The economic exploitation of children may damage their health, minds, morals and personalities. It can cause children to be crippled, maimed and killed. It may be associated with malnutrition, disease, and mental and physical impairments that can be genetically transferred. Abuse of child labour creates and perpetuates the miseries of poverty, illiteracy, and sickness and a class of persons whose later social assistance needs can only cause the imposition of greater taxes on their former employers. It also creates a class that is disaffected and a source of political instability. Child labour abuse is criminal in most developed countries, but it is not always reported or detected. In some developing countries exploitation of children has led to conditions of slavery and forced prostitution. Extreme poverty forces many young people into the labour market at a very early age. Even as a large group, children possess little strength; in small numbers they are yet more highly exploitable. Their vulnerability is manipulated, not only where there is greed and callousness, but also as part of traditional social patterns. Typical childhood labour includes family farming, family craftwork, craft piecework, rubbish collection ("rag-pickers"), small tasks carried out by young people on their own account or for third parties, seasonal work in agriculture, various trade "apprenticeships", the sweatshop system (carpet making, weaving etc), maid-of-all-work labour in a situation of virtual bondage, porter, sweeper, pickpocket, youth prostitution, bond service, unpaid family workers in household enterprises, and subsistence activities, such as repairing and maintaining dwellings and farm buildings and carrying water over long distances.
Unicef estimated in 2014 that approximately 150 million children are engaged in child slavery, worldwide.
In all regions children it has become less common that children are employed in the larger and more modern industrial undertakings. Changed management attitudes, the introduction of more sophisticated machinery and rationalized production methods, the increased importance of high productivity, the presence of trade unions, the enactment of minimum age laws and the strengthening of inspection services have all contributed to the virtual elimination of child labour in such undertakings. However, child labour in factories has not altogether disappeared. Appreciable numbers of children clearly below the legal minimum age are employed in small marginal factories that rely on keeping wages and other costs to a minimum. Such factories are most numerous in Asia and, to a somewhat lesser extent, in Latin America and the Middle East, but they also exist in parts of Southern Europe and even in depressed areas of more industrialized regions. They seem to be particularly concentrated in certain industries; textiles, clothing manufactures, food processing and canning. In India, recent statistics show that children earn on average half the adult wage, gross violations of regulations and exploitation are rife, conditions are unhealthy and accidents frequent.
Child workers are frequently represented as apprentices or learners, and many of them undoubtedly are in a sense, but the training they get is often minimal, the work strenuous, the treatment that of servants and the pay far below standard. In some cases such as the hand-made carpet industry, the work is handed out to women by middlemen who have none of the responsibilities of employers, and is performed at home by the women with their daughters or girls from other families. The girls are often practically infants and their employment and conditions of work are subject to no control. Similar practices are found in many countries in handicraft work. Craftsmen are given jobs on contract and are paid strictly by results; the payment and conditions of work of the child 'helpers' they commonly employ are their responsibility. Child labour in construction is found throughout most of Asia, Latin America and the Middle East.
Another largely uncontrolled and widespread occupation for children, traditional in many of the developing countries, is domestic service. In some countries it is common for very young children – mainly girls in Central America, the Middle East and some parts of Asia – to be brought to cities from rural areas by their parents, or purported parents, and virtually sold into domestic service. The children are usually unpaid and the practice is often described as "adoption". It is generally rationalized by the argument that these children enjoy much better conditions than they had in their previous homes. But, while this may often be true, in the total absence of outside control there is always a potential danger of overwork, neglect, mistreatment and exploitation. Non-industrial child labour is also a problem in Southern Europe, though different in nature and degree. Children below the legal minimum age are employed fairly widely in shops, cafÃ©s and restaurants and to a much lesser extent in markets and street trades. Employment is often combined with school attendance, or at least school enrolment, and provides a supplement to family income. In the more developed countries this problem sometimes also arises, but again it is of a different nature - it is not usually the case here that large numbers of children below the minimum age are being employed under illegal conditions or without safeguard and supervision.
In 2004, the ILO listed some national estimates of the prevalence of children in domestic labour: 700,000 in Indonesia, 559,000 in Brazil, 250,000 in Haiti, 264,000 in Pakistan, 200,000 in Kenya and 100,000 in Sri Lanka. Girls working in domestic service represent 22 percent of the one million children aged 10 to 14 working in Brazil; In the Peruvian capital alone it was estimated that 150,000 girls under 18 work in domestic service. Terre des Hommes, which focuses its efforts on children's issues, extrapolates this data to determine that several million youngsters work as domestics; the majority in Africa, South America and Asia.