- The caramel coloring in brown sodas contains known carcinogens.
“Two contaminants in the coloring, 2-methylimidazole and 4-methylimidazole, have been found to cause cancer in animals… According to California’s strict Proposition 65 list of chemicals known to cause cancer, just 16 micrograms per person per day of 4-methylimidazole is enough to pose a cancer threat, and most popular brown colas, both diet and regular, contain 200 micrograms per 20-ounce bottle.”[1, 6]
- 10% of sodas contain heart-damaging flame retardants.
Brominated vegetable oil (BVO), present in some sodas, sports drinks, and juices, is an industrial chemical also used as a flame retardant in plastics. It’s already been banned in Japan and Europe. Studies have connected BVO with heart damage in rodents. People on soda binges have reported symptoms similar to those of bromine poisoning. Researchers suspect that it builds up in body fat, possibly leading to behavioral problems, infertility, and heart lesions. Sodas with BVO (not a complete list): Mountain Dew, Fanta Orange, Gatorade Thirst Quencher Orange, Powerade Strawberry Lemonade, and Sunkist Pineapple. The FDA does require BVO to be labeled. [1, 2]
- Aspartame is a suspected carcinogen.
The scientists behind a 2005 study of rats concluded: “The results of this mega-experiment indicate that APM [aspartame] is a multipotential carcinogenic agent, even at a daily dose of 20 mg/kg body weight, much less than the current acceptable daily intake.” 
- Nearly all aluminum cans are lined with bisphenol a (BPA).
BPA is an endocrine disruptor linked to infertility, cancers, genital defects in males, diabetes, and a slew of other health problems. [1, 6] Pepsi claims it has never used BPA.  (But if that’s so, why are they so squirrely with their language on their site’s FAQ about BPA?) Coke still has no plans to remove it from their cans.
- Most (if not all) non-organic sodas contain GMOs.
Most soda ingredients are derived from corn, and most non-organic corn in the US is of a genetically modified variety. There is no human epidemiological data to show whether GMOs are safe or not. We are the guinea pigs. In other animals, GMOs have been linked to infertility, accelerated aging, and digestive tract damage. 
- Non-diet soda has been linked to increases in fat buildup around the liver and skeletal muscles, which can contribute to insulin resistance and diabetes.
“The study revealed that people who drank a regular soda every day for six months saw a 132 to 142 percent increase in liver fat, a 117 to 221 percent jump in skeletal fat, and about a 30 percent increase in both triglyceride blood fats and other organ fat. Their consumption also led to an 11 percent increase in cholesterol…” 
- All sodas contain synthetic phosphates or phosphoric acid.
Too much phosphate intake can lead to heart and kidney problems, muscle loss, osteoporosis, and accelerated aging (i.e. dying sooner).[1, 5]
- Diet sodas have been linked to increased risk of stroke and heart attack.
People who drank diet soda on a daily basis were found to have a 43% higher risk of having a stroke or heart attack than people who drank no soda over the 10-year period of the study (published in 2012). 
- Even diet sodas have been linked to significant weight gain.
“Researchers from the University of Texas Health Science Center monitored 475 adults for 10 years, and found that those who drank diet soda had a 70 percent increase in waist circumference over the 10-year study, compared with those who didn’t drink any soda. Those who drank more than two diet sodas per day saw a 500 percent waist expansion! A separate study the same researchers conducted on mice suggested that it was the aspartame, which raised blood glucose levels, that caused the weight gain; when your liver encounters too much glucose, the excess is converted to body fat.”
- Saccharin has been found to be preferable to cocaine in rats in very small doses.
In one study, rats offered the choice of cocaine or saccharin picked the saccharin 94% of the time — even if the rats were cocaine addicts. The rats preferred sucrose at a similar rate, but the concentration of sucrose was 20 times the concentration of saccharin in order to make them equal in sweetness.
- The artificial sweeteners in diet sodas do not break down in our bodies, and they end up polluting our waterways.
These sweeteners include sucralose (“Splenda”), saccharin, and acesulfame K (“Sunett”/”Sweet One”). “A recent test of 19 municipal water supplies in the U.S. revealed the presence of sucralose in every one. It’s not clear yet what these low levels are doing to people, but past research has found that sucralose in rivers and lakes interferes with some organisms’ feeding habits.” 
- Soda packaging kills birds and other wildlife.
The plastic pieces of soda packaging, like bottle caps and can attachments, often end up in waterways and the ocean, where birds, sea turtles, and other wildlife either mistake them for food, filling up their stomachs until they starve to death, or become entangled in them. 
- “9 Disturbing Side Effects of Soda.” Rodale.com.
- “Brominated battle: Soda chemical has cloudy health history.” Environmental Health News. 12 Dec. 2011.
- “Diet Soda A Day Linked With Higher Risk of Stroke, Heart Attack.” HuffPo.com. 1 Feb. 2012.
- “Still drinking diet soda? Don’t be a fashion victim!” Grist. 11 Feb. 2011.
- “Not aging fast enough? Drink a soda!” Grist. 27 Apr. 2010.
- “Aspartame is not the only thing in diet cola that can kill you.” Grist. 17 Feb. 2011.
- “Questionable Chemical Could Seep Into Your Soda.” Rodale.com. 11 Mar. 2010.
- “Intense Sweetness Surpasses Cocaine Reward.” Lenoir, Magalie, et al. PLoS ONE. 2007.