Use of LC50 in aquatic regulatory toxicology-Disharmony in global harmonization of hazard classification of chemicals

In regulatory aquatic toxicology, acute toxicity studies with chemicals are conducted with a species of fish, crustacea, and or alga. The LC50/EC50 obtained from these studies is used for the hazard classification and labeling of the chemicals. The methods like probit or logit analysis and Litchfield and Wilcoxon method are prescribed in the OECD guidelines to determine the LC50. In the present study, LC50s were calculated using probit analysis, Litchfield & Wilcoxon method, and also using the method by Trevan (the inventor of median lethal dose) using three sets of concentration-mortality data of fish acute toxicity tests. The slopes of the concentration-mortality curves, fiducial limits (95% confidence interval) of LC50s, and ‘mode’ of the concentration-mortality curves were compared. Though the methods used in the study resulted in more or less similar LC50s, the LC10 and LC90, slopes and ‘mode’ differed considerably, indicating that LC50 does not reveal the exact toxicity profile of a chemical. The LC50 calculated using Finney’s probit analysis provides better information on the toxicity profile of a chemical than the LC50calculated by Litchfield & Wilcoxon method. While interpreting LC50, the mortality occurred below 16 % (eg.,LC10) and above 84 % (eg.,LC90), slope and ‘mode’ of the concentration-mortality curve may also be considered. It is worth having a relook at the current practice of hazard classification and labeling of the chemicals based only on LC50 in regulatory aquatic toxicology.

Comparative Study of Parents' Satisfaction Rate toward Baiturrahmah Daycare Service

This research aims to investigate satisfaction change rate of parents before and after they drop their children at Baiturrahmah Daycare. Implementing the quantitative approach, data is gathered through questionnaire and literary studies. Research hypotheses are tested through the Wilcoxon method by comparing two paired samples. With 5% test rate, the results show that there are no significant parents satisfaction rate increase before and after they drop their children. Furthermore, according to the samples’ opinions, their expectations of the service quality before they drop their children met what service they are provided by the daycare—this discouraged the satisfaction rate increase.

ACUTE AND SUBCHRONIC TOXICITY OF GRANULES OF TIEN LIET THANH GIAI BY EXPERIMENTAL TRIAL

Objectives: Study on the acute and subchronic toxicity of granules of Tien liet thanh giai (TLTG). Methods: Define LD50 of granules of TLTG in the mice by Litchfield – Wilcoxon method. Subchronic toxicity: TLTG was been given orally to rabbit with the daily dose of 1,2g and 3,6g/kg body weight for 3 successive months. The measurements of the liver, kidney and blood were followed before, during and after the trial. Results: There was no mice died during 72 hours and there was no toxic signs observed in the mice after 7 days observed. There was no changes in parameters of the liver and kidney, and hematopoietic system. Conclusion: LD50 can not be defined in the mice. There was no subchronic toxicity in rabbit with the daily dose of 1,2g and 3,6g/kg body weight. Keywords: Acute toxicity, subchronic toxicity, experiment.

The chemical evaluation of pyrethrum flowers (Chrysanthemum cinerariaefolium): A comparison of several methods

1. Comparative analyses of pyrethrum flowers have been carried out by the methods of Tattersfield, Seil, Ripert, Haller & Acree and Wilcoxon.2. The methods were of value in indicating the relative richness in pyrethrins of the samples tested, but discrepancies were seen in the absolute values of the pyrethrins I and II recorded. Under present conditions and until a standard method of analysis is agreed upon, it would appear requisite to state the method employed in the evaluation of the flowers.3. The Wilcoxon method has given higher figures for the pyrethrin I content than the Seil method. The degree of divergence between the results depended upon the richness of the flowers, and upon the excess of acid used in distilling the volatile acid in the Seil method. The relationship between the amount of the pyrethrin I acid present and the titration recorded in the Wilcoxon method was not a linear one.4. The question of the solvent to be used for the initial extraction of the flowers has been briefly discussed.