Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks

Abstract

Pregnant women in Africa, Asia and Suriname, and some immigrants in Western societies, traditionally consume clay products known by a variety of names such as mabele, calabash chalk, sikor and pimba. Furthermore, clay is used for health purposes in Western societies. Because certain clays can contain high levels of metals and metalloids, the aim of this study was to determine lead, arsenic, mercury and cadmium in clay products for oral use available on the Dutch market. Traditional clays originating from Africa (n = 10) and Suriname (n = 26), and health clays (n = 27) were sampled from 2004 up to and including 2012. Total metal and metalloid contents were measured by ICP-MS and showed maximum levels of lead, arsenic, mercury and cadmium of 99.7, 45.1, 2.2 and 0.75 mg kg⁻¹, respectively. In the absence of maximum limits for these type of clays, the potential exposure was estimated from the determined concentration, the estimated daily use level of the clays, and the estimated bioaccessibility of the different metals and arsenic. The intake estimates were compared with existing health-based guidance values. For lead, the use of 34 of the 36 traditional clays and two of the 27 health clays would result in intake levels exceeding the toxicological limit by up to 20-fold. Use of 15 of the 35 traditional clays and 11 of the 27 health clays would result in intake levels exceeding the toxicological limit for inorganic arsenic by up to 19-fold. Although limited bioaccessibility from the clay may limit the exposure and exceedance of the health-based guidance values, it was concluded that lead and arsenic intakes from some clay products could be of concern also because of their use by pregnant women and the potential developmental toxicity. As a result the use of these products, especially by pregnant women, should be discouraged.

Geophagic earths consumed by women in western Kenya contain dangerous levels of lead, arsenic, and iron

“…High arsenic levels have been reported in geophagic samples from both Bangladesh and Dutch markets (Al-Rmalli, Jenkins, Watts, & Haris, 2010; Nyanza, Joseph, Premji, Thomas, & Mannion, 2014; Reeuwijk et al, 2013). In contrast, studies of geophagic earths from other sites have detected arsenic at low or nonexistent levels, with no significant impact on blood arsenic levels (Mathee et al, 2014; Tayie, Koduah, & Mork, 2013).…”

“…Geophagic materials can limit essential nutrient absorption and impair uptake of beneficial pharmaceuticals (Hooda, Henry, Seyoum, Armstrong, & Fowler, 2004; Gomes, 2017). Further, some geophagic samples have high concentrations of pathogenic bacteria, parasites, and/or heavy metals (Geissler, Mwaniki, Thiong’o, & Friis, 1998a; Marschner, Welge, Hack, Wittsiepe, & Wilhelm, 2006; Odongo, Moturi, & Mbuthia, 2015; Reeuwijk et al, 2013; Kutalek et al, 2010).…”

Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

“…As some are available in the Dutch market, Reeuwijk et al 143 Other work reported in the last year generally referred to methods of analysis rather than presenting new data. Despite the recognition of this problem, clay-based products are consumed by pregnant women and others in many parts of the world.…”

Matrix-derived combination effects influencing absorption, distribution, metabolism and excretion (ADME) of food-borne toxic compounds: implications for risk assessment

“…46,47 This appeared to be of importance when evaluating the risks associated with geophagy, the practice of eating clay or soil, as practiced by for example children and pregnant and lactating women on parts of the African continent, in Asia, and in South and Central America. 48 Complex formation between metals and matrix components.…”