Re: Splenda is A Poisonous Substance
First, there have been no long-term human toxicity studies on sucralose until after the FDA approved sucralose for human consumption. What's that all about?
Lord GH, Newberne PM. Renal mineralization -- a ubiquitous lesion in chronic rat studies. Food Chem Toxicol 1990 Jun;28:449-55.
Concerns have also been raised about the effect of Sucralose on the thymus gland, a gland that is important to the immune system. Significant thymus shrinkage was found in several rat studies. The following, from the NICNAS (part of the Australian government), discusses the absorption of Sucralose and its effect on the Thymus glands of rats:
"When administered orally, between 11-27% of Sucralose is absorbed from the gastrointestinal tract in male humans. The remaining sucralose is excreted in feces. Following gastrointestinal absorption, between 20-30% of the sucralose is broken down into two metabolites. The remaining sucralose is excreted in urine.
The immunotoxicity of Sucralose was assessed in groups of Sprague-Dawley rats (13/sex/group) dosed by gavage with 0-3000 mg/kg bw/day for 28 days. A significant decrease in mean thymus weight was noted in males dosed with 3000 mg/kg bw/day. The NOEL for immunological endpoints was determined to be 750 mg/kg bw/day (USFDA 1998).
In a two generation reproductive toxicity study, groups of 60 Sprague-Dawley CD rats (30/sex) were dosed with 0, 0.3, 1, and 3% Sucralose in the diet for 10 weeks prior to breeding and throughout two successive generations. A significant decrease in thymic weight of 40% was detected in both generations at the 3% dose level." Moreover, the rats so fed were only 7-20% underweight vs the average for the control group.
In this particular study rats who were severely starved to the point of 30% weight loss, but not fed Sucralose, only had their thymus shrink by an average of 7%. Versus the 40% average thymus shrinkage for the rats that were fed 3% sucralose. This is very troubling to some people, because the thymus gland is the organ that matures T-Cells in the body.
It is important to know that conclusive results can never be drawn for toxicology studies that are carried out on animals. They can only be used as a rule of thumb, or a general guideline, due to the extreme differences between test animals, and humans. A very good example of this is the toxicity of chocolate when fed to small animals.
Summary of studies
*  - NICNAS-The Australian Government regulator of industrial chemicals' PDF