Ocular Trauma from Ballast Fluid after aTractorTire Explosion

Abstract

Agricultural injury is common and preventable. This study was carried out toinvestigate a preventable eye injury case in which a tire service employee was blindedwhile observing the charging of ballast fluid into a tractor tire on a farm. Ballast fluid iscommonly added to tires to enhance tractor stability and traction. It is usually a calciumchloride (CaCl2) solution of sufficient concentration to prevent freezing in winter. Inthis case, in the course of pumping used ballast fluid into a 20-yr-old tire, the tire treadwas breached and sprayed ballast fluid into the patients face. The force of the blast wassufficient to knock the patient backward and to break his eye glasses. The patient wastransported directly to a local hospital where he received his initial first aid, 20 minafter the fluid exposure. By that time there was severe ocular trauma. The patients lefteye developed anterior segment necrosis that included the cornea, conjunctiva, andsuperficial sclera. The right eye showed conjunctival necrosis, corneal edema, scleralischemia, and anterior segment inflammation. Analysis of the ballast fluiddemonstrated apparent osmolality of 6960 mOsmL1, considerably higher than thephysiologic value of 280 mOsmL1. 1,2-Benzisothiazolin-3-one (BIT) and relatedcompounds were identified and BIT was shown to be present at 680 ngmL1. Theconcentrations of organics in the fluid were likely too low to have contributedsignificantly to the injury. In vivo toxicology studies performed in anesthetized rabbitsdemonstrated that the ballast fluid administered without force could not reproduce theseverity of injury observed in the patient. Based upon investigation of the incident,medical records, chemical analyses and toxicology studies, it appears that a combinationof physical trauma and hyperosmotic tissue damage was the mechanism of injury. Earlytreatment by aggressive irrigation with water or saline in the field may have reduced theseverity of the injury and prevented the patients blindness. However, changes inhuman factors (e.g., use of face shields, no spectators), equipment (e.g., automaticpressure relief valves on pumps), and environment (e.g., perform work in tire shops,place eyewash bottles on service vehicles) could have prevented or minimized thisinjury.