The aim of this work was to determine the bioaccumulation of fluoride and some metals (Cu, Zn, Pb) in tissues of snails under strictly controlled conditions expecting with this approach to verify the hypothesis that snails are suitable for the monitoring of environmental hazards. Additionally, the toxicity of fluorides administered orally on the energy balance of the snail's foot was investigated basing on concentrations of nucleosides, nucleotides and their products measured with high-performance liquid chromatography (HPLC). Two parallel snail cultures were started. The effect of dose on tissue levels of fluoride and metals was studied in the first part of the experiment. The second part served to study the effects of fluoride on energy metabolism of foot muscle (Tab. 1). Quantitation of fluoride and metal levels was done in soft tissues (foot, hepatopancreas) and shells of snails. Qualitative and quantitative analysis of purine compounds was performed in slices of foot. Fluoride concentrations in pulverized shells were measured using an ion-selective electrode. Gas chromatography served to determine fluoride concentrations in soft tissues (hepatopancreas and foot). Concentrations of metals were determined spectrophotometrically. Fluoride and metal content was calculated basing on weight of the pulverized sample. Purines were measured in foot muscle slices with high-performance liquid chromatography (HPLC). Concentrations were adjusted for protein content of sample. Concentrations of the following nucleosides, nucleotides and their products were determined: ATP, ADP, AMP, Ado (adenosine), GTP, GDP, GMP, Guo (guanosine), Hyp (hypoxanthine), IMP, Ino (inosine), Xan (xanthine), Urd (uridine), UA (uric acid), NAD+, and NADP (Fig. 1.). Statistical analysis was done with non-parametric test of Kruskal-Wallis, Mann-Whitney U-test and Spearman Rank Correlation Coefficient.
Conclusions: 1. Accumulation in the shell was significantly increased at the lowest concentration of fluoride, but levels remained below those in the foot or hepatopancreas. It can be inferred that due to low sensitivity, accumulation of fluoride in soft tissues is not a suitable indicator for biomonitoring purposes. Shells seem to be more suited for this aim. 2. Due to low sensitivity, accumulation of metals in soft tissues is not a suitable indicator for biomonitoring purposes. 3. Fluoride had a statistically significant effect on the energy metabolism in muscle, especially on the content of AMP and GMP (Fig. 3, 4). The content of adenylate derivatives was increased (Fig. 3, 4) and phosphorylation of ADP to ATP was inhibited (Fig. 2, 5). 4. An increase in TAN and AEC with 1330 mg F-/kg seems to result from inhibition by fluoride of energy-consuming processes (Fig. 5). 5. In cases of high levels of fluoride it seems reasonable to measure the content of AMP, GMP, Guo or the value of AEC which appear to serve as universal indicators of depressed metabolic function (Fig. 3, 4, 5, 6).