The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) classifies Pica as the habitual intentional consumption of non-food and non-nutritive substances (like laundry starch, ice, soap, chalk, and kaolin) for at least one year (Diagnostic and Statistical Manual of Mental Disorders, DSM-5). Pica disorder is usually unnoticed, under-reported, and causes serious harm to consumers.1 Pica is categorized into 36 different typologies2 among which the most common are amylophagy (eating raw starch), pagophagy (eating large quantities of ice) and geophagy.3 Geophagy is the recurrent intentional, craving and purposive eating of soil, in particular clay substances. The practice of geophagy is deeply embedded in cultural traditions, and in many cultural contexts earth eating is seen as normal. Due to the increasing environmental (chemical, microbiological, physical) hazards and the practice prevalence among the most biologically vulnerable populations with potentially adverse health consequences, geophagy has become a public health concern.4,5 As observed and documented in many areas of the world for at least two millennia, geophagy is widespread in sub-Saharan Africa. Very little is currently known about geophagy practice in Chad. Based in N’Djamena, Chad, this study sought to collect data on: source, type, and form of geophagic soil at purchase; event, daily frequency, daily cost, duration of soil eating; habits at consumption and storage; specific motivation of soil eating and habit-forming events; expected health benefits and awareness of health risks; chance for intervention.


Study site

N’Djamena (N 12˚ 06, E 15˚ 02) is the capital and largest city of the Republic of Chad. It is located in the center-west of the country, on both banks of the Chari River. Its population is estimated at 1,178,361 inhabitants, with an average density of 2356.72 inhabitants/km2 as per the 2015 census. The city is divided in 10 districts. Each district has 2-3 main markets. The climate is Sahelian, marked by a dry season (November-April) and a rainy season (May-October). The annual average rainfall is 510 mm with a maximum rainfall in the month of August (175 mm). The average maximum temperature is 41˚C in April while the minimum can drop to 14˚C in January. Indeed, climate is of paramount importance in studies investigating the risk of carry-over of contaminants from the environment to humans.6


We conducted a regional based cross-sectional study using a structured questionnaire on November and December 2020. We visited 1 randomly selected main food market in each of the 10 district of N’Djamena city. In each food market we randomly selected 10 vending points of geophagic soil. In each vending point, we interviewed 1 geophagist coming for purchasing soil. In total, we interviewed 100 geophagists, i.e. 10 geophagists distributed in 100 randomly selected selling points in 10 food markets distributed in the 10 districts of the city. Participants enrolled in the study on voluntary basis. They had diverse ages, according to the exclusion criteria of under 15, above 65, and mental ill.


A standardized, anonymous, self-administered open-ended questionnaire designed specifically for the study was used. Its purpose was mainly to investigate knowledge and practice of geophagy. A preliminary structured questionnaire was developed following a review of published literature to suit the research needs.2 The questionnaire was tested for reliability, validity and accuracy. The pre-test was undertaken on a randomly selected sample of 10 participants in each district of N’Djamena, based on mentioned inclusion criteria. People sampled in the pre-test were not included in the study. Based on the pre-test feedback, necessary modifications of the questionnaires were carried to avoid misleading information. The final questionnaire consisted of 20 questions: 4 on general information, 8 on knowledge and practice of geophagy, and 8 on the reason/motivation for geophagy.

Data collection and analysis

Participants were invited to complete a self-administered questionnaire. The interviewer monitored the participant while filling the questionnaire so as to avoid interferences and preserve independent answers. The answered questionnaires were then harvested and processed for data entering and analysis. The data were analyzed using IBM SPSS statistics 20.0 software.


In the study, 100 inhabitants of N’Djamena participated and completed the questionnaire. The majority in the sampled population were women (98%) within the age range of 17-65 (mean age 30.4); most of the participants (61%) were 15-31.

The majority of them always got the soils from the local markets (77%) while others got them also from neighboring countries like Cameroon and Nigeria (Table 1). Among soil types, kaolin figured out as the most consumed soil followed by laterite (Figure 1); some individuals reported to eat kaolin and laterite together or a mixture of them with other soils. A slightly greater proportion of respondents in the age group 15-30 preferred kaoline followed by laterite. Pearson Chi-Square = 6.245 revealed that age is significantly associated with soil type consumed (pv. 283) (Table 2).

Table 1.Source, type, and form of geophagic soil at purchase, according to this pilot survey.
Chad (market, river, pits, wells, holes) 77 Kaolin 63 Granulated 66
Cameroon 18 Laterite 29 Crushed 23
Cameroon and Nigeria 3 Koalin/laterite 4 Powder/crush 8
Nigeria 1 Koalin/others 2 Granulated/powder 1
I don’t know 1 Kaolin/laterite/others 1 Granulated/crushed 1
Laterite/others 1 Powder 1
Figure 1
Figure 1.Types and forms of geophagic soils commonly marketed in N’Djamena, Chad.
Table 2.Soil type consumed by age group.
kaolin laterite kaolin/ laterite kaolin/ laterite/ others koalin/ others laterite/ others Total
15-⁠30 years 37(60.7%) 17(27.9%) 4(6.6%) 0(0.0%) 2(3.3%) 1(1.6%) 61
31-⁠65 years 26(66.7%) 12(30.8%) 0(0.0%) 1(2.6%) 0(0.0%) 0(0.0%) 39
Total 63(63.0%) 29(29.0%) 4(4.0%) 1(1.0%) 2(2.0%) 1(1.0%) 100

Granulated soil was the preferred consumed form, followed by crushed and powdered soils (Table 1). Granulate and crushed soils were the most consumed forms of soil in both age groups (15-30; 31-65). Pearson Chi-Square 6.917 revealed that age groups were significantly associated with the form of soil consumed by the study participants (pv > 0.227) (Table 3).

Table 3.Forms of soil consumed by age group.
granulated powder crushed granulated/
15-⁠30 years 41(67.2%) 1(1.6%) 11(18.0%) 0(0.0%) 1(1.6%) 7(11.5%) 61
31-⁠65 years 25(64.1%) 0(0.0%) 12(30.8%) 1(2.6%) 0(0.0%) 1 (2.6%) 39
Total 66(66.0%) 1(1.0%) 23(23.0%) 1(1.0%) 1(1.0%) 8(8.0%) 100

The majority of subjects practiced soil eating for at least 4 times/day and spent about 50-150 FCFA depending on soil type. The practice was very common during pregnancy (56%), to mitigate nausea, gastritis, sickness, and pain (15%), at any time of life (14%) or rare (7%). Interestingly, the 8% of subjects consumed soil independently of specific event (Table 4).

Table 4.General characteristics of soil eating (event, daily frequency, daily cost, duration) in N’Djamena, Chad.
Pregnancy 56
Nausea/gastritis/sickness/pain 15
At any time 14
Rarely 7
No reason 8
1 -3 times 46
>4 times 54
50-150 97
160-1300 3
0-5 years 66
6- 10 years 22
> 10 years 12

Concerning the individual history of soil eating, 66% of the respondents practiced geophagy for at least 5 years, 22% for 6-10 years, and 12% reported to have been practicing geophagy for over 10 years (Table 4).

With regards to preparation, 84% of respondents reported that they either suck or crush soil before eating, 5% do that during meals, and 11% dissolve soil in water (Table 5). Most of them store the soil in package at home (95%) while the 5% of them store geophagic soil outdoor.

Table 5.Geophagy: habits at consumption and storage, according to this pilot survey.
Suck/crunch 84 Plastic bags/bags/hand bags 86
Within meal 5 Cups/small jars 9
Dissolved in water 11 Outdoor 5

Regarding specific reasons or motivation for the practice of geophagy, majority of the respondents confirmed pregnancy as main motivation followed by pleasure at taste, zeal for improved skin texture, and mitigation of diseases’ symptoms (Table 6). With respect to habit forming event, most of the respondents indicated both personal predisposition to the geophagy practice and suggestion by a friend, or family members (sister, mother) (Table 6). In this frame, it was interesting to figure out how geophagic soil is always sold at the food market, because it is appreciated by part of the population (Figure 2). This suggested to the authors a subtending bias towards consumers’ conceiving of soil as something useful from the nutritional viewpoint (e.g. nutraceutical).

Table 6.Specific reasons or motivation for the geophagy practice, and habit-forming events, according to the present survey.
Pregnancy 42 Nobody 39
Good taste 34 Friend 39
Improved skin texture 11 Sister 15
Diseases during pregnancy 3 Mother 7
Disturbs during pregnancy 5
Diseases 4
Disease and disturbs during pregnancy 1
Figure 2
Figure 2.Geophagic soil is sold among food items at the food market in N’Djamena, Chad.

With regards to the supposed advantages of geophagy, 35% of the respondents reported expected protective effect against diseases like cancer and gastritis, 25% of them reported expected effect in mitigating nausea and vomiting, while 19% of them expect mitigation of pain. Only 2% of respondents seem not to have specific expectation on the geophagy practice, and 25% of them just expect pleasure from palatable soil (Table 7). As for the health hazards, 95% were completely unaware of geophagy related risks for health due to exposure to hazards like pathogens, toxic chemicals and radioactive substances (Table 7).

Table 7.Expected health benefits and awareness of risks possibly associated with ingestion of geophagic soil, according to the present survey.
Avoid diseases
(gastritis, cancer)
35 No 93
Avoid nausea/vomiting 25 Yes 7
Avoid pain 19
Good taste 19
I don’t know 2

Interestingly, 57% of the respondents were ready to recommend the practice to others, while 43% of them were against the option of recommending it (Table 8). The 94% of the respondents never received warning about the risk for health posed by the ingestion of soil.

Table 8.Propagation of the practice, according to the survey, and chance for intervention on this culture-rooted habit.
Would you recommend geophagy to others? % Has anyone ever warned you about the risks of consuming soil? %
No 43 No 94
Yes 57 Yes 6


To our knowledge, this is the first exploratory study conducted on the geophagic practice in Chad thus far. Geophagy is a common practice in N’Djamena. Of the 100 soil eating participants, 98% were women and 61% were between the age 15-31 (mean age 30.4), thus confirming women in childbearing age as main population sub-group practicing geophagy. In general, women (mainly during pregnancy, lactation, or in postpartum) and children are the most common consumers of soil, while geophagy is rarely reported by men.7 Our findings confirm how some men eat soil in secret, due to the general attribution of this practice to women. The prevalence of geophagy among pregnant women found in this study (56%) is in line with the scenario of west and east Africa (65-73%).8–11 The findings of this study substantiated the following considerations discussed below.

Out of craving for non-food products (e.g. kaolin, also known as white dirt chalk, or white clay) during pregnancy to relieve nausea and abdominal troubles, control diarrhea, increase salivation, remove toxins and alter odor or taste, consumption of soil seems also being influenced by smell and taste. About the habit-forming reasons, our findings are in line with studies demonstrating the role of family, friends and personal curiosity.12 Indeed, geophagy has multifactorial motivation, where physiological and cultural factors are central.4 Both vendors and consumers should be informed of the potential deleterious effects of eating soil13 due to e.g. aerobic bacteria, enterobacteriaceae, fungi7,14 and metals/metalloids like arsenic, cadmium, lead, mercury, and nickel.7,15–18 Moreover, recent findings highlight how geophagic matrices could reduce the bioavailability of micronutrients while introducing toxic substances19; the understanding of personal habits are crucial for proper diagnoses in medical settings.20

Noticeably, geophagic samples in Chad mainly come from local sites. Kaolin figures out among the country’s natural resources (along with petroleum and natron) and this finding could motivate ad hoc studies on the safety (and relevant seasonality) of local clay quarries. The possible use in cosmetics should be assessed, as well: this study highlighted the role of clays also in this field (e.g., skin texture).

Due to culture rooted nature of geophagy, huge scientific evidence (e.g. Chad-specific health risk assessment of soil consumption) is needed to convince medical doctors and traditional healers to be proactive in managing the benefits-to-risk ratio of this traditional practice/remedy in ethno-medicine).21

Interestingly, 57% of the respondents were ready to recommend the practice to others, while 43% of them -while uninformed and unaware of risks- were against the option of recommending it. Indeed, this information throws a light on the perception trend growing in the population. Analyzing people’s preparedness and proactivity on previously unrecognized/overlooked exposure scenario put important milestones towards awareness raising, informed choice, and empowerment of communities.22,23

The widespread unawareness about the health risk of soil eating linked with unfounded belief in health protective effect against diseases like cancer highlight the urgent need of awareness campaigns. Noteworthy, specific damaging effects of geophagy such as anemia and intestinal troubles are well documented.24

The vending of geophagic clays among food items at food market should be prohibited to avoid feeding the misleading idea of geophagic clays as nutraceutical (Figure 3).16

Figure 3
Figure 3.Local vendor of geophagic soil at the Dembé market, N’Djamena, Chad.


From this study, which appears to be the first conducted in Chad thus far, soil ingestion is a “culture-bound syndrome”, i.e. an ancestral tradition and a culturally-transmitted form of pica, apparently not selectively associated with other psychopathology. The observed trend against the option of recommending the ingestion of soil suggests an increasing negative perception of the geophagic practice. This is all the more interesting if we consider that the same subjects were uninformed and unaware of health risks posed by geophagy. Based on the findings of this work, we recommend awareness campaigns on: i) the health risk of soil eating, ii) the erroneous belief of, e.g., its protective effect against cancer, iii) the misleading communication subtended by the vending of soil among food items. Evidence-based discussion with medical doctors and traditional healers will benefit of health risk assessment of geophagic Chadian samples and context-specific safety assessment of local quarries.


Authors acknowledge the work done by the Noodles no-profit organization ( on the prevention of health risk factors in Africa.


Authors acknowledge the Istituto Superiore di Sanità for covering publication fees.

Authors’ contribution

DK and CF conceptualization and design of the investigation, writing; LNN, MB, AH field interviews; AT supervision.

Competing interests

The authors completed the ICMJE Disclosure of Interest Form (available upon request from the corresponding author) and disclose no relevant interests.

Correspondence to:

Kimassoum Djimadoum PhD, Ministère de la santè publique et de la prevention, N’Djamena, Chad; [email protected]

Chiara Frazzoli, PhD, Istituto Superiore di Sanità, Via Giano della Bella 34, 00162 Rome, Italy; [email protected]