Amid a nationwide outbreak of vaping-related lung illnesses, a Massachusetts laboratory has developed a way to test for an additive thought to be tied to the illnesses.

MCR Labs, a marijuana testing lab in Framingham, said Wednesday that it had developed a test for vitamin E acetate. The lab plans to offer the test free for a limited time, and lab officials are willing to share their methodology with other labs and public health agencies.

The lab test is geared toward marijuana products, not nicotine products.

MCR Labs president Michael Kahn warned that the test does not determine whether the product is safe. “Just because it’s something that doesn’t have vitamin E acetate doesn’t mean it’s safe,” Kahn said. “All we’re saying is it doesn’t have this specific thing. ... The consumer needs to be careful, get product from trusted sources, make sure they understand what they’re consuming.”

As of Sept. 12, the U.S. Centers for Disease Control reported 380 cases of lung illnesses and six deaths, spread across 36 states and one territory, from patients with a history of using e-cigarettes or other vaping products. The patients were mixed on whether they used products with nicotine or THC, which is the main active ingredient in marijuana.

There have been no confirmed or probable cases in Massachusetts. But state public health authorities say they are investigating 38 reports that have come in since the Department of Public Health required health care providers to report any potential vaping-related pulmonary diseases.

The CDC has not yet identified a cause of the illnesses, but some officials investigating the outbreak have said they are looking at the use of vitamin E acetate, an oily chemical sometimes used as an additive in vape cartridges.

The Massachusetts Cannabis Control Commission recently decided to mandate in its new rules, which have not yet been finalized, that all additives used in vape cartridges and other marijuana products be listed on the package’s ingredient list.

MCR labs began running tests earlier this month to make sure their method was accurate, and it is now ready to provide the screen to commercial businesses and the public. Kahn said the lab worked quickly to develop the test because “it’s a problem today, and every day that goes by someone can get hurt.”

Kahn said the lab will offer up to two free tests per individual, likely for the next month. So any person with a product in Massachusetts — bought legally or illegally — can bring it in to be tested. The lab will also offer the tests to commercial clients, such as marijuana retailers or manufacturers.

Marijuana cannot legally be brought over state lines so the lab can only tests products brought in from Massachusetts.

The lab typically takes three to five days to perform tests, but Kahn said if there is a large influx in demand for the new test, it could take longer.