The Multixenobiotic resistance system as a possible protective response triggered by microplastic ingestion in Mediterranean mussels (Mytilus galloprovincialis): Larvae and adult stages.

The emerging paradigm on plastic pollution in marine environments is that microsize particles (MPs) have far more subtle effects than bigger fragments, given their size range overlapping with that of particles ingested by filter-feeders. The impacts include gut blockage, altered feeding and energy allocation, with knock-on effects on widespread physiological processes. This study investigated whether ingestion of polystyrene MPs (PS-MPs) triggers protective processes in marine mussels. The Multixenobiotic resistance (MXR) system is a cytoprotective mechanism acting as an active barrier against harmful xenobiotics and a route of metabolite detoxification. Both larvae and adults were employed in laboratory experiments with different concentrations of 3-µm PS-MPs (larvae), and 3-µm and 45-µm PS-MPs (adults) matching size range of planktonic food through the mussel lifecycle. Embryos grown in the presence of 3-µm PS-MPs showed significant reduction of MXR activity and down-regulation of ABCB and ABCC transcripts encoding the two main MXR-related transporters P-glycoprotein and the Multidrug resistance-related protein, respectively. In adults, effects of PS-MPs were assessed in haemocytes and gills, which showed different modulation of MXR activity and ABCB/ABCC expression according to MP size (haemocyte and gills) or particle concentration (haemocyte). These data showed that modulation of MXR activity is part of a generalized response triggered by particle ingestion.

Aluminum exposure for 60days at an equivalent human dietary level promotes peripheral dysfunction in rats.

Aluminum (Al) is a neurotoxic associated with a number of chronic human diseases. We investigated the effects of Al exposure at doses similar to human dietary levels and at a high level exposure to Al on the peripheral nervous system. Wistar male rats were divided into two major groups and received orally: 1) First group - Low level - rats were subdivided and treated for 60days: a) Control - received ultrapure water; b) AlCl3 - received Al at 8.3mg/kg body weight (bw) for 60days; and 2) Second group - High level - rats were subdivided and treated for 42days: C) Control - received ultrapure water through oral gavage; d) AlCl3 - received Al at 100mg/kg bw for 42days. Von Frey hair test, plantar test, the presence of catalepsy and the spontaneous motor activity were investigated. Reactive oxygen species, lipid peroxidation and total antioxidant capacity, immunohistochemistry to investigate the nerve inflammation and, the specific presence of Al in the sciatic nerve fibers were investigated. Al exposure at a representative human dietary level promotes the development of mechanical allodynia, catalepsy, increased inflammation in the sciatic nerve, systemic oxidative stress and, is able to be retained in the sciatic nerve. The effects of low-dose Al were similar to those found in rats exposed to Al at a dose much higher (100mg/kg). Our findings suggest that Al may be considered toxic for the peripheral nervous system, thus inducing peripheral dysfunction.

Improved physiologically based pharmacokinetic model for oral exposures to chromium in mice, rats, and humans to address temporal variation and sensitive populations.

A physiologically based pharmacokinetic (PBPK) model for hexavalent chromium [Cr(VI)] in mice, rats, and humans developed previously (Kirman et al., 2012, 2013), was updated to reflect an improved understanding of the toxicokinetics of the gastrointestinal tract following oral exposures. Improvements were made to: (1) the reduction model, which describes the pH-dependent reduction of Cr(VI) to Cr(III) in the gastrointestinal tract under both fasted and fed states; (2) drinking water pattern simulations, to better describe dosimetry in rodents under the conditions of the NTP cancer bioassay; and (3) parameterize the model to characterize potentially sensitive human populations. Important species differences, sources of non-linear toxicokinetics, and human variation are identified and discussed within the context of human health risk assessment.

Ingestion of marine debris by loggerhead sea turtles, Caretta caretta, in the Adriatic Sea.

We examined the occurrence of marine debris in the gastrointestinal tract of 54 loggerhead sea turtles (Caretta caretta) found stranded or incidentally captured dead by fisheries in the Adriatic Sea, with a curved carapace length of 25.0-79.2 cm. Marine debris was present in 35.2% of turtles and included soft plastic, ropes, Styrofoam and monofilament lines found in 68.4%, 42.1%, 15.8% and 5.3% of loggerheads that have ingested debris, respectively. The dry mass of debris per turtle was low, ranging from <0.01 to 0.71 g, and the ingestion was not significantly affected by sex or body size (all p>0.05). Marine debris averaged 2.2 ± 8.0% of dry mass of gut content, with a maximum of 35% found in a juvenile turtle that most likely died due to debris ingestion. Considering the relatively high occurrence of debris intake and possible sub-lethal effects of even small quantities of marine debris, this can be an additional factor of concern for loggerheads in the Adriatic Sea.

Effects of subchronic simazine exposure on some biometric, biochemical, hematological and histopathological parameters of common carp (Cyprinus carpio L.).

OBJECTIVES: This study assessed the subchronic effects of a triazine compound, simazine, on common carp (Cyprinus carpio L.) though, via by means of biometric, biochemical, hematological, and histological examination. DESIGN: One-year-old fish were exposed to simazine at four concentrations, 0.06, (reported concentration in Czech rivers), 4, 20, and 50 microg L-1 for 28 days and compared to carp in a non-treated control group. RESULTS: Exposure of fish to simazine at 0.06 microg L-1 had no effect on measured parameters. However, exposure to simazine at the concentrations of 4, 20, 50 microg L-1 showed significant differences in biochemical, hematological, and histopathological profiles of fish compared to controls. CONCLUSION: Our data suggest that simazine in the recorded environmental concentration 0.06 microg L-1 had no effect on common carp. Subchronic exposure to 4, 20, and 50 microg L-1 of simazine was associated with alterations in biochemical and hematological indices and in fish organ tissues.

Terbutryn toxicity to Danio rerio: effects of subchronic exposure on fish growth.

OBJECTIVES: The aim of this study was to investigate effects of subchronic exposure to sublethal levels of terbutryn on growth and on histopathological changes in Danio rerio. DESIGN: The acute toxicity tests were performed on the juvenile stage of Danio rerio according to OECD No. 203 Fish, Acute Toxicity Test. The juvenile growth tests were performed on D. rerio according to the OECD method No. 215. Fish at the age of 20 days were exposed to the terbutryn environmental concentration commonly detected in the Czech rivers (0.02 microg L-1) and the range of sublethal concentrations of terbutryn (0.06, 0.2, 0.6 and 2 mg L-1) for 28 days. RESULTS: The 96hLC50 terbutryn mean value for the juvenile stage of D. rerio was 5.71 +/- 0.46 mg L-1. A significant decrease (p < 0.01) in the fish growth caused by terbutryn was observed in the concentration of 0.6 mg L-1. The value of NOEC was 0.2 mg L-1 and LOEC was 0.6 mg L-1 of terbutryn. We found the damage to tubular system of kidneys in the concentration of 0.6 mg L-1 of terbutryn. CONCLUSION: The environmental concentration of terbutryn in the Czech rivers did not have any effects on growth and on histopathological changes in D. rerio and this concentration is lower than determined LOEC and NOEC values of terbutryn.

Effects of phenol on barrier function of a human intestinal epithelial cell line correlate with altered tight junction protein localization.

Phenol contamination of soil and water has raised concerns among people living near phenol-producing factories and hazardous waste sites containing the chemical. Phenol, particularly in high concentrations, is an irritating and corrosive substance, making mucosal membranes targets of toxicity in humans. However, few data on the effects of phenol after oral exposure exist. We used an in vitro model employing human intestinal epithelial cells (SK-CO15) cultured on permeable supports to examine effects of phenol on epithelial barrier function. We hypothesized that phenol disrupts epithelial barrier by altering tight junction (TJ) protein expression. The dose-response effect of phenol on epithelial barrier function was determined using transepithelial electrical resistance (TER) and FITC-dextran permeability measurements. We studied phenol-induced changes in cell morphology and expression of several tight junction proteins by immunofluorescence and Western blot analysis. Effects on cell viability were assessed by MTT, Trypan blue, propidium iodide and TUNEL staining. Exposure to phenol resulted in decreased TER and increased paracellular flux of FITC-dextran in a dose-dependent manner. Delocalization of claudin-1 and ZO-1 from TJs to cytosol correlated with the observed increase in permeability after phenol treatment. Additionally, the decrease in TER correlated with changes in the distribution of a membrane raft marker, suggesting phenol-mediated effects on membrane fluidity. Such observations were independent of effects of phenol on cell viability as enhanced permeability occurred at doses of phenol that did not cause cell death. Overall, these findings suggest that phenol may affect transiently the lipid bilayer of the cell membrane, thus destabilizing TJ-containing microdomains.

"Just add water": regulating and protecting the most common ingredient.

The Institute of Food Technologists has issued this Scientific Status Summary to provide readers with an overview of drinking water standards and regulations, freshwater resources, water pollution and predominant sources of contamination, and the effects of agriculture and food processing on water quality and wastewater treatment.

[Subchronic toxic effects of fish muscle-bound MCLR].

Subchronic oral gavage toxicity of MCLR in water and in fish muscle was examined in male Balb/C mice for 13 weeks to assess the safety of aquatic products. The results showed that the liver coefficient (p < 0.05), the activities of ALT and AST (p < 0.01) increased significantly and distinct centrilobular to midzonal hepatucellular occurred after oral gavage of dissolved MCLR at a dose of 68.75 microg/kg (body weight), but neither influence on the activities of BUN and Cr nor histological changes on kidney were observed at any time point. In contrast, the administration of fish muscle-bound MCLR at the same dose resulted in no obvious subchronic toxicity in mice, except that the increase of liver coefficient (p < 0.05) and the activity of ALT (p < 0.01) can be observed only at the first week. It was concluded that the toxicity of fish muscle-bound MCLR was much lower than that of dissolved MCLR.

Triphenyltin and tributyltin, single and in combination, promote imposex in the gastropod Bolinus brandaris.

Specimens of Bolinus brandaris (neogastropod) were injected with a single dose of 500 ng/g body weight (b.w.) of tributyltin chloride (TBTCl) or triphenyltin chloride (TPTCl), or a mixture of both compounds (250 ng TBT/g b.w.+250 ng TPT/g b.w.), for a period of up to 31 days. At the end of 4 weeks, significant increases in the female penis size of those gastropods injected with TBT (P<0.05), TPT (P<0.05), or the mixture TBT+TPT (P<0.01) were recorded. In parallel, a group of animals was injected with the neuropeptide APGWamide but this compound failed to promote imposex, suggesting that APGWamide is not involved in imposex promotion in B. brandaris. Acetylcholinesterase activity, a biomarker of neurotoxicity, was determined in the neuroganglia at the end of the experiment, but no significant differences among treatments were found. Overall, these results support the hypothesis that TPT also acts as an endocrine disrupter in this neogastropod species. Our observations also highlight, for the first time, synergistic effects of organotin mixtures having imposex promotion as an endpoint.

Human respiratory uptake of chloroform and haloketones during showering.

Inhalation is an important exposure route for volatile water contaminants, including disinfection by-products (DBPs). A controlled human study was conducted on six subjects to determine the respiratory uptake of haloketones (HKs) and chloroform, a reference compound, during showering. Breath and air concentrations of the DBPs were measured using gas chromatography and electron capture detector during and following the inhalation exposures. A lower percentage of the HKs (10%) is released from shower water to air than that of chloroform (56%) under the experiment conditions due to the lower volatility of the HKs. Breath concentrations of the DBPs were elevated during the inhalation exposure, while breath concentrations decreased rapidly after the exposure. Approximately 85-90% of the inhaled HKs were absorbed, whereas only 70% of the inhaled chloroform was absorbed for the experiment conditions used. The respiratory uptake of the DBPs was estimated using a linear one-compartment model coupled with a plug flow stream model for the shower system. The internal dose of chloroform normalized to its water concentration was approximately four times that of the HKs after a 30-min inhalation exposure. Approximately 0.3-0.4% of the absorbed HKs and 2-9% of the absorbed chloroform were expired through lung excretion after the 30-min exposure. The inhalation exposure from a typical 10-15 min shower contributes significantly to the total dose for chloroform in chlorinated drinking water but only to a moderate extent for HKs.

The toxic effects of nonylphenol on the reproductive system of male rats.

Male Sprague-Dawley (SD) rats were exposed to 4-t-nonylphenol (NP) by gavage at dosages of 0, 125 and 250 mg/kg/day for 50 days. Organ weights of liver, kidney, testis and epididymis were measured. Sperm number in the head of epididymis was counted. Several hormones including testosterone, luteinizing hormone and follicle stimulating hormone were measured. Testicular sections were observed by light and electron microscopy. Terminal dideoxynucleotidyl transferase dUTP nick end labeling assay was performed to probe the apoptotic cells in seminiferous tubules. When rats were treated with nonylphenol at 250 mg/kg/day, the absolute and relative weight of epididymis decreased dramatically, while the relative weights of kidney and liver increased by 14 and 22%, respectively. In addition, the sperm density of the head of epididymis and the testosterone level descended at 250 mg/kg/day. The levels of luteinizing hormone and follicle stimulating hormone increased in both nonylphenol treated groups. Pathological changes were detected by microscopy and the transferase dUTP nick end labeling (TUNEL) assay showed that the number of apoptotic cells in testes increased with nonylphenol in a dose-dependent manner.

Impact of nitrate intake in drinking water on the thyroid gland activity in male rat.

The purpose of this study was to determine the effects of nitrate on both the activity of the thyroid gland and other biological parameters. After 5-month treatment, nitrate 150 and 500 mg/l induced a significant decrease in the serum level of thyroid hormone T3. For T4, the 500 mg/l dose only reduced its plasma level. On the other hand, nitrate induced a dose-dependent increase in the weight of the thyroid gland. The histological study of the thyroid gland shows vacuolisation and an increase in the size of the follicles accompanied by a flatness of follicular epithelium with nitrate 150 and 500 mg/l. We concluded that the presence of high concentrations of nitrate in drinking water influence the growth, induce morpho-functional modifications of the thyroid gland and might be considered as a goitrigenic factor.

Effects of long-term exposure of the red swamp crawfish Procambarus clarkii to a mixture of two herbicides, 2,4-dichlorophenoxyacetic acid and monosodium methanearsonate, and associated human health risks.

2,4-dichlorophenoxyacetic acid and monosodium methanearsonate are often sold in commercial mixtures. Bioconcentration studies have been performed for each of these herbicides individually, but little information exists concerning long-term exposure to a mixture of these herbicides. The following study examined the uptake of arsenic in crawfish after long-term exposure to this mixture, and the health risks associated with consumption of these crawfish. Bioconcentration and depuration experiments using a 50:50 by concentration mixture of the two herbicides, with and without surfactant, were performed to quantify how much arsenic is concentrated in the edible tissue of the crawfish. Of the three tissues (muscle, gill, and hepatopancreas) sampled hepatopancreas bioconcentrated the highest amount of arsenic. Surfactant significantly reduced this uptake but did not affect bioconcentration of arsenic into other tissues. Surfactant had no effect on depuration of arsenic from any of the tissues. Cooking lowered hepatopancreatic arsenic content, possibly as a result of structural changes in the hepatopancreas. Assessment of the human health risk associated with consuming these crawfish showed an exposure dose at the high end of consumption that was approximately twice the reference dose for arsenic. Cancer risks were averaged at approximately 7 extra tumors in a population of 10,000 and 6 extra tumors in a population of 10,000 resulting from a lifetime consumption of crawfish exposed to the herbicide mixture without and with surfactant, respectively.

Changes in cross-fostered Sprague-Dawley rat litters exposed to perchlorate.

Ammonium perchlorate is used as an oxidizer in rocket fuel. It has become a groundwater contaminant, dissociating to ammonium cation and perchlorate anion. The perchlorate ion competes with iodide for uptake into the thyroid, reducing thyroid hormone production. Pregnant Sprague-Dawley rats were given either untreated or perchlorate (1 mg/kg-day) treated drinking water beginning on gestation day 2. One set of control and exposed dams was sacrificed on gestation day 20. The litters from the second set of control and exposed dams were crossed immediately after parturition and were sacrificed at postnatal day 10. Dam serum and thyroid, pooled fetal sera, and male and female pup sera were collected and analyzed for perchlorate, thyroid-stimulating hormone (TSH), triiodothyronine (T(3)), and thyroxine (T(4)). Control pups receiving perchlorate through lactation had serum levels at postnatal day 10 of 0.54 microg/ml and 0.56 microg/ml for male and female pups, respectively, whereas exposed fetuses had serum perchlorate levels of 0.38 +/- 0.04 microg/ml. Female pups receiving perchlorate lactationally had significantly lower levels of serum T(4) than control pups and prenatally exposed pups. Serum T(4) levels in male pups were not affected by perchlorate. Serum thyroid hormone levels from gestational perchlorate exposure were restored to control values by postnatal day 10. In utero perchlorate-exposure decreased serum T(4) levels in the fetus. Gestational studies in conjunction with a cross-fostering study design helped discern thyroid hormonal changes caused by perchlorate exposure during the perinatal period.

Tributyltin induces human neutrophil apoptosis and selective degradation of cytoskeletal proteins by caspases.

Tributyltin (TBT) has frequently been used as a pesticide and in biocidal paints for marine vessels, leading to its presence in the environment. Although TBT was recently found to induce apoptosis in different immune cells, by a mechanism that is not fully established, its effect on neutrophils is not known. In this study, it was found that TBT induced apoptosis in human neutrophils as assessed by cytology, flow cytometry, and degradation of the microfilament-associated protein gelsolin. Furthermore, data showed that TBT induced neutrophil apoptosis by a caspase-dependent mechanism, since addition of z-Val-Ala-Asp(MOe)-CH(2)F (z-VAD-FMK) in the culture prevented the effect of TBT. It was also found that the cytoskeletal proteins gelsolin, paxillin, and vimentin, but not vinculin, were degraded by TBT via caspases, as assessed by immunoblotting. Data indicate that gelsolin, paxillin, and vimentin are three caspase substrates involved in both spontaneous and TBT-induced neutrophil apoptosis. Cells were not necrotic as assessed by trypan blue dye exclusion, and this is in agreement with the absence of vinculin degradation. Evidence indicates that TBT-induced fragmentation of cytoskeletal proteins via caspases is a process that is tightly regulated.

Marine debris ingestion in loggerhead sea turtles, Caretta caretta, from the Western Mediterranean.

Marine debris represents an important threat for sea turtles, but information on this topic is scarce in some areas, such as the Mediterranean sea. This paper quantifies marine debris ingestion in 54 juvenile loggerhead sea turtles (Caretta caretta) illegally captured by fishermen in Spanish Mediterranean waters. Curved carapace length was measured, necropsies were performed and debris abundance and type was recorded. Different types of debris appeared in the gastrointestinal tract of 43 turtles (79.6%), being plastics the most frequent (75.9%). Tar, paper, Styrofoam, wood, reed, feathers, hooks, lines, and net fragments were also present. A regression analysis showed that the volume of debris increased proportionally to the size of the turtles. The high variety of debris found and the large differences in ingestion among turtles indicated low feeding discrimination of this species that makes it specially prone to debris ingestion. Our data suggest that more severe control of litter spills and greater promotion of environmental educational programmes are needed in the Western Mediterranean.

Long-term effects on male reproduction of early exposure to common chemical contaminants in drinking water.

We evaluated sequelae to early exposure of male rabbits to drinking water containing chemicals typical of ground water near hazardous waste sites. The mixture (p.p.m. at 1x) was 7.75 arsenic, 1.75 chromium, 9.25 lead, 12.5 benzene, 3.75 chloroform, 8.5 phenol and 9.5 trichloroethylene. Dutch-Belted does received mixture at 0x (deionized water; control), 1x or 3x as drinking water from day 20 pregnancy through weaning. Exposure of individual males (7-9/treatment) continued until 15 weeks (adolescence); then, all males received deionized water. At 57-61 weeks of age, ejaculatory capability and seminal, testicular, epididymal and endocrine characteristics were evaluated. At 10 opportunities with a female teaser, all seven control males ejaculated every time, but 12 of the 17 treated males failed to express interest, achieve erection and/or ejaculate on one to five occasions; four of the 12 accomplished ejaculation with a second male teaser. Total spermatozoa/ejaculate and daily sperm production were unaffected. However, treatment caused (P < 0.03) acrosomal dysgenesis and nuclear malformations. Baseline serum concentrations of LH were lower, but with borderline significance (P = 0.05). Testosterone secretion after exogenous human chorionic gonadotrophin (P < 0.04) was low. Thus, even at 45 weeks after last exposure to drinking water pollutants, mating desire/ability, sperm quality, and Leydig cell function were subnormal.