Graduation Year

2009

Document Type

Thesis

Degree

M.S.P.H.

Degree Granting Department

Public Health

Major Professor

Stuart Brooks, M.D.

Keywords

Reticulocytosis, Aminodinitrotoluene, Aplastic Anemia, Breathing Zone, Methemoglobin, Extravascular Hemolysis, Time Weighted Average

Abstract

2,4,6-Trinitrotoluene, TNT, is an explosive used in munitions production that is known to cause both aplastic and hemolytic anemia in exposed workers. Deaths have been reported secondary to both varieties of anemia. Studies have shown that TNT systemic absorption is significant by both the respiratory and dermal routes. A literature review revealed that the most recent review article on TNT exposure arguing for a TWA drop from the PEL to the TLV was in 1977 -- this article cited anemia issues in addition to other untoward effects of TNT.

No studies encountered looked at hemoglobin change or anemia cases in respiratory protected workers, this present effort may be the first. TNT PEL (1.5mg/m 3), REL (0.5mg/m 3), and TLV (0.1 mg/m 3) 8 hr TWAs all with skin notations (based on animal models and TNT urine metabolite extrapolation in TNT workers suggesting important role of skin absorption). The earliest effects of systemic TNT poisoning involve hgb and hematocrit drop. The investigator hypothesized that respiratory protection alone is insufficient to protect TNT workers from the risk of anemia development and hemoglobin concentration drop.

A retrospective observational study design was incorporated utilizing a records review of TNT vapor air concentration values and worker Hgb values for 8 sets of workers in respiratory protection at a demilitarization operation from October 2006 to April 2007 in order to observe whether or not respiratory protection provided adequate protection against anemia development and hemoglobin change; and to help characterize the probable role of TNT skin absorption on hemoglobin change and anemia risk. Worker baseline hgbs were compared with their exposure hgbs for statistically significant hgb concentration changes (two-tailed paired t-tests), and anemia cases were recorded. Mean hgb changes within each of the 8 groups of workers were then regressed on mean TNT air concentrations (10 hr TWAs) using air sampling levels that were performed closest in time to exposure hgbs.

Statistically significant hgb concentration drops and anemia cases were apparent at values about the REL and PEL in respiratory protected workers. There were no anemia cases or statistically significant hgb drops at values about the TLV, however. For mean TNT air concentrations from 0.12/m 3 to 0.31/m 3 there was strong positive linear association with regard to magnitude of hgb change (r=0.996). The results appear to confirm the necessity of the skin notation for TNT. However, the TLV seems to be protective against the possibility of anemia risk principally by the dermal route in workers who are respiratory protected. A question does still remain, however, as to anemia risk in workers who are below the TLV who may not be using respiratory protection.

The absence of a continued linear association between mean TNT air concentrations and mean hgb change above the 0.31 mg/m 3 TNT level most likely reflects a marrow response, as the TNT levels evident in the study are reported to be mainly associated with extravascular hemolysis with a minimal, or non-existent, aplastic component assumed. This study adds evidence to the argument that the TLV should be adopted as the new PEL.

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