Hazardous child labor is challenging to define and quantify in the context of acute or chronic toxic exposures--either of which may cause significant disease and disability. Epidemiologic occupational studies in adults have documented many harmful outcomes secondary to exposure to toxic substances. Occupational surveillance efforts often have focused on acute injuries because they are more readily identified. Fassa has been able to compile data concerning injuries to child laborers but notes, "There is great need for studies in developing countries ... on the impact of child labour on illness." Although injuries may be underreported or undocumented among child laborers, acute injury is, at least, potentially recordable. This is in sharp contrast to toxic exposures, where exposure assessment is usually difficult and costly. This is especially true when it is done after an exposure has taken place. The outcomes of most toxic workplace exposures to children remain unknown. The Agency for Toxic Substances and Disease Registries (ATSDR) notes that in similar environments, children may have greater exposures than adults: "Pound for pound of body weight, children drink more water, eat more food, and breathe more air than adults," and "In some instances, children are less able than adults to detoxify chemicals and are thus more vulnerable." Children who begin work at an early age have many more years to develop illness than an adult doing the same work. A household survey of child laborers in Ethiopia found that a high proportion (greater than 90%) of children in both urban and rural areas of the country reported non-use of protective equipment. However, it is the experience of present author D.P. that this equipment is rarely if ever adequate, even when made available. For example, protective equipment such as respirators or impermeable gloves are designed for adults, and thus do not properly fit children. In defining hazardous child labor, the larger context of public health cannot be ignored. The study of child labor needs to take into account the baseline health of exposed individuals. In developing countries, the poorest and most vulnerable children are most often involved in work in order to earn money for survival. These children are also likely to already lack basic necessities of food and medical care, predisposing them to diarrhea, anemia, and micronutrient deficiencies. Underlying nutritional conditions may make children more susceptible to the effects of toxic substances such as lead. In addition, child laborers also may be exposed to lead and other toxic substances from their poor living conditions.