Biomedical subjects
Publications and source records attributed to R I Ehrlich.
A case of baker's asthma with a fatal outcome is described. Clinical features and the circumstances of death are recounted. While the case documents the potential severity of occupational asthma, it also illustrates the difficulties of managing occupational asthma in the absence of good social security.
To determine whether death rates from asthma have been rising in South Africa, asthma mortality rates among coloured and white South Africans were calculated from official figures for the years 1962-1988. Sharp increases in the 1960s were noted in both groups. Since the early 1970s whites rates have generally shown a downward trend. In contrast, coloured rates have remained high, with a marked excess of male deaths. In the age stratum 5-34 years, there has been considerable fluctuation, with the long-term trend being slightly downward. Some increase in death rates occurred among the young in the early 1980s, but coloureds in this age group have shown falling rates in the most recent years. Coloured death rates in the younger age stratum have, however, continued to exceed whites rates, although by a decreasing margin, and have been high by international comparison. These group disparities are unlikely to be due to differences in certification or in coding. Variation in prevalence or severity of asthma may explain some of the disparity. However, these group differences, taken with well-known inequalities in medical care, suggest that preventable determinants of asthma deaths related to access to and quality of medical care may be important and accordingly a target for preventive strategies.
There has been growing public concern over reports of increasing air pollution in the Cape Peninsula. Attention has been focused on the 'brown haze' and on photochemical smog. Because of deficiencies in the monitoring equipment, information on trends in photochemical smog levels over the past decade is limited. Trends in oxides of nitrogen, one of the main precursors of photochemical smog, and therefore an indicator of the potential for its formation, were examined for the period 1984-1993. Meaningful data for determining trends were available from only a single site. Increases in mean monthly levels, peak hourly levels and the number of times guidelines were exceeded were demonstrated. Given the dynamics of formation of photochemical smog and the particular role of motor vehicles, it is argued that the trends measured at this site are probably an underestimate of the trends in other parts of the Cape Town metropolitan area. Some of the precursors of photochemical smog, notably nitrogen dioxide, and some of its components, notably ozone, have been shown to be detrimental to respiratory health at levels close to, or below, current recommended guidelines. A continuing increase in these pollutants will therefore result in more respiratory illness, particularly among susceptible groups. This calls for an upgrading of monitoring of air pollution in Cape Town and for appropriate steps to prevent its further increase.
To determine whether hospital admissions for acute childhood asthma were rising in Cape Town in line with the experience of other countries, Red Cross War Memorial Children's Hospital's records for the period 1978-1990 were analysed. These were compared with total admissions for non-surgical causes and lower respiratory tract illness as well as those for bronchiolitis and pneumonia. Asthma admissions showed a sharp upward trend from 1978 to 1984, a slower rise through 1987 and a levelling off since. The profile of hospital admissions for respiratory illness was also analysed. Black children were under-represented among asthma admissions compared with those for pneumonia. Asthma admissions occurred throughout the year but showed seasonal peaks in May and November. Reasons for these trends and patterns are discussed, as well as hypotheses for further research into the epidemiology of asthma in South Africa.
There is a paucity of data on pesticide-related morbidity and mortality in South Africa. A review of notifications to the western Cape office of the Department of National Health and Population Development from 1987 to 1991 was undertaken to describe the epidemiological profile of pesticide poisoning in the region. Two hundred and twenty-five cases of pesticide poisoning were identified, of which the majority were from rural areas. Farmers, farm workers and their families were most frequently involved in poisoning events, which included accidents arising outside of workplace production (44%), self-inflicted injury (35%) and direct occupational contamination (11%). Farm pesticide stores were the most frequent source of pesticide and a seasonal variation in the trend of poisoning events could be discerned; this corresponded to agricultural spraying practices in the region. The mortality rate was significantly higher among those with self-inflicted injury, particularly farm workers. A concurrent review of hospital admissions for 1991 found that 78% of cases had not been notified. In view of the key role of surveillance in reducing pesticide-related morbidity and mortality, a call is made to improve notification of pesticide poisoning so as to facilitate control of an important potential public health problem.
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A general account is given of the problems of assessing the impact of human exposure to toxic waste sites, including the identification of truly exposed populations and of exposure pathways. Epidemiological studies of populations at risk are briefly reviewed and methodological problems summarised. These include the use of relatively weak study designs, inadequate exposure assessment and recall biases associated with symptom reporting among anxious residents living in the vicinity of waste sites. In South Africa, health risks associated with exposure to toxic waste sites need to be viewed in the context of current community health concerns, competing causes of disease and ill-health, and the relative lack of knowledge about environmental contamination and associated health effects. A nonspecific deterioration of health and well-being is more likely to result from waste site exposures than is overt clinical disease. Socially acceptable policies and controls may have to be based on criteria other than demonstrable ill-health. Detailed inventories and registries of the nature of disposed materials need to be maintained, sites of poorly controlled disposal in the past identified and selective environmental monitoring conducted. Epidemiological studies may be justified in situations where exposures well in excess of acceptable norms are demonstrated. An integrated national waste management policy for the country is urgently needed.
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The clinic of the National Centre for Occupational Health is described as an example of a referral clinic for occupational disease. The activities and limitations of the clinic are described. Trends relevant to the development and running of such clinics in the RSA are considered. Features of clinical occupational medicine which distinguish it from other medical specialties are discussed, as is the problem of where to site such a clinic.
Silicosis outside the mines in South Africa has received little legislative or public attention. Between 1972 and 1986 217 such cases were seen at the National Centre for Occupational Health clinic, including 46 cases of progressive massive fibrosis. The relatively high proportion of cases of progressive massive fibrosis (21%), of patients less than or equal to 40 years at diagnosis (21% of blacks) and with exposures of less than or equal to 10 years (18%) indicate high silica exposures in industry. Four industries accounted for 83% of the cases--foundries, ceramics factories, refractories, and ore and stone crushing. Radiologically, readings of a mixture of rounded and irregular opacities were not uncommon (14%). Lymphadenopathy was very uncommon (less than 1%), while pleural thickening other than loss of the costophrenic angle was absent. Prevalences of symptoms, signs and lung function abnormality were high, probably owing to a range of factors other than silicosis. Cases of progressive massive fibrosis had significantly higher prevalences of these clinical abnormalities. When two separate lung function prediction equations were applied to the observed values in these cases, the number that met criteria for 'abnormality' differed. This finding has important implications for compensation. Recommendations include control of silica-using industries and careful occupational history-taking by clinicians.
A case of accelerated silicosis in a shotblaster in an iron foundry is described. The clinical course was notable for the rapid progression of cor pulmonale and the appearance of clubbing over a period of 2-3 months. Radiographic and pathological features atypical of the more chronic forms of the disease are described. The importance of the occupational history and the need for the strictest respiratory protection in such work are illustrated. Stringent control of this type of operation is urgently needed.
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Medical practitioners need to elicit a comprehensive occupational history from their patients, since this may play an integral part in establishing the diagnosis, may indicate the most appropriate form of management, and will ensure that claims for Workmen's Compensation are initiated when appropriate. This history can also assist in identifying undetected workplace hazards and in formulating and testing hypotheses concerning the relationship of work to health. The particular problems encountered in taking an occupational history effectively in the RSA are discussed.
To determine the most important sources of environmental tobacco smoke exposure to young children, the authors studied the associations among urinary cotinine, reported household smoking habits, and socioeconomic variables in 575 schoolchildren aged 6-11 y. The school children were among a population of prodigious smokers in Cape Town, South Africa. Eighty percent of the children were exposed to environmental tobacco smoke. Maternal smoking, which was adjusted for creatinine, accounted for 21.8% of the variation in urinary cotinine--more than all other sources combined. The male parent and other household smokers accounted for 12.7% of the variation, and socioeconomic indicators explained an additional 4.8%. By defining the ecological variable of smoking prevalence per school, the authors estimated a "community" contribution of 3.3%. The relative importance of different sources of smoke should be taken into account in the prevention of environmental tobacco smoke exposure in young children. Most importantly, of all the sources of environmental tobacco smoke, mothers' smoking habits had the greatest impact on exposure to children.