Potential hazards of toxic metals found in toothpastes commonly used in Nigeria

Background. Toothpastes have multi-functional configurations as oral care products. They can however constitute a possible source, amongst others, of toxic metal exposure in public health. Indeed, the public health impact of personal hygiene and consumer products is largely unknown. Objective. To determine the level of toxic metals (lead, cadmium, cobalt, chromium, nickel) in toothpastes available in Nigeria, (home produced and imported), and assess the potential risk to the people. Material and Method. The samples of toothpastes commonly used in Nigeria were tested. Using a market basket protocol thirty five different brands of toothpaste were used. Samples were digest by addition of 10 mL mixture of conc. nitric and hydrochloric acids (HCl:HNO3, 3:1), followed by heating to dryness. 20 mL deionized water was added, stirred and filtered. The filtrate was made up in standard volumetric flask and lead, cadmium, chromium, cobalt and nickel concentrations were determined using the atomic absorption spectrophotometry 205A. The daily intake of metals and target hazard quotient (THQ) were then calculated. Results. Pepsodent and Flodent had the highest levels of lead at respectively 23.575 and 18.092 mg/kg while Colgate Herbal had the highest nickel of 18.535 mg/kg. The daily intake estimates of all imported toothpaste samples were below the stated upper limits (UL). All target hazard quotients were also found to be below one. Conclusions. Although the UL, THQ and daily intake rates were all normal, the high levels of lead in some of the toothpastes an important concern to public health suggesting that pre-marketing safety studies of toothpastes may be worthwhile for the regulatory authorities.