Ignore all animal studies when there loads of human studies available.
Unequivocally, artificial sweeteners are safe up to a certain daily dosage (which is so high you have no way of hitting it).
Here's some souces you can dig into:
An overview of the safety of sucralose. Grotz VL, Munro IC. Regul Toxicol Pharmacol. 2009 Oct;55(1):1-5.
Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies. B. A. Magnuson, G. A. Burdock, J. Doull, R. M. Kroes, G. M. Marsh, M. W. Pariza, P. S. Spencer, W. J. Waddell, R. Walker, G. M. Williams. Crit Rev Toxicol. 2007; 37(8): 629–727.
Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels. Anton SD, Martin CK, Han H, Coulon S, Cefalu WT, Geiselman P, Williamson DA. Appetite. 2010 Aug;55(1):37-43.
Erythritol: an interpretive summary of biochemical, metabolic, toxicological and clinical data. Munro IC, Berndt WO, Borzelleca JF, Flamm G, Lynch BS, Kennepohl E, Bär EA, Modderman J. Food Chem Toxicol. 1998 Dec;36(12):1139-74.
Gain weight by "going diet?" Artificial sweeteners and the neurobiology of sugar cravings: Neuroscience 2010. Yang Q. Yale J Biol Med. 2010 Jun;83(2):101-8.
Gastrointestinal tolerance of erythritol and xylitol ingested in a liquid. Storey D, Lee A, Bornet F, Brouns F. Eur J Clin Nutr. 2007 Mar;61(3):349-54.
Nonnutritive sweetener consumption in humans: effects on appetite and food intake and their putative mechanisms. Mattes RD, Popkin BM.Am J Clin Nutr. 2009 Jan;89(1):1-14.
Sugar substitutes: Health controversy over perceived benefits. Tandel KR. J Pharmacol Pharmacother. 2011 Oct;2(4):236-43.