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Communications to the Editor |

Pneumonitis and Herbicide ExposurePneumonitis and Herbicide Exposure FREE TO VIEW

Daniel A. Goldstein, MD; Glenn Johnson, CIH; Donna R. Farmer, PhD; Mark A. Martens, PhD; Jon E. Ford, PhD; Mark R. Cullen, MD
Author and Funding Information

Affiliations: * Monsanto Company, St. Louis, MO † Solaris Company, San Ramon, CA ‡ Yale University, New Haven, Connecticut. Dr. Cullen is a consultant to the Monsanto Company.,  Ben-Gurion University, Beer Sheba, Israel

Correspondence to: Daniel A. Goldstein, MD, Product Coordinator, Monsanto Company, 800 N Lindberg Blvd, St. Louis, MO 63167



Chest. 1999;116(4):1139-1140. doi:10.1378/chest.116.4.1139
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To the Editor:

We agree with Pushnoy et al (December 1998)1 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,23 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.23 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.

Pushnoy, LA, Avnon, LS, Care, RS (1998) Herbicide (Roundup) pneumonitis.Chest114,1769-1771. [PubMed] [CrossRef]
 
Tominack, RL, Yang, GY, Tsai, WS, et al Taiwan National Poison Center survey of glyphosate-surfactant herbicide ingestions.Clin Toxicol1991;29,91-109
 
Talbot, AR, Shaiw, MH, Huang, JS, et al Intentional self poisoning with glyphosate containing herbicides (Roundup): a review of 93 cases.Hum Exp Toxicol1991;10,1-8. [PubMed]
 

Pneumonitis and Herbicide Exposure

To the Editor:

The 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)1due 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.2

As we stated in our article, the patient worked in a small, hot room with a ventilator blowing over the bucket containing the clogged parts and manifolds toward him. He worked on cleaning the parts continuously for 4 h. Even though the vapor pressure of glyphosate is relatively low at 25°C,2 we have concluded that the patient’s clinical symptomatology resulted from exposure and inhalation of a mixture of vapor and air-borne droplets containing glyphosate. This conclusion is based mainly on two facts: (1) the clinical picture of burns of the mucosal lining of the pharynx and larynx (glyphosate is a weak organic acid, highly soluble in water); and (2) the pulmonary parenchymal picture of acute toxic pneumonitis.

Technical glyphosate contains an active ingredient (n-phosphonomethyl-glycine) plus surfactants and inert substances. It is our assumption that part of the parenchymal reaction was due to the effect of a surfactant (such as polyoxyethylene amine) on the alveolar lining, leading to extensive alveolar involvement, as was shown on the chest radiograph. This effect of an external surfactant on lung parenchyma seems quite plausible, but admittedly, based just on clinical evidence.

In conclusion, we maintain that this worker was affected by exposure to vapors and air-borne particles of Roundup and that he developed an acute pulmonary reaction to this exposure.

References
Pushnoy, LA, Solling Avnon, L, Carel, RS Herbicide (Roundup) pneumonitis.Chest1998;114,1769-1771. [PubMed] [CrossRef]
 
IPCS Environmental Health Criteria 19: glyphosate. Geneva, Switzerland: WHO, 1994.
 

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References

Pushnoy, LA, Avnon, LS, Care, RS (1998) Herbicide (Roundup) pneumonitis.Chest114,1769-1771. [PubMed] [CrossRef]
 
Tominack, RL, Yang, GY, Tsai, WS, et al Taiwan National Poison Center survey of glyphosate-surfactant herbicide ingestions.Clin Toxicol1991;29,91-109
 
Talbot, AR, Shaiw, MH, Huang, JS, et al Intentional self poisoning with glyphosate containing herbicides (Roundup): a review of 93 cases.Hum Exp Toxicol1991;10,1-8. [PubMed]
 
Pushnoy, LA, Solling Avnon, L, Carel, RS Herbicide (Roundup) pneumonitis.Chest1998;114,1769-1771. [PubMed] [CrossRef]
 
IPCS Environmental Health Criteria 19: glyphosate. Geneva, Switzerland: WHO, 1994.
 
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