{'fraction_non_alphanumeric': 0.02470888952002272, 'fraction_numerical': 0.021584777051973873, 'mean_word_length': 5.392014519056262, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Stillbirths and male irradiation

Little (1999) recently reviewed the evidence that paternal preconception irradiation in the Sellafield workforce (Parker et al 1999) and among Japanese atomic bomb survivors (Otake et al 1990) might be associated with an increased risk of stillbirth. He concluded that the association reported for radiation workers was statistically incompatible with the absence of an association seen among the exposed Japanese parents. These studies and analyses illustrate the considerable difficulty in assessing stillbirths conceived by men exposed to ionising radiation at work. For example, occupational doses may not be sufficiently large to result in a detectable effect and maternal factors that are associated with stillbirths and important to adjust for may not be available. These papers also bring to focus a relevant but not well-studied public health issue, namely, what are the reproductive risks for men and women exposed to potential mutagens? We wish to emphasise here the theoretical and practical advantages of addressing this issue in persons not with low dose occupational or acute atomic bomb exposures, but with higher dose medical experiences; in particular, in survivors of cancers of childhood, adolescents, and young adulthood (Blatt 1999, Bryne et al 1998, Sankila et al 1998, Green et al 1997, Hawkins and Stevens 1996). Unlike radiation workers, cancer survivors have detailed medical records, not only of exposure doses and dates, but also of potentially confounding variables, such as intercurrent illness, personal and familymedical history, and drugs, that can greatly influence the occurrence of stillbirths and other adverse pregnancy outcomes. The types and doses of exposure vary widely among cancer survivors, providing the opportunity to seek dose–response associations and to conduct nested case-control analyses, even of interacting variables such as radiation, chemotherapy and family history. For example, our so-called Five-Center Study showed no excess of genetic disease in the 2198 offspring of 1062 cancer survivors (Byrne et al 1998). The survivors included 27% who had therapies that might affect future reproductive outcomes (radiation below the diaphragm and above the knees, or chemotherapy with an alkylating agent, or both). Their offspring were compared with those of the remaining 73% who had surgery alone or some other nonmutagenic therapy. In our new study, called the Childhood Cancer Survivor Study (Rauck et al 1999), we are calculating specific radiation doses using radiotherapy records and phantom simulations. Preliminary tabulation of 6339 survivors who had radiotherapy shows substantial doses to the gonads, with 46% receiving over 100 mSv and 11% greater than 1000 mSv. In contrast, the median dose in the occupational cohort was only 30 mSv and no worker received greater than 911 mSv (Parker et al 1999). As long-time patients, cancer survivors are accessible and, indeed, eager to cooperate in health studies and are already in the healthcare system, usually at an academic specialty hospital. Detailed health and therapy records coupled with direct contacts improve enormously the likelihood of having an interpretable finding, in part because confounding variables can be identified in detail. For example, in the case of stillbirths, we will be able to adjust for the extremely important maternal causes of stillbirth (e.g., age, parity, cigarette smoking, diabetes and high blood pressure) and circumstances at delivery.