To Tributyltin Research Articles

Chronic tributyltin toxicity experiments with the chesapeake bay copepod,Acartia tonsa

Repeated chronic toxicity experiments were conducted with the Chesapeake Bay zooplankter Acartia tonsa to evaluate its sensitivity to tributyltin (TBT). Experiments were initiated with A. tonsa nauplii <48 h old. All tests were conducted with continuous-flow conditions and measured TBT concentrations. Results from a 9-d range finding experiment and two 6-d chronic experiments are presented. TBT test concentrations were maintained with minimal fluctuations over time and toxicity results were similar in the repeated chronic experiments. The range-finding experiment demonstrated severe reductions in survival of A. tonsa at the lowest measured concentration (0.029 μg TBT/L). In the 6-d experiments, 0.023 and 0.024 μg TBT/L were the lowest measured TBT concentrations to significantly reduce survival relative to the controls (i.e., lowest observed effect concentration [LOEC]). No observed effect concentrations (NOEC) measured at 0.012 and 0.010 μg TBT/L were used to calculate chronic values of 0.016 and 0.017 μg TBT/L for these two experiments. A. tonsa nauplii are very sensitive to TBT relative to other estuarine organisms. These toxicity data are environmentally relevant since TBT concentrations exceeding the chronic value for A. tonsa have been reported from numerous locations in Chesapeake Bay.

Effect of tributyltin on chemiluminescent response of phagocytes from three species of estuarine fish.

The effect of in vitro exposure to tributyltin (TBT) on the chemiluminescent (CL) responses of kidney macrophages was examined in oyster toadfish (Opsanus tau), hogchoker (Trinectes maculatus) and Atlantic croaker (Micropogonias undulatus). Phagocytic activity was evaluated using a luminol-amplified chemiluminescent (CL) assay with zymosan as the stimulus. Following brief exposure to selected doses of TBT, the CL response of toadfish and hogchoker phagocytes was found to be significantly decreased at 400 micrograms/L TBT, while the croaker phagocytic activity was significantly decreased at 40 micrograms/L TBT. With 18 hr-exposure to TBT, the effect on the CL response was noticeable at lower doses (40 micrograms/L TBT for toadfish and 4 micrograms/L TBT for hogchoker).

Flow cytometric comparison of the effects of trialkyltins on the murine erythroleukemic cell

Cellular effects of exposure to tributyltin (TBT), triethyltin (TET), or trimethyltin (TMT) were investigated by flow cytometry employing the murine erythroleukemic cell (MELC) as a model cellular system. Cell viability was investigated by the carboxyfluorescein diacetate (CFDA) uptake/propidium iodide (PI) exclusion method: above a critical concentration (exposure for 4 h), which was specific for each of the trialkyltin compounds, the cell becomes permeable to PI, indicating loss of viability. Cellular CF fluorescence (derived from intracellular hydrolysis of CFDA) increased as a function of alkyltin concentration below the critical concentration and decreased as viability decreased above the critical concentration. Relative membrane potential, monitored with a cyanine dye (DiOC6), correlated with viability (PI exclusion), remaining essentially unaltered below the critical concentration and decreasing above it. At/above 1 μM TBT, 5 μM TET, or 100 μM TMT, the cell cycle was blocked in the G 2/M phase. The 90° light scatter (a measure of refractive index), axial light loss (a measure of volume), and fluorescein isothiocyanate (FITC) fluorescence (a measure of protein content) of nuclei isolated from trialkyltin-treated MELC by detergent treatment, increased as a function of organotin dose. Fluorescence and interference microscopy revealed increased quantities of residual cytoplasmic tags adherent to the nuclei as a function or organotin dose, apparently resulting from increased cytoplasmic resistance to detergent-mediated solubilization. The effects of the trialkyltins correlated with their lipophilicity (octanol/water coefficient). These data support the hypothesis that fixation (protein denaturation, cross-linking, etc.) is an important mode of organotin cytotoxicity.

Tributyltin is a teratogen in producing deformities in limbs of the fiddler crab, Uca pugilator.

Exposure to tributyltin (TBT) produces deformities in regenerating limbs of the fiddler crab,Uca pugilator. This study was designed to ascertain whether there was a “sensitive period” during the four-week regeneration time following multiple autotomy, during which TBT exposure was more likely to result in malformations. Groups of crabs underwent autotomy of the chela plus five walking legs, and were exposed to 5.0 or 0.5 μg/L TBT continuously or only during week one, week 2, week 3, or week 4. Regeneration was monitored, and after ecdysis regenerated limbs were examined. The degree of malformation was evaluated on a scale, and for each crab the scores for each of its abnormalities were added together to arrive at an “abnormality index.” While the mean abnormality indices for crabs exposed during week one or week four were quite low, the indices for those exposed during week two were comparable to those of crabs exposed continuously, and those exposed during week three were only slightly lower. This indicates that the sensitive period is during weeks two and three, which is the time of basal growth, when the major events of differentiation and morphogenesis take place. Males were much more susceptible than females, due to the greater sensitivity of their regenerating major chela, compared to the minor chela of females. For both sexes, the regenerating chela was responsible for most of the abnormality index, even though there were five walking legs regenerating also.

Histopathological effects in Atlantic salmon, Salmo salar L., attributed to the use of tributyltin antifoulant

In Atlantic salmon, Salmo salar, growers exposed to tributyltin (TBT)-treated nets for 4 days the gill epithelium had lifted. Multiple point hyperplasia at the tips of secondary lamellae resulting in apparent branching suggested that this antifouling agent may interfere with normal growth. An increased number of leucocytes in the retina was also noted. At 7 weeks post exposure, raised levels of TBT were found in the liver, eye, skin and other organs. Extensive hyperplasia occurred in the dermal layers of the skin, resulting in protruding scales, particularly near the lateral line. An increase in eye opacities was also recorded. The use of TBT as an antifouling agent for fish farm cages was banned in 1987 by the U.K. government; hence the cause of this pathology has now been removed.