Geophagy practices and the content of chemical elements in the soil eaten by pregnant women in artisanal and small scale gold mining communities in Tanzania

Abstract

BackgroundGeophagy, a form of pica, is the deliberate consumption of soil and is relatively common across Sub-Saharan Africa. In Tanzania, pregnant women commonly eat soil sticks sold in the market (pemba), soil from walls of houses, termite mounds, and ground soil (kichuguu). The present study examined geophagy practices of pregnant women in a gold mining area of Geita District in northwestern Tanzania, and also examined the potential for exposure to chemical elements by testing soil samples.MethodWe conducted a cross sectional study using a convenience sample of 340 pregnant women, ranging in age from 15–49 years, who attended six government antenatal clinics in the Geita District, Tanzania. Structured interviews were conducted in June-August, 2012, to understand geophagy practices. In addition, soil samples taken from sources identified by pregnant women practicing geophagy were analysed for mineral element content.ResultsGeophagy was reported by 155 (45.6%) pregnant women with 85 (54.8%) initiating the practice in the first trimester. A total of 101 (65%) pregnant women reported eating soil 2 to 3 times per day while 20 (13%) ate soil more than 3 times per day. Of 155 pregnant women 107 (69%) bought pemba from local shops, while 48 (31%) consumed ground soil kichuguu. The estimated mean quantity of soil consumed from pemba was 62.5 grams/day. Arsenic, chromium, copper, iron, manganese, nickel and zinc levels were found in both pemba and kichuguu samples. Cadmium and mercury were found only in the kichuguu samples. Based on daily intake estimates, arsenic, copper and manganese for kichuguu and copper and manganese for pemba samples exceed the oral Minimum Risk Levels designated by the U.S. Agency for Toxic Substance and Disease Registry.ConclusionAlmost 50% of participants practiced geophagy in Geita District consistent with other reports from Africa. Both pemba and kichuguu contained chemical elements at varying concentration, mostly above MRLs. As such, pregnant women who eat soil in Geita District are exposed to potentially high levels of chemical elements, depending upon frequency of consumption, daily amount consumed and the source location of soil eaten.

Assessment of Lead, Arsenic, Cadmium and Mercury Levels in Earthenware Clay Deposits at Mankessim, in Mfantsiman District, Ghana

“…These levels of Hg might be lower in the end product as the metal has the tendency to evaporate during the firing process because of high volatility of Hg at higher temperatures. However, other studies reported as high as 2.4 µg/g, 1.4 µg/g and 1.5 µg/g of Hg in Accra, Abidjan and Nigeria, geophagy clays, which are eaten directly 7 , as well as a mean of 0.53 µg/g in clay deposits in Vume in the Volta region of Ghana 5 and a mean concentration of 0.046 µg/g of Hg in geophagy soil in Tanzania 6 .…”

“…These levels were within the safe levels of 80.0 µg/g 17 . One study observed a mean of 6.5 µg/g of Pb in geophagy soil in Tanzania 6 , while another study also reported 27.70±2.90 µg/g of Pb in geophagic white clay at Abuakwa in the Ashanti region of Ghana 18 . The lead levels in the samples from Mankessim were lower than the levels reported from other regions, where the clay is eaten directly.…”

“…Arsenic, mercury, lead and cadmium are referred to as toxic elements and have been linked to adverse reproductive outcomes, neurological disorders and impaired cognitive development in children 6 . For example, one study reported high levels of arsenic, lead and cadmium in geophagy clay eaten by Bangladeshi pregnant women 7 .…”

Healing and edible clays: a review of basic concepts, benefits and risks

“…The determination of both essential and toxic elements present in the clay soil commonly consumed by pregnant women, in order to assess safety, has been recently carried out, for example, in Tanzania by Mwalongo and Mohamed (2013) and Nyanza et al (2014) and in Nigeria by Lar et al (2014), Igeoma et al (2014) and Owumi and Oyelere (2015). Kikouama and Baldé (2010) to compensate eventual dietary deficiencies in Fe and Zn have designed clay-containing pellets bearing certain Fe and Zn amounts; such pellets were able to be retained for few hours by flotation in the highly acidic stomach cavity in order to favour and optimize the controlled release and gastrointestinal absorption of those essential trace elements.…”

Inactivation of Escherichia Coli, Salmonella Enterica and Naturally Occurring Microorganisms in Edible Geophagic Clay under Real Sunlight

“…The types of earth materials consumed vary from one locality to the other. Nyanza et al [18] reported that pregnant women in Tanzania preferred soil from the wall of houses, termite mounds and ground soil but commonly (69%) eat soil sold in the markets. And other studies reported that most of the geophagists (95%) purchase it from the markets [19; 20].…”