Glaser's "Chemistry is in the News"
To Accompany Wade Organic Chemistry 4/e.
Chapter 20. Carboxylic Acids.
Phthalates are found in familiar things like hospital IV bags, toys like Rub-a-Dub Ernie and almost any other soft PVC product. You might say phthalates are what make plastics more plastic. There is growing concern about whether they make it more dangerous, too.
Phthalates are the predominant group of plastic softeners. Over 95 percent of all phthalates are used in flexible PVC. Each year, an estimated 850,000 tons of phthalate esters are used for PVC in Western Europe alone. In individual toys, phthalates might constitute 10 to 40 percent of the material. These chemicals are derived from phthalic acid. The most common are diethyl phthalate, di-n-octylphthalate and di(2-ethylhexyl)phthalate. This glossary lists other types and their components.
Because phthalates are not actually integrated in the polymer, they can be released from plastics into their surroundings. In the body, they may function as carcinogens called peroxisome proliferators, linked to liver and kidney cancer. In the worst case scenario, the imagery is disturbing: toddlers sucking toxic teethers, receiving intravenous carcinogens while donating plasma, or having a thin layer of phthalates on your ham and cheese.
However, these convenient media images may be greatly exaggerated. Phthalates are widely treated as low-risk toxins at small concentrations. It all depends on whom you ask. Greenpeace argues that both the concentration of free phthalates and their effects are understated. Of course, plastics groups like the European Council for Plasticisers and Intermediates or the Chlorine Chemistry Council claim the risk is minimal. The U.S. Consumer Products and Safety Commission has marked the issue for further study, while some European nations have already banned phthalates in baby toys.
In a society that takes the convenience of plastics for granted, broad sanctions against PVC would raise a snarl of economic, political and scientific issues, and we can expect to hear more on this issue.Pertinent Text References
Question 1: What is the common general structures for phthalates, and how are they formed?
A. ortho-disubstituted aromatic ring, contain an ester. Formed by reaction of phthalic acid and an alcohol.
Question 2: What factors will be studied in more depth to judge phthalates' potential as a health hazard?
A. Factors for further study include: the degree to which toxicity in animals translate to humans; whether the actual concentration of freed phthalates conforms to estimates or established limits; the mechanism that makes them carcinogenic.
Question 3: Evaluating the evidence submitted for and against phthalates, do you think one side is more convincing in scientific aspects as opposed to other types of persuasion? (When evidence is sponsored by Greenpeace, or the plastics industry, do you think either has an advantage in credibility or logic when their respective biases are considered, too?)
A. For your consideration.
Question 4: Greenpeace campaign against phthalates extends to advocating broader bans against all PVC. Why?
A. PVC releases dioxins when burned and also releases HCl during recycling, which makes it difficult to process.
Question 5: Think about the prevalence of soft PVC and its advantages in cost. Do you think the United would ever be willing to take drastic regulatory steps against it? Have we become so accustomed to environmental alarms that crop up in the media that we become jaded about acting about them or do you believe we will develop a more activist society in this respect?
A. For your consideration.