Document pBGwKXz52DOQR9bG0LvEkJVmk

1098 ft tL? -- ftiWC&fc THFIANOT,NmIMHMl2, 197j . ANf NCFPIIAI I1. AND SPUTA HlltlSA IN OHIO ATATI AM) l\ rAINP HOSPITAL, OHIO "U l.t L { 1 i:( \4 !! J 1! the discrimination of vector of meant can be tested for signifi cance. A high discrimination between the malformation group and its matched controls appeared within the fint 10 of the 24 variables (see accompanying figure). Even with S variables a significant discrimination of both groups at \% level was found. The discrimination of both groups was alto possible without the two factors "abortiooVstillbirths in mothers family" and "hours of daily wort". So, even in a sample with facton each not discriminating significantly between both groups, the linear discriminance analysis makes it possible to discriminate between the malfor mation group and the matched controls. This might mean that the malformations in our sample can be explained as caused by the combination of many minor factors (extrinsic and intrin sic). Imutut fur Humangvnttik, Ktimkum dr Johann Wolfgung. (k*t he-1 nivemtit, Frankfurt am Main. f Federal Republic of Germany. J. Ki finfbrfcht K. -H. Dfcfnhardt CONGENITAL MALFORMATIONS AND VINYL CHLORIDE Six,--In March, I97S, a significantly increased rate of cen tra]-nervous-system (c.n.s.) malformations was reported in 3 Ohio communities where polyvinyl chloride (p.v.c.) polymeris ation plants are located;1 the increase was not uniform and appeared more prominent in the Painesville area. There are two p.v.c. plants in Painesville, one of which began operation in 1949 and the other in 1967. The birth-defect rates were computed from birth-certificate data for 1970-73 and were compared with similar data for the entire State of Ohio. This study suggested a relationship between the higher rates of c.k.s. malformations and the increased risk of exposure to vinyl chloride in these communities. By analysing data collected through the Center for Disease Control's hospital-based birth defects monitoring programme (b.d.m.p.),1 *we examined this relationship. Two hospitals parti cipating in the b.d.m.p. are located in cities with polymerisa tion plants: one is in Pennsylvania, the other in Painesville, Ohio. c.N.s.-malformation rates for white infants bom in these two hospitals in 1970-74 were compared with the rates for white infants in each State. No increase was seen in the Penn sylvania hospital, but an increase, primarily in anencephalv and spina bifida, was noted in the Painesville hospital for the foTaTVlmri970-74 (see table). The b.d.m.p. hospital data for Painesville were compared with birth-certificate data from the Ohio department of health, and 1 additional case not included in the b.d.m p. report was added, bringing the total to 15. 30 controls, the first normal white infant born before and after each case, were selected from the hospital birth registry. Medical records for eases and controls were reviewed to confirm the diagnosis and to obtain, among other data, the parents' occupation and residence at the time of the infant's birth. In addition, parents of 14 of the fleeted children were interviewed about previous occupations and residences. ^ The study revealed that none of the interviewed parents of affected infants had ever worked at either of the two p.v.c.-polymerisation plants in Painesville (I set of parents could not be located, but records show that they did not aotk at these plants at the time of their infant's binh); 2 of the fathers of controls had worked at one of the plants at the time of their infants' births. None of the parents in either group lived within 2 miles of the two plants. The chi-square test of significance was used in comparing the distances from' residence and work-place of mothers and fathers to the p.v.c. plants for cases and controls. Comparisons were made it distances of 1 to 10 miles, in 1-mile increments. A significantly larger proportion of control mothers than case mothers worked - (Including housewives) witnin a lU-milc fadiUS 61 the p.v.c. 1 Plant, at the 9Vr contidcncelevei. inis is proEably a chance DLUnTence amongmultiplecouiparisons. --VmyT Chloride is a known carcinogen,1 and concern has arisen over its possible teratogenic effects. This concern stems from recent studies which have shown (a) an increase inmuia- genicity in bacterial assay systems4 5and (b) increased breakage in chromosomes of p.v.c.-polymerisation workers.* The Ohio Department of Health study1 is the only report that has sug gested that vinyl chloride causes birth defects in man. 3Although the follow-up study reported here confirmed a modcriU Increase in c.N.s. maliormalions in ramesvillc, Uhio, no association was found with vinyl-chloride exposure] Cancer and Binh Defecis Division, Bureau of Epidemiology. Center for Disease Control. Atlanta. Georgia JOJ33. 1.5 A Larry D. Edmonds, Henry Falx Jack E. Nissim LATE COMPLICATIONS OF TUBAL LIGATION . Sir,--Unlike Mr Darwish and Dr Saafan (Nov. 15, p. 97*1. we are uncertain as to the aetiology of the laic sequel* of female sterilisation, which they refer to as menstrual irregu larity, but in our study it will be noted we looked specifically at menorrhagia and dysmenorrhtxa. It seems unlikely that a p\v' chosomatic cause could be present when two different ted t. Infime, P. in Proceeding, of the Contemn* on Occup.noiul CarcinogenTM il the New York Academy of Science. 25 March. 1975. New York im ihe pres*). 2. Center for Diseate Control Congenital Malformation* Surveillance Annual Summary 1974. Atlanta. 1975. i. Center foe Diieite Control Morbidity and Mortality tl'eeklv Report. I cb. 9, 1974. p 49 4. R.nnug. L1., Johmiion, A., Kernel, C. Wschmenler. C. A- Amh<'. 1974, J, 194. 5. Kunei-O.noto, F, Lambert, B, Linditen. J. Lancet, 1975, i, 439. ASI 00008960 1