Uptake of lead by inhalation of motor exhaust

Abstract

Tetraethyl lead was labelled with 203 Pb, added to petrol, and burnt in an engine. The exhaust aerosol was inhaled by volunteers, usually after it had been stored in a box, but in a few experiments directly, a few metres downwind of the engine. The percentage deposition in the lung, uptake to blood and excretion of the labelled lead were measured. The percentage deposition in the lung depended on the length of the respiratory cycle. For a 4 s cycle (15 breaths/min) the deposition was 35 ± 2 (s. e.)%. Most of the 203 Pb was removed from the lung with a half life of about 6 h. About half of the amount deposited in the lung was in the blood at 50 h after inhalation. A similar fraction was in the blood at the same time after injection of 203 PbCl 2 in saline solution. From this and other evidence it is deduced that most of the 203 Pb passed from the lung to the blood plasma. About half was removed to bone and other tissues, and half became attached to red cells. From about 72 h onwards, the amount of 203 Pb in blood declined with a mean biological half life of 16 d. Assuming that the same half life applies beyond the period for which measurements were made, the results can be used to predict that con­tinuous (24 h/d) exposure to 1 μ g/m 3 of exhaust lead over a period of months will given an average contribution of about 1 μg/l00 ml to blood lead. Results of other work on experimental and industrial exposure of persons to lead in air appear consistent with this.

Reduction in biomass burning aerosol light absorption upon humidification: roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

“…Reports and images of particle collapse are commonly found in the literature (Chamberlain et al, 1975;Colbeck et al, 1997;Hallett et al, 1989;Huang et al, 1994;Jimenez et al, 2003;Mikhailov et al, 2006;Nelson, 1989;Weingartner et al, 1995;Weingartner et al, 1997;Zuberi et al, 2005) dating as far back as 1975. In a study of uptake of lead by inhalation of motor exhaust, Chamberlain et al (1975) observed a more "homogenous" structure of previously chain aggregate carbonaceous material after it was exhaled from a humid human lung. It was reported that this was similar to the effect on chain aggregate-type aerosol that was drawn through a humidifier.…”

“…It was reported that this was similar to the effect on chain aggregate-type aerosol that was drawn through a humidifier. Chamberlain et al (1975) postulated that the chain aggregate particle collapses in wet air due to the discharge of electrostatic forces. A later explanation cited by Hallett et al (1989) and Weingartner et al (1995Weingartner et al ( , 1997 is that condensation of water in small angle cavities of the branched structure leads to capillary forces that collapse the asymmetric particle.…”

Lead exposures and biological responses in military weapons systems: Aerosol characteristics and acute lead effects among US Army artillerymen: Final report

“…Only 1-2% of 50 jig of lead as Pb(NO3) 2 dried onto a personnel sampler filter went into solution after 72 h of incubation in simulated lung fluid at room temperature (approximately 23 0C). In contrast, we know that persons exposed by inhalation to lead oxide aerosol have shown dissolution and movement into blood of about 50% of the lead initially deposited in the lung (Ch75).…”

Effect of aerosol size on the blood lead distribution of industrial workers

“…These depend on particle density, size, and shape as well as particle solubility and the rate and depth of respiration [National Academy of Sciences, 19721. It has been estimated that for most common lead aerosols of mixed particle size between 30% and 50% of the total inhaled lead mass will be retained in the alveolar region and completely absorbed [Kehoe, 1961;Task Group on Lung Dynamics, 1966;National Academy of Sciences, 1972;Chamberlain et al, 1975;Ratcliffe, 19811. The larger particles deposit in the nose, throat, and upper airways, where they are cleared to the gastrointestinal tract by ciliary action [Muir, 19721. CPA assumed that all lead particulates not deposited and absorbed through the alveoli are ingested.…”