城区大气颗粒物中有机氯农药的含量与分布

采用FA-3型气溶胶粒度分布采样器采样,对北京和天津2个样点夏季大气中不同粒径颗粒物上有机氯农药残留量进行分析.在所有分级样品中均检测出δ-HCH,p,p'-DDD和p,p'-DDT,其他有机氯农药只在部分样品中被检出.北京样中HCHs(α-HCH+β-HCH+γ-HCH+δ-HCH)含量为0.240ng/m3,DDTs(p,p'-DDT+p,p'-DDD+p,p'-DDE)含量为0.962ng/m3,天津样品中HCHs含量为0.581 ng/m3,DDTs含量为1.874ng/m3.天津样中有机氯农药残留明显高于北京样.大气颗粒物上的有机氯农药粒径分布特征为:北京样中HCHs和DDTs含量随粒径均呈单峰分布,而天津样中HCHs呈三峰态分布,DDTs呈较弱的单峰态分布.HCHs和DDTs两类化合物的质量中值直径和分散度分别在2.1～2.5μm和3.1～3.7μm范围内.      

Sublethal concentrations of azinphos-methyl induce biochemical and morphological alterations in Rhinella arenarum embryos

Considering that amphibians are good sentinels of environmental conditions, Rhinella arenarum embryos were used to investigate the effects of sublethal concentrations of the organophosphorus insecticide azinphos-methyl, focusing on its anticholinesterasic or pro-oxidant actions and its possible connection with the appearance of morphological alterations. Early amphibian embryos exposed to azinphos-methyl displayed a protective response through glutathione S-transferase induction, along with superoxide dismutase inhibition. At intermediate embryonic stages, embryos exposed to azinphos-methyl displayed superoxide dismutase inhibition and morphological alterations, although cholinesterase activity was not altered, suggesting that molecular targets other than cholinesterase were involved in the development of morphological alterations. At the end of embryonic development, decreases in reduced glutathione and cholinesterase inhibition were observed, along with a significant increase in the number of malformed embryos. The connection between biochemical alterations and the appearance of malformations was not evident in R. arenarum embryos. However, increased glutathione S-transferase and decreased superoxide dismutase activities could be considered as early markers of exposure to azinphos-methyl. The results obtained demonstrate that sublethal concentrations of azinphos-methyl are a serious threat to toad embryos in their natural habitats because biochemical and morphological alterations could impair their ability to deal with environmental stresses.     

Effect of curacron toxicity on the total serum protein content of Cyprinus carpio

An experiment was conducted on freshwater fish Cyprinus carpio to study the effect of the pesticide curacron on total serum protein. Curacron is an organophosphate pesticide and used by the farmers to protect their crops. This pesticide reaches the aquatic ecosystem by direct or indirect means and affects aquatic fauna. LC50 for curacron for C. carpio was calculated by the log-dose/probit regression line method and found to be 0.38?ppm at 96?h. Three sub-lethal concentrations (0.1, 0.01, and 0.001?mL?L^?1) were selected to expose the fish for 1, 7, 14, and 21days. Changes in total serum protein were observed at all pesticide concentrations and exposure periods. Total serum protein was decreased from control. At 1 and 7 days, the decrease was quantitative at all concentrations, while at 14 and 21 days, the fall was significant at all concentrations. Hence, human population may be at risk by consuming these contaminated fish.     

The effects of pesticides on greenhouse workers and their produced products

Pesticides are chemicals used in agriculture but are known to produce adverse effects on humans. In this study, blood activities of superoxide dismutase (SOD), catalase (CAT), aspartate transaminase (AST), alanine transaminase (ALT), gamma-glutamyl transaminase, lactate dehydrogenase (LDH), and levels of malondialdhyde (MDA) were determined in 44 greenhouse workers (24 tomato workers, 20 clove workers) and in tomato (24 samples) and clove (20 samples) products. At the end of this study, blood MDA levels and activities of ALT, AST, and LDH levels in greenhouse workers were significantly increased while SOD and CAT activity levels fell significantly. Pesticide residues were not found in agricultural worker blood. Malathion residues (average 0.8?ppm) were detected in tomatoes (8 samples) in these greenhouses. Data suggest that the health of the greenhouse workers may be adversely affected by pesticides.     

Bacillus thuringiensis pesticide exposures reported to Texas poison centers

One of the most common types of microbial pesticides used is Bacillus thuringiensis. Although generally considered safe, exposures to B. thuringiensis pesticide do occur where management by healthcare providers is sought. The objective of this investigation was to describe B. thuringiensis pesticide exposures reported to Texas poison centers. Cases were all B. thuringiensis pesticide exposures reported to Texas poison centers during 2000–2010. The distribution of cases was determined for various demographic and clinical factors. Of 115 total cases, 64% occurred during May–July. The rate per 1,000,000 population was 14.3 in central Texas and 4.4 in the rest of the state. Of the patients, 56% were of an age 20 years or older and 55% were male. The exposure routes were 57% by ingestion, 30% by dermal contact, and 11% by inhalation. The patient was managed on site in 93% of the exposures and only one exposure was judged to be potentially serious. B. thuringiensis pesticide exposures reported to Texas poison centers were more frequently reported from the central region of the state. The majority of exposures occurred during April–July, involved adults and males, occurred by ingestion or dermal route, were managed on site and did not result in serious outcomes.     

Pesticide in the Mississippi River floodplain and its possible linkage to colon cancer risk in the US

Result of this study shows that elevated colorectal cancer risk in Mississippi River floodplain of the United States is likely linked to historically high pesticide application. Mississippi River basin produces about 80% of major US crops and has about two-thirds of US pesticides used for agriculture. Historically, heavy pesticide application and agricultural irrigation were reported to result in high pesticide residues in surface water, fish and wells of Mississippi embayment. Risk ratio of colorectal cancer incidence in 86 counties of Mississippi River floodplain was about 29% higher than that of other counties in the 48 contiguous states. Risk ratio of colon cancer mortality in 63 counties of Mississippi embayment was 33% higher than that of other counties in the 48 states between 1999 and 2016. Risk ratios of colorectal cancer incidence and colon cancer mortality in Mississippi River floodplain are higher after smoking and diabetes factors were filtered off. Previous studies have linked exposure to pesticide with type-II diabetes and the latter was linked to increasing colon cancer risk by about 27%. Result here suggests that pesticide may be an independent risk factor directly associated with elevated colon cancer risk in Mississippi River floodplain.     

Effects of repeated pesticide exposure on the peripheral and central nervous systems

This study was designed to compare organic farmers (comparison group) and pesticide-using farmers (pesticide group) in terms of neurobehavioral performance and sensorimotor function. The subjects were recruited in October 2004 from Chungnam Province and the neighboring Jeolla Province in western South Korea. Psychological assessment was carried out using the Wechsler Adult Intelligence Scale, the Mini-Mental State Examination, and the Bender Gestalt test. Neuroselective sensory nerve conduction threshold was measured at both left and right middle fingers by using an electrodiagnostic device to determine current perception thresholds (CPTs). Three independent CPT measurements were obtained from each test site by using sinusoidal stimuli at three frequencies. CPT testing showed no difference between the two groups. No significant differences were found in the large myelinated (2000?Hz stimulation; cutaneous touch, pressure), small myelinated (250?Hz stimulation; mechanoreceptive, pressure, temperature, fast pain) and small unmyelinated (5?Hz stimulation; polymodal nociceptive, temperature, slow pain, postganglionic sympathetic) C-fibers. Furthermore, there was no difference found between the pesticide and comparison groups in psychological variables, including intelligence quotient, orientation, memory, calculation, similarities, visual sensitivity, and psychomotor speed. In conclusion, chronic pesticide exposure has no apparent effect on either the peripheral or central nervous system in Korean farmers.     

Levels of plasma B-esterases and glutathione-S-transferase activities in three South American toad species

We determined the normal levels of butyrylcholinesterase (BChE), carboxylesterase (CbE), and glutathione S-transferases (GST) activities in three South American toad species in order to establish reference values for field pesticide monitoring purposes. Interspecies variations in B-esterase and GST activities were examined according to body mass. In addition, comparative inhibition of BChE and CbE activities using malaoxon, and chemical reactivation of malaoxon-inhibited BChE activity using pyridine-2-aldoxime methochloride (2-PAM) were investigated. Bufo fernandezae had average activity values for BChE: 17.31 mmol min^?1 ml^?1; CbE: 621.49 nmol min^?1 ml^?1 and GST: 1.94 mmol min^?1 ml^?1 while B. arenarum enzymatic average activities were BChE: 9.51 mmol min^?1 ml^?1; CbE: 270.07 nmol min^?1 ml^?1, and GST: 1.59 mmol min^?1 ml^?1; finally Bufo schneideri had enzymatic mean values of BChE: 2.08 mmol min^?1 ml^?1; CbE: 301.95 nmol min^?1 ml^?1, and GST: 1.60 mmol min^?1 ml^?1. Moreover, we found an allometric relationship between plasma BChE and CbE activities and body size for the three toad species. We suggest that B. fernandezae would be the species with a higher tolerance capacity to organophosphorous insecticides compared to the other toad species, while B. schneideri may be the most vulnerable toad species to field pesticide exposure, although some other factors (e.g., brain AChE sensitivity or pesticide metabolism by phosphotriesterases) should be also taken into account. The malaoxon-inhibited BChE activity of the three toad species was reactivated in the presence of 2-PAM, and it is recommended as a specific and sensitive methodology in the assessment of field exposure to OP insecticides together to compare BChE activity levels between OP-exposed and nonexposed individuals.     

太湖水体中5种有机磷农药混合物生态风险评价

有机磷农药是一类广泛分布于我国水环境中的污染物,即使在水体中的污染水平处于规定“安全标准”之下,其联合暴露产生的风险仍有可能威胁水生生态安全。采用基于浓度加和模型与生物敏感度分布曲线的混合物风险商法,评价了太湖水体中敌敌畏、对硫磷、甲基对硫磷、马拉硫磷和乐果5种有机磷农药混合物产生的生态风险。结果表明：2003～2004年期间3个不同时期太湖水体中5种有机磷农药的混合物生态风险商(RQ_m )均大于1,有机磷农药混合物在2003～2004年期间对太湖水生生物构成了一定威胁。     

Effect of Widespread Agricultural Chemical Use on Butterfly Diversity across Turkish Provinces

Although agricultural intensification is thought to pose a significant threat to species, little is known about its role in driving biodiversity loss at regional scales. I assessed the effects of a major component of agricultural intensification, agricultural chemical use, and land‐cover and climatic variables on butterfly diversity across 81 provinces in Turkey, where agriculture is practiced extensively but with varying degrees of intensity. I determined butterfly species presence in each province from data on known butterfly distributions and calculated agricultural chemical use as the proportion of agricultural households that use chemical fertilizers and pesticides. I used constrained correspondence analyses and regression‐based multimodel inference to determine the effect of environmental variables on species composition and richness, respectively. The variation in butterfly species composition across the provinces was largely explained (78%) by the combination of agricultural chemical use, particularly pesticides, and climatic and land‐cover variables. Although overall butterfly richness was primarily explained by climatic and land‐cover variables, such as the area of natural vegetation cover, threatened butterfly richness and the relative number of threatened butterfly species decreased substantially as the proportion of agricultural households using pesticides increased. These findings suggest that widespread use of agricultural chemicals, or other components of agricultural intensification that may be collinear with pesticide use, pose an imminent threat to the biodiversity of Turkey. Accordingly, policies that mitigate agricultural intensification and promote low‐input farming practices are crucial for protecting threatened species from extinction in rapidly industrializing nations such as Turkey. Efectos del Uso Extensivo de Agroquímicos sobre la Diversidad de Mariposas en Provincias Turcas