RAYMOND SINGER,
PH.D.
A
Professional Association
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36
Alondra Road / Santa Fe, New Mexico / 87505
Alternate office: 180 E.
79th Street / Suite 1-C / New York, N.Y. / 10021
Telephone: (505) 466-1100 /
Fax: (505) 466-1101 / E-mail: ray.singer@gmail.com
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.