Study objective-The aim ofthe study was to examine cardiovascular risk factors to see how these might explain differences in cardiovascular disease mortality among Chinese, Malays, and Indians in the Republic of Singapore. Comparisons were made between the respondents, the sample, and the sampling frame, and no major discrepancies were found by age, sex, and ethnic group; the youngest age group had slightly lower response rates than the older ones. PROCEDURESAll clinics were held on Saturday mornings between 0900 and 1200 hours and the subjects were asked to fast from 2100 hours the previous evening. A questionnaire was administered by a field investigator (a nurse trained in interview techniques) and personal details including ethnic group (derivation previously described),' present and past occupations, medical history, drug usage, diet, and family medical history were obtained. Questions were asked on alcohol intake (including frequency, type and quantity, similar to those used in the British Regional Heart Study2 based on the UK General Household Survey 1972-73),3 smoking (same questionnaire as used in MONICA project of WHO),4 and chest pain.

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SUMMARY Lead concentrations in maternal blood, umbilical cord blood, and breast milk from 114 women who were not occupationally exposed to lead were determined by graphite atomic absorption spectrophotometry. The mean concentrations of lead in maternal blood, umbilical cord blood and breast milk were 0O7, 0-55, and 0-23 iimol/l, respectively. A significant correlation was observed between maternal and umbilical cord blood (r=063). A lower correlation was noted between maternal blood and breast milk (r=0.29). These results suggest that lead freely crosses the placental barrier from mother to fetus and the transfer of this heavy metal from maternal tissues to breast milk is possible, but the metabolic mechanisms are more complicated. In addition, a longitudinal study was conducted of concentrations of lead in breast milk in nine lactating women. Results suggested no significant change in the content of lead in breast milk during early lactation.The toxicology of lead has been well studied. The contention that excessive absorption of lead in pregnant women may pose a danger to the fetus has also been examined. ' Infants and children are particularly susceptible to the toxicity of lead because of their developing central nervous system, small body size, higher rate of absorption, and tendency to put objects into their mouths.2 Lead also has a higher affinity for fetal haemoglobin.3

The neuropsychological performance of a group of 49 workers occupationally exposed to lead was compared with a matched control group of 36 non-exposed workers. The psychometric measurements were composed of tests covering a broad range of different neuropsychological functions, particular emphasis being given to perceptual motor ability and attention concentration functioning. A questionnaire to assess subjective symptoms in mood, sleep disturbance, poor concentration and forgetfulness, somatic complaints, and social passivity was also included in the battery of tests. Compared with the controls, the performance of the lead workers was found to be significantly poorer for digit symbol, Bourdon-Wiersma, trail making test (part A), Santa Ana test, flicker fusion, and simple reaction time. In terms of subjective symptoms the exposed group also reported significantly more complaints of anxiety and depressed mood, poor concentration and forgetfulness, and other somatic complaints. These differences were observed among lead workers with a mean blood lead value of 2-35 umol/l (SD 0-7).