Those That Remain Caught in the "Organic Matter Trap": Sorption/Desorption Study for Levelling the Fate of Selected Neonicotinoids.

With projections suggesting an increase in the global use of neonicotinoids, contemporary farmers can get caught on the "pesticide treadmill", thus creating ecosystem side effects. The aim of this study was to investigate the sorption/desorption behavior of acetamiprid, imidacloprid, and thiacloprid that controls their availability to other fate-determining processes and thus could be useful in leveling the risk these insecticides or their structural analogues pose to the environment, animals, and human health. Sorption/desorption isotherms in four soils with different organic matter (OC) content were modelled by nonlinear equilibrium models: Freundlich's, Langmuir's, and Temkin's. Sorption/desorption parameters obtained by Freundlich's model were correlated to soil physico-chemical characteristics. Even though the OC content had the dominant role in the sorption of the three insecticides, the role of its nature as well as the chemical structure of neonicotinoids cannot be discarded. Insecticides sorbed in the glassy OC phase will be poorly available unlike those in the rubbery regions. Imidacloprid will fill the sorption sites equally in the rubbery and glassy phases irrespective of its concentration. The sorption of thiacloprid at low concentrations and acetamiprid at high concentrations is controlled by hydrophilic aromatic structures, "trapping" the insecticides in the pores of the glassy phase of OC.

Those That Remain: Sorption/Desorption Behaviour and Kinetics of the Neonicotinoids Still in Use.

In January 2023, the derogation loophole was closed on "emergency authorisations" for the use of three out of five neonicotinoids in all EU states. In this study, we analysed the sorption/desorption behaviour and kinetic parameters of acetamiprid and thiacloprid, the two neonicotinoids that are still approved for use, either regularly or under emergency authorisations in the EU, and widely used worldwide. Sorption and desorption curves in four soils with different organic matter content were analysed using four kinetic models, namely, Lagergren's pseudo first-order model, two-site model (TSM), Weber-Morris intraparticle diffusion model and Elovich's model. Kinetic parameters were correlated to soil physico-chemical characteristics. To determine the mutual influence of soil characteristics and sorption/desorption parameters in the analysed soils, a factor analysis based on principal component analysis (PCA) was performed. Even though the two insecticides are very similar in size and chemical structure, the results showed different sorption/desorption kinetics. The model that best fits the experimental data was TSM. Thiacloprid showed a more rapid sorption compared to acetamiprid, and, in all soils, a higher proportion sorbed at equilibrium. Intra-particle diffusion seemed to be a relevant process in acetamiprid sorption, but not for thiacloprid. Desorption results showed that acetamiprid is more easily and more thoroughly desorbed than thiacloprid, in all soils. The kinetic behaviour differences stem from variations in molecular structure, causing disparate water solubility, lipophilicity, and acid-base properties.

Surveillance of Legionella pneumophila: Detection in Public Swimming Pool Environment.

The bacterium Legionella pneumophila is a ubiquitous microorganism naturally present in water environments. The actual presence of this opportunistic premise plumbing pathogen in recreational swimming pools and hot tubs in the northwestern part of Croatia has not been investigated. This study aimed to analyze the presence of the opportunistic pathogen L. pneumophila in public swimming pool water in Primorje-Gorski Kotar County (N = 4587) over a four-year period (2018-2021). Additionally, the second aim was to investigate the connection between the presence of L. pneumophila and pool water physicochemical parameters using mathematical predictive models. The presence of L. pneumophila was detected in six pool samples. Five positive samples were found in the water of indoor hot tubs filled with fresh water, and one positive sample in an outdoor recreational saltwater pool. A predictive mathematical model showed the simultaneous influence of chemical parameters dominated by the temperature in saltwater and freshwater pools, as well as the significant influence of free residual chlorine and trihalomethanes. Our results pointed out that keeping all physicochemical parameters in perfect harmony is necessary to reach the best disinfection procedure and to avoid the optimum conditions for L. pneumophila occurrence.

Emerging Contaminant Imidacloprid in Mediterranean Soils: The Risk of Accumulation Is Greater than the Risk of Leaching.

Imidacloprid (IMI) is an extensively used neonicotinoid insecticide whose occurrence in the environment is a worldwide problem. Its sorption/transport properties are recognized as one of the key knowledge gaps hindering policymaking regarding its international routine monitoring in soils. Therefore, we studied IMI transport behaviour in Croatian Mediterranean soils using column experiments. Breakthrough curves were analysed using the two-site adsorption model and compared against dimethoate (DIM). Transport parameters were correlated to soil physicochemical properties. The results indicate that IMI shows a high degree of preference for soil organic matter over any other soil constituent. For IMI, the clay did not exhibit any sorption activity, while hematite did act as an active sorbent. Contrarily, hematite increased the leachability of DIM by blocking the active sorption sites on clay platelets. Both hematite and clay sorption acted as type-2 (i.e., rate-limiting) sites. In all soils, IMI exhibited lower short-term leachability than DIM. Combined with a body of data concerning other aspects of IMI environmental behaviour, the results indicate that the risk of accumulation of IMI in the soil is greater than the risk of contamination by leaching. Thus, continuous monitoring of IMI in soils should be incorporated into future soil health protection programs.

The Labin Region, an ecologically vulnerable geographical area in Croatia: Mortality characteristics in an area polluted by industrial over a 40-year period.

The history of the Labin region in Croatia includes intensive industrial development with repercussions of pollution on environment and health. Assuming that prolonged exposure to polluted environments causes qualitative changes in mortality, the aim was to analyse the mortality characteristics of the population of the Labin Region for the 1968-2008 period based on data from the Croatian Bureau of Statistics. Public health and social opportunities in this geographical area carry a long-term burden of exposure to an industrial polluted environment with outcomes expressed by mortality or/and morbidity in the population. This study includes data on 11,903 deaths, most of which due to diseases of the circulatory, respiratory and digestive systems as well as neoplasms. In the third and fourth decade of the study period, a group of neoplasms showed significant increases, while the increase in respiratory diseases were more gradual. The female population died mostly from diseases of the circulatory and endocrine system as well as neoplasms, while the male population mainly died from diseases of the digestive system and external causes. This research provides guidelines that could create better public health, raising the quality of life and contribute to a future environmental protection in local communities by targeted policies.

Disinfecting Action of Gaseous Ozone on OXA-48-Producing Klebsiella pneumoniae Biofilm In Vitro.

Klebsiella pneumoniae is an emerging multidrug-resistant pathogen that can contaminate hospital surfaces in the form of a biofilm which is hard to remove with standard disinfectants. Because of biofilm resistance to conservative disinfectants, the application of new disinfection technologies is becoming more frequent. Ozone gas has antimicrobial activity but there is lack of data on its action against K. pneumoniae biofilm. The aim of this study was to investigate the effects and mechanisms of action of gaseous ozone on the OXA-48-procuding K. pneumoniae biofilm. A 24 h biofilm of K. pneumoniae formed on ceramic tiles was subsequently exposed to different concentrations of ozone during one and two hours to determine the optimal ozone concentration. Afterwards, the total bacteria count, total biomass and oxidative stress levels were monitored. A total of 25 ppm of gaseous ozone was determined to be optimal ozone concentration and caused reduction in total bacteria number in all strains of K. pneumoniae for 2.0 log10 CFU/cm2, followed by reduction in total biomass up to 88.15%. Reactive oxygen species levels significantly increased after the ozone treatment at 182% for the representative K. pneumoniae NCTC 13442 strain. Ozone gas in the concentration of 25 ppm caused significant biofilm reduction but did not completely eradicate the K. pneumoniae biofilm formed on ceramics. In conclusion, ozone gas has great potential to be used as an additional hygiene measure in joint combat against biofilm in hospital environments.

Effects of Long-Term Lead Exposure on Antioxidant Enzyme Defense System in Organs of Brown Hare (Lepus europaeus Pallas) as a Bioindicator of Environmental Pollution in Croatia.

In Croatia, Podravina is a well-known lead-polluted region due to the intensive exploitation of natural gas, a highly developed agricultural industry, and a traffic hub with several heavily traveled roads. It represents a natural environment with a great variety of wildlife, especially hares (Lepus europaeus Pallas), which may serve as an indicator for environmental quality assessment. This study was conducted to estimate the bioaccumulation of lead in hare liver, kidney, muscle, and brain during long-term exposure and its impact on the oxidative status of the organism and to investigate a possible lead exchange ionic mechanism in the brain. In the organs of two hare groups (experimental from polluted area and control from the island of Krk), Ca, Fe, Mg, Na, lead concentrations, and antioxidant enzyme defense system were analyzed. The accumulation of lead was highest in the brain (3.7-fold higher compared to the control group) and lowest in the liver (1.6-fold higher compared to the control group). Kendall-Tau and multiple regression analysis showed that the increased lead content caused a stronger exchange of Ca and Na ions in the brain. We proposed that lead either mobilizes intracellular cation stores or causes competitive displacement of Ca from the binding site in intoxicated cells. A linear predictive model for cell intoxication by lead was proposed, where GPx and SOD were predominantly influenced by long-term lead exposure. The presented results showed that long-term lead exposure in hares negatively affected their oxidative status and caused the strongest toxicity in the brain and muscles, making their survival and/or population vulnerable.

Juniperus communis essential oil limit the biofilm formation of Mycobacterium avium and Mycobacterium intracellulare on polystyrene in a temperature-dependent manner.

Formation of biofilms allows bacterial cells to survive in adverse environments. Nontuberculous mycobacteria are ubiquitous in aqueous environments, where they adhere to surfaces and create a biofilm. This has led to the emergence of healthcare-associated infections and the use of biomaterials in medicine. Essential oils (EO) are substances of natural origin whose effect on microorganisms has been the subject of numerous studies. Here, we investigated the effect of Juniperus communis EO on nontuberculous mycobacteria and their early and mature biofilm formation in sterilised tap water. The combination of Juniperus communis EO and increasing ambient temperature showed a synergistic effect on the reduction of biofilm formation of Mycobacterium avium and Mycobacterium intracellulare on a polystyrene surface. A significant antibiofilm effect of Juniperus communis EO was also found at subinhibitory concentrations, suggesting a potential role for it as an alternative disinfectant of natural water.

Sea water whirlpool spa as a source of Legionella infection.

Bacterial pneumonia caused by the inhalation of aerosols contaminated with Legionella spp. is also known as Legionnaires' disease. In this study, we report a case of pneumonia caused by Legionella pneumophila sg.1 in a 58-year-old man who visited a sea water-filled whirlpool within a hotel and spa complex. The patient's Legionella urine antigen test was positive for L. pneumophila sg.1. During the field study, samples were taken from both the outdoor and indoor sea water-filled pools. Samples from the whirlpool were culture positive for L. pneumophila sg.1. Typing results indicated sea water isolate belonged to Sequence type ST82 and Allentown/France MAb subgroup. In vitro experiments showed that L. pneumophila strains are able to survive within sea water up to 7 days, and survival time is prolonged with sea water dilution. Also, our results indicate that L. pneumophila Allentown strain was the most resistant to adverse conditions in sea water with the highest values of DT50 (420 min) and DT90 (1,396 min). The possible source of infection was adding potable water for filling up the whirlpool. The survival of the L. pneumophila in additionally conditioned sea water should be considered in a further study.

Sorption and leaching potential of organophosphorus insecticide dimethoate in Croatian agricultural soils.

Dimethoate is an organophosphorus insecticide still used in Croatia and worldwide, with polar structure and high water solubility that make it prone to leaching. This study analyzed how physico-chemical properties of soils affected dimethoate sorption and mobility. For that purpose, five soil samples were collected from three Croatian regions (two coastal and one mountain region). Dimethoate sorption process was analyzed using the batch procedure while its mobility and leaching potential was investigated by column experiment. The results showed that dimethoate sorption can be adequately described by Freundlich model. All isotherms were of L-type with varying degrees of non-linearity, indicating different sorption efficiencies and distribution of sorption sites energies among the soils. Energy distribution was broader in soils richer in organic matter (OM). KF values indicated relatively low sorption efficiency for all soils, with an increase of KF values proportional to OM content. Mechanisms involved in dimethoate sorption and mobility were analyzed by fitting the breakthrough curves (BTCs) with two mathematical models, namely one-site equilibrium (ELM) and two-site nonequilibrium sorption model (NELM). Correlations were quantified by Kendall-Tau test, which revealed the strongest correlation of KF value with OM content, cation exchange capacity and the humic acid content, while correlations with pH, clay content and A465nm/A665nm ratio were negative and insignificant. Based on these findings, a model for prediction of leaching potential was formed. A simplified model for dimethoate sorption/transport was proposed.

Juniper and immortelle essential oils synergistically inhibit adhesion of nontuberculous mycobacteria to Acanthamoeba castellanii.

Acanthamoeba is an opportunistic protozoon, widespread in the aquatic environment, where it can be in endosymbiosis with over 30 pathogenic bacteria, including nontuberculous mycobacteria (NTM). Protozoa play a crucial role in mycobacterial pathogenesis and serve as a reservoir of infection. Since the first step in bacteria making contact with amoebae is adhesion, we were interested in investigating whether essential oils (EOs) can affect it. To that end we investigated the effects of juniper (Juniperus communis) and immortelle (Helichrysum italicum) EOs against Mycobacterium avium, M. intracellulare, and M. gordonae in tap water and against their adhesion to Acanthamoeba castellanii by combining them in synergistic EO concentrations. M. avium and M. intracellulare adhered to A. castellanii to a greater extent than M. gordonae. The adhesion of all NTMs was prevented by the subinhibitory concentrations of EOs. When comparing the effect of synergistic combinations of EOs and the effect of a single concentration from a combination, a higher percentage of adhesion inhibition in all synergistic combinations observed, except against M. gordonae. Neither oil was cytotoxic to A. castellanii. Our findings suggest that the EOs or their components weaken the contact of environmental NTMs and free-living amoebae and indirectly diminish their pathogenic potential, which could be of value in developing strategies for maintenance of water supply systems.

Aucubin administered by either oral or parenteral route protects against cisplatin-induced acute kidney injury in mice.

Aucubin is pharmacologically active natural compound which possesses numerous beneficial properties. This study aimed to evaluate the protective effect of aucubin against cisplatin (CP)-induced acute kidney injury in mice and the mechanism of its action. Aucubin was administrated to mice orally or intraperitoneally (ip) (1.5 and 5 mg/kg) for two consecutive days, two days after ip injection of cisplatin (CP), 11 mg/kg. Treatment with aucubin by both routes of administration ameliorated histopathological changes and reduced elevated serum markers of kidney injury. CP administration increased renal expression of heme oxygenase-1 (HO-1) and 4-hydroxynonenal (4-HNE), as well as tumor necrosis factor-alpha (TNF-α), which was dose-dependently ameliorated by aucubin. Moreover, aucubin reduced increased renal expression of cleaved caspase-3 and -9 and decreased poly (ADP-ribose) polymerase (PARP) cleavage. Mechanistically, aucubin suppressed the activation of several signaling pathways involved in inflammation and apoptosis, including nuclear factor-kappa B (NF-κB), signal transducer and activator of transcription 3 (STAT3), Akt, extracellular signal-regulated kinase 1/2 (ERK1/2) and forkhead box O3a (FOXO3a). Parenteral application was marginally but statistically more effective in reducing CP-induced kidney injury than oral administration. The findings of this study suggest that aucubin acts as a protective agent against CP-induced nephrotoxicity, which should be further investigated.

Synergistic potential of Juniperus communis and Helichrysum italicum essential oils against nontuberculous mycobacteria.

OBJECTIVE: The present study evaluated the possible synergistic antimycobacterial interactions of Juniperus communis and Helichrysum italicum essential oils (EO). METHODS: Antimycobacterial potential was tested against Mycobacterium avium and Mycobacterium intracellulare using broth and water dilution method and checkerboard synergy method. Antiadhesion and antibiofilm effect of EOs was evaluated on biotic (HeLa cells) and abiotic surface (polystyrene). To evaluate the possible mechanisms of action, cellular leakage of proteins and DNA was tested and structural changes were visualized with a transmission electron microscope. RESULTS: MIC, minimum bactericidal concentration (MBC) and minimal effective concentration (MEC) were 1.6 mg ml-1 for J. communis EO and 3.2 mg ml-1 for H. italicum EO against both mycobacteria. All combinations of EOs in checkerboard synergy method produced fractional inhibitory concentration index values ranging from 0.501 to 1.5, corresponding to synergistic, additive or indifferent effects. Mycobacterium avium showed a greater tendency to create biofilm but these EOs at subinhibitory concentrations (sMIC) effectively blocked the adhesion and the establishment of biofilm. The exposure of both mycobacteria to MICs and sMICs lead to significant morphological changes: acquired a swollen form, ghost-like cell, disorganized cytoplasm detached from the cell wall. OD value of supernatant for both mycobacteria exposed to EOs have confirmed that there is a leakage of cellular material. CONCLUSION: The leakage of the cellular material is noticeably higher in sMIC, which is probably due to cell wall damage. sMIC of both EOs have an additive or synergistic effect, reducing MICs, limiting adhesion and preventing the formation of biofilms.

Antimycobacterial potential of the juniper berry essential oil in tap water.

Mycobacterium avium complex-related diseases are often associated with poorly maintained hot water systems. This calls for the development of new control strategies. The aim of this study was to investigate the activity of essential oils (EOs) from the Mediterranean plants, common juniper, immortelle, sage, lavandin, laurel, and white cedar against Mycobacterium avium ssp. avium, Mycobacterium intracellulare, and Mycobacterium gordonae in culturing broth and freshwater as their most common habitat. To do that, we developed a new method of water microdilution to determine their minimal effective concentrations (MEC). The most active EO was the one from the common juniper with the MEC of 1.6 mg mL-1. Gas chromatography / mass spectrometry the juniper EO identified monoterpenes (70.54 %) and sesquiterpenes (25.9 %) as dominant component groups. The main monoterpene hydrocarbons were α-pinene, sabinene, and ß-pinene. The juniper EO significantly reduced the cell viability of M. intracellulare and M. gordonae at MEC, and of M. avium at 2xMEC. Microscopic analysis confirmed its inhibitory effect by revealing significant morphological changes in the cell membrane and cytoplasm of all three bacteria. The mode of action of the juniper EO on the cell membrane was confirmed by a marked leakage of intracellular material. Juniper EO has a great practical potential as a complementary or alternative water disinfectant in hot water systems such as baths, swimming pools, spa pools, hot tubs, or even foot baths/whirlpools.

Evaluation of the Antioxidant Capacity, Antimicrobial and Antiproliferative Potential of Fir (Abies alba Mill.) Honeydew Honey Collected from Gorski kotar (Croatia).

The paper examines the antiproliferative, antimicrobial and antioxidative effects of fir (Abies alba Mill.) honeydew honey from mountain region of Croatia (Gorski kotar) as a potential replacement for standard antibiotics and chemotherapeutic agents. Cell viability, annexin V assay and flow cytometry analysis served to analyse the antiproliferative effect on, apoptosis induction in and cell death of cancer cell lines: HeLa, MCF-7, SW620, CFPAC-1, MIA PaCa-2 and normal diploid human fibroblasts (BJ). Antimicrobial activity was tested against Staphylococcus and Acinetobacter strains by agar well diffusion and microdilution assays. The DPPH˙ assay determined the radical scavenging activity, while mathematical models helped to evaluate the kinetic data of DPPH˙ inhibition. Antiproliferative effect on all tested cell lines and the prominent effect on normal diploid human fibroblasts (BJ), colorectal adenocarcinoma (SW620, metastatic) and breast epithelial adenocarcinoma (MCF-7, metastatic) was observable. The mechanisms of antiproliferative effect included accumulation of cells in the sub-G1 phase in all tested cells and induction of apoptosis in SW620 and MCF-7 cells predominantly. The antibacterial assays showed that antibiotic-resistant strains of both bacteria, including multi-resistant strain A. baumannii ATCC® BAA-1605™, were sensitive to all tested honey samples. Radical scavenging assay suggests that antioxidants present in the honey possess different radical suppressing abilities and that they react at different rates with radicals, thereby causing two steps of reaction. The results of the study indicate that Croatian fir honeydew honey has a therapeutic potential due to the strong biological activity and can serve to protect human health.

Stevia and stevioside protect against cisplatin nephrotoxicity through inhibition of ERK1/2, STAT3, and NF-κB activation.

We investigated the effect of natural sweetener Stevia rebaudiana and its constituent stevioside in cisplatin (CP)-induced kidney injury. Male BALB/cN mice were orally administered 10, 20, and 50 mg/kg body weight of Stevia rebaudiana ethanol extract (SE) or stevioside 50 mg/kg, 48 h after intraperitoneal administration of CP (13 mg/kg). Two days later, CP treatment resulted in histopathological changes showing kidney injury. Increased expression of 4-hydroxynonenal (4-HNE), 3-nitrotyrosine (3-NT), and heme oxygenase-1 (HO-1) in mice kidneys suggested oxidative stress. CP treatment also increased renal expression of nuclear factor-kappaB (NF-κB) p65 subunit and phosphorylated inhibitor of NF-κB (IκBα), as well as expression of pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α). Induction of apoptosis and inhibition of the cell cycle in kidneys was evidenced by increased expression of p53, Bax, caspase-9, and p21, proteolytic cleavage of poly (ADP-ribose) polymerase (PARP), with concomitant suppression of Bcl-2 and cyclin D1 expression. The number of apoptotic cells in kidneys was also assessed. CP administration resulted in activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3). Both SE and stevioside attenuated CP nephrotoxicity by suppressing oxidative stress, inflammation, and apoptosis through mechanism involving ERK1/2, STAT3, and NF-κB suppression.

Involvement of α-, γ- and δ-Tocopherol Isomers fromPumpkin (Cucurbita pepo L.) Seed Oil or Oil Mixtures inthe Biphasic DPPH˙ Disappearance Kinetics.

The antioxidant activity of three types of pumpkin seed oil or oil mixtures (cold- -pressed, produced from roasted seed paste and salad) produced in the northern part of Croatia and the kinetics of their behaviour as free radical scavengers were investigated using DPPH˙. In addition, the involvement of oil tocopherol isomers (α-, γ- and δ-) in different steps of DPPH˙ disappearance and their impact on the rate of reaction were analysed. The kinetics of DPPH˙ disappearance is a two-step process. In the first step, rapid disappearance of DPPH˙ occurs during the first 11 min of the reaction, depending on the oil type, followed by a slower decline in the second step. To describe DPPH˙ disappearance kinetics, six mathematical models (mono- and biphasic) were tested. Our findings showed that γ- and δ-tocopherols affected DPPH˙ disappearance during the first step, and α-tocopherol in the second step of the reaction. Moreover, α-tocopherol demonstrated 30 times higher antioxidant activity than γ- and δ-tocopherols. The results indicated the biphasic double-exponential behaviour of DPPH˙ disappearance in oil samples, due to the complexity of reactions that involve different tocopherol isomers and proceed through different chemical pathways.

Preexposure to Olive Oil Polyphenols Extract Increases Oxidative Load and Improves Liver Mass Restoration after Hepatectomy in Mice via Stress-Sensitive Genes.

Polyphenols can act as oxidants in some conditions, inducing redox-sensitive genes. We investigated the effect of preexposure to the olive oil polyphenols extract (PFE) on time-dependent changes in the hepatic oxidative state in a model of liver regeneration-a process in which oxidative stress associated with the metabolic overload accounts for the early events that contribute to the onset of liver self-repair. Liver regeneration was induced by one-third hepatectomy in mice. Prior to hepatectomy, mice were intraperitoneally given either PFE (50 mg/kg body weight) or saline for seven consecutive days, while respective controls received vehicle alone. Redox state-regulating enzymes and thiol proteins along with the mRNA levels of Nrf2 gene and its targets γ-glutamylcysteine synthetase and heme oxygenase-1 were determined at different time intervals after hepatectomy. The liver mass restoration was calculated to assess hepatic regeneration. The resulting data demonstrate the effectiveness of preexposure to PFE in stimulating liver regeneration in a model of a small tissue loss which may be ascribed to the transient increase in oxidant load during the first hours after hepatectomy and associated induction of stress response gene-profiles under the control of Nrf2.

Metallothioneins and trace elements dyshomeostasis induced by exposure to gasoline vapor in mice.

To investigate the effects of air pollution related with the gasoline/petrochemical industry the expression of metallothionein I (MT-I) mRNA and tissue metals were analyzed in organs of mice, exposed to gasoline (G) vapor in laboratory conditions. Control groups consisted of intact mice and of those exposed in the metabolic chamber to fresh air. The data obtained by RT-PCR and inductively coupled plasma spectrometry have shown that exposure to G vapor leads to upregulation of MT-I mRNA in organs that receive a strong respiratory and olfactory input or participate in gasoline degradation and elimination (lungs, brain, kidney and liver). Besides, in the brain and in the lungs, kidney and liver a decreased tissue content of Zn²âº or Cu²âº and Mg²âº was found (p<0.001). Some of these changes were obtained also in mice closed in the metabolic chamber, pointing to the involvement of stress-induced mechanisms in the transcriptional regulation of MTs.

Mathematical prediction of imidacloprid persistence in two Croatian soils with different texture, organic matter content and acidity under laboratory conditions.

In the present laboratory study, persistence of imidacloprid (IMI) as a function of initial insecticide concentration and soil properties in two Croatian soils (Krk sandy clay and Istria clay soils) was studied and described mathematically. Upon fitting the obtained experimental data for the higher concentration level (5 mg/kg) to mathematical models, statistical parameters (R (2), scaled root mean squared error and χ (2) error) indicated that the single first-order kinetics model provided the best prediction of IMI degradation in the Krk sandy clay soil, while in the Istria clay soil biphasic degradation was observed. At the lower concentration level (0.5 mg/kg), the biphasic models Gustafson and Holden models as well as the first-order double exponential model fitted the best experimental data in both soils. The disappearance time (DT50) values estimated by the single first-order double exponential model (from 50 to 132 days) proved that IMI can be categorized as a moderately persistent pesticide. In the Krk sandy clay soil, resulting DT50 values tended to increase with an increase of initial IMI concentration, while in the Istria clay soil, IMI persistence did not depend on the concentration. Organic matter of both experimental soils provided an accelerating effect on the degradation rate. The logistic model demonstrated that the effect of microbial activity was not the most important parameter for the biodegradation of IMI in the Istria clay soil, where IMI degradation could be dominated by chemical processes, such as chemical hydrolysis. The results pointed that mathematical modeling could be considered as the most convenient tool for predicting IMI persistence and contributes to the establishment of adequate monitoring of IMI residues in contaminated soil. Furthermore, IMI usage should be strictly controlled, especially in soils with low organic matter content where the risk of soil and groundwater contamination is much higher due to its longer persistence and consequent leaching and/or moving from soil surface prior to its degradation.