Determination of lead in capillary blood using a paper punched disc atomic absorption technique. Application to the supervision of lead workers.

392-398. The presence of lead in blood is the most incontrovertible evidence of absorption but hitherto the need for venepuncture has limited its determination in the supervision of industrial workers. Micro-methods using atomic absorption spectrophotometry (AAS) have, however, made possible the development of a sufficiently reliable test using a drop of blood obtainable by ear prick for use in the field for screening purposes. A micro-sampling method by AAS is compared with a routine polarographic procedure (POL) using venous blood (corr. coeff. = 0·990). The pipetting of microlitres of blood can be eliminated by spotting the blood onto filter paper, allowing it to dry in air, and then using a punched-out standard disc of dried blood for analysis instead. Correlation of this method (PD) with the micro-sampling technique (AAS) is good (r=0·981). The PD method using capillary blood also correlates acceptably with the micromethod using venous blood (r = 0·913). A pilot field study using capillary blood estimated by the PD technique showed that with this method blood can be collected by ear prick in factories for monitoring workers in the lead industry, thus eliminating the need for routine venepuncture.