NIOSH criteria for a recommended standard for occupational exposure to carbon-black (1333864) are presented. Data is given on biologic effects of exposure, workplace environmental concentrations, work practices, sampling, and analytical methods. Toxicologic and epidemiologic evidence is presented which suggests that carbon-black may cause adverse pulmonary and cardiovascular effects. Effects of exposure on the skin are also reported. Carbon-black is defined as spherical particles and aggregates of material consisting of more than 85 percent elemental carbon, obtained by hydrocarbon decomposition or combustion. Carbon-black produced in the US is used in the rubber, ink, paint, and paper industries. If workplace concentrations of polycyclic aromatic hydrocarbons (as cyclohexane extractable material) in the carbonaceous matter exceed 0.1 percent by weight, then the carbon-black is to be handled as a suspect carcinogen. Because current data is insufficient to support a reduction in the current Federal limit of 3.5 milligrams per cubic meter, NIOSH proposes that the present limit be maintained.