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I. Leonard Bernstein,¹ Jonathan A. Bernstein,¹ Maureen Miller,¹ Sylva Tierzieva,¹ David I. Bernstein,¹ Zana Lummus,¹ MaryJane K. Selgrade,² Donald L. Doerfler,³ and Verner L. Seligy⁴

¹Division of Immunology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
²Experimental Toxicology Division; ³Biostatistics and Research Support Staff, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
⁴Environmental and Occupational Toxicology Division, Environmental Health Centre, Health Protection Branch, Department of Health Canada, Ottawa, Ontario, Canada

Abstract

Although health risks to pesticides containing Bacillus thuringiensis (Bt) have been minimal, the potential allergenicity of these organisms has not been evaluated. Therefore, a health survey was conducted in farm workers before and after exposure to Bt pesticides. Farm workers who picked vegetables that required Bt pesticide spraying were evaluated before the initial spraying operation (n = 48) and 1 and 4 months after (n = 32 and 20, respectively) . Two groups of low- (n = 44) and medium- (n = 34) exposure workers not directly exposed to Bt spraying were also assessed. The investigation included questionnaires, nasal/mouth lavages, ventilatory function assessment, and skin tests to indigenous aeroallergens and to a variety of Bt spore and vegetative preparations. To authenticate exposure to the organism present in the commercial preparation, isolates from lavage specimens were tested for Bt genes by DNA-DNA hybridization. Humoral immunoglobulin G (IgG) and immunoglobulin E (IgE) antibody responses to spore and vegetative Bt extracts were assayed. There was no evidence of occupationally related respiratory symptoms. Positive skin-prick tests to several spore extracts were seen chiefly in exposed workers. In particular, there was a significant (p < 0.05) increase in the number of positive skin tests to spore extracts 1 and 4 months after exposure to Bt spray. The number of positive skin test responses was also significantly higher in high (p < 0.05) than in low- or medium-exposure workers. The majority of nasal lavage cultures from exposed workers was positive for the commercial Bt organism, as demonstrated by specific molecular genetic probes. Specific IgE antibodies were present in more high-exposure workers (p < 0.05) than in the low and medium groups. Specific IgG antibodies occurred more in the high (p < 0.05) than in the low-exposure group. Specific IgG and IgE antibodies to vegetative organisms were present in all groups of workers. Exposure to Bt sprays may lead to allergic skin sensitization and induction of IgE and IgG antibodies, or both. Key words: Bacillus thuringiensis, Bt genes, farm workers, IgE sensitization, IgG antibodies, nasal lavage, pesticides. Environ Health Perspect 107:575-582 (1999) . [Online 7 June 1999]

http://ehpnet1.niehs.nih.gov/docs/1999/107p575-582bernstein/ abstract.html

Address correspondence to I.L. Bernstein, Division of Immunology, 231 Bethesda Ave., Cincinnati, OH 45267-0563 USA. Telephone: (513) 558-5795. Fax: (513) 558-3799. E-mail: bernstil@email.uc.edu

This paper has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. EPA, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

We thank I. Kosel and J.M. Rancourt (Health Canada) for technical assistance. We appreciate the cooperative efforts of the administrators of Mercy Hospital and the muck farm community of Willard, Ohio. We are especially grateful to the farm workers who participated in this investigation.

This study was supported by EPA cooperative agreement #822898. This research was supported by U.S. EPA grant CR822898-01-02 to I.L.B. and the National Biotechnology Strategy Fund (Health Canada and Industry Canada) to V.L.S.

Received 4 January 1999 ; accepted 19 March 1999.