Chemical Studies on the Fate of Pesticides and Heavy Metals in the Tropical Environment

热带环境中持久性有害化学品的持续和大规模使用由于其全球污染和生态毒理学影响而引起极大关注。为了阐明有机氯杀虫剂和重金属等化学物质的行为和命运，本研究计划在具有代表性的热带气候的南印度水稻种植区进行。结果表明：①六氯环己烷（六六六）、滴滴涕等持久性有机氯杀虫剂在所有环境介质和生物群中均有较高浓度的存在；在8月至1月的空气和水样中，这些有机氯含量较高，反映了杀虫剂的施用主要在水稻开花季节。目前的数据可能有助于解释“点源”地区在全球有机氯污染中的作用，因为印度是仍在大量使用持久性杀虫剂的国家之一。2)比较了热带（印度）和温带（日本）地区的空气、水和水稻土中有机氯杀虫剂的残留水平，得出结论认为，在热带地区，由于高温和强降雨，大量施用的化学物质迅速逃逸到大气和水圈中，因此在热带环境中化学品的持续使用可能会引起全球污染的警告。3)热带地区持久性有机氯的特定模式不仅存在于大气和水圈中，也存在于其他环境中。对母乳的分析显示，严格素食者的母乳中六氯环己烷和滴滴涕的含量最高。相反，非素食者和渔民群体的浓度较低。这些结果表明，在印度，与发达国家不同，蔬菜是饮食接触有机氯杀虫剂的主要途径。将印度母乳中有机氯含量与其他国家进行比较，发现印度和中国的六氯环己烷含量极高，说明目前这两个国家是六氯环己烷污染的主要点源国家。我们还首次在印度母乳中检测到多氯联苯残留，但其含量与其他发展中国家一样低。少

The continuous and large scale use of persistent and hazardous chemicals in the tropical environment are of great concern due to their global contamination and ecotoxicological impacts. In order to elucidate the behavior and fate of these chemicals such as organochlorine insecticides and heavy metals, the present research program has been undertaken in the paddy growing area of South India which has a representative tropical climate. The summary of our findings during the three year program (1987-1989) is as follows:1) Persistent organochlorine insecticides such as HCH (BHC) and DDT were detected in all the environmental media and biota with quite high concentrations. In air and water samples, these organochlorines showed higher levels from August to January, reflecting the application of insecticides largely during the flowering season of rice. The present data may aid in interpreting the role of a "Point Source" area in the global contamination of organochlorines since India is one o … More f the countries still using the persistent insecticides in large quantities.2) When the residue levels of organochlorine insecticides in air, water and paddy soil from tropical (India) and temperate (Japan) regions were compared, it was concluded that in the tropics, much larger quantities of applied chemicals were escaped rapidly into atmosphere and hydrosphere due to the high temperature and heavy rainfall and hence the continuing usage of chemicals in the tropical environment might be alarming in the context of their global contamination.3) The specific pattern of persistent orgaochlorines in tropical regions is seen not only in atmosphere and hydrosphere but also in other regimes. Analyses of human breast milk indicated the highest level of HCH and DDT in strict vegetarian group. In contrast, non-vegetarian and fishermen community showed lower concentrations. These results suggest that in India, unlike developed countries, vegetables are the principal routes of dietary exposure to organochlorine insecticides. Comparison of organochlorine levels of Indian breast milk with those of other countries revealed that HCH levels were extremely high in India and China, suggesting that they are the major point source countries of HCH pollution as of now. We also detected PCB residues for the first time in Indian breast milk, however levels were low as in other developing countries. Less