New research from the Norwegian University of Science and Technology suggests that more than 4,000 different chemicals are used in the manufacture of common plastics for food packaging and other applications.

Led by Martin Wagner, a biologist at the university, the study reported that 4,000 is likely a conservative number, given there are over 5,000 different kinds of plastic on the market, and that the majority of plastic products contain even more unknown and potentially harmful chemicals than previously suspected.

According to Wagner, the difficulty in determining how many chemicals are used to create everyday plastics is due to the complexity of solutions used in their manufacture.

As Wagner explained, "This is because, practically speaking, it's impossible to trace all of these compounds. And manufacturers may or may not know the ingredients of their products, but even if they know, they are not required to disclose this information."

To demonstrate the difficulty of the chemical analysis, Wagner and a team of researchers examined the chemical makeup and toxicity of eight different common plastics used in the making of sponges and yogurt cups, for instance. The team discovered that three of four products contained toxic chemicals and that many plastics induced oxidative stress. Some contained endocrine disruptors.

However, the team could not conclusively determine which specific chemicals were to blame. Researchers could identify only 260 of the 1,400 substances they found in the plastics. In other words, many of the plastic chemicals are still unknown, thereby making it impossible to determine if they pose a risk to the consumer.

"Plastics contain chemicals that trigger negative effects in a culture dish," said Wagner. "Even though we do not know whether this will affect our health, such chemicals simply shouldn't be in plastics in the first place."

The team’s findings are published in the journal Environmental Science and Technology

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