You’ve heard this a million times before but it’s worth repeating: Your skin is your largest organ, so what you put on it will without a doubt end up inside your body. That’s why it’s not only important to be conscious of what you’re slathering on, but also what you’re spraying on your skin every day.GALLERY: 20 Natural Fragrances to Know“Fragrance enters your body through your skin but also through your nose and lungs, so it has three points of entry—and the lungs give direct access to the blood stream,” says Patricia Malemes, owner and founder of Agape & Zoe, a natural beauty and perfume line in Dallas, Texas.The trouble is, it’s not always super-obvious what’s really inside that pretty glass bottle of perfume. Since fragrance formulas are considered a “secret recipe” and top-secret information, the FDA doesn’t make companies list every single ingredient individually. A laundry list of possibly toxic chemicals can read as just “fragrance” on the box.But never fear. We’ve decoded some of the common lingo and terms so you can sniff out which ingredients are not up to snuff.MORE: Are Your Cosmetics Toxic? Pthalates, Parabens, Polycyclic/Nitro MuskWhen phthalates and parabens are in perfume, as well as other beauty goods such as skincare products and nail polish, their main purpose is to preserve a product’s lasting power on your skin, as well as its shelf life, while synthetic (polycyclic/nitro) musk is added to some fine fragrances because using the actual oil secreted by animal glands is definitely a no-no (yuck!). These three P’s have all been shown to have hormone disrupting activity. As that scary description implies, they can mess with your body’s natural production and balance of hormones—and in women, that most likely equals estrogen. What’s more, research shows synthetic musk could pose a toxicity risk (a study on mussels found that synthetic musk intensifies the toxicity of other pollutants, leading to accumulation and cellular damage). Trace levels have also been found in the water supply because their molecular makeup can’t break down.In the past, phthalates, parabens and synthetic musk were deemed safe by the scientific community. But because they’ve been used in almost everything—from plastic water bottles to detergent, body wash and candles—what were once trace amounts in the body could become amplified (aka bioaccumulation). The result? Safe turns into, well, toxic. Studies on long-term and excessive exposure to these ingredients have been linked to a slew of scary health conditions including breast cancer, dementia, Alzheimer’s disease, birth defects and sperm damage.MORE: Beauty’s Most Controversial Chemicals  Natural and Organic“Traditionally [in the beginning history of perfume] fragrances were made of the most precious and prized ingredients and they were all natural,” says Margo Marrone, founder of The Organic Pharmacy in London. (Think pure essences of bergamot, jasmine, rose, orange blossom and spices.) “The quality of a fragrance depended on the quality of the ingredients and the best were always kept for fine fragrances.” Now, for a slew of reasons—from not being able to fully extract the aromas of some flowers (like gardenia) or the popularity of creating conceptual scents (e.g. fresh air or metallic essences), fragrances often contain man-made molecules in place of natural extracts. An all-natural fragrance will have ingredients such as natural grain alcohol, essential oils and other plant materials listed on the box. And remember, there’s a difference between the entire formula being natural and having some naturally-derived ingredients thrown into the mix.Organic takes fragrances one step further and avoids the chemicals and poisonous pesticides used in non-organic farming, explains Marone. “Organic scents that have notes of, for example, vanilla, lavender and rose use oils that come from actual organic vanilla beans, lavender fields and rose petals,” explains Danny Seo, eco-expert in Bucks County, Penn., and author of the syndicated column “Do Just One Thing.”According to Seo, choosing a natural or organic fragrance means that you’re more likely to avoid the possible allergic or unhealthy reactions caused by chemical ingredients. Bonus: The fragrances themselves have a depth and complexity that man-made ingredients cannot achieve.MORE: Your Non-Toxic Nail Polish GuideEssential Oils vs. Synthetic NotesAn essential oil is the liquid (that usually isn’t oily at all, FYI) pulled right from the leaves, stems, flower or bark of a plant by a process called steam or water distillation. While having essential oils in your fragrance sounds amazing, keep in mind that just because it’s au-natural doesn’t mean that it can’t be irritating or potentially hazardous (as anyone with intense floral allergies will attest to).That’s why some experts argue there’s a real need for synthetics in fragrances—because of impossible-to-extract essential oils, a perfumer wants to add a doesn’t-exist-in-nature note or because the real deal is toxic. Pulled right from a sci-fi movie, computers churn out huge combos of molecules of the intended scent and then a real-life ‘sniffer’ decides what it actually smells like (Sniff, sniff…“Banana!”).Also, man-made molecules in your perfume may decrease the scent’s carbon footprint. “By the time a natural extract goes through all the necessary processes and lands in your bottle, the carbon footprint could be enormous,” says Katherine Growney, founder of Saffron James perfume in Honolulu, Hawaii.However, other perfume makers are concerned about synthetics: “Synthetic perfumes contain sensitizers [chemicals that can cause allergic reactions, including asthma, wheezing, headaches and contact dermatitis] and hormone-disrupting chemicals that mimic estrogen and affect the thyroid, such as petrochemicals, phthalates, parabens, phenols, etc.,” says Eleanor Jane, perfumer and founder of Tallulah Jane fragrances in New York City. Yet they are still preferable to many perfumers because “synthetics have much greater tenacity, in that they are often discernible from across a room and will stay with the wearer for many, many hours.”Just be aware that some fragrances tout that they contain natural ingredients, but in some cases, they may contain a few synthetic notes as well. “A tiny fraction containing, say, real rose oil, does not make the 99 percent of the chemically-based formula any safer,” says Seo. “It’s like putting oregano into a cigarette—it’s still bad for you to smoke it.” The bottom line: “You have to make a personal choice on the kind and amount of ingredients and chemicals you feel comfortable with in the total of all of your personal care products,” says Growney. “It’s definitely a personal choice and there’s no right or wrong answer.”