Eugenol is sometimes called clove oil because it is the active element in cloves. It causes the aromatic smell typical of cloves and because of this property is often found in perfumes. Eugenol’s properties make it a good local antiseptic and analgesic. It is used in dentist offices to make zinc-oxide eugenol paste for temporary fillings. Eugenol also demonstrates antifungal and antimicrobial activity, showing efficacy against Candida albicans biofilms, Listeria monocytogenes and Escherichia coli. Eugenol is further described to induce reactive oxygen species (ROS) production and to scavenge ROS, thus demonstrating prooxidant and antioxidant effects. Also, Eugenol is used as a pesticide.

Methylparaben (E number E218) is preservative in the food, cosmetic, and pharmaceutical industries. It is completely absorbed through the skin or after ingestion and and it is hydrolyzed to para-hydroxybenzoic acid, and metabolites are rapidly excreted in the urine. Methylparaben is on the FDA generally regarded as safe list.

Formaldehyde is a naturally occurring organic compound, and an important industrial precursor to many other materials and organic compounds. Formaldehyde solution (formalin) is used as a disinfectant. Formaldehyde vapors are toxic, upon entry formaldehyde reacts readily with macromolecules, including DNA to form DNA-protein and DNA-DNA cross-links.

Cobalt is a lustrous, silvery-blue magnetic metal. Cobalt is a bioessential element due to its location at the centre of vitamin B12. Vitamin B12 plays a number of vital roles in the physiology of the human body. Cobalt is also important in treatments of radiotherapy in the form of the isotope 60Co. Other medical uses of cobalt include the detection of tumours and metastases, sterilisation of surgical equipment and the imaging of damage to the brain. Cobalt is also used in the prosthetic alloys sector, being utilised in hip, knee and dental replacements. There are inorganic cobalt complexes that elicit biological effects with potential use as pharmaceutical agents. Three classes of cobalt complexes are present: 1) complexes that directly act on biomolecules through ligand exchange, 2) complexes that modify the activity of ligated drugs and 3) complexes that are activated by bioreduction to either (I) yield a cobalt effector species or (II) release a small molecule drug. Cobalt can cause a distinctive, rapidly progressive and reversible depression of cardiac systolic function, which is readily distinguished from other causes of cardiomyopathy.

Gold chloride (AUCl3), dihydrate, also called gold trichloride or auric chlorise, is a compound comprised of gold and chloride. It exists as a chloride-bridged dimer, both as a solid and as a vapor. AUCl3 is very hygroscopic and highly soluble in water and ethanol. It is used in organic chemistry as a mild acid catalyst and as a alternative to mercury salts. It is known to cause allergic reactions in subjects with known gold allergy.

Nearly 60 years ago, chromium, as the trivalent ion, was proposed to be an essential element, but the results of new studies indicate that chromium currently can only be considered pharmacologically active and not an essential element. Chromium is a mineral that humans need in very small quantities. Good sources include broccoli, liver, and brewers' yeast. Taking chromium by mouth is effective for preventing chromium deficiency. It is also taken by mouth for depression, Turner's syndrome, polycystic ovary syndrome (PCOS), lowering "bad" cholesterol, raising "good" cholesterol in people taking heart medications called beta blockers, obesity, metabolic syndrome, heart attack, schizophrenia, bipolar disorder, binge eating disorder, and a disease called reactive hypoglycemia. Chromium has been marketed as an agent to reduce body mass and develop muscle; however, such marketing claims are no longer allowed in the United States because they are not supported by experiments. Trivalent chromium has also been proposed as a therapeutic agent to increase insulin sensitivity and affect lipid metabolism. Although effective in certain rodent models, beneficial effects in humans have not been unequivocally established.

Methylchloroisothiazolinone is an active ingredient in many preservatives marketed under various brand names. It is effective against gram-positive and gram-negative bacteria, yeast, and fungi. Pure Methylchloroisothiazolinone is not commercially available. Kathon CG contains a mixture of Methylisothiazolinone (MI) and Methylchloroisothiazolinone (MCI) in ratio 3:1. Kathon was used in various rinse-off and leave-on formulations including hair products, shampoos, skin care products, bath products, eye and facial makeup, wet wipes and suntan products. The Commission envisages amending Annex V of the Cosmetics Regulation (EC) No. 1223/2009 to restrict the use of methylchloroisothiazolinone to rinse-off products, as suggested by the SCCS.

Parabens are widely used preservatives in basic necessities such as cosmetic and pharmaceutical products. It was found, that butylparaben has estrogenic and antiandrogenic properties and is known to reduce sperm counts in rats following perinatal exposure. In addition was observed, that butylparaben exerted endocrine disrupting effects on both male and female offspring. In 2009-2010, 80 pregnant women from Ottawa Canada participated in the Plastics and Personal-Care Product Use in Pregnancy (P4) Study. Women kept a diary of products that they used 24 h prior to and during the collection. All parabens measured in maternal urine had moderate to high reproducibility. Women who used lotions in the past 24 h had significantly higher geometric mean paraben concentrations (80-110%) in their urine than women who reported no use in the past 24 h. Women who used shampoo, conditioner, and cosmetics also showed 70-80% higher butylparaben concentrations in their urine.

Hydroxycitronellal is a perfume ingredient with a medium strength floral scent, reminiscent of lily and sweet tropical melon. It is produced synthetically from naturally occurring scent chemical citronellal. It is on the CFR - Code of Federal Regulations Title 21 list of synthetic flavoring substances and adjuvants. Hydroxycitronellal is banned in the European Union because of its toxic properties. Hydroxycitronellal is an allergen. Hydroxycitronellal has being shown to consistently modulate CCR5, CCL27, CCL2 and CCR7 in immature dendritic cells. Hydroxycitronellal is a TRPM8 agonist.

Ethylparaben is produced naturally and found in several fruits and insects, where it acts as an antimicrobial agent. Ethylparaben is mainly used as antiseptics in cosmetics, food and medicine (E number E214). It is also can be used as feed preservatives and antiseptic for bacteria. Ethylparaben is readily absorbed from the gastrointestinal tract or through the skin. It is hydrolyzed to p-hydroxybenzoic acid and rapidly excreted in urine without accumulating in the body. Under the Federal Food, Drug, and Cosmetic Act (FD&C Act), cosmetic products and ingredients, other than color additives, do not need FDA approval before they go on the market. Broad concentration ranges reported in each product category in 1981 were < 0.1% and > 0.1% to 1%. Studies show the in vivo estrogenicity of MP and EP at human exposure levels, and indicate that populations exposed to large amounts of MP and EP may have a high burden of estrogenicity-related diseases.