# Anti-Breast Cancer Activity of Essential Oil:
## 3 Result
### Toxicity and Side Effect of Essential Oils  
The largest and most diversified collection of naturally occurring substances is comprised of terpenes, also referred to as terpenoids. They are mostly present in plants and make up the bulk of essential oils made from plants. Terpenes have numerous bioactive and pharmacological properties, as well as a variety of medical applications. Terpenes also provide for flexibility in the route of administration and the reduction of side effects in addition to these qualities. Terpenes are natural substances that are unlikely to harm healthy cells or have any negative side effects, which attracts many researchers to explore their potential as a cancer treatment [138]. [PERSON] et al. conducted toxicity research of essential oils in 2017, and the findings show that these compounds exhibit relative selectivity to the predator _Chrysoperla externa_; nevertheless, some compounds also showed sublethal effects on reproduction. Carvacrol and thymol, two phenolic monoterepenoids, were less toxic than natural pyrethrins (the toxicity standard) in these bioassays, but they were more acutely lethal than other terpenoids screened, with an LD\({}_{50}\) of 20,000 g/g. R-(+)-limonene was found to have sublethal impacts on fecundity and fertility, whereas oregano oil merely had a fecundity-related effect [139].  
On laboratory animals, usually rats, the potential toxicity of various essential oils and their constituents was studied. The median lethal dose (LDso) test was used to assess acute toxicity in rats, and the results showed that most essential oils have an LDso of 1-20 g/kg, indicating low toxicity. Some essential oils, such as lemon oil, have an LDso of greater than 5 g/kg in humans. Therefore, the deadly dose for an adult weighing 70 kg would be 350 g, which is difficult to achieve under normal circumstances. The EOs from Boldo leaf, Chenopodium, Mentha pulegium (pennyroyal), Satureja hortensis (savory), and Thuja are a few notable outliers; they showed an LDsp between 0.1 and 1 g/kg in rats, signaling a high toxicity and recommending the need for necessary care while using them. Since some of the resultant compounds, such as the oxidation products of limonene, are potentially skin sensitizers, essential oils are subject to oxidative deterioration. [PERSON] et al. (2021) formulated _Citrus sinensis_ and _Citrus limon_ essential oils using chitosan nanoparticles to improve the anti-breast cancer. This idea is also a solution to protect the instability of limonen and keep them from being easily oxidized [140]. Additionally, in order to boost activity against breast cancer cells, [PERSON] et al. (2021) used chitosan to create na-noparticles of Syzygium aromaticum essential oils with the predominant amount of egeunol (MDA-MB-468) [109]. Therefore, proper essential oil storage is required to maintain their potency and lower the likelihood of negative responses. Essential oils should be kept in tightly sealed containers in a refrigerator or in a cool, dark location (brown bottles). Although the Flavor and Extract Manufacturers Association (FEMA) awarded most essential oils the GRAS (generally recognized as safe) certification, it should be noted that these oils were only tested as flavors with very low concentrations in the tested goods. Particular hazardous consequences, either local or systemic, for a concentrated essential oil, could manifest under certain conditions [141; 142].