Maria Ludovica Saccà

Environmental fate of the antiviral drug Tamiflu in two aquatic ecosystems.

The antiviral drug Tamiflu (Oseltamivir Phosphate, OP), has been indicated by the World Health Organization as a first-line defense in case of an avian influenza pandemic. Recent studies have demonstrated that Oseltamivir Carboxylate (OC), the active metabolite of the prodrug OP, has the potential to be released into water bodies. The present laboratory study focused on basic processes governing the environmental fate of OC in surface water from two contrasting aquatic ecosystems of northern Italy, the River Po and the Venice lagoon. Results of this study confirmed the potential of OC to persist in surface water. However, addition of 5% of sediments resulted in rapid OC degradation. Estimated half-life of OC in water/sediment of the River Po was 15 days. After three weeks of incubation at 20 degrees C, more than 8% of (14)C-OC evolved as (14)CO(2) from water/sediment samples of the River Po and Venice lagoon. At the end of the 21-day incubation period, more than 65% of the (14)C-residues were recovered from the liquid phase of both Po and Venice water/sediment samples. OC was moderately retained onto coarse sediments from the two sites. In water/sediment samples of the River Po and Venice lagoon treated with (14)C-OC, more than 30% of the (14)C-residues remained water-extractable after three weeks of incubation. The low affinity of OC to sediments suggests that presence of sediments would not reduce its bioavailability to microbial degradation.

Meeting Report: Risk Assessment of Tamiflu Use Under Pandemic Conditions

On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the Environment: Implications of Use under Pandemic Conditions to assess the potential human health impact and environmental hazards associated with use of Tamiflu during an influenza pandemic. Based on the identification and risk-ranking of knowledge gaps, the consensus was that oseltamivir ethylester-phosphate (OE-P) and oseltamivir carboxylate (OC) were unlikely to pose an ecotoxicologic hazard to freshwater organisms. OC in river water might hasten the generation of OC-resistance in wildfowl, but this possibility seems less likely than the potential disruption that could be posed by OC and other pharmaceuticals to the operation of sewage treatment plants. The work-group members agreed on the following research priorities: a) available data on the ecotoxicology of OE-P and OC should be published; b) risk should be assessed for OC-contaminated river water generating OC-resistant viruses in wildfowl; c) sewage treatment plant functioning due to microbial inhibition by neuraminidase inhibitors and other antimicrobials used during a pandemic should be investigated; and d) realistic worst-case exposure scenarios should be developed. Additional modeling would be useful to identify localized areas within river catchments that might be prone to high pharmaceutical concentrations in sewage treatment plant effluent. Ongoing seasonal use of Tamiflu in Japan offers opportunities for researchers to assess how much OC enters and persists in the aquatic environment.

Dissipation and removal of oseltamivir (Tamiflu) in different aquatic environments

The antiviral drug oseltamivir (Tamiflu) has received recent attention due to the potential use as a first-line defense against H5N1 and H1N1 influenza viruses. Research has shown that oseltamivir is not removed during conventional wastewater treatments, thus having the potential to enter surface water bodies. A series of laboratory experiments investigated the fate and the removal of oseltamivir in two surface water ecosystems of Japan and in a municipal wastewater treatment plant located in Northern Italy. Persistence of oseltamivir in surface water ranged from non-detectable degradation to a half-life of 53d. After 40d, <3% of radiolabeled oseltamivir evolved as (14)CO(2). The presence of sediments (5%) led to a significant increase of oseltamivir degradation and mineralization rates. A more intense mineralization was observed in samples of the wastewater treatment plant when applying a long incubation period (40d). More precisely, 76% and 37% of the initial radioactivity applied as (14)C-oseltamivir was recovered as (14)CO(2) from samples of the biological tank and effluent water, respectively. Two bacterial strains growing on oseltamivir as sole carbon source were isolated and used for its removal from synthetic medium and environmental samples, including surface water and wastewater. Inoculation of water and wastewater samples with the two oseltamivir-degrading strains showed that mineralization of oseltamivir was significantly higher in both inoculated water and wastewater, than in uninoculated controls. Denaturing gradient gel electrophoresis and quantitative PCR analysis showed that Tamiflu would not affect the microbial population of surface water and wastewater.

Removal of oseltamivir (Tamiflu) and other selected pharmaceuticals from wastewater using a granular bioplastic formulation entrapping propagules of Phanerochaete chrysosporium

The capacity of the ligninolytic fungus Phanerochaete chrysosporium to degrade a wide variety of environmentally persistent xenobiotics has been largely reported in the literature. Beside other factors, one barrier to a wider use of this bioremediation fungus is the availability of effective formulations that ensure easy preparation, handling and application. In this series of laboratory experiments, we evaluated the efficiency of a granular bioplastic formulation entrapping propagules of P. chrysosporium for removal of four selected pharmaceuticals from wastewater samples. Addition of inoculated granules to samples of the wastewater treatment plant of Bologna significantly increased the removal of the antiviral drug oseltamivir (Tamiflu), and the antibiotics, erythromycin, sulfamethoxazol, and ciprofloxacin. Similar effects were also observed in effluent water. Oseltamivir was the most persistent of the four active substances. After 30d of incubation, approximately two times more oseltamivir was removed in bioremediated wastewater than controls. The highest removal efficiency of the bioplastic formulation was observed with the antibiotic ciprofloxacin. Microbiological DNA-based analysis showed that the bioplastic matrix supported the growth of P. chrysosporium, thus facilitating its adaptation to unusual environment such as wastewater.

Deterioration of bioplastic carrier bags in the environment and assessment of a new recycling alternative

Increasing environmental concerns and the introduction of technologies based on renewable resources have stimulated the replacement of persistent petroleum-derived plastics with biodegradable plastics from biopolymers. As a consequence, a variety of products are currently manufactured from bioplastic, including carrier bags. This series of studies investigated the deterioration of carrier bags made with Mater-Bi (MB), a starch-based bioplastic, in soil, compost and two aquatic ecosystems, a littoral marsh and seawater. Results from the laboratory study indicated that bioplastic carrier bags were rapidly deteriorated in soil and compost. After three months of incubation, weight loss of specimens was of 37% and 43% in soil and compost, respectively. Conversely, little deterioration was observed in specimens buried in soil under field conditions or exposed to water of a littoral marsh and of the Adriatic Sea. These findings were consistent with the greater number of bacteria and especially fungi capable of degrading MB that were recovered from soil and compost with respect to the two aquatic ecosystems. Considering that a variety of microbial isolates are capable of using MB as a source of carbon, a new alternative to recycle these MB-based carrier bags was explored. More specifically, starchy residues from bags were fermented by the fungus Rhizopus oryzae to produce up to 35 mg of lactic acid per g of bag residues.

Application of bioplastic moving bed biofilm carriers for the removal of synthetic pollutants from wastewater

In this series of laboratory experiments, the feasibility of using moving bed biofilm carriers (MBBC) manufactured from existing bioplastic-based products for the removal of bisphenol A, oseltamivir, and atrazine from wastewater was evaluated. After 10-d incubation, cumulative evolution of (14)CO(2) from control (no MBBC) wastewater spiked with (14)C-labeled bisphenol A, oseltamivir or atrazine, accounted for approximately 18%, 7% and 3.5% of the total added radioactivity, respectively. When wastewater samples were incubated with freely moving carriers, greater removal of the three chemicals was observed. More specifically, cumulative (14)CO(2) evolution of the three xenobiotics increased of 34%, 49%, and 66%, with respect to the control, respectively. Removal efficiency of MBBC was significantly increased by inoculating these bioplastic carriers with bioremediation bacterial strains. Results from this study suggest that the concept behind the moving bed biofilm reactor technology can also be extended to biodegradable carriers inoculated with bioremediation microorganisms.

Occurrence of Bacillus thuringiensis harboring insecticidal cry1 genes in a corn field in Northern Italy

Bacillus thuringiensis (Bt) is a ubiquitous bacteria widely used as a biopesticide to control a number of important insect pests. Since the mid-1990s, genetically modified (GM) plants expressing Bt genes have been used as an effective tool to control a wide range of insect pests. In recent years, a wide number of articles addressing the environmental impact of genetically modified plants have been published. However, only a few have addressed the occurrence and distribution of the indigenous Bt population in agricultural systems. Here, culturing and molecular methods were used to study the occurrence of Bt harboring insecticidal cry1 genes in a corn field. Samples of corn leaves and soil were collected in July and August 2007 from a 10 ha corn field in Northern Italy. The results showed that the highest Bt density was in leaves located near the soil surface. The incidence of Bt isolates harboring antilepidopteran cry1 genes was 42% of the total tested isolates. Approximately 20% of the Bt isolates harbored the cry1Ab and cry1Ac genes. Similarly to Bt density, the highest abundance of isolates harboring cry1 genes was found in leaves collected near the plant collar. Less than 9% of the Bt isolated from soil harbored cry1 genes. Density of Bt was reduced by application of the insecticide chlorpiryfos. This effect appeared to be due to simply washing off effects of the insecticide treatment to the corn phyllosphere. This study showed that Bt was fairly abundant in the corn agroecosystem and that the high incidence of isolates harboring antilepidopterean cry1 genes could have a role in preserving the sustainability of the agroecosystem.