Pneumonitis and Herbicide Exposure

Abstract

To the Editor: We agree with Pushnoy et al (December 1998)1Pushnoy LA Avnon LS Care RS Herbicide (Roundup) pneumonitis.Chest. 1998; : 1769-1771Abstract Full Text Full Text PDF Scopus (11) Google Scholar that acute-care physicians frequently assume that harmful effects resulting from exposures to agricultural herbicides are due to organophosphate compounds. However, we must disagree with the authors’ conclusion that the pneumonitis in this case was the result of exposure to Roundup (Monsanto Co; St. Louis, MO). No information is provided to demonstrate how airborne exposure could have occurred. Neither glyphosate (an organophosphonate herbicide that does not inhibit cholinesterase) nor any components of the finished product (Roundup) become significantly airborne through vaporization, even in a poorly ventilated space. While the equipment being repaired could have generated an aerosol, such equipment would normally contain a highly diluted form of the product and would produce a droplet of nonrespirable size (200+ μm). Skin absorption of Roundup is inconsequential and has never been demonstrated to cause pulmonary injury. In short, there is no plausible route of exposure to Roundup in this case, making a causal relationship highly unlikely. Occupational pneumonitis has never been reported in connection with Roundup. Although there are reports of the aspiration of Roundup concentrate resulting in lung injury,2Tominack RL Yang GY Tsai WS et al.Taiwan National Poison Center survey of glyphosate-surfactant herbicide ingestions.Clin Toxicol. 1991; 29: 91-109Crossref Scopus (64) Google Scholar3Talbot AR Shaiw MH Huang JS et al.Intentional self poisoning with glyphosate containing herbicides (Roundup): a review of 93 cases.Hum Exp Toxicol. 1991; 10: 1-8Crossref PubMed Scopus (102) Google Scholar almost all reported pulmonary effects have occurred following suicidal ingestion of the undiluted Roundup concentrate and appear to be the result of cardiovascular toxicity producing nonvasogenic pulmonary edema.2Tominack RL Yang GY Tsai WS et al.Taiwan National Poison Center survey of glyphosate-surfactant herbicide ingestions.Clin Toxicol. 1991; 29: 91-109Crossref Scopus (64) Google Scholar3Talbot AR Shaiw MH Huang JS et al.Intentional self poisoning with glyphosate containing herbicides (Roundup): a review of 93 cases.Hum Exp Toxicol. 1991; 10: 1-8Crossref PubMed Scopus (102) Google Scholar Further, clinical experience with ingestion or aspiration is not applicable to purported vapor inhalation. Other possible sources of exposure not discussed by the authors include the following: use of compressed air (generating an aerosol consisting predominantly of diesel fuel); use of a chlorinated solvent in conjunction with smoking (generating phosgene); welding (metal fume fever); or the occurrence of unreported pulmonary aspiration (siphoning or blowing out parts using the mouth). Nonoccupational causes consistent with the clinical course have not been excluded. Physicians are often quick to conclude that a reported chemical exposure is responsible for a temporally associated clinical illness. In such cases, a thorough medical history, a situation-specific exposure assessment, and an evaluation of the physical and toxicologic properties of the material in question are essential if valid conclusions are to be drawn. Further investigation of this case may have revealed a more plausible occupational cause. Lacking this, the relationship between occupational activity and pulmonary pathology in this case is more likely coincidental. Pneumonitis and Herbicide ExposureCHESTVol. 116Issue 4PreviewThe points brought up in the letter of Goldstein et al are well taken, and some of them were not addressed in our article (December 1998)1 due to the concise presentation of the case report. However, as we have taken a detailed occupational history from the concerned patient, we can reject most of the alternative exposures suggested by Goldstein et al (welding, use of compressed air, use of chlorinated solvents, or nonoccupational causes). It is also known that dermal absorption of Roundup (Solaxis Group, Monsanto, San Ramon, CA) is very low. Full-Text PDF