There is no specific information about dark green nails in the search results. However, there are several articles that discuss non-toxic and natural nail polish brands, ingredients to avoid, and the benefits of using clean nail polish. Here are some positive and negative aspects of nail polish ingredients and materials:

Positive:

• Some nail polish brands are non-toxic and made with natural ingredients, such as wood pulp, wheat, cotton, potatoes, and corn.
• Some nail polish brands are vegan, cruelty-free, and have plant-based ingredients.
• Some nail polish brands are 9-free or 12-free, meaning they do not contain certain toxic chemicals, such as formaldehyde, formaldehyde resin, toluene, xylene, dibutyl phthalate (DBP), camphor, parabens, and ethyl tosylamide.
• Solvents in nail polish help the nail polish flow smoothly.
• Colorants used in nail polish include organic pigments/dyes derived from petrochemicals and inorganic mineral pigments, such as iron oxides.

Negative:

• Some nail polish brands contain toxic chemicals, such as the "toxic trio" (toluene, formaldehyde, and DBP), formaldehyde resin, camphor, and ethyl tosylamide.
• Some nail polish brands contain controversial additives, such as aluminum powder, which is on the no-go list.
• Some nail products and polishes contain chemicals of concern, such as acrylamide, benzophenone, and BHA.
• Some nail polish solvents, such as ethyl acetate and butyl acetate, can be harmful if inhaled or ingested in large amounts.
• Some nail polish colorants derived from petrochemicals can be harmful to the environment.

In summary, it is important to choose non-toxic and natural nail polish brands that do not contain harmful chemicals. Solvents and colorants used in nail polish can also have positive and negative aspects.