High content of hexavalent chromium in cement samples from three African countries

Abstract

We have recently described that chromium is a common contact allergen identified by patch tests in African countries.¹ The minimal eliciting threshold concentration for hexavalent chromium (Cr(VI)) that results in 10% of patients having a positive patch test is 1 mg/kg (1 ppm).² Cement is an important source of chromium exposure.^{3, 4} Since 2005, cement may not be used in countries of the European Union (EU) if the concentration of Cr(VI) is >2 mg/kg, which has significantly reduced the prevalence of allergic contact dermatitis (ACD) caused by cement in EU.^{3, 4} To determine whether Cr(VI) in cement could be a contributing cause to the high prevalence of ACD to chromium in African countries, we have performed an analysis of total chromium (Cr) and Cr(VI) in eight random samples of cement purchased in three African countries. [Correction added on 2 October 2024, after first online publication: The heading ‘INTRODUCTION’ has been removed in this version.]

Cement samples were randomly selected based on their availability in do-it-yourself markets in Tanzania, Ghana and South Africa. The chemical analysis of the cement samples was performed by ALS Denmark, Humlebæk. The total amount of Cr was measured by the standard DS 259:2003 (https://webshop.ds.dk/standard/52829/ds-259-2003) and DS/EN 16170:2016 (https://webshop.ds.dk/standard/M300697/ds-en-16170-2016). The amount of Cr(VI) was measured by the standard DS/EN 15002:2015 (https://webshop.ds.dk/standard/M279556/ds-en-15002-2015), DS/EN ISO 15192:2021 (https://webshop.ds.dk/standard/M336548/ds-en-iso-15192-2021) and DS/EN ISO 17294-2:2016 (https://webshop.ds.dk/standard/M287184/ds-en-iso-17294-2-2016).

Compared to a recently published analysis of 45 samples of cement from EU and non-EU countries,⁴ the total amount of Cr in the samples from the three African countries was relatively low (Table 1). However, the content of Cr(VI) was alarmingly high. In six out of the eight samples, the Cr(VI) content was ≥16 mg/kg, that is, more than eightfold higher than the maximal allowed concentration in the EU.

Historically, cement has been the most common and important cause of chromium allergy.³ Since regulations dictating that cement must not contain more than 2 mg/kg (2 ppm) Cr(VI) came into force in EU, ACD caused by cement has markedly been reduced in the EU countries.^{3, 4} The high frequencies of positive reactions to potassium dichromate in patch test studies from African countries suggest that exposure to chromium is high in these countries.¹ Studies from Ethiopia, including occupational exposure, found that up to 67% of construction workers suffer from chromium allergy, supporting that cement could be a key source of exposure to chromium.^{1, 5} Our results support that a targeted effort in reducing the concentration of Cr(VI) in cement, for example, by adding ferrous sulfate,⁶ coupled with measures to prevent direct skin contact with cement could considerably reduce chromium allergy in at least two of the three African countries included in this study.

Nikolaj Menné Bonefeld: Investigation; writing – original draft; visualization; data curation; formal analysis. Torkil Menné: Investigation; writing – original draft; writing – review and editing; supervision; conceptualization. Ulrik Ahrensbøll-Friis: Investigation; writing – review and editing. Anne-Sofie Østergaard Gadsbøll: Validation; writing – review and editing. Christian William Wang: Validation; writing – review and editing. Thor Grundtvig Theander: Validation; writing – review and editing. Elisante John Masenga: Validation; writing – review and editing. Daudi Mavura: Validation; writing – review and editing. Herielly Msuya: Validation; writing – review and editing. Michael Fokuo Ofori: Validation; writing – review and editing. Henrik Kløverpris: Validation; writing – review and editing. Niels Ødum: Validation; writing – review and editing. Charlotte Menné Bonefeld: Conceptualization; investigation; funding acquisition; visualization; writing – review and editing; supervision; resources. Carsten Geisler: Supervision; resources; conceptualization; investigation; writing – original draft; writing – review and editing; visualization; funding acquisition.

The authors declare no conflict of interest.