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Organic chemicals in the aquatic ecosystem may inhibit algae growth and subsequently lead to the decline of primary productivity. Growth inhibition tests are required for ecotoxicological assessments for regulatory purposes. In silico study is playing an important role in replacing or reducing animal tests and decreasing experimental expense due to its efficiency. In this work, a series of theoretical models was developed for predicting algal growth inhibition (log EC 50 ) after 72 h exposure to diverse chemicals. In total 348 organic compounds were classified into five modes of toxic action using the Verhaar Scheme. Each model was established by using molecular descriptors that characterize electronic and structural properties. The external validation and leave-one-out cross validation proved the statistical robustness of the derived models. Thus they can be used to predict log EC 50 values of chemicals that lack authorized algal growth inhibition values (72 h). This work systematically studied algal growth inhibition according to toxic modes and the developed model suite covers all five toxic modes. The outcome of this research will promote toxic mechanism analysis and be made applicable to structural diversity.

A fire risk assessment helps in determining the chances of a fire to occur and the dangers resulted from fire outbreak. Analysing the activities undertaken within the premises; the potential harm of the fire it could cause to the people in, and around the premises is an important issue. The aim of this study was to assess the risk and consequences of a fire outbreak in the trade zone of Nyarugenge. A cross sectional and quantitative methods were used in this study. Fire hazards resulting from readily combustible or highly flammable materials, sources of heat, and people at risk were studied. The likelihood that a fire will occur and the consequences of such a fire on the people in trade zone of Nyarugenge were analysed using a Simple Risk level Estimator. Based on the analysis, 92.71% of the premises had no firefighting equipments in the trade zone 83.33 % of the premises had non-inspected electrical installation and none of them had smoke alarm or heat detectors. Smokers’ materials ranked the highest source of ignition 26% followed by lighting equipments 19%, Cooking Equipment Ranked the third13% followed by Naked flame and misused electrical equipment 12%. The results of the study indicated that the likelihood of a fire in the trade zone of Nyarugenge was high and has significant potential for serious injury or death to occupants.