Abstract
This paper comments on a recently reported case of the mother of a 4-month-old microcephalic child who issued a claim against the National Railways on the ground that her boy's malformation was caused by CO intoxication during an accidental train fire about one year ago in the Hokuriku Tunnel during her third month of pregnancy. The author picked up the following five issues which are considered to be important for estimation of cause-effect relationship regarding the malformation and introduced the present state of knowledge for each of the issues. 1. Pathology, complication, genetic background of the child as well as the maternal history should be elucidated with all possible details. The obtained findings will allow the exclusion of a certain entity of microcephaly. 2. All known causal factors of microcephaly including the related animal studies should be referred to. 3. All case reports on CO poisoning during pregnancy with special reference to type of anomalies shown in the offspring should be studied. The results of animal studies on experimentally induced CO poisoning during pregnancy should also be considered. 4. Critical period with respect to induced microcephaly should be compared with the mother's stage of pregnancy when the accident accurred. Use of human and animal studies on radiation-induced microcephaly will be helpful in this respect. 5. Possible teratogenic effects of other concurrent environmental influences such as emotional shock and medical treatment undergone by the respective pregnant mother, should be considered.
