Agrichemicals have been misused by rice farmers in Vietnam for a long time. This thesis has studied the rice farmers’ knowledge, risk awareness and risk perception to get an understanding of the rice farmers’ agrichemical management. 15 rice farmers in An Giang province in the Mekong Delta, Vietnam were interviewed in 2015 when the winter-spring rice was cultivated. Field method Contextual Inquiry was used to observe and interview the rice farmers. The rice farmers in Mekong Delta, Vietnam think that they are exposed to a medium risk when handling pesticides. They think that pesticides are the most effective pest controlling method. They do not use any protective gear because the weather is to hot which makes the protective gear uncomfortable to wear, even though the majority of the farmers have experienced health effects. The farmers overuse agrichemicals. The rice farmers can increase their gross income if they start using agrichemical more responsible. The majority of the farmers do not follow recommendations established in research. The Vietnamese government have a big responsibility to implement new laws to create a healthier and more environmentally sound agriculture.

Abstract This research focuses on developing former mining sites situated in the south of the City of Johannesburg that are contaminated with radon gas. This well-located land would be suitable for development of houses for low – to – moderate-income earners, preferably those living +10km away from the city centre. Former mining land has been developed in other countries both in Europe and in America. The results from international experience shows that houses had been developed on sites contaminated with radon and people had lived longer than 35 years without contracting lung cancer. The literature reviewed reveals that radon is the world’s second greatest cause of lung cancer after cigarette smoke. There are local and international norms and standards that development of land contaminated with radon should adhere too. In South Africa, the National Nuclear Regulator (NNR) sets the norms and standards for development of land contaminated with radon in which compliance with international norms and standards has been predetermined. Utilisation of the former mining land south of the City of Johannesburg will reduce development of houses at the periphery and will bring people closer to employment opportunities, amenities, transportation, services and facilities required for sustainable housing environment. Radon-contaminated land was visited, and surveys were administered to get different opinions from people who are close to mine dumps and those who are far from the Central Business District. The results show that people are interested and prepared to take the risk of living in areas contaminated with radon. The City of Johannesburg’s former mining land should therefore be considered to meet the goals of housing units. Therefore, former mining land should in future be developed for housing purposes, provided approval has been granted by the relevant government departments.

Lead (Pb) is a known toxicant that affects young children. It is believed that old water reticulation systems are prone to lead leaching from the walls of lead pipes and fixtures where water is conveyed to households. Many households in Christchurch city particularly in the Northwestern and Central parts of the city contain old water reticulation systems thereby, putting children at considerable health risks. The purpose of this dissertation is to identify the hazards of lead exposure that comes from old water reticulation system of Northwest (NW) Christchurch water supply to households, characterize the health risks due to such contamination and, finally, to suggest possible ways to minimize the hazards. This is accomplished by conducting a systematic review of literature on the exposure patterns of lead from reticulation systems and a literature review of the possible dose response patterns of health effects of lead contamination from old water reticulation systems on children. Thus, this dissertation involves a literature based risk assessment of lead contamination of drinking water supply in the Northwest Christchurch Zone and particularly, its effects on young children. The selection process of the research studies is based on whether they offer accurate and suitable information on the risk of adverse mental function in infants and young children due to environmental lead exposure; whether the studies have been peer reviewed by qualified scientists; whether the results are confirmed by other studies; and involves only human subjects. Future research may consider whether lead levels in drinking water are seasonal; whether these values are significant to health or, the possible role of the government in tightening product controls when monitoring the availability and health risk of high lead drinking water supply plumbing products available in the New Zealand market.

Firewood is a dominant household fuel type used in many developing countries. Even in countries where there is improved access to electricity, most households still rely on firewood for their energy needs. Harvesting of some wood is illegal, however the high poverty rate, absence of alternative fuels and lack of law enforcement means even the protected wood species will continue to be used, with consequent pressure on the forests. Furthermore, the combustion of firewood for domestic use takes place in poorly ventilated homes emitting hazardous pollutants, which causes indoor air pollution and affect human health. The use of firewood as a household fuel can be superimposed nearly perfectly on that of socioeconomic development. Additionally, the use of household firewood is invariably associated with poverty in countries, in communities within a country and in households within a community. Indoor air pollution studies on human health should then consider socio-economic factors which seem to be one of the determinants of both firewood use and ill health, a determinant which is often neglected in most indoor air pollution studies. Domestic inhalation of firewood smoke is one of the mechanisms linking socio-economic (poverty) to disease. The current study sought to determine a baseline of wood usage and health risks caused by volatile organic compounds in Senwabarwana villages. This study integrated observations, ethnobotanical meta-analysis and experimental into one comprehensive integrated environmental health risk assessment framework to assess the risks associated with exposure to volatile organic compounds from firewood combustion. Basic information about firewood usage, socio-economic dynamics and perceived health problems related to volatile organic compounds was collected using a structured questionnaire. The Vac-U-Chamber was used to sample the air. The results show that firewood is extensively used in poorly ventilated kitchens for cooking and home heating in Senwabarwana villages. Ten priority firewood plant species are frequently used in the study area, namely Mohweleri (Combretum apiculatum), Moretshe (Dichrostachys cinera), Motswiri (Combretum imberbe), Mokgwa (Acacia burkei), Mushu (Acacia tortilis), Motshe (Cussonia paniculate), Mokata (Combretum hereroense), Mphata (Lonchocarpus capassa), Mokgalo (Ziziphus mucronate) and Mogwana (Grewia monticola), in their order of preference. The results also indicated thirteen common reasons or factors that influence the hoice of firewood plant species by households, the main four being: (i) the embers formed during combustion, (ii) heat value, (iii) low ash content and (iv) availability of the firewood plant species. Further analysis revealed several uses and ranking thereof, including reviewing the national status and legal profile of each identified plant species. The study found that most of the firewood species used in Senwabarwana Village were indigenous. Major drivers of firewood use are household income, educational status of breadwinners, family sizes, and place of residence, fuel affordability and accessibility, among others. Concentrations of benzene, toluene, ethylbenzene and xylene per plant species were studied to assess the risk exposed to the Senwabarwana community. Literature indicates that these pollutants have several health effects associated with acute exposure such as eye, nose and throat irritation, headaches, dizziness, nausea and vomiting. Both hazard quotient and hazard index were found to be less than one indicating no risk exists with the use of plant species used for firewood in Senwabarwana even to sensitive individuals. The risk of developing health effects due to the presence of the studied volatile organic compounds can be assessed as negligible. Since firewood is a more convenient source of energy, it is recommended that the size of the windows be extended for ventilation. Agroforesty should also be implemented as a conservation method. The wood that emits less concentration of pollutants be used for firemaking. / Environmental Sciences