RAYMOND SINGER, PH.D.
A Professional Association
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Singer, R. (1999). Neurobehavioral screening of child and adult bystander exposure to toluene diisocyanate application. Fundamental and Applied Toxicology, Supplement: The Toxicologist, 48, 1-S, March, p. 359.
Rationale: Toluene diisocyanate (TDI) is a well known respiratory sensitizer. Less widely reported are its potentially permanent neurotoxic properties. TDI is incorporated into sprayed urethane foam elastomeric coatings, such as roofing materials. Application to surfaces at occupied schools puts children and others (such as the sick and elderly) at risk, who may be more vulnerable to TDI toxicity than is the average male worker, for whom occupational standards have been promulgated.
Scope: Over 500 gallons of roofing products containing .6% TDI at 135 degrees F was sprayed by workers in full protective gear over 27,000 sq. ft. of low-level roof of an occupied school building. Numerous students and teachers were exposed to the products and developed respiratory sensitivity symptoms.
Assessment approach: A brief neurobehavioral screen (1 hour of testing) was administered to 10 subjects six years post-exposure with troubling respiratory symptoms (asthma, chronic bronchitis) associated with roofing materials containing TDI. The assessment included tests which have an established normative base and that are known to be sensitive to neurotoxicity, including the Benton Visual Retention test, subtests of the WAIS-III battery (Digit Symbol, Digit Span, and Block Design), a logical memory test, the Neurotoxicity Screening Survey, and tests for malingering and distortion.
Summary of findings: Positive symptoms on the Neurotoxicity Screening Survey were found in 7/9, with 2/9 results borderline. Neurobehavioral test results (signs) were positive in 26/39 tests (67%), borderline in 5/39 (13%) and within normal limits in 8/39 (21%). All test results of malingering were negative.
Conclusion: Findings are consistent with TDI neurotoxicity. Psychogenic causes are unlikely explanations of the illness in part due to negative malingering and distortion test results, positive cognitive deficits and duration of symptoms.