Investigation of thallium as a contaminant in dietary supplements marketed for weight loss and physical fitness

Abstract

Dietary supplements are drastically growing as a category of consumer products all over the world. The abuse of supplements marketed for slimming purposes and physical fitness has been observed worldwide in recent years, which raises concerns in terms of public health. In this study, different types of dietary supplements marketed and delivered through the e-commerce were studied for the determination of thallium as a hazardous inorganic contaminant. The total content of thallium was determined by a sensitive voltammetric method after a microwave-assisted oxidative digestion of the sample. In addition, a comparative spectrometric method was applied for validation of the results in the samples. The maximum concentration found for thallium was found to be 2.89 mg kg⁻¹, which well agree with the comparative measurement. Considering the 32 studied formulations, it can be pointed out that ∼24% of the of dietary supplements presented Tl concentrations at concentrations higher than 1 mg kg⁻¹. The results permitted the assessment of the health risk related to thallium from contaminated samples, based on the calculation of the estimated daily intake (EDI) and the risk quotient (HQ). The highest daily intake of thallium was calculated as 82.0 µg day⁻¹ in a protein-based supplement, which is equivalent to an EDI of 1.17 µg kg⁻¹day⁻¹. This work highlights the need to develop regulations on the limits of toxic elements such as thallium in widely consumed dietary supplements, as well as an in-depth look at the adverse effects caused by this element in the human body.

Keywords:

• Dietary supplements
• thallium contamination
• exposure assessment
• daily intake
• electrochemical method

Author contributions

LMC supervised, wrote the original and final draft, edited the final manuscript. IT has conducted the experiments for the measurement of thallium and sample manipulation. JD conducted the measurements of thallium by ICP-OES. TDM has analyzed the data and edited the final manuscript. SN supervised the experiments and edited the final manuscript All authors reviewed the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded by grants provided by CNPq (process number 315969/2021-0) foundation (Brazil) and FUNDEP [project number 28536].