主要研究了2,6-二硝基甲苯(2,6-DNT)和4-硝基甲苯(4-NT)两种硝基芳烃对虹鳉鱼的急性毒性、亚急性毒性及联合毒性效应,旨在为渔业水质标准的制定与完善提供可靠的科学依据。研究表明,2,6-DNT的急性毒性大于4-NT,二者的96 h LC50值分别为(25.22±0.19)mg/L和(60.26±0.09)mg/L;亚急性毒性研究中,两种化合物的各种质量浓度在40天内,对试验动物的生长有不同程度的影响;应用Marking相加指数法评价二者的联合毒性,结果表明其联合毒性为协同。 相似文献
The devastating effects of earthquakes have been demonstrated repeatedly in the past decade, through moderate and major earthquakes such as the October 1987 Whittier Narrows earthquake (5.9 on the Richter scale), the October 1989 Loma Prieta earthquake (7.1) and the January 1994 Northridge earthquake (6.7). While 'official' tallies of injuries and deaths are reported for each event, the numbers vary from report to report. For Northridge, the number of injuries vary between 8,000 and 12,000; the number of deaths from 33 to 73 (Peek-Asa et al., 1997; Durkin, 1996).While official estimates are commonly reported following disasters, the study of actual numbers, types and causes of casualties has not developed. In this paper, we identify the numbers and risk factors for injuries within community-based samples across three earthquakes in urban California. We first report the numbers and types of injuries in each earthquake and then identify risk factors specifically associated with the Northridge earthquake 相似文献
Six cases of macrocystic and one case of microcystic congenital adenomatoid lung malformation were diagnosed by ultrasound between 20 and 31 weeks of gestation. Combined polyhydramnios and fetal hydrops was present in three cases, polyhydramnios alone in one case, and isolated fetal hydrops also in one case. In the remaining two cases, both polyhydramnios and fetal hydrops were absent. Fetal outcome was poor, i.e., two terminations of pregnancy, three early neonatal deaths, and two survivors. 相似文献
Goal, Scope and Background Chlorite (ClO2ˉ) is a primary decomposition product when chlorine dioxide (ClO2) is added during water treatment; therefore
the toxic effects of both compounds on aquatic organisms are possible. Limited data are available concerning their toxicity
to fish. The aim of this study was to investigate sensitivity of rainbow trout to acute and chronic toxicity of chlorine dioxide
and chlorite, and to estimate the Maximum-Acceptable-Toxicant-Concentration (MATC) of those compounds in fish.
Methods The acute and chronic toxicity of chlorine dioxide and chlorite to larval and adult rainbow trout was investigated in 96-hour
to 20-day laboratory exposures evaluating the wide range spectrum of biological indices under semi-static conditions.
Results and Discussion Median lethal concentration (96-hour LC50) values derived from the tests were: 2.2 mg/l for larvae; 8.3 mg/l for adult fish
and 20-day LC50 for larvae was 1.6 mg/l of chlorine dioxide, respectively. Chlorite was found to be from 48 to 18 times less
acutely toxic to larvae and adult fish, correspondingly. Both chemical compounds induced similar toxic effects in rainbow
trout larvae during chronic tests (they affected cardio-respiratory and growth parameters), but chlorine dioxide had a higher
toxic potency than chlorite. A significant decrease in the heart rate and respiration frequency of larvae was established.
However, within an increase in exposure duration recovery of cardio-respiratory responses was seen to have occurred in larvae
exposed to chlorite. Meanwhile, in larvae exposed to chlorine dioxide, a significant decrease in cardio-respiratory responses
remained during all 20-day chronic bioassays. Chlorine dioxide also more strongly affected growth parameters of rainbow trout
larvae at much lower test concentrations. Decreased rate of yolk-sack resorption occurred only in the tests with chlorine
dioxide.
Conclusions Maximum-Acceptable-Toxicant-Concentration (MATC) of 0.21 mg/l for chlorine dioxide and of 3.3 mg/l for chlorite to fish was
derived from chronic tests based on the most sensitive parameter of rainbow trout larvae (growth rate). According to substance
toxicity classification accepted for Lithuanian inland waters, chlorine dioxide and chlorite can be referred to substances
of \moderate\ toxicity to fish.
Recommendations and Outlook Due to its very reactive nature, chlorine dioxide is rapidly (in a few hours) reduced to chlorite, which is persistent also
as a biocide but 16 times less toxic to fish, according to MATC. Therefore, it is much more likely that fish will be exposed
to chlorite than to chlorine dioxide in natural waters. Presently accepted, the Maximum-Permitted-Concentration of total residual
chlorine (TRC) in waste-water discharging into receiving waters is 0.6 mg/l. If this requirement will not be exceeded, it
is unlikely that fish would be exposed to lethal or even to sublethal concentrations of chlorine dioxide or chlorite. Furthermore,
chlorine dioxide does not generate toxic nitrogenous (chloramines) or carcinogenic organic residuals (trihalomethanes). All
these properties make chlorine dioxide a more promising biocide than chlorine. 相似文献
Objective: A large portion of child restraint systems (car seats) are installed incorrectly, especially when first-time parents install infant car seats. Expert instruction greatly improves the accuracy of car seat installation but is labor intensive and difficult to obtain for many parents. This study was designed to evaluate the efficacy of 3 ways of communicating instructions for proper car seat installation: phone conversation; HelpLightning, a mobile application (app) that offers virtual interactive presence permitting both verbal and interactive (telestration) visual communication; and the manufacturer's user manual.
Methods: A sample of 39 young adults of child-bearing age who had no previous experience installing car seats were recruited and randomly assigned to install an infant car seat using guidance from one of those 3 communication sources.
Results: Both the phone and interactive app were more effective means to facilitate accurate car seat installation compared to the user manual. There was a trend for the app to offer superior communication compared to the phone, but that difference was not significant in most assessments. The phone and app groups also installed the car seat more efficiently and perceived the communication to be more effective and their installation to be more accurate than those in the user manual group.
Conclusions: Interactive communication may help parents install car seats more accurately than using the manufacturer's manual alone. This was an initial study with a modestly sized sample; if results are replicated in future research, there may be reason to consider centralized “call centers” that provide verbal and/or interactive visual instruction from remote locations to parents installing car seats, paralleling the model of centralized Poison Control centers in the United States. 相似文献
Objective: The objective of this study was to describe demographic and injury characteristics of hospitalized injured patients involved in e-bike and motorized scooter accidents at a national level in Israel divided by different road user groups: riders and pedestrians.
Methods: This was a retrospective study based on data from the National Trauma Registry, between January 1, 2013, and December 31, 2015. All hospitalized casualties due to the involvement of an e-bike or motorized scooter were included. The type of hospitalized road user was further categorized and described by different variables.
Results: During the study period, the Israel Trauma Registry identified 795 hospitalized patients due to an e-bike or motorized scooter accident, with a dramatic 6-fold increase from 2013 to 2015. Although the majority of the injured patients were riders, 8% were pedestrians. Among the total casualties, 33% were children aged 0–14 years and among pedestrians 42% were children and 33% were seniors (ages 60+). Five persons died in hospital, 3 riders and 2 pedestrians.
Conclusions: E-bike and motorized scooter riders represent the majority of patients hospitalized due to related traffic incident. This finding questions the social and economic advantages of electric-powered 2-wheeled vehicles. 相似文献
Objective: The objective of this study is to use a validated finite element model of the human body and a certified model of an anthropomorphic test dummy (ATD) to evaluate the effect of simulated precrash braking on driver kinematics, restraint loads, body loads, and computed injury criteria in 4 commonly injured body regions.
Methods: The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant (M50-O) and the Humanetics Hybrid III 50th percentile models were gravity settled in the driver position of a generic interior equipped with an advanced 3-point belt and driver airbag. Fifteen simulations per model (30 total) were conducted, including 4 scenarios at 3 severity levels: median, severe, and the U.S. New Car Assessment Program (U.S.-NCAP) and 3 extra per model with high-intensity braking. The 4 scenarios were no precollision system (no PCS), forward collision warning (FCW), FCW with prebraking assist (FCW+PBA), and FCW and PBA with autonomous precrash braking (FCW + PBA + PB). The baseline ΔV was 17, 34, and 56.4 kph for median, severe, and U.S.-NCAP scenarios, respectively, and were based on crash reconstructions from NASS/CDS. Pulses were then developed based on the assumed precrash systems equipped. Restraint properties and the generic pulse used were based on literature.
Results: In median crash severity cases, little to no risk (<10% risk for Abbreviated injury Scale [AIS] 3+) was found for all injury measures for both models. In the severe set of cases, little to no risk for AIS 3+ injury was also found for all injury measures. In NCAP cases, highest risk was typically found with No PCS and lowest with FCW + PBA + PB. In the higher intensity braking cases (1.0–1.4 g), head injury criterion (HIC), brain injury criterion (BrIC), and chest deflection injury measures increased with increased braking intensity. All other measures for these cases tended to decrease. The ATD also predicted and trended similar to the human body models predictions for both the median, severe, and NCAP cases. Forward excursion for both models decreased across median, severe, and NCAP cases and diverged from each other in cases above 1.0 g of braking intensity.
Conclusions: The addition of precrash systems simulated through reduced precrash speeds caused reductions in some injury criteria, whereas others (chest deflection, HIC, and BrIC) increased due to a modified occupant position. The human model and ATD models trended similarly in nearly all cases with greater risk indicated in the human model. These results suggest the need for integrated safety systems that have restraints that optimize the occupant's position during precrash braking and prior to impact. 相似文献