Davide Calamari

Presence of therapeutic drugs in the environment

Therapeutic drugs can contaminate the environment because of metabolic excretion, improper disposal, or industrial waste. To assess the extent of this contamination, we listed drugs thought to be putative priority pollutants according to selected criteria, and measured them in Lombardy, Italy. Most drugs were measurable in drinking or river waters and sediments, suggesting that pharmaceutical products are widespread contaminants, with possible implications for human health and the environment.

Conifer needles as passive biomonitors of the spatial and temporal distribution of DDT from a point source

Needles of two conifer species, Picea abies and Pinus nigra, were used as passive samplers for monitoring air contamination by sampling at increasing distances from a suspected point source of DDT. Needle concentrations declined with increasing distance downwind of the point source allowing to identify spatial and temporal trends of accumulation. This suggested that conifer needles are effective biomonitors of contamination levels in areas characterized by the presence of semi-volatile substances. Differences in uptake were apparent between the species. Needle morphology and structure were studied with scanning electron microscope (SEM) as were dimensional parameters (surface area, volume). The results suggest that the concentrations depend on a mechanism involving the inner structure of the needles, specifically the number and accessibility of resin channels rather than their surface area. Pine needles have more channels with greater accessibility than spruce. The results suggest that spruce is more suitable for short term measurement while pine for determining long term cumulative exposure.

The toxicity of mixtures of metals and surfactants to rainbow trout (Salmo gairdneri rich.)

Abstract The toxicity to rainbow trout of two metals (copper and mercury) and three detergents (two anionics and one non-ionic) were determined with an exposure period of 14 days. Each compound was tested separately and as a metal-detergent pair. The results show that for the mixtures of anionic detergents and metals a “more-than-additive” effect exists, while for the mixture of non-ionic detergent and metal the toxic effect is probably “less-than-additive”. These findings are compared with existing data in the literature and the underlying reasons for these effects are discussed.

Novel homologs of the multiple resistance regulator marA in antibiotic-contaminated environments

Antibiotics are commonly detected in the environment as contaminants. Exposure to antibiotics may induce antimicrobial-resistance, as well as the horizontal transfer of resistance genes in bacterial populations. We selected the resistance gene marA, mediating resistance to multiple antibiotics, and explored its distribution in sediment and water samples from surface and sewage treatment waters. Ciprofloxacin and ofloxacin (fluoroquinolones), sulphamethoxazole (sulphonamide), erythromycin, clarythromycin, and spiramycin (macrolides), lincomycin (lincosamide), and oxytetracycline (tetracycline) were measured in the same samples to determine antibiotic contamination. Bacterial populations from environmental samples were challenged with antibiotics to identify resistant isolates. The gene marA was found in almost all environmental samples and was confirmed by PCR amplification in antibiotic-resistant colonies. 16S rDNA sequencing revealed that the majority of resistant isolates belonged to the Gram-positive genus Bacillus, not previously known to possess the regulator marA. We assayed the incidence of marA in environmental bacterial populations of Escherichia coli and Bacillus by quantitative real-time PCR in correlation with the levels of antibiotics. Phylogenetic analysis indicated the possible lateral acquisition of marA by Bacillus from Gram-negative Enterobacteriaceae revealing a novel marA homolog in Bacillus. Quantitative PCR assays indicate that the frequency of this gene in antropised environments seems to be related to bacterial exposure to water-borne antibiotics.

Assessment of persistent and bioaccumulating chemicals in the aquatic environment

In recent years several national and international organizations have initiated actions to control the use and release of persistent, bioaccumulative and toxic substances (PBTs). Consequently, a number of criteria have been proposed for the classification of these parameters. The scientific bases for PBTs assessment has grown a great deal over the last decades. In some specific areas reliable predictive capability exists while in other areas considerable uncertainty is still present. This paper will briefly point out the achievements and limitations of the knowledge on persistence and bioaccumulation with reference to the aquatic environment.

Environmental risk assessment of pesticides on aquatic life in Xiamen, China

This paper describes the results of the environmental risk assessment of the pesticides used in agriculture in Xiamen, China. The goal was to assess the impact on water resources, particularly on fisheries and mariculture. Data on ecotoxicological properties of the pesticides and their physico-chemical profile were collected. The simulation of the environmental behaviour of the pesticides in relation to the load applied onto the agricultural areas was done using the SoilFug model. Risk assessment was performed, pesticides approximate concentrations have been calculated, chemicals at highest risk were identified, and risk management measures were indicated. This study could represent a cost-effective method that may be used before engaging in expensive monitoring programs for pesticide use in developing countries, where analytical facilities are lacking.

Risk assessment of etofenprox (vectron®) on non-target aquatic fauna compared with other pesticides used as Simulium larvicide in a tropical environment

Within the rotational scheme developed by the Programme to fight the resistance of Simulium damnosum to chemical larvicides, there was an operational gap at discharges between 5 and 70 m3 s(-1) for the treatment of rivers where resistance to organophosphates was present. The use of permethrin and carbosulfan was precluded because of risk of environmental impact and, Bacillus thuringiensis ser. H-14 treatments were not envisageable due to cost and logistics constraints. Among the possible complementary groups of larvicides tested, the pseudo-pyrethroids, held promise, because of a mode of action similar to that of pyrethroids, but along with a usually lower toxicity for fish. Etofenprox, one of the pseudo-pyrethroids tested, shows a global detachment of non-target insects in 24 h close to that of pyraclofos, an organo-phosphorus compound (27 against 23%). In laboratory conditions, six times the operational dose which is 0.03 mg l(-1) 10 min, is needed to cause 50% mortality of Caridina sp. (a small shrimps species) and 30 times this same dose for 95% mortality. For fish species, a safety margin of 400-800 times the operational dose is observed for Oreochromis niloticus and 200-400 times for Tilapia zillii.

Analysis of the effects of rotational larviciding on aquatic fauna of two Guinean rivers: the case of permethrin.

Within the Onchocerciasis Control Programme about 50,000 km of west African rivers have been regularly sprayed with larvicides to control the vector of dermal filariasis caused by Onchocerca volvulus. Since the beginning of the programme invertebrates and fish data were collected to monitor adverse effects on non-target organisms. The regular series of biological and hydrological data collected in two Guinean rivers were analysed to evaluate the effects of rotational larviciding with particular attention to permethrin, as preliminary acute toxicology tests and semi-field experiments suggest it has stronger effects on non-target fauna in respect to other larvicides. Invertebrates and fish variations in biomass and species richness are seasonal and flow-related and the results presented here do not support any evidence of specific effects of permethrin application on the biological targets monitored. Larvicide applications influence community structures, putting pressure on some taxonomic groups, causing, for example, the rarefaction of some taxa. In spite of the above results, the scarcity of some invertebrate systematic units does not result in a significant reduction of total invertebrate density because of the corresponding increase in other systematic units. In nature the studied aquatic communities would rarely be in equilibrium because of frequent natural stresses, such as drought and spate events, the biological variations discussed are to be considered ecologically acceptable.

Pharmaceuticals as Environmental Contaminants: Modelling Distribution and Fate

Concern is growing over the environmental consequences of the use of drugs for human and animal health. Long term treatments for several illnesses are a common mass practice in human health care (e.g. diuretics, beta blockers, antibiotics), a number of females are taking daily hormones to prevent unwanted pregnancies, modern life stress is handled very frequently through sedatives and tranquillizers, moreover there is in animal farming a general trend towards the intensification of production methods and production gains based on greater reliance on pharmaceuticals, feed additives, hormones and potent parasiticides (Halling-Sorensen et al. 1998).

Microorganisms' activity and energy fluxes in Lake Varese (Italy): a field method.

Microorganisms are fundamental components of energy fluxes in aquatic ecosystems. Interest in plankton production and respiration has recently stimulated exploration of the use of electron transfer system (ETS) activity in oceanography and limnology. If we consider microorganism production (MP) and microorganism respiration (MR), due to aerobic and anaerobic metabolism, microorganism growth efficiency can be defined as MGE = MP/(MP + MR). In order to calculate MGE, we measured independently the two components of ETS (photosynthesis electron transfer system activity (PETS) and respiration electron transfer system activity (RETS)) during an annual cycle using a portable biosensor microorganisms amperometric detector system (MiDAS) on the site. MGE was calculated in samples collected from the photic and aphotic zones and the superficial sediment and ranged between 0.60 and 0.45 and dropped to 0.15 at the end of the summer. This substantial decrease is probably due to the prevalence of the anaerobic-heterotrophic metabolism after a pronounced state of anoxia during the summer algal bloom.