Safety is the most important value and practice that all students, teachers, and advisors uphold when conducting microbiology and synthetic biology studies. At UCS-X, we prioritize safety by protecting laboratory personnel and the environment.

Before conducting our experiments, all participants received online education on lab safety, including proper use of laboratory equipment and how to handle accidents, among other topics. Additionally, our laboratory was equipped with safety devices, such as a fume hood, eyewash station, safety shower, and a designated trash bin. Throughout the experiments, we always made sure that at least one teacher was present to guide us if any procedures were performed incorrectly.

Additionally, we must follow some laboratory safety rules:

1. Lab coats must be worn before entering the lab and must not be removed from the experimental area.
2. Gloves must be worn when conducting experiments.
3. Waste must be disposed of in designated waste bins.
4. No food or drinks are allowed in the lab.
5. Equipment must be washed and dried, and any spills cleaned up.
6. Ongoing experiments must never be left unattended.

The E. coli strains we used in our research project, DH5α and BL21(DE3), were non-pathogenic, which are classified as Risk Group 1 organisms to produce various enzymes.

The enzymes that we were aiming to produce are a kind of XCP2-protease, which are non-toxic and safe. The genes that we inserted into the plasmid were from Carica papaya, Actinidia eriantha, Abrus precatorius, Cicer arietinum, and Cajanus cajan were non-toxic and safe.

For waste disposal, after everyday experiments, we subjected the experimental consumables to high-temperature sterilization treatment, and these wastes would be sent to a biowaste integrated processing plant for special treatment, so that these biowastes wouldn't mix with household waste to contaminate the environment, and the release of bacteria could be prevented.

Overuse of papain can break down skin proteins excessively, compromising the skin barrier. Another concern is its potential to cause allergic reactions in some individuals, as the allergenicity of papain and its isoenzymes has not been fully explored.

So, we have made an instruction for our products:

1. People with known allergies to papaya or latex (cross-reactivity possible) or active eczema, rosacea, or open wounds, and pregnant or breastfeeding individuals should avoid using it.
2. Apply a small amount of the product (e.g., behind the ear or inner forearm). Wait 24–48 hours to check for redness, itching, or swelling. Discontinue use immediately if irritation occurs.
3. Cleanse skin before applying papain products
4. Avoid contact with eyes and broken skin.
5. Use sparingly—a thin layer is sufficient.
6. Avoid mixing with strong exfoliants (AHAs/BHAs, retinoids) to prevent irritation. Pair with hydrating ingredients (hyaluronic acid, ceramides) to support the skin barrier.

And, we have a suggestion of the concentration of papain and its isoenzymes added into the skin care products.