<P> In adults, occupational exposure is the main cause of lead poisoning . People can be exposed when working in facilities that produce a variety of lead - containing products; these include radiation shields, ammunition, certain surgical equipment, developing dental x-ray films prior to digital x-rays (each film packet had a lead liner to prevent the radiation from going through), fetal monitors, plumbing, circuit boards, jet engines, and ceramic glazes . In addition, lead miners and smelters, plumbers and fitters, auto mechanics, glass manufacturers, construction workers, battery manufacturers and recyclers, firing range instructors, and plastic manufacturers are at risk for lead exposure . Other occupations that present lead exposure risks include welding, manufacture of rubber, printing, zinc and copper smelting, processing of ore, combustion of solid waste, and production of paints and pigments . Parents who are exposed to lead in the workplace can bring lead dust home on clothes or skin and expose their children . Occupational exposure to lead increases the risk of cardiovascular disease, in particular: stroke, and high blood pressure . </P> <P> Lead may be found in food when food is grown in soil that is high in lead, airborne lead contaminates the crops, animals eat lead in their diet, or lead enters the food either from what it was stored or cooked in . </P> <P> Some lead compounds are colorful and are used widely in paints, and lead paint is a major route of lead exposure in children . A study conducted in 1998--2000 found that 38 million housing units in the US had lead - based paint, down from a 1990 estimate of 64 million . Deteriorating lead paint can produce dangerous lead levels in household dust and soil . Deteriorating lead paint and lead - containing household dust are the main causes of chronic lead poisoning . The lead breaks down into the dust and since children are more prone to crawling on the floor, it is easily ingested . Many young children display pica, eating things that are not food . Even a small amount of a lead - containing product such as a paint chip or a sip of glaze can contain tens or hundreds of milligrams of lead . Eating chips of lead paint presents a particular hazard to children, generally producing more severe poisoning than occurs from dust . Because removing lead paint from dwellings, e.g. by sanding or torching creates lead - containing dust and fumes, it is generally safer to seal the lead paint under new paint (excepting moveable windows and doors, which create paint dust when operated). Alternatively, special precautions must be taken if the lead paint is to be removed . In oil painting it was once common for colours such as yellow or white to be made with lead carbonate . Lead white oil colour was the main white of oil painters until superseded by compounds containing zinc or titanium in the mid-20th century . It is speculated that the painter Caravaggio and possibly Francisco Goya and Vincent Van Gogh had lead poisoning due to overexposure or carelessness when handling this colour . </P> <P> Residual lead in soil contributes to lead exposure in urban areas . It has been thought that the more polluted an area is with various contaminants, the more likely it is to contain lead . However, this is not always the case, as there are several other reasons for lead contamination in soil . Lead content in soil may be caused by broken - down lead paint, residues from lead - containing gasoline, used engine oil, tire weights, or pesticides used in the past, contaminated landfills, or from nearby industries such as foundries or smelters . Although leaded soil is less of a problem in countries that no longer have leaded gasoline, it remains prevalent, raising concerns about the safety of urban agriculture; eating food grown in contaminated soil can present a lead hazard . </P>

Which of the following is not among the common signs of mild lead toxicity