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M Hannan

Publications and source records attributed to M Hannan.

6 recordsLinked to original sources
PubMed1991

Observations and an interpretation of dose-response relationships for cellular transformation in terms of induced (T) repair.

Both radiation-induced lethality and transformation frequency have been observed to plateau or diminish abruptly at relatively low dose levels and then increase with increasing doses, but at a reduced incremental rate. Discontinuities in dose-response relationships are postulated to correspond to the induction of a repair system ('T' repair) not functional at lower doses, i.e. below the induction threshold dose (Tt). Anomalies (discontinuities) in dose-response relationships and effects of dose fractionation previously noted are qualitatively explained in terms of this model.

Animals↗
PubMed1987

Lead poisoning in automobile radiator mechanics.

Exposure to lead occurs during automobile radiator repair when soldered joints are heated, but this relatively common hazard has received little public recognition. We therefore studied lead exposure among automobile radiator mechanics in the Boston area. Twenty-seven shops were surveyed, and most were found to be small and poorly ventilated. Seventy-five workers were interviewed and tested for blood lead and free erythrocyte protoporphyrin levels. Fifty-six of the 75 actually repaired radiators, and they had a mean blood lead level of 37.1 micrograms per deciliter (range, 16 to 73). Thirty-nine percent of these mechanics had levels higher than 40 micrograms per deciliter; hematologic, neurologic, and renal effects are known to develop at or above this blood lead level. Multiple regression analysis showed that the number of radiator repair work stations (an index of exposure) was the variable most significantly associated with increased blood lead levels. We conclude that excessive exposure to lead occurs frequently among radiator repair workers and should be prevented by improved ventilation, engineering controls, and the use of respirators (if indicated) while working.

Adult↗