The use of plants and herbal ingredients in cosmetics is widespread, but these natural products may contain concerning levels of toxic heavy metals. A recent study analyzed the concentrations of lead, cadmium, and mercury in several plant species commonly used in cosmetics and cosmetology. The results reveal that these plants can accumulate significant amounts of toxic metals, likely from environmental pollution. While external use poses less risk than oral consumption, repeated application of contaminated cosmetics could potentially lead to the gradual accumulation of metals in the body over time, resulting in adverse health effects.

The Study and Key Findings

The study examined six herb species widely used in cosmetics for their skin and hair benefits: horsetail, nettle, St. John’s wort, wormwood, yarrow, and cottonwood. Samples were obtained from the wild in two regions of Poland and from commercial herbal products purchased in stores. The researchers tested for lead (Pb), cadmium (Cd), and mercury (Hg) using atomic absorption spectroscopy.

The results showed detectable levels of all three toxic metals in the plant samples. Lead had the highest concentrations (4.67-23.8 mg/kg), followed by Cadmium (0.01-1.51 mg/kg) and Mercury (0.005-0.028 mg/kg). Among the species, nettle contained the most Lead, yarrow the most Cadmium, and horsetail the most Mercury on average. St. John’s wort had the lowest observed levels of the metals overall.

Compared to the wild-harvested plants, commercially purchased herb samples had significantly higher Lead levels. The authors suggest storage and processing may have introduced Lead contamination. There were no major differences in Cadmium and Mercury concentrations between commercial and wild-harvested samples.

Plant metal levels also varied based on geographic collection area. Samples from a more industrialized region had higher Pb and Hg, while an agricultural area had higher Cd in the wild plants. This indicates environmental pollution affects metal uptake.

Potential Health Risks from Toxic Metals

The presence of lead, cadmium, and mercury in these cosmetic plants is concerning due to the well-established toxicity of these metals. Even though toxicity depends on dosage, there is no known safe level of exposure. Potential health effects include:

• Lead: Neurotoxicity, impaired organ function, hypertension, reproductive issues
• Cadmium: Kidney damage, bone loss, cancer
• Mercury: Neurotoxicity, kidney damage, skin reactions

Dermal absorption of metals from cosmetics is lower than from oral ingestion. However, regular long-term use could lead to bioaccumulation in the body over time. Those who commonly use herbal skin and hair products may be at particular risk of overexposure. Certain populations, such as children, pregnant women, and those with impaired excretion, may be more vulnerable to effects at lower doses.

While the study focused on Poland, cosmetic plants can accumulate heavy metals in other geographic regions as well. Environmental pollution is a worldwide issue, and toxic metal levels in soil and water can be high even in rural areas. Consumers should be aware of potential contaminants in natural cosmetic ingredients.

Recommendations for Safer Use

The authors note that while some environmental contamination is difficult to avoid completely, steps should be taken to minimize toxic metals in cosmetics where possible. They advise the cautious use of herbal cosmetic products, especially with regular or long-term application.

Here are some recommendations for reducing potential exposure to plant-derived cosmetics:

1. Look for brands that source ingredients from areas with lower pollution levels when possible
2. Avoid informal products that are not tested for purity and safety
3. Rotate the use of different cosmetic products to avoid overuse of any single item
4. Store products properly to avoid introducing contamination
5. Follow package directions carefully and avoid overuse
6. Keep use limited on damaged or broken skin where absorption may be greater
7. Consult with a doctor if experiencing symptoms potentially related to use

More research is needed to establish definitive metal concentration thresholds for safe levels in cosmetics. Until then, consumers should take reasonable precautions. While herbal cosmetics can provide benefits, an awareness of the potential risks allows for better-informed usage.