Blood cholinesterase levels among agricultural workers in four Asian countries

In this study whole blood cholinesterase activities were determined (tintometric method) of agricultural pesticide users exposed to organophosphorus compounds in Indonesia, Malaysia, Sri Lanka and Thailand. Analysis of the data demonstrated a universal relationship between cholinesterase levels and the time between the last exposure to organophosphorus compounds and the day of blood collection for cholinesterase determination. It is suggested that it takes approximately 5 days before whole blood cholinesterase levels revert to their normal values. No relationship between whole blood cholinesterase levels and the sex of pesticide users was demonstrated except in Sri Lanka where female sprayers had lower values. It is suggested that these lower values are associated with the anaemic status of female agricultural workers. No relationship between whole blood cholinesterase level and age was demonstrated. The measurement of pre-exposure cholinesterase values is essential for comparison of values after pesticide application.     

Using psychometric ability to improve education in ultrasound-guided regional anaesthesia: a multicentre randomised controlled trial

The learning curve for novices developing regional anaesthesia skills, such as real-time ultrasound-guided needle manipulation, may be affected by innate visuospatial ability, as this influences spatial cognition and motor co-ordination. We conducted a multinational randomised controlled trial to test if novices with low visuospatial ability would perform better at an ultrasound-guided needling task with deliberate practice training than with discovery learning. Visuospatial ability was evaluated using the mental rotations test-A. We recruited 140 medical students and randomly allocated them into low-ability control (discovery learning), low-ability intervention (received deliberate practice), high-ability control, and high-ability intervention groups. Primary outcome was the time taken to complete the needling task, and there was no significant difference between groups: median (IQR [range]) low-ability control 125 s (69–237 [43–600 s]); low-ability intervention 163 s (116–276 [44–600 s]); high-ability control 130 s (80–210 [41–384 s]); and high-ability intervention 177 s (113–285 [43–547 s]), p = 0.06. No difference was found using the global rating scale: mean (95%CI) low-ability control 53% (95%CI 46–60%); low-ability intervention 61% (95%CI 53–68%); high-ability control 63% (95%CI 56–70%); and high-ability intervention 66% (95%CI 60–72%), p = 0.05. For overall procedure pass/fail, the low-ability control group pass rate of 42% (14/33) was significantly less than the other three groups: low-ability intervention 69% (25/36); high-ability control 68% (25/37); and high-ability intervention 85% (29/34) p = 0.003. Further research is required to determine the role of visuospatial ability screening in training for ultrasound-guided needle skills.     

A study of the cardiac effects of DDT in laboratory animals

The claim that the hearts of animals chronically exposed to DDT are unduly sensitive to the cardiotoxic effects of vasopressin was reexamined. Rats and rabbits were fed a diet containing DDT for 8 months and were given weekly doses of vasopressin, which causes a temporary myocardial ischaemia. Electrocardiograms, recorded at 2-week intervals, showed no significant increase in the incidence of cardiac arrhythmias in the DDT-fed animals. Intravenous noradrenaline given at the end of the 8-month period did not produce a greater incidence of arrhythmias in the DDT-fed animals than in the controls. Isolated heart muscle preparations from the DDT-fed and control rats did not differ in their peak developed tensions and maximum rates of tension development. DDT, TDE, and DDE levels in heart muscle and fat were below detectable levels in the control rats, whereas in the DDT-fed rats they were at least 100 times those normally found in human tissues.     

Neuropsychological studies on lead workers in Singapore.

The neuropsychological performance of a group of 49 workers occupationally exposed to lead was compared with a matched control group of 36 non-exposed workers. The psychometric measurements were composed of tests covering a broad range of different neuropsychological functions, particular emphasis being given to perceptual motor ability and attention concentration functioning. A questionnaire to assess subjective symptoms in mood, sleep disturbance, poor concentration and forgetfulness, somatic complaints, and social passivity was also included in the battery of tests. Compared with the controls, the performance of the lead workers was found to be significantly poorer for digit symbol, Bourdon-Wiersma, trail making test (part A), Santa Ana test, flicker fusion, and simple reaction time. In terms of subjective symptoms the exposed group also reported significantly more complaints of anxiety and depressed mood, poor concentration and forgetfulness, and other somatic complaints. These differences were observed among lead workers with a mean blood lead value of 2.35 mumol/l (SD 0.7).     

A computerized data acquisition system for infusion devices--a clinical support tool, or a risk management tool?

A prototype computerized system for automatic data collection from multi-vendor infusion devices was constructed. The system was specifically designed around the needs of the critical care environment, and a survey of clinical staff was conducted to determine the functional requirements. Hardware, software and system configuration was based on the Medical Information Bus IEEE 1073 standard for medical device data communications. The infusion devices were configured into device communication controllers (DCC), which were polled at 0.25 Hz by a PC configured as a bedside communication controller (BCC). The system stores data samples after intervals of 1 ml of drug delivery and following any changes in the infusion rate. The system demonstrated significant opportunities for supporting clinical care and for the management of health care technology.     

Airway responsiveness of firefighters after smoke exposure.

Ventilatory function and airway reactivity of 20 firefighters were studied one hour before and one hour after exposure in a smoke chamber. None showed an increase in airway reactivity to inhaled histamine before exposure. Eight (80%) of the regular firefighters, however, had an increase in airway reactivity after exposure in the smoke chamber. After six hours, three of the firefighters still had increased airway reactivity. All were non-reactive after 24 hours but the ventilatory function of the three firefighters who were reactive after six hours did not return to baseline values. The duration of service as a firefighter is the major contributing factor to the change in airway reactivity. This increase in airway responsiveness among regular firefighters suggests that some form of chronic epithelial injury is needed before an increase in airway responsiveness is seen.     

Epithelioma cuniculatum: A case report

Epithelioma cuniculatum (carcinoma cuniculatum) is a rare, low-grade verrucous carcinoma of the foot first described in 1954. We present a case report of a 55-year-old man with an enlarging lesion on the sole of his right foot. Despite initial benign pathology the lesion continued to grow, soften in consistency and develop a foul odour. Repeat biopsy showed a well-differentiated squamous cell carcinoma and below-the-knee amputation was required. Epithelioma cuniculatum presents as a slow growing mass on the plantar aspect of the foot. Diagnosis is often delayed and may require multiple biopsies. Lesions rarely metastasise but more commonly invade locally requiring wide surgical excision.     

Survey of acute pesticide poisoning among agricultural workers in four Asian countries

The study investigated the extent of acute pesticide poisoning in selected agricultural communities in Indonesia, Malaysia, Sri Lanka and Thailand, as well as the contributing factors, because it is believed that this type of poisoning is a major problem in developing countries, but not in the industrialized countries, despite their extensive use of pesticides. The study confirmed the existence of this problem, which was found to be due to inadequate knowledge of the safe practices in the use of pesticides among users and to the lack of suitable protective clothing for use by agricultural workers in hot and humid climates.     

Biomarkers, screening and ethics

Rapid scientific advances, such as those in biomarker technology,have made a significant impact on the ethics and practice ofoccupational health. Biomarkers are extensively used in occupationalhealth practice. In the pre-employment stage, preventive orpredictive testing can be performed. Preventive testing aimsto avert accidents that may occur if a medically unfit workerundertakes a job that he is unable to perform. For safety sensitivejobs, routine testing of a worker's functional capacity in theactual job would suffice in most cases. However, a recentlyquotes application of a test is the screening for mutationsof the cardiac myosin-heavy chain and troponin genes among asymptomaticpersons with a family history of sudden death from hypertrophicobstructive cardiomyopathy. Predictive testing hopes to forecastthe risk of a worker developing an illness. The aims may vary.One aim may be to exclude a susceptible worker from workingin a hazardous environment. Another aim may be to avoid employmentof a worker who is likely to develop an illness which couldlead to higher employer health care costs. A pertinent questionto consider is whether the test undertaken is to benefit theindividual or to fulfil some administrative or financial need.Among exposed workers, screening may be conducted for biomarkersof exposure or effect. As the aim is to prevent the onset ofclinical illness, the physician must take responsibility forinitiating requests for screening. The appropriate responseto the effect of technical and societal advances on ethics isthe updating of ethical guidelines by the profession. However,in the context of unvalidated biomarkers being used for screening,it may be necessary to require a regulatory body to ensure thatthe tests are accurate and effective, and that they are notused to discriminate against individuals.