an 80 W mercury vapor lamp. The mineralization of ETU was determined by total organic carbon analysis, and ETU degradation was qualitatively monitored by the reduction of UV absorbance at 232 nm. A higher mineralization efficiency was obtained by using the photo-peroxidation process (UV/H₂O₂). Approximately 77% of ETU was mineralized within 120 min of the reaction using [H₂O₂]₀ = 400 mg L^?1. The photo-Fenton process mineralized 70% of the ETU with [H₂O₂]₀ = 800 mg L^?1 and [Fe²⁺] = 400 mg L^?1, and there is evidence that hydrogen peroxide was the limiting reagent in the reaction because it was rapidly consumed. Moreover, increasing the concentration of H₂O₂ from 800 mg L^?1 to 1200 mg L^?1 did not enhance the degradation of ETU. Kinetics studies revealed that the pseudo-second-order model best fit the experimental conditions. The k values for the UV/H₂O₂ and photo-Fenton processes were determined to be 6.2 × 10^?4 mg L^?1 min^?1 and 7.7 × 10^?4 mg L^?1 min^?1, respectively. The mineralization of ETU in the absence of hydrogen peroxide has led to the conclusion that ETU transformation products are susceptible to photolysis by UV light. These are promising results for further research. The processes that were investigated can be used to remove pesticide metabolites from drinking water sources and wastewater in developing countries.