The National Institute for Occupational Safety and Health (NIOSH) would like to inform the occupational health community of the possibility of adverse effects to the testes and the hemopoietic (blood forming) system in workers exposed to glycidyl ethers. During development of a NIOSH criteria document on glycidyl ethers, a pattern of research findings emerged which indicates that some of the glycidyl ethers may be capable of producing testicular atrophy and hemopoietic abnormalities in various species of laboratory animals. Additionally, after the issuance of the June 1978 NIOSH criteria document, a 1957 study was released to NIOSH reporting testicular atrophy in laboratory rats exposed to n-butyl glycidyl ether. While none of the individual research reports are conclusive with respect to the ability of glycidyl ethers to produce permanent changes to the testes or hemopoietic system in laboratory animals, some of the changes observed may act as predisposing factor to systemic problems. NIOSH is not aware of any studies investigating the possibility of occurrence of testicular atrophy or hemopoietic abnormalities occurring in humans exposed to glycidyl ethers. The possibility of these effects occurring in humans is reason for concern. Therefore, NIOSH requests that any information regarding testicular atrophy or hemopoietic abnormalities observed in workers exposed to glycidyl ethers be reported to the NIOSH Division of Surveillance, Hazard Evaluations, and Field Studies, Industry-Wide Studies Branch, Medical Section, Telephone: (513) 684-3593. NIOSH advises strict adherence to the detailed recommended occupational standard described in the glycidyl ethers criteria document. Particular attention should be given to appropriate medical surveillance in order to detect testicular atrophy or hemopoietic abnormalities in exposed workers. NIOSH requests that producers, distributors, users, professional associations, and unions transmit this information to their customers, employees, associates and members.