historically, microalgae have been used as bio-indicators of aquatic health and this can be seen in several studies across the world. often at the bottom of the food chain, microalgae constitute the primary producer of energy of many freshwater ecosystems. diatoms, a group of microalgae, have been shown to exhibit extreme sensitivity to varying environmental parameters thereby making them as an excellent candidate for studying the impacts of pollutants such as pharmaceuticals and personal care products (ppcps). the contamination of ppcps is common in our inland water bodies with a potential to get into our drinking water supply. this study explores 1. the single and mixture effects of ppcps on two isolated microalgal species belonging to the diatom community. 2. the presence of ppcps (ibuprofen, estrone, and triclosan) in the nearshore waters of lake simcoe and their impacts on algal community. the laboratory studies consisted of assessment of the toxicological effects of the three ppcps (ibuprofen, 17-β estradiol, and triclosan) on two diatom species, asterionella formosa and diatoma tenuis, by performing growth inhibition tests. the field component involved assessment of several environmental and algal parameters in the surrounding areas of three waste water treatment plants (wwtps) that discharge their effluents via a creek to lake simcoe. the results indicated that 1. the toxicological values of ppcps on the two diatom species varied amongst one another. 2. the combined effects of ppcps were higher than the effects of single toxicity. 3. ppcp contamination is prevalent in the water outside of wwtps (as far as the point of confluence with lake simcoe). 4. the algal parameters varied according to the presence of ppcps in the surface waters. 5. estrone exhibited negative effects on the diatom community.