Paper I found describing the contents of the chemtrails:

In 2016, a study assessed the risks to human health if solar geoengineering involving stratospheric aerosols was used. The most recommended materials have been analyzed: sulfur dioxide, hydrogen sulfide, carbonyl sulfide, black carbon, and specially engineered discs (nanoparticles) composed of metallic aluminum, aluminum oxide and barium titanate. The health effects of a potential exposure to these aerosols are: respiratory, cardiovascular, gastrointestinal, hematologic, musculoskeletal, hepatic, renal, endocrine, dermal, ocular, metabolic, immunologic, neurologic, reproductive, developmental, genotoxic, cancer, death. In addition, there is no knowledge of toxicity, and therefore no exposure standards, for barium titanate.

https://www.degruyter.com/document/doi/10.1515/reveh-2021-0060/pdf