Aspartame is broken down in the body into a series of chemical compounds that have been shown to cause health risks - not the least of which is severe worsening of depression symptoms in persons already suffering from depression. Infact, a medical study on the effects of aspertame on clinical depression had to be suspended due to the severity of the observed response in test subjects. Splenda, on the other hand, is not metabolized by the body. It passes through with almost no absorbtion.
The presence of Cl is thought to be the most dangerous component of sucralose (Splenda).But, since it is 600x sweeter than sugar you use it in very small amounts, most of it is innert filler. In a tsp of Splenda you get over 600x LESS chlorine than in a tsp of table salt.(Sodium Chloride or NaCl)