Topical cosmetics are among the most consumed perorations worldwide. In this study, we explored the prevalence of cosmetics usage and examined some of the most common topical cosmetic products in terms of organoleptic properties, microbial load and heavy metal impurities (Fig. 4). This study showed that the participants used at least 5 products daily (Fig. 2). These preparations are intended to be in contact with several parts of the skin; thus, they can serve as vehicles for transmitting many pathogenic organisms2. The skin has defensive mechanisms that can protect the body from external matter; therefore, complete sterility is not essential for cosmetics. However, there is a threshold limit of microorganisms that can be handled by the skin9. This is especially true when cosmetics are applied around the eyes, on injured skin, on children under the age of three, on elderly individuals, and on compromised individuals.
The European Scientific Committee on Consumer Safety (SCCS) is a nonprofit organization composed of scientists from diverse professions who assess the safety of cosmetic components16. According to the SCCS ‘Notes of Guidance for Testing of Cosmetic Ingredients and Their Safety Evaluation,’ the microbial count must not exceed 100 (cfu)/g or ml for the products intended for children under 3 years or the products intended to be used in the eye area or mucous membranes. However, the microbial count should not exceed 1000 cfu/g for other products.
Moreover, the US FDA microbiological limits in cosmetics specify that the total number of microorganisms per gram or milliliter generally should not exceed 500 cfu/g for eye-area products and those for children < 3 years old, whereas the acceptable limit for all other topical cosmetics is ≤ 1000 cfu/g.
Both the SCCS and FDA consider the presence of opportunistic pathogens (Escherichia coli (E. coli), S. aureus, Pseudomonas aeruginosa (P. aeruginosa) or Candida albicans (C. albicans)) to be of significant concern.
Our results (Fig. 3) showed that both of the tested baby products exceeded the SCCS permitted limit. This is crucial since babies have a weak immune system, allowing the pathogen to easily enter their system if the skin is damaged17. This syndrome starts with irritability, fever, malaise, and a highly sensitive rash that appears within 24–48 h. Moreover, our study found that the makeup powder, hair cream and hair oil serum also exceeded the limit, with microbial loads of 1161.5 cfu/ml, 1467.5 cfu/ml and 1128 cfu/ml, respectively (Table 2).
In this study, 14 samples of the tested products showed microbial contamination. S. aureus was the most prominent microorganism found in 12 of the samples. In alignment with the study results, published studies have detected S. aureus as the main isolated microorganism in a variety of cosmetics items, in addition to other microorganisms, such as Candida, Rhodotorula, Salmonella, Citrobacter, Klebsiella, Pseudomonas aeruginosa and Alcaligenes9,18,19,20,21,22. S. aureus is a normal skin microorganism, but it may also act as an opportunistic pathogen that can cause a variety of skin and soft tissue infections23. Eczema, acne, erythematous rash and other skin infections can result from contaminated product usage24. The presence of S. aureus in eye products can cause infection to the external and internal tissues of the eye, including the tear duct, cornea conjunctiva, and posterior chambers, triggering profound damage that may lead to blindness25.
The other detectable microorganism that was found in 10 tested product samples was Bacillus species. Bacillus species are transient skin microflora. The group Bacillus cereus is a Bacillus genus subdivision that currently includes eight formally recognized closely genetically related species that can cause focal necrotizing cellulitis in the skin19. Bacillus cereus contamination can lead to serious eye infections. This is especially true for cosmetics that are used on the eyes or near the eye, as found in this study in a makeup powder. This might be attributed to how powders easily come into contact with air and contain ingredients from a natural sources, such as talc in the formulation, which might increase the contamination level19. A published study showed that a Bacillus cereus with a microbial load as low as 100 cfu/ml caused infection in a susceptible animal model26. Abscesses, bacteremia/septicemia, wound and burn infections, ear infections, ophthalmitis, osteomyelitis, peritonitis, and respiratory and urinary tract infections have all been linked to Bacillus species. The majority of these diseases arise as secondary or mixed infections in immunocompromised individuals, but a high proportion are primary infections in healthy people27. In this study, we investigated the products as soon as they were opened, yet contamination was still found in some of the tested products. Most cosmetics are multiuse items that must retain low levels of contamination during consumer usage, which means that their preservation mechanisms must be efficient against contaminants that come into touch with the product after it has been opened25.
Heavy metal contamination in cosmetics is another serious issue. The Federal Food, Drug, and Cosmetic Act issued by the US suggests limits for some heavy metal impurities in cosmetics, such as lead, arsenic and chromium28. The maximum recommended limit of Pb as an impurity in cosmetics is 10 ppm. Cosmetic lip items (such as lipsticks, lip glosses, and lip liners) and externally applied cosmetics (such as eye shadows, blushes, shampoos, and body lotions) are covered by this guidance. The US FDA also limits the presence of Pb in cosmetic additives to 20 ppm. Our results showed that 6 of the tested cosmetic products exceeded this limit, and the highest value of Pb, 78.31 ppm, was found in sample 20 (toothpaste). Similarly, a study that investigated the same product and brand found but used atomic absorption spectrophotometry found that Pb exceeded the recommended limit with a value of 23.57 ppm29. In our study, we found that toothpastes were among the top most contaminated products that are used daily (Fig. 2). The accumulation of Pb by using lead-containing cosmetics regularly can result in serious side effects30. These side effects can vary from abdominal pain, headache and loss of appetite to more complicated manifestations, such as brain damage, renal dysfunction and paralysis31,32. Pregnant women can experience miscarriage or premature birth and give birth to babies with low birth weight33.
The US FDA has also set the limit for Cr in cosmetics additives to 50 ppm, and most of our tested cosmetic products exceeded this limit. In agreement with this finding, a study that tested nine of the most expensive brands of mascara and eye shadow from the Saudi market found that the level of Cr was higher than the acceptable limit in an eyeshadow product with a value of 7000 ppm34. Digestive, skin and ocular problems are linked to high exposure to Cr35.
Arsenic is limited to 3 ppm in cosmetics additives by the US FDA, and our tested cosmetic products exceeded this limit in samples 12 (makeup powder), 13 (makeup mousse cream), 14 (mascara), 15 (deodorant), 18 (lipstick), 19 (toothpaste), and 20 (toothpaste). The highest concentration of As was found in sample 19 (toothpaste) (221.96 ppm). Long-term exposure to arsenic might result in skin conditions such as lesions and skin, bladder and lung cancers36.
Since there are no limits set for other metals in cosmetics, such as Al, Mn, Fe, Co, Ni, Cu, and Zn, the US Pharmacopeia chapter <232> has established acceptability metal impurity criteria for drug products. Even though these guidelines are meant for drugs in different dosage forms, they may be relevant to avoid undesirable consequences. For example, Cd as an elemental impurity should be limited to 0.5 ppm, where in our tested cosmetic products, samples 1 (sunblock cream), 15 (deodorant), 19 (toothpaste), and 20 (toothpaste) greatly exceeded this limit (Table 3). The continued use of cadmium-contaminated products may cause heart diseases, hypertension, kidney and liver damage, and a weak immune system37.
The USP limits Co as an elemental impurity to 5 ppm, wherein tested cosmetic product samples 12 (makeup powder), 14 (mascara), 19 (toothpaste), and 20 (toothpaste) exceed this limit, and the highest value (22.71 ppm) was detected in sample 12 (makeup powder). Similarly, other cosmetic products exceeded the 5 ppm limit, such as an eyeliner (11.80 ppm)38. Long-term exposure to cosmetic products that are contaminated with Co may cause skin irritation13 Ni should not exceed 20 ppm according to the USP. Interestingly, most of the tested cosmetic products in this study exceeded this limit, and the highest value was detected in sample 19 (toothpaste). The major concern with nickel is allergic contact dermatitis, which can be a serious issue for patients with chronic eczema39,40. The only metal level that did not exceed the USP limit in any of the tested samples was Cu. This elemental impurity should be limited to 300 ppm, and all tested cosmetic products were below this value.
Unfortunately, there are no stated FDA or USP limits for other metals, such as aluminum, iron, zinc, and manganese. Short exposure to lower levels of manganese may lead to erythema and eczema, while chronic exposure has been linked to neurological disorders, such as loss of coordination and balance, forgetfulness, anxiety, and insomnia40,41,42,43. In this study, the highest concentrations of Mn and Fe were detected in sample 14 (mascara). Similarly, Aldayel et al.34 investigated nine of the most expensive brands of mascara and eyeshadow from the Saudi market and found that the concentration of Fe was high in the mascara products. Moreover, frequent use of cosmetics that contain aluminum has been linked to neurological disorders such as Alzheimer’s disease, but the exact mechanism is unknown40,44. According to studies, high exposure to Zn, and Cu may lead to the interaction between them that can lead to abnormal Zn metabolism, so the balance between Zn and other nutrients could be destroyed45.
The highest concentrations of Al and Zn in this study were detected in sample 19 (toothpaste) and sample 20 (toothpaste), respectively. In alignment with this result, Al and Zn concentrations were high in different brands of toothpaste31,46.
Based on our tested cosmetic products, the highest levels of Pb, Cr, As, Ni, Zn, Al impurities were found in toothpaste. Interestingly, our results showed that toothpaste was the most frequently used cosmetic product in both sexes (Fig. 2). Therefore, both the quality and safety of cosmetics preparations must be more rigorously regulated.
Although there are some legal criteria to consider during cosmetics manufacture, this study showed that these regulatory procedures are not completely effective. Tests are required by authoritative agencies to ensure the safety and quality of cosmetic products or ingredients before they are put on the market. Moreover, the raw materials should be selected and handled properly by manufacturers.