High lead levels cause decreased vitamin D and haemoglobin synthesis as well as anemia, acute central nervous system disorders, and possibly death.
[3] Pre-industrial human BLL measurements are estimated to have been 0.016 μg/dL, and this level increased markedly in the aftermath of the industrial revolution.
Children in populations adjacent to industrial centers in developing countries often have average BLL measurements above 25 μg/dL.
In the United States, the average blood level for children aged 1–5 years fell from 15.2 μg/dL in 1976–1980 to 0.83 μg/dL in 2011–2016, a change largely attributed to phasing out leaded gasoline.
Bone lead measurements from two Native American populations living on the Pacific coast and the Colorado River between 1000 and 1300 A.D. show that BLLs would have been approximately 0.016 μg/dL.
[3] The National Academies evaluated this issue[12] in 1991 and confirmed that the blood lead level of the average person in the US was 300 to 500 times higher than that of pre-industrial humans.
Clair Patterson originally developed techniques to measure tiny concentrations of lead in his quest to determine the age of Earth.
When he discovered that preindustrial humans had far less lead in their bodies than all modern humans, he wrote: "It seems probable that persons polluted with amounts of lead that are at least 400 times higher than natural levels, and are nearly one-third to one-half that required to induce dysfunction, that their lives are being adversely affected by loss of mental acuity and irrationality.
[3] BLL measurements from developed countries decreased markedly beginning in the late 1970s, when restrictions were placed upon lead use in gasoline, petrol, paint, soldering material and other products.
[15] As of 2009, coal combustion was considered to be an important source of Pb air pollution in China, the eastern U.S., and to some extent, in Europe.
[20] The Centers for Disease Control and Prevention (CDC) states "No safe blood lead level in children has been identified.
Even low levels of lead in blood have been shown to affect IQ, ability to pay attention, and academic achievement.
[22] Adults who are exposed to a dangerous amount of lead can experience anemia, nervous system dysfunction, weakness, hypertension, kidney problems, decreased fertility, an increased level of miscarriages, premature deliveries, and low birth weight of their child.
[24] A 2018 study in the American Economic Journal: Applied Economics found that for Rhode Island children born 1997–2005 (and therefore exposed to historically low levels of lead), "a one-unit decrease in average blood lead levels reduces the probability of being substantially below proficient in reading (math) by 0.96 (0.79) percentage points on a baseline of 12 (16) percent.