During colonial times, health policies in Africa strongly focused on controlling endemic infectious diseases, such as sleeping sickness or malaria, which constituted substantial threats for European expatriates, military expeditions, and local populations. Apart from the publications about the mining industry in South Africa, as reflected by the 1930 Johannesburg Conference on silicosis (see next section on post-colonial era), the scientific literature on occupational health and safety under colonial rule in Africa is sparse.

A notable exception concerns the phosphate mines in France’s protectorates in North Africa. In a well-documented chapter of a doctoral dissertation devoted to the Gafsa phosphate mining region in Tunisia [22], Gruskin addressed both the health issues faced by the workforce of the Compagnie des phosphates et des chemins de fer de Gafsa – workplace injuries (including “fake” injuries), intestinal parasite infections, and dust hazard – and dental fluorosis (“darmous”) found in the population around the mine as a result of environmental fluorine pollution. In Morocco, industrial extraction of phosphates by the state company Office Chérifien des Phosphates began in the 1920s [23]. In a 1953 publication [24], Jean Rodier (1920–2003) – who documented (also by means of documentary films) the clinical and other features of manganism among phosphate miners [25] – wrote a comprehensive overview (though without providing quantitative epidemiological data or literature references) of the various existing (or potential) occupational health problems in the Moroccan phosphate mines. These included: harsh working conditions under high temperature and humidity, and specific diseases caused by exposure to lead, manganese, antimony, cobalt, arsenic, inhaled dust particles, low oxygen, toxic gases, fluorine, and hookworm. Following the detection, in 1937, of “ankylostomosis” in the underground Khouribga mine, an intensive detection program by systematic feces examinations initially revealed an “enormous proportion” (up to 66%) of infestation among underground mineworkers, but improved fecal hygiene, individual “prophylaxis” (oral administrations of tetrachloroethylene) and continued surveillance led to substantial reductions in infestation [26, 27]. Rodier concludes with interesting (and for the era, rather progressive) considerations regarding collective and individual preventive measures [24].

Italian colonial rule, especially during the Fascist period, also left its mark on the occupational health landscape in Africa. In Libya and Italian East Africa, indigenous laborers were subjected to forced labor under harsh environmental and working conditions. Infrastructure projects, including roads, railways, and agricultural developments, exposed African workers to risks such as heatstroke, infectious diseases, malnutrition, and respiratory illnesses [28]. Although Fascist propaganda promoted the image of modern and efficient colonial health systems, these initiatives largely prioritized the needs of Italian settlers, with minimal investment in the health of the African workforce [29]. In Eritrea, agricultural labor policies under Italian colonialism worsened health conditions among workers, who faced high rates of malnutrition, parasitic infections, and exhaustion due to the heavy reliance on forced labor [28]. More broadly, the exploitation of indigenous labor in the Italian colonies reflected the same patterns observed in other colonial contexts, where occupational risks for African workers were exacerbated by systemic neglect and racial hierarchies [30]. A further element of occupational health policy during Italian colonialism was the extension of social insurance mechanisms to the colonies. After the conquest of Libya (1911–1912) and especially during the 1930s, the Italian National Accident Insurance Fund (Cassa Nazionale Infortuni), renamed INFAIL (Istituto Nazionale Fascista per l’Assicurazione contro gli Infortuni sul Lavoro), established branch offices in Africa [31, 32]. These services largely prioritized Italian settlers and workers, however, offering minimal protection to indigenous laborers, who remained highly vulnerable and faced significant disparities in compensation for occupational injuries and diseases [32].

In the following, we describe, in more detail, the paradigmatic case of how health and safety were approached and managed in the Katanga mining industry during Belgian colonial rule.

During the period of the “Congo Free State” (1885–1908) under the private ownership of King Leopold II (1835–1909), the exploitation of natural resources concerned mainly ivory and natural rubber. In 1908, the Congo Free State came under the jurisdiction of the Belgian state to become a colony, known as the Belgian Congo, until its independence in 1960 [33]. Under Belgian colonial rule, the extraction of mineral resources would be a dominant source of benefit for the metropole. Belgian geologist Jules Cornet (1865–1929), who laid the foundations of Congolese geology during the Bia-Francqui expedition of 1892, is credited with having described Congo’s southernmost region as a “geological scandal” because of its wealth and diversity of mineral resources [34].

The organization of industrial mining formally started in 1900 with the creation of the Comité Spécial du Katanga (CSK) followed, in 1906, by the creation of the Union Minière du Haut-Katanga (UMHK), a private company that got a monopoly for metal mining and processing (and related operations) in the Congolese portion of the African Copperbelt [35,36,37]. UMHK’s first copper ingot was smelted in 1911, and by 1922 the company belonged to the five principal world producers of copper. Copper production rose from 50,000 tons in 1923 to 139.000 tons in 1930. Production decreased during the economic crisis of the 1930s, but picked up after 1935 and intensified massively to contribute (not without repression of social unrest) to the allied effort during World War Two.

In addition to copper, UMHK produced several other commodities such as zinc and cobalt, as well as radium and uranium. The uranium needed for the Manhattan project A-bomb on Hiroshima came from the Shinkolobwe mine. The post-war years saw the golden age of the UMHK with an extension of mines and refining plants, as well as power plants and other infrastructures. In 1960, the company produced a record 300,000 tons of copper and had 20,000 employees. After Congo’s independence (30 June 1960), the mining activities of the UMHK continued under various other statutes and names. Its assets were nationalized in 1967. The current heirs of the UMHK are the Gécamines (Générale des Carrières et des Mines), on the one hand, and the multinational UMICORE, on the other [35,36,37].

The general paradigm of colonial rule is to exploit a colonized country’s natural resources for the benefit of the metropole. Belgian colonial administration operated under a paternalistic ideology, epitomized by the phrase “dominer pour servir” (“to dominate to serve”). This in essence racist mindset allowed colonizers to rationalize their exploitative practices as part of a broader mission to “civilize the indigenous population.” The colonial governance relied on a “colonial trinity” comprising the state (with its administration consisting of Belgian nationals and its “Force Publique” under Belgian commandment), private companies (such as UMHK), and the church (mainly Catholic missions) providing social services like education and healthcare.

During the early period of industrial mining in the Katanga Copperbelt, the UMHK faced technological problems and difficulties to export production over very long distances to ocean ports, but one of the most serious issues was the shortage of workers in the sparsely populated southern Katanga. Therefore, workers had to be recruited, more or less forcefully, by private recruiters and companies such as the Bourse du Travail du Katanga (which operated from 1910 to 1927) and then by the Office Central du Travail du Katanga. Thousands of single men were thus recruited from neighboring areas but also from distant regions outside the Congo. As shown in a medical report from 1926 by Richard Bruynoghe (1881–1957), professor at the University of Louvain, mortality among workers was very high (up to 200/1000), with deaths occurring mainly during the first month of employment, this being attributed to a combination of “very defective conditions” during travel, poor initial nutritional state, high susceptibility of natives to respiratory infections, rudimentary collective housing in camps, cold weather, poor food quality, and insufficient preparation and training for mining work (causing numerous accidents) [38].

The economic consequences of labor shortage led, in 1928, to a policy shift towards “stabilization” of the workforce. This move was strongly inspired by UMHK’s medical doctors, under the direction of Dr. Leopold Mottoulle (1884–1964) who headed both the medical department and the department of the Main-d’Œuvre Indigène (M.O.I.). The new social policy aimed to solve the shortage of healthy workers by improving the recruiting conditions (see below), improving housing and sanitary conditions, and increasing the quantity and quality of food rations. Henceforth men would be allowed (and encouraged) to be accompanied by their wife and to settle in family housing provided by the company. Progressively, numerous social measures were instituted for UMHK employees and their families: hospitals and schools (carefully segregated between whites and blacks), and the Œuvre pour la Protection de l’Enfance Noire (O.P.E.N.). This “totalitarian” policy was conducted without worker participation; unions were forbidden [39]. Nevertheless, organized forms of resistance did occur, including a violently repressed strike in December 1941 [40].

In 1946, Mottoulle concluded that the efforts to stabilize the workforce had been successful and led to improved productivity, a decreased need to recruit workers from far away, and a substantial decline in morbidity and mortality, thereby achieving a substantial population growth [41]. The “generous” social provisions for UMHK workers and their families continued through the subsequent years [42]. In a self-congratulatory book celebrating the UMHK’s 50th anniversary in 1956, the company prided itself for its “oeuvre sociale” having created a prosperous, happy and loyal African workforce, thus conspicuously ignoring past worker protests [43].

The efforts of the UMHK’s medical service focused on ensuring that the workforce would be in good general health for the company’s economic benefit. One important endeavor consisted in applying severe procedures to recruit new workers from distant regions in the Belgian Congo, Ruanda-Urundi and elsewhere. As described in detail in a 1933 publication by UMHK’s “médecin en chef” René Van Nitsen, potential recruits (and their families) were first brought to a “camp de concentration”, where they received “abundant food” and rested a few days before being directed to a “camp de préparation”, where they underwent a “severe selection” (see Fig. 3) and medical preparation (including vaccinations and deworming) for the long journey (by train or ship) to Katanga, where they would receive education for 28 days in a “camp d’acclimatation et de préparation médicale” to lead them progressively towards a new way of life [44].

Measurement of the Indice de Pignet, based on height, weight and chest circumference as developed by a French military doctor in 1901, to assess robustness of potential recruits [From Van Nitsen,1933]

The annual reports of the UMHK medical department (1917–1965) [part of the archives of the UMHK, which are kept in Brussels at the Archives générales du Royaume, Dépot Joseph Cuvelier (AGR2)] provide figures of mortality and morbidity, separately for the M.O.E. (Main d’Œuvre Européenne) and the M.O.I., for the period 1917 to 1965 [45, 46]. These reports focused almost exclusively on infectious diseases, such as malaria (the main cause of morbidity), pneumonia (the main cause of mortality), tuberculosis, intestinal diseases (dysentery, typhoid, parasites), and venereal diseases. Reports of the M.O.I. provide figures on occupational accidents, which in the early decades were responsible for two-thirds to half the hospitalizations. Until 1930, work-related injuries, even mild ones, were often followed by tropical phagedenic ulcers leading to very long hospital stays and a high cost of bandages. These complications were prevented by wearing foot and leg protection, and early finding and wound care by specialized nurses on mining sites.

However, neither in these reports, nor in the scholarly literature (e.g., Dibwe dia Mwembu’s doctoral thesis [47]), are there data about the prevention, let alone epidemiology, of specific occupational diseases caused by exposure to metals, gases or vapors, ionizing radiation, noise, or musculoskeletal disease. Awareness of the risk of dust-induced lung disease did exist but according to Van Nitsen “We know of no cases of occupational diseases in Katanga, such as silicosis in the gold mines of South Africa. Nevertheless, with the increasing number and variety of industries, workers will have to be protected from some vapors or toxic dusts” [44].

The occurrence of silicosis among the M.O.I. first appeared in the annual reports of the medical department from 1941 onwards (i.e., about ten years after the operational start of the underground Prince Leopold mine of Kipushi) and sporadic cases continued to be mentioned in subsequent years, with variable incidence and without serious documentation. Work on “aerosology” by Lucien Dautrebande (1894–1969) from the University of Liège led to field experiments aimed at decreasing exposure to respirable dusts by aerosolizing sodium chloride solutions in the Kipushi mine [48]. However, no scientific publications exist about the outcome of these experiments.

In summary, after a period of an extremely harsh regime for the workforce of the UMHK, the medical department played an essential role to achieve a stabilization of the workforce, through improvements in general living conditions, health care, and paternalistic social measures. The UMHK medical activity was largely devoted to the prevention and care of tropical infectious diseases for mineworkers and their families. Little attention was devoted to specific occupational diseases, except for accidents and, to some extent, silicosis. In this sense, the practice of medicine at UMHK epitomizes the concept of “mining medicine”, as a specific part of “colonial medicine” which, throughout the history of colonialism, was an integral tool in support of imperial interests [49, 50].