Researchers urge improved methods for detecting FDA- and EU-banned cosmetic ingredients

25 Aug 2022 --- Indonesian researchers have reviewed the existing analytical methods used to detect cosmetic ingredients that are restricted and prohibited by the US Food and Drug Administration (FDA) and EU legislation. They flag that improving these systems is critically needed to ensure that beauty products are kept free of dangerous compounds.

The researchers from Universitas Padjadjaran say that the safety of some cosmetic products is a concern as they may contain prohibited ingredients and be used widely by the public. Some compounds can be banned when they are harmful to the skin and can cause cancer, congenital disabilities and developmental and reproductive disorders.

At times, adverse effects from these toxic compounds may also “lead to comas,” warn the scientists.

Regional differences in cosmetic regulations
The researchers further underscore that cosmetic products are regulated differently in different regions of the globe. “This makes it difficult to ensure compliance in all countries. The harmonization of regulatory frameworks was carried out to address this problem.” 

“For example, in the EU, the cosmetic regulatory framework is provided by Regulation (EC) No. 1223/2009, which has overall responsibility for cosmetic legislation. In the US, laws related to cosmetic products are regulated by the FDA and the Fair Packaging and Labeling Act (FPLA).” 

Though some dangerous ingredients may be banned in the EU and the US, countries outside these markets may still use them. 

In this latest review, ingredients were tested based on FDA and EU standards. Preservatives were tested using sweeping-micellar electrokinetic chromatography (sweeping-MEKC) and spectrophotometry. Coloring additives were tested using chromatography and atomic absorption spectrophotometry (AAS).

 Antiperspirants were tested using colorimetric. A whitening agent in this category was tested using AAS, ICP, enzyme-linked immunosorbent assay (ELISA) and electrochemistry. The researchers say that the safety of some cosmetic products is a concern as they may contain prohibited ingredients and be used widely by the public. 

Meanwhile, chromatography was used to test flavoring agents, antibacterial agents and fragrances.

Bithionol causes sensitivity
An example of a prohibited antibacterial ingredient is bithionol – an aromatic organic compound “widely used” as preservatives in soaps, toothpaste, lotions and creams. However, it is now prohibited from being used in topical preparations

To analyze bithionol, a method of electrophoresis combined with sweeping-MEKC can improve the detection sensitivity. “This method was developed in 2021 by Zheng et al., and no one else has published a different analysis method yet,” note the authors. 

“This method has high sensitivity, a high enrichment factor, a simple operating system, good repeatability and a low cost for detecting bithionol in cosmetic samples.”

Formaldehyde in doses?
Formaldehyde releasers are commonly used in cleansing and skincare products. However, they may also cause allergies when used in excess.

It is rare to add the pure compound to final cosmetics. “Instead, formaldehyde donors or formaldehyde releasers are added as they release small amounts of formaldehyde over time during multiple hydrolysis reactions in the presence of water,” explain the researchers. 

In the EU, formaldehyde can be used up to 0.1% in cosmetics. However, if it exceeds 0.05% (500 mg/kg), it must clearly state: “contains formaldehyde” on the label. 

According to the researchers the most common method is to convert formaldehyde to its derivative (with 2,4-dinitrophenylhydrazine.

Additionally, there is a new method using smartphone readers to determine whether formaldehyde is present in cosmetics.

Detecting poisonous cadmium
Cadmium is another prohibited mineral in combination with different elements. 

“It is also one of the most toxic elements and can cause bone decalcification, kidney dysfunction, brain damage, reproductive failure and poisoning. Excessive exposure to cadmium impairs lung function and increases the risk of lung cancer,” warn the researchers. 

Studies have successfully used graphite furnace atomic absorption spectrometry (GFAAS; Varian 240FS AA) with an autosampler and deuterium light to determine cadmium levels in cosmetics. Another test is laser-induced breakdown spectroscopy, a new spectroscopic analysis technique used for multi-element detection.

Tracing toxic pigments
Color additives include dyes and pigments, which are either water or oil-soluble and can make products attractive. 

Azo dyes are flagged as mutagenic, genotoxic and carcinogenic as skin bacteria can break them down into carcinogens. Yellow quinoline also causes genotoxic effects, according to a study. Improving analytical methods are needed to provide alternatives for revealing dangerous ingredients to ensure safety. 

Compared to the other methods listed by the researchers, Reversed-phase high-performance liquid chromatography with a PDA detector is widely used due to its high accuracy, sensitivity and precision and requires only a short analysis time. 

Heavy metal zirconium complexes
The researchers analyzed zirconium, which is a very reactive heavy metal that can be found in various other forms.

“In cosmetics, zirconium can be used as an antiperspirant in aerosol preparations, lotions, creams or ointments,” highlight the researchers. However, it is prohibited in the EU as it can cause mild asthma, granulomas and lung fibrosis if inhaled.

“Air-soluble zirconium can form aerosols and cause tissue damage at exposed sites and systemic reactions can also occur.” 

Colorimetry with direct and fusion procedures was the method of analysis used in 1976 to detect the heavy metal. 

Chloroform in toothpaste?
According to the researchers, chloroform is a liquid that can be used as a solvent for the production of chemicals and as an ingredient in cosmetics such as toothpaste. 

Its carcinogenic effects have been observed in mice. However, it is noted that though there is a lack of evidence of its carcinogenic effects in humans, it is still concluded to be detrimental to humans. 

Additionally, there are few methods to analyze chloroform in cosmetic preparations, one of which is gas-liquid chromatography, used to test toothpaste. 

Dangerous antifungal
Halogenated salicylanilides have antiparasitic and antifungal properties and are widely used as antibacterial agents in cosmetic preparations. However, the researchers say that it is not allowed in cosmetics because they are photosensitizers and cross-sensitizers and can cause health issues. Some compounds can be banned when they are harmful to the skin and can cause cancer, congenital disabilities and developmental and reproductive disorders. 

The scientists highlight the high-performance liquid chromatography (HPLC) method assisted by Magnetic-Solid Phase Extraction (MSPE). 

In 2021, Li et al. developed an analytical method for hexachlorophene analysis using the capillary zone electrophoresis (CZE) method with a UV detector.

Poisonous fragrances
Coumarin is a powder or crystal with a vanilla aroma and a bitter taste that is widely used as a fragrance agent in cosmetics and can also be added to sunscreen products to increase tanning induced, the researchers say. 

“Coumarin can be used at a concentration of 0.01% for rinse-off cosmetic products and 0.001% for leave-on cosmetic products,” they add. However, if ingested orally, coumarins can cause nausea, diarrhea and hepatotoxicity.

The linear retention index approach (LRI), HPTLC, GC-MS, UPLC-MS/MS are methods used to analyze coumarin. “The combination of the LRI approach and MS/MS detection allows for highly reliable identification of each analyte.” 

Furocoumarins are structurally similar to coumarins and are found in citrus essential oils. It has been banned in the EU due to causing phototoxicity, hyperpigmentation, erythematous rash, blisters and sunburn if exposed to UV-A radiation. Long-term use can cause cancer. 

“Ultrasonication and solid-phase extraction techniques can be used as extraction procedures,” say the researchers. “However, in 2021, a more sensitive and selective method was developed, with the LRI approach.” 

Mercury in skin lightening
The US FDA allows mercury as a preservative in cosmetics for use in the eye area and can have a maximum value of 65 ppm (0.0065%). However, in other cosmetics, it may exist as a trace element of <1 part per million. In EU law, mercury is prohibited except in exceptional cases such as a preservative in limited amounts, underscore the researchers. 

“However, in many cases, mercury is used as a whitening agent because of its ability to inhibit the enzyme tyrosinase, which plays a role in melanin production,” they detail.

“Continuous exposure to mercury can cause various health problems such as irritation, allergies and the appearance of dark spots on the skin. Mercury absorbed into the body can cause brain and kidney damage; in pregnant women, it can interfere with fetal development. Mercury has also been known to have a carcinogenic effect on users.”  

They outline methods used to determine mercury levels, including ELISA, AAS, atomic emission spectroscopy, capillary electrophoresis, electrochemical sensors and mass spectroscopy.

“AAS was a better general method for determining mercury in cosmetic samples. The AAS method is widely used because it is highly sensitive, specific, and can detect mercury even at shallow levels,” conclude the researchers. 

By Venya Patel