In developed countries, nonwhite people with low levels of education living in poorer areas are most at risk for elevated lead.[37] In the US, the groups most at risk for lead exposure are the impoverished, city-dwellers, and immigrants.[55] African-American children and those living in old housing have also been found to be at elevated risk for high blood lead levels in the US.[159] Low-income people often live in old housing with lead paint, which may begin to peel, exposing residents to high levels of lead-containing dust.
Risk factors for elevated lead exposure include alcohol consumption and smoking (possibly because of contamination of tobacco leaves with lead-containing pesticides).[115] Adults with certain risk factors might be more susceptible to toxicity; these include calcium and iron deficiencies, old age, disease of organs targeted by lead (e.g. the brain, the kidneys), and possibly genetic susceptibility.[67] Differences in vulnerability to lead-induced neurological damage between males and females have also been found, but some studies have found males to be at greater risk, while others have found females to be.[24]
In adults, blood lead levels steadily increase with increasing age.[10] In adults of all ages, men have higher blood lead levels than women do.[10] Children are more sensitive to elevated blood lead levels than adults are.[160] Children may also have a higher intake of lead than adults; they breathe faster and may be more likely to have contact with and ingest soil.[84] Children ages one to three tend to have the highest blood lead levels, possibly because at that age they begin to walk and explore their environment, and they use their mouths in their exploration.[24] Blood levels usually peak at about 18–24 months old.[7] In many countries including the US, household paint and dust are the major route of exposure in children.[84]