Geophagic practice and characterisation of plant remains in geophagic soils in Sekhukhune Area, Limpopo Province, South Africa

Abstract

Certain communities in Sekhukhune area are known to be practicing geophagia. Existing standard questionnaires as adopted to generate data on human geophagia included aspects on demography, socio-economics, cultural, ecological, physico-chemical aspects, indigenous knowledge and health effects of geophagic consumers. These data were gathered through distribution of questionnaires to 200 geophagic participants, of which 135 were from Ga-Nchabeleng Village and 65 from Mphanama Village. Both the Villages were based in the rural settlements in Sekhukhune area. In this study the behaviour of geophagic individuals was investigated and cytotoxicity of plant remains consumed in geophagic soils was evaluated for any toxicity. A total of 17 different geophagic sites were identified. Six geophagic sites each were from Ga-Nchabeleng Village and six from Mphanama Village. Five other sites were selected from sites where geophagia was not practiced and were recorded as the control sites. All the 17 soil samples were analysed using Munsell Soil Color charts for soil colour classification. Samples of plant remains were collected from the same geophagic sites where soil samples were collected. Due to similar plants and vegetation type from 17 different geophagic sites, a composite study was adopted. Geophagic consumers in Ga-Nchabeleng Village identified four plant species of plant remains consumed in the soil in the area and Mphanama village identified five species different from Ga-Nchabeleng plants. Samples of plant remains were grouped according to comparable features or characteristics. Sample 1 of plant remains was composed mainly of grasses; Cynodon dactylon, Aristida congesta and Eragrostis rigidior whereas sample 2 of plant remains was composed of Acacia plant; Vachellia tortilis. The two samples of plant remains were collected from Ga-Nchabeleng Village. Sample 3 of plant remains was composed of creeping, perennial weed herbs; Alternanthera pungens Kunth and Alternanthera lorentzii. Sample 4 of plant remains was composed of prominent woody plants; Combretum apiculutum, Kirkia wilmsii and Boscia albitrunca. Samples of plant remains 3 and 4 were collected from Mphanama Village study sites. Sample 5 of plant remains was the control site and composed mainly of Acacia plants; Vachellia nilotica, Acacia vii mearnsii and Vachellia tortilis and were collected from sites not used for geophagic practices. The plant remains parts mostly consumed were roots (50%) in Ga-Nchabeleng, whereas in Mphanama Village they were stems (54.5%) and the control site had leaves at 62.5%. The five samples of plant remains were recovered using physical separation method. The plant remains were washed and dried. Retch Muhle grinding machine was used to ground the samples. Methanol was used in the extraction of all the samples of plant remains. The result from the administration of the questionnaire revealed that geophagia in this area was practiced by both male and female Sepedi-speaking individuals. Ga-Nchabeleng Village had more female geophagic participants, whereas Mphanama Village had more males who have almost undergone secondary school. However, in general for the study there were more female geophagic consumers. Geophagic consumers ingest soil known locally as Mobu, Letsopa or Leraga collected mostly from the riverbanks, mountains/hills and valleys with only a few that indicated termite mounds. Geophagic consumers in the study used colour, among other things, to describe their soil of preference. The study consisted of 200 participants of whom 172 represented the geophagic group and 28 were the control group, aged between 18-65 years analysed using chi-square crosstabulation. There was no significant difference in human health effects associated with geophagia between the geophagic group and the control group. There was also no association established between soil consumption and other non-food substances between geophagic group and control group. Chi-square (χ2) analyses revealed a significant association of gender with geophagic habits (p<0.05), while there was no association of age, educational level, income source and marital status (p>0.05) with geophagic habits. Findings of the survey when two villages are combined revealed that more females (75.60%) practice geophagia compared to males (24.40%). The respondents from both study sites preferred digging technique when collecting the soil. It was established that craving was mainly the reason behind the practice in the study area. Hygiene and environmental conditions were not considered when mining viii geophagic soil as the majority of them used dirty utensils, hands for collection and non-sterile bags and tins for packaging. Some of the soils were collected close to waste dumping sites as seen whilst visiting geophagic mining sites. Majority of the consumers had little or no knowledge that the soil could be harmful or if it contained any contaminants. This sample of interviewees provided valuable information on human geophagic practices in Sekhukhune area. It became clear that this practice was entrenched in the cultural behaviour of people in the area and a need for educating them on health related aspects. The cytotoxicity of methanolic extracts of plant remains on HEK-293T cell line was evaluated using MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay for cell viability. The 50% cytotoxic concentration (CC50) was defined as the compound’s concentration (500, 250, 125, 62.5, 31.25, 15.625 and 7.8125 μg/ml) required for the reduction of cell viability by 50%. Evaluation of cell viability showed the methanolic extracts of plant remains on HEK-293T cell line ranged in the order of plant remains extract=3>1>4>2>5 according to their cytotoxicity activities. Plant remains extract 3 from Mphanama Village showed high cytotoxicity with a CC50 of 13.75 μg/ml, followed by plant remains extract 1 at 16.68 μg/ml, plant remains extract 4 at 58.95 μg/ml, plant remains extract 2 at 92.75 μg/ml and the control at 251.4 μg/ml, respectively. In the study only the methanolic extract was investigated for cytotoxicity using HEK-293T cell line. Further research need to be conducted on the individual plants of each plant remains to be able to have conclusive results on the cytotoxicity profile. This will indicate which specific plant part is toxic or whether they exhibit a higher CC50 only when in combination.