Potential Hazards of Toxic Metals Found in Toothpastes Commonly Used in Nigeria

Overview

Orisakwe and colleagues measured lead, cobalt, total chromium, nickel, and cadmium in 35 toothpaste products purchased in Port Harcourt, Nigeria. The paper reports finished-product mg/kg concentrations for 20 local/manufactured-in-Nigeria toothpastes and 15 imported toothpastes, then models daily metal intake and target hazard quotients from incidental toothpaste ingestion. The source names commercial products in its tables and abstract, so this page reports category-level ranges and strata only under the HMI brand firewall.

Key numbers

• Article identity: original article in Rocz Panstw Zakl Hig 2016;67(2):197-204; received 04.11.2015; accepted 21.03.2016; no DOI is printed in the extracted PDF.
• Sample frame: 35 toothpaste products purchased in March 2013 from supermarkets/shopping malls in Port Harcourt, Rivers State, Nigeria. The paper classifies 20 as local/manufactured in Nigeria and 15 as foreign/imported.
• Analytical basis: concentrations are finished toothpaste as purchased, reported in mg/kg. No wet/dry conversion or ppm conversion was performed for this page.
• Overall concentration ranges across all 35 toothpastes (mg/kg): lead (Pb) 4.514-23.575; Co 1.055-16.336; total chromium (Cr) <0.001-10.854; nickel (Ni) 5.472-18.631; cadmium (Cd) <0.001-2.490.
• Local/manufactured-in-Nigeria toothpastes (n=20, mg/kg): Pb 4.514-23.575; Co 1.989-12.712; total Cr <0.001-5.968; Ni 5.472-18.631; Cd <0.001-1.284.
• Imported toothpastes (n=15, mg/kg): Pb 6.329-18.092; Co 1.055-16.336; total Cr <0.001-10.854; Ni 8.975-18.535; Cd <0.001-2.490.
• Limits of detection: Cd, total Cr, Co, and Ni 0.001 mg/kg; Pb 0.01 mg/kg; blank values read as 0.00 mg/kg for all metals in deionized water with electrical conductivity below 5 uS/cm.
• Daily-intake model: the study adapted 0.264 g/person/day toothpaste ingestion, 60 kg body weight for adults, and THQ inputs including exposure frequency 365 days/year, exposure duration 35 years, adult body weight 60 kg, and child body weight 15 kg.
• Source-side oral reference doses and upper tolerable daily intakes in Table 3: Pb RfD 0.004 mg/kg/day, UL 0.240 mg/day; Cd RfD 0.001 mg/kg/day, UL 0.064 mg/day; total Cr RfD 1.5 mg/kg/day, no UL set; Ni RfD 0.020 mg/kg/day, UL 1 mg/day; Co RfD 0.043 mg/kg/day, no UL set.
• Risk-model outputs: the authors state that all target hazard quotients were below 1; DMI and THQ values for children were lower than adults in their model. They also state that all imported toothpaste daily-intake estimates were below the cited ULs.
• Source-side inconsistency: the text states that one local toothpaste’s cadmium daily-intake estimate exceeded the Garcia-Rico et al. UL, while the abstract/conclusion state the UL, THQ, and daily-intake rates were normal. This page preserves the inconsistency rather than resolving it.

Methods (brief)

The authors used a market-basket protocol and bought 35 toothpaste products from supermarkets/shopping malls in Port Harcourt, Rivers State, Nigeria, in March 2013. Samples were divided into local/manufactured-in-Nigeria and foreign/imported groups. The method text states that Teflon labware was cleaned in a trace-metal-clean sequence; samples were dry-ashed by heating at 200oC for 45mins, then in a furnace at 500oC, followed by digestion with 10 mL concentrated aqua regia (HCl:HNO3, 3:1). Digests were diluted with 20 mL deionized water, filtered, made up in volumetric flasks, and measured by flame atomic absorption spectrophotometry 205A.

Samples were analyzed in triplicate, and replicate analyses of several samples had an error range of +/- 2%. The paper reports LODs for Cd, total Cr, Co, Ni, and Pb, but does not report certified reference materials or recovery percentages.

Speciation: chromium is reported as total Cr. The paper does not report Cr(VI), inorganic arsenic, methylmercury, or total mercury.

Related evidence

• Toothpaste (Cat 2)
• Lead
• Cadmium
• Cobalt
• Chromium
• Nickel

Update history

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