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Biomedical subjects

K E Powell

Publications and source records attributed to K E Powell.

At least 73 records · Page 4Linked to original sources
PubMed1983

Paraquat and marijuana: epidemiologic risk assessment.

In March 1978, 13 (21 per cent) of 61 marijuana samples from the southwestern United States were found to be contaminated with the herbicide paraquat, a pulmonary toxin, in concentrations from 3 to 2,264 parts per million. The source of the contamination was an aerial spraying program in Mexico, supported indirectly by United States funds. To evaluate US exposure, a nationwide survey of the paraquat content of confiscated marijuana was conducted. The survey found 33 (3.6 per cent) of 910 marijuana specimens to contain detectable paraquat. In states adjacent to Mexico (Census Region VI), 23 (12.8 per cent) of 180 specimens were contaminated. Combustion testing indicated that approximately 0.2 per cent of paraquat on marijuana passes into smoke. From these data, we projected that 100-200 marijuana smokers in Census Region VI would be exposed by inhalation to 500 micrograms or more of paraquat per year, a dose judged to represent a health hazard; nationally, between 150 and 300 smokers were projected to have such exposure. Another 6,000 persons in Region VI and 9,000 nationally were projected to be at risk of exposure to between 100 and 499 micrograms of paraquat annually. The risk of paraquat exposure was greatest among those smokers who make one large purchase of marijuana per year. No clinical cases of paraquat poisoning were recognized among marijuana smokers during these studies, but no systematic national search for such cases was undertaken.

Cannabis↗
PubMed1982

An epidemiologic study of the benefits and risks of running.

To better estimate rates of certain benefits and risks of recreational running, we sent questionnaires to 1,250 randomly selected male and 1,250 female registrants for a 10-km road race. The response rate was 55% for men and 58% for women. Telephone interviews of a randomly selected group of nonrespondents indicated that the only significant differences between respondents and nonrespondents were that (1) respondents were older than nonrespondents, (2) more male nonrespondents had stopped running during the year after the race, and (3) more male nonrespondents had been hit by thrown objects. One year after the race, 89% of male and 79% of female respondents were still running regularly. Eighty-one percent of men and 75% of women who smoked cigarettes when they began running had stopped smoking after beginning recreational running. Giving up smoking was significantly more common for current runners than for "retired" runners. Weight loss was commonly associated with running and was greater in those persons who were overweight when they began running. More than a third of respondents had a musculoskeletal injury attributed to running in the year after the race and about one seventh of all respondents sought medical consultation for their injury. The risk of injury increased with increasing weekly mileage. This study uses epidemiologic methods to quantify some of the benefits and risks of running.

Accidents↗
PubMed1982

Concurrent evaluation of epidemic St. Louis encephalitis: are you on the upward or downward side of the curve?

Laboratory confirmation of reported cases of St. Louis encephalitis (SLE) lags 2-4 weeks behind onset of illness. A review of our experience in Mississippi in 1975 and 1976 suggests that plotting the number of reported suspects greater than or equal to 50 years of age by date of onset and adjusting for reporting delays can help determine when the peak of the epidemic has passed. This method circumvents the obligatory delay of serologic tests, minimizes the bias of publicity and intensive surveillance, and may avoid promoting control procedure which are expensive, dangerous, and of uncertain efficacy.

Adolescent↗
PubMed1982

Preventing severe heat injury in runners: suggestions from the 1979 Peachtree Road Race experience.

Of an estimated 17632 participants of the 1979 Peachtree Road Race, a 10-km race held at 0800 on 4 July in Atlanta, Georgia, 29 had severe heat injury (collapse with altered mental status and rectal temperature of 39.7 degrees C or greater); all 29 recovered promptly. The temperature was 24.0 degrees C; the relative humidity, 83%; and the wet bulb-globe index, 23.0 degrees C. Compared with unaffected participants matched by age, sex, and predicted finishing time, case-runners were taller, had slower best recent 1.6-km and 10-km times, had run less in June, were more likely to achieve 89% of estimated maximum aerobic capacity during the race, less often splashed with water, were more likely to have underestimated their predicted finishing times based on their best recent 10-km times, and were more likely to live in Georgia. Height, sprinkler use, and underestimating predicted finishing times were each significant in the presence of the others. These observations suggest that participants of similar races, particularly those taller than 179.2 cm, should splash with water at least twice and base their predicted finishing times on their best recent 10-km times; adherence to these recommendations by runners at risk should reduce their severe heat injury risk at least 8.1 times.

Athletic Injuries↗
PubMed1981

Acute rheumatic fever in Mississippi: a survey of hospitalized cases, 1964 to 1973.

The incidence of acute rheumatic fever in Mississippi was estimated by reviewing the hospital charts of Mississippi residents with a discharge diagnosis of acute rheumatic fever from 1964 through 1973. The average annual incidence was 1.5 cases/100,000 population for primary attacks and 0.4 cases/100,000 population for recurrent attacks. The annual incidence was highest for the group aged 19 to 14 years, with 4.8 cases/100,000 population for primary attacks and 1.4 cases/100,000 population for recurrences. These rates are significantly lower than rates reported from similar surveys in Nashville, Baltimore, New York City, and the Navajo reservation. Age-adjusted rates of primary and recurrent attacks were higher for blacks than for whites, but the proportion of attacks that were recurrences did not differ by race. The proportion of attacks that were severe (cardiomegaly, pericarditis, or congestive heart failure) was significantly greater for blacks than for whites. No significant change in incidence was detected in the ten-year period. Among persons with primary attacks, only 18% are known to have had an antecedent pharyngitis and consulted a physician. Only 21% of persons with secondary attacks are known to have been receiving chemoprophylaxis.

Acute Disease↗
PubMed1981

Foreign-born persons with tuberculosis in the United States.

Two recent surveys of selected states and cities suggest that foreign-born persons account for approximately 15 per cent of the new cases of tuberculosis reported annually in the areas surveyed. In both surveys the largest number of foreign-born persons came from the Western Hemisphere, the next largest from Asia. The largest number of foreign-born persons with tuberculosis are in the 15-29 year age group, presumably because most entering aliens are in this age group. Among persons with tuberculosis, a larger per cent of foreign-born patients have extrapulmonary disease than do native-born patients. About 50 per cent of the foreign-born persons with tuberculosis entered the United States within the five years prior to onset of disease. Within the United States, significant inter-area variation exists in the proportion of persons with tuberculosis who are foreign-born and in countries of origin of these persons.

Adolescent↗
PubMed1979

Sperm count depression in pesticide applicators exposed to dibromochloropropane.

Male pesticide applicators who worked with the nematocide dibromochloropropane (DBCP) were examined to determine the possible testicular toxicity from this exposure. Infertility and azoospermia which were first noted among factory workers exposed to DBCP were not observed among the applicators. Sperm count depression, however, was associated with the duration of exposure in the current year but not with exposure in past years. The extent of exposure to DBCP in the current year was also associated with an elevation of serum follicle stimulating hormone (FSH) but not of luteinizing hormone (LH). Sperm count depression was limited to applicators involved in irrigation setup work and in the calibration of equipment. These results suggest that the testicular toxicity of DBCP for men may occur in a shorter period than was previously reported, that the effect may be reversible in men with mild sperm count depression, and that public health measures might be directed at controlling specific application techniques.

Antinematodal Agents↗
PubMed1978

Cutaneous sporotrichosis in forestry workers. Epidemic due to contaminated Sphagnum moss.

In December 1975 and January and February 1976, an epidemic of cutaneous sporotrichosis occurred in Mississippi among forestry workers and other persons exposed to sphagnum moss used in packing pine seedlings. Seventeen cases were identified, 15 of which were from patients who had been exposed to sphagnum moss from a single source. Attack rates were significantly higher among workers exposed to this moss than among those not exposed. Sporothrix schenckii was cultured from the implicated batch of sphagnum moss but not from other batches. The source of contamination of the sphagnum moss that caused this epidemic and sphagnum moss associated with similar epidemics is unknown. One worker without cutaneous sporotrichosis may have had asymptomatic pulmonary sporotrichosis.

Agricultural Workers' Diseases↗
PubMed1978

Epidemiology of St. Louis encephalitis and other acute encephalitides.

Cases of acute encephalitis reported to the CDC are divided into five groups: arboviral (8% of the 1965 to 1974 total), enteroviral (2%), post-infection (25%), encephalitis due to other known agents (3%), and encephalitis of indeterminate etiology (62%). With increased use of live virus vaccines against measles, mumps, and rubella, postinfection encephalitis has decreased, and SLE had become one of the most common preventable encephalitides in the United States. In 1975 SLE virus caused at least 1,791 cases of encephalitis, 42% of the reported total. In addition, the age distribution of persons with encephalitis of indeterminate etiology suggests that SLE virus may be an important contributor to that caegory during the summer months. The warm-weather transmission cycle of the SLE virus is well established. The reservoir is birds. The principal vector is the peridomestic C. pipiens mosquito in the Midwest and South and the rural C. tarsalis in the West. Man is an incidental and dead-end host. The winter reservoir is unknown. Human illness occurs in the summer. Asymptomatic human infections are about 200 times more common than symptomatic infections. Clinical attack rates and severity of illness increase with age. Case-fatality ratios of 35 to 38% have been reported for persons 60 years of age and older. For unknown reasons, SLE virus causes periodic major epidemics. The epidemics are more noticeable and better studied in major cities, but they probably affect rural areas as well. SLE is more common in areas of the country with warm climates. Epidemics in the North, when they occur, begin later but are of the same duration as epidemics in the South. Presumably, large epidemics of SLE can be prevented by mosquito control programs. Cumbersome and possibly insensitive diagnostic techniques impair our evaluation and understanding of SLE and other encephalitides. Insufficient information about the factors causing or preceding SLE epidemics impedes successful preventive measures. The use of emergency mosquito control programs after an epidemic has started has not been shown to reduce the number of human cases.

Age Factors↗
PubMed1977

St Louis encephalitis. The 1975 epidemic in Mississippi.

In 1975, 229 laboratory-documented cases of St Louis encephalitis, 36 of which resulted in death, occurred in Mississippi. A total of 58% of these persons had encephalitis, 15% had aseptic meningitis, 21% had a febrile illness with no known CNS involvement, and 6% had other syndromes. Attack rates and case-fatality ratios increased with age. Although 60% of the cases occurred in a four-county area of northwest Mississippi, cases occurred in 42 of the 82 counties throughout the state. The epidemic erupted almost simultaneously, with variable intensity, in widely separated areas. Mosquito-control, measures were applied, but the results were not quantified.

Adolescent↗
PubMed1976

St. Louis encephalitis: clinical and epidemiologic aspects, Mississippi, 1974.

During July, August, and September 1974, 23 confirmed or presumptive cases of St. Louis encephalitis occurred in Mississippi. Attack rates were highest in the northwest corner of the state and among persons over 70 years of age. Rural and urban residents had similar attack rates. Nine persons have not resumed their pre-illness level of activity because of residual neurologic impairment six months after their illness. Additional cases of St. Louis encephalitis are expected in the next few years.

Adult↗