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The mafic to felsic rocks at Yzerfontein form part of a composite 535 Ma post-orogenic pluton belonging to the Cape Granite Suite (CGS) of the Pan-African Saldania Belt of southwestern Africa. The pluton ranges from olivine gabbros (mostly at the northern end) to quartz monzonites, with monzonites the most abundant rock type. Minor felsic rocks in the form of quartz microsyenites and monzogranite occur more toward the southern end. The comparatively unaltered gabbro/monzonite has pyroxene δ18O values of 6.4‰, consistent with a mildly crustal-contaminated mantle-derived magma. Published εNd values of -1.9 to -0.3 similarly reflect crustal contamination of these mafic to intermediate rocks. The pluton is crosscut by extensive hydrothermal veining. Early quartz veining was followed by the precipitation of pyrite, calcite, tourmaline, jasper, epidote and a final stage involving the formation of barren quartz veins. The veins contain low-salinity (3 to 11 wt.% NaCl eq.), three phase (liquid + vapour ± opaques) fluid inclusions with total homogenisation temperatures of 125 to 320°C. The δ18O values of the quartz veins range from 9.8 to 14.7‰ and the fluid inclusion δD values range from -9 to -17‰. These ranges, together with the low salinities, are consistent with a meteoric origin for the vein fluids. Bulk-rock δ18O values range from 7.3 to 13.3‰ consistent with interaction of near surface fluids at temperatures of <300°C with the magmatic rocks. Open-space filling textures in quartz veins suggest vein formation in a hydrostatic regime. These, together with fluid inclusion isochores, suggest temperature-pressure conditions of no more than 170 to 300°C at ~0.5 kbar and no more than 1.6 kbar. The mineralised veins represent a shallow, poorly developed and possibly low-grade epithermal system. The mineralisation is likely related to drawdown of meteoric fluids during sub-solidus cooling of the dominantly intermediate pluton with little to no magmatic fluid influence. The mineralisation is poorly developed, possibly due to a lack of mixing between different fluid types. The various magmatic rocks, varying from mafic through dominantly intermediate to minor felsic, represents a minor mantle-derived mafic component of the Cape Granite Suite and likely related to the heat source that gave rise to voluminous crustal melting that generated the granitic magmas of the majority of the CGS. [ABSTRACT FROM AUTHOR]

The Leerkrans Formation of the Wilgenhoutsdrif Group is a succession of highly sheared metasedimentary and metavolcanic rocks separating the western margin of the Archean Kaapvaal Craton from the polydeformed and highly metamorphosed Proterozoic Namaqua Sector of the Namaqua-Natal Province. This study presents the results of a comprehensive petrographic, geochemical and isotopic study of the metavolcanic rocks of the Leerkrans Formation. Rocks of a basaltic member, a quartz porphyry and a second stratigraphically higher basaltic unit were sampled, with those of the lower basaltic member further subdivided based on their petrographic features and geochemical characteristics. Extensive alteration (chloritisation and epidotisation) of the volcanic rocks make identification of the precursor lithology difficult. Highly chloritised and epidotised metabasalts from the Lower Basalt are typically flow-banded, massive, vesicular or amygdaloidal, and have primitive tholeiitic, MORB-like geochemical characteristics and positive epsilon Nd(t) (ε Nd(t)) values (+4.2 to +6.1), with enriched large ion lithophile element (LILE) contents relative to primitive mantle suggesting derivation from a depleted mantle source. Some of the basalts of this unit have alkaline within-plate tholeiite characteristics. The Upper Quartz Porphyry is comprised of less altered felsic volcanic rocks which have pyroclastic or tuffaceous textures. The geochemistry of these rocks, which display a tholeiitic affinity with fractioned REE patterns and LILE enrichment relative to the high field strength elements (HFSE) and primitive mantle, along with negative (ε Nd(t) values (-4.8) indicate that the rocks are derived from crustal melting. U-Pb single zircon SHRIMP dating of zircons from a felsic pyroclastic rock from this unit yields an age of 1289 ± 9 Ma. The Upper Basalt and Mixed Zone of the Leerkrans Formation are comprised of basaltic lavas showing similar geochemical features to the Lower Basalt. The metavolcanic rocks of the Leerkrans Formation overlap in age with the oldest units of the ∼1.3 to ∼1.23 Ga Areachap Group, the polydeformed and highly metamorphosed remnants of a volcanic arc that separates the western margin of the Kaapvaal Craton from the Namaqua Sector. The Leerkrans Formation likely represents the remnants of a related back-arc basin to the volcanic arc which was accreted onto the western margin of the craton. The Leerkrans Formation escaped high-grade metamorphism and polyphase deformation that affected the Areachap arc during the Namaquan Orogeny due to being thrust back onto the Kaapvaal Craton during early arc accretion. [ABSTRACT FROM AUTHOR]

The Broken Hill-type Ph-Zn-Cu-Ag massive sulphide mineralisation at Aggeneys in the Northern Cape Province, South Africa has been subjected to peak metamorphic temperatures ranging between 670 to 690°C and pressures between 3.4 and 4.5 kbar. Due to the Ag and Bi rich nature of the ore, these conditions, based on previous experimental studies, may have been sufficient to allow partial melting of the sulphides to occur. Such features as (1) concentrations of low melting point chalcophile elements (LMCE), which include the metals Pb, Zn, Ag, Ga, As, Se, Cd, In, Sb, Te, Hg, Tl and Bi, (2) sulphide inclusions containing a number of different LMCE-bearing minerals within high temperature metamorphic gangue minerals, (3) low interfacial angles between two LMCE-bearing sulphides, such as galena and sphalerite, and LMCE-bearing sulphides and resistate minerals, particularly silicates, (4) LMCE-bearing sulphides filling fractures within metamorphic silicate minerals, (5) coarse recrystallised pegmatite bodies of galena and chalcopyrite crosscutting the regional foliation in the ore body and (6) the presence of a transgressive Mn selvage around the orebodies have all been recognised at Aggeneys and may be indicators of sulphide partial melting. The abundance of pyrrhotite in the orebodies, particularly in the lower ore body (LOB) may, in part, be due to partial melting of pre-metamorphic pyrite during peak metamorphism. Some euhedral pyrite in the LOB may similarly have been derived from desulphidation of pyrrhotite with falling temperatures. The Aggeneys ores also shows other typical features of metamorphosed sulphide ores, such as recrystallisation, remobilisation, deformation and annealing, many of which have contributed to obscuring previous textural features. The extent of sulphide partial melting is likely to have been small, and its effects obscured by later deformation, remobilisation and recrystallisation. It may, however, have played a small role in locally upgrading the ore. This study examines the petrography of the sulphides and their ore textures. Analytical techniques to examine the composition of the sulphides and of multiphase sulphide inclusions are to be undertaken. More extensive studies using numerous techniques are also required in order to clarify this topic. [ABSTRACT FROM AUTHOR]

Background: Cervical cancer is an important cause of death throughout the world, especially in less developed countries. Reports of trends in cervical cancer mortality from less developed countries have been limited by poor data quality and inaccurate population estimates. This paper examines trends in cervical cancer mortality in South Africa from 1949 to 1990 and discusses the impact of cytology screening on these trends.Methods: Analysis of national mortality statistics and reconstructed population data.Results: The age-standardized mortality rates for Whites declined after the mid 1960s, while that for Coloureds rose, particularly before the 1970s. These trends were affected predominantly by trends among women in the 35-64 age range.Conclusions: The pattern of mortality in successive birth cohorts for Whites is consistent with a reduction in age-specific mortality following the advent of cytological screening. The same pattern is not evident in trends for Coloureds, among whom screening has apparently had a minor impact if any at all. The apparent lack of impact of screening in those groups of women most at risk of cervical cancer lends weight to demands for the implementation of equitable and rational screening programmes for cervical cancer in South Africa and internationally. [ABSTRACT FROM AUTHOR]

Background: The opportunistic basis on which screening has been conducted in South Africa has resulted in multiple rescreening of a small proportion of the population (which excludes most women at high risk) and low population coverage. There has consequently been a failure of screening to impact on the incidence of cervical cancer in most of the population.Aim: To propose the use of the ratio of smears showing cervical intra-epithelial neoplasia (CIN)III: smears showing signs of malignancy as an indicator for the surveillance of equity in cervical cytology screening, and to apply this indicator to an area of the Western Cape of South Africa.Results: Marked inequity in screening is demonstrated between metropolitan and non-metropolitan area, and between different non-metropolitan districts. Inequity in screening between different age groups of women is also found, and this is associated with an inappropriately young age distribution of screening activity.Conclusions: The application of this indicator in the routine surveillance of screening activity may be useful in monitoring progress towards the implementation of more equitable screening programmes, and the validity of the indicator should be tested in other settings. [ABSTRACT FROM AUTHOR]

Background: Surveillance is a critical public health tool for the control of pesticide poisoning. However, surveillance activities in developing countries are bedevilled by multiple problems, and inferences made from review of flawed data may lead to mistaken policy decisions., Methods: Results of intensified surveillance from an intervention project in the Western Cape Province of South Africa were compared to the pattern of poisonings reported in routine notifications to the health authorities for a control farming district and in the study district over a 5-year period preceding the study. Intensified surveillance data results were also contrasted with policy approaches based on routine notifications and on Regional Poison Centre reports., Results: Poisoning rates reported in the study area increased almost 10-fold during the intervention period. Compared to intensified surveillance, hospital and health authority sources greatly underestimate the proportion of cases due to occupational poisoning, and overestimate suicide as a proportional cause. In addition, the risks for women appear underestimated from routine notifications. Assumptions that a lack of awareness is responsible for most poisonings are not borne out by the empirical data when reporting is intensified., Conclusions: Current policy assumptions are faulty, may result in inappropriate blame being attributed to victims and, by relying on information as the main element of education, may shift responsibility onto the individual. Improvements in the surveillance system should aim to restructure the types of data collected, and facilitate intra-governmental and inter-sector collaboration. The culture of monitoring based on report writing must change to one of surveillance that leads to intervention.

Aim: The poor state of reporting of pesticide poisoning is widely recognised as a hindrance to the development of preventive programmes that aim to address this important cause of mortality and morbidity in farm workers. This study aimed to assess the extent to which notification could be improved by enhancing passive surveillance procedures., Methods: An awareness campaign targeting a range of health care providers was conducted in a rural farming area. This included improving the availability of cholinesterase testing and encouraging all providers to notify on suspicion. Existing reporting forms were supplemented with additional questions, and notification took place through existing channels. The rate of notification in the study area was compared with that in surrounding areas and previous years., Results: Fourteen poisoning events involving 56 people were reported, with 2 events together accounting for 44 cases. All patients were hospitalised. Over 90% of cases occurred on farms, with the farm store being the most common source of pesticide. Only one case was notified by a general practitioner. The rate of notification in the study area was approximately tenfold that of previous years and of the surrounding area for the same year (P < 0.0001)., Conclusion: Although the enhanced surveillance programme resulted in an increase in notifications, the programme appears to have been ineffective in detecting mild cases of poisoning or in improving notification on suspicion by general practitioners.

Objective: To describe the patterns of use of injectable progestogen contraceptives (IPCs) among coloured and black women in the Western Cape. These data are part of an ongoing study in the Western Cape, the main aim of which is to explore the relationship between IPCs and breast cancer., Design: A population-based case-control study of breast cancer risk in relation to the use of IPCs among coloured and black women., Setting: The Western Cape, including the Cape metropole and surrounding rural areas., Study Subjects: All coloured and black women with newly diagnosed breast cancer, resident in the study area and below age 55 years, who present at either of the two tertiary care hospitals in the Western Cape are recruited. Controls are a sample of hospitalised patients representative of the populations from which the patients are drawn. Cases are frequency-matched to controls according to cross-tabulation of age, ethnic group and residential area in a ratio of approximately 1:3., Measurements: Questionnaires are administered by trained nurse interviewers, information is elicited on a wide range of variables, including sociodemographic variables, medical history, family history of breast disease, lifetime history of all methods of contraception and use of non-contraceptive female steroids, reproductive variables, cigarette smoking, alcohol consumption and other potentially confounding variables., Results: Between January and December 1994, 122 incident cases and 389 controls were enrolled. Ever-use of IPCs among the controls was 72% (N = 280) and use for 5 years or more was 30% (N = 117). Use of IPCs in the distant past was common, with 61% (N = 232) of all controls having initiated use 10 or more years previously. Current use was also high (19%). Other contraceptive methods were used far less commonly., Conclusion: Coloured and black women in South Africa have been using and continue to use IPCs for more commonly and for longer periods than women anywhere else in the world. It is therefore especially important to evaluate the risk of breast cancer and other health effects of IPCs. The rates of use identified in this study ensure that there will be adequate statistical power to evaluate long-term use, use in the distant past and current use of IPCs.

Objective: Cervical cytology screening is widely accepted as an important strategy in the control of cervical cancer. With increasing competition for health resources the need for information on the cost-effectiveness of different screening programmes has become critical. This paper describes the cost of screening via a mobile clinic, and compares the cost-effectiveness of screening via a mobile clinic with that of screening at established clinics., Method: Data were obtained from work studies, review of clinic and health authority records and key informant interviews. In addition to describing the actual cost of the project over the first year, a projection is made of the cost of operating the mobile clinic under non-research conditions. Sensitivity analysis is used to adjust for differences in yield and follow-up in comparing the cost-effectiveness in each setting., Results: The cost of the project over 1 year was R185,795. The projected cost of running such a project under non-research conditions for 1 year is R291,858. The cost-effectiveness of screening at the mobile clinic was 57% less than that of screening at the established clinics. Sensitivity analysis indicated that for any given yield and follow-up rate, the projected cost-effectiveness of screening at the mobile clinic is 15-28% less than for the established clinics., Conclusion: These findings raise questions about the appropriateness of using mobile clinics in areas where there are established health services.