Estimated prevalence of noise-induced hearing threshold shifts among children 6 to 19 years of age: the Third National Health and Nutrition Examination Survey, 1988-1994, United States.

OBJECTIVE: This analysis estimates the first nationally representative prevalence of noise-induced hearing threshold shifts (NITS) among US children. Historically, NITS has not been considered a common cause of childhood hearing problems. Among children, NITS can be a progressive problem with continued exposure to excessive noise, which can lead to high-frequency sound discrimination difficulties (eg, speech consonants and whistles). METHODS: The Third National Health and Nutrition Examination Survey (NHANES III) was conducted from 1988 to 1994. NHANES III is a national population-based cross-sectional survey with a household interview, audiometric testing at 0.5 to 8 kHz, and compliance testing. A total of 5249 children aged 6 to 19 years completed audiometry and compliance testing for both ears in NHANES III. The criteria used to assess NITS included audiometry indicating a noise notch in at least 1 ear. RESULTS: Of US children 6 to 19 years old, 12.5% (approximately 5.2 million) are estimated to have NITS in 1 or both ears. In the majority of the children meeting NITS criteria, only 1 ear and only 1 frequency are affected. In this analysis, all children identified with NITS passed compliance testing, which essentially rules out middle ear disorders such as conductive hearing loss. The prevalence estimate of NITS differed by sociodemographics, including age and sex. CONCLUSIONS: These findings suggest that children are being exposed to excessive amounts of hazardous levels of noise, and children's hearing is vulnerable to these exposures. These data support the need for research on appropriate hearing conservation methods and for NITS screening programs among school-aged children. Public health interventions such as education, training, audiometric testing, exposure assessment, hearing protection, and noise control when feasible are all components of occupational hearing conservation that could be adapted to children's needs with children-specific research.

Exposure of the U.S. population to lead, 1991-1994.

Blood lead measurements were obtained on 13,642 persons aged 1 year and older who participated in Phase 2 of the Third National Health and Nutrition Examination Survey (NHANES III) from 1991 through 1994. NHANES III is a national representative survey of the civilian, noninstitutionalized U.S. population. The overall mean blood lead level for the U.S. population aged 1 year and older was 2.3 microgram/dl, with 2.2% of the population having levels >=10 microgram/dl, the level of health concern for children. Among U.S. children aged 1-5 years, the mean blood lead level was 2.7 microgram/dl, and 890,000 of these children (4.4%) had elevated blood lead levels. Sociodemographic factors associated with higher blood lead levels in children were non-Hispanic black race/ethnicity, low income, and residence in older housing. The prevalence of elevated blood lead levels was 21.9% among non-Hispanic black children living in homes built before 1946 and 16.4% among children in low-income families who lived in homes built before 1946. Blood lead levels continue to decline in the U.S. population, but 890,000 children still have elevated levels. Public health efforts have been successful in removing lead from population-wide sources such as gasoline and lead-soldered food and drink cans, but new efforts must address the difficult problem of leaded paint, especially in older houses, as well as lead in dust and soil. Lead poisoning prevention programs should target high-risk persons, such as children who live in old homes, children of minority groups, and children living in families with low income.

Prevalence of hearing loss among children 6 to 19 years of age: the Third National Health and Nutrition Examination Survey.

CONTEXT: Hearing loss in children influences the development of communication and behavioral skills, but few studies in the United States have used pure-tone audiometry to derive hearing loss prevalence estimates for children. OBJECTIVE: To describe the prevalence of hearing loss among US children by sociodemographic characteristics, reported hearing loss, and audiometric screening factors. DESIGN: National population-based cross-sectional survey with an in-person interview and audiometric testing at 0.5 to 8 kHz. SETTING/PARTICIPANTS: A total of 6166 children aged 6 to 19 years completed audiometry in the mobile examination center of the Third National Health and Nutrition Examination Survey conducted between 1988 and 1994. MAIN OUTCOME MEASURE: Hearing loss, defined as audiometric threshold values of at least 16-dB hearing level based on a low or high pure-tone average. RESULTS: A total of 14.9% of children had low-frequency or high-frequency hearing loss of at least 16-dB hearing level, 7.1% had low-frequency hearing loss of at least 16-dB hearing level, and 12.7% had high-frequency hearing loss of at least 16-dB hearing level. Most hearing loss was unilateral and slight in severity (16- to 25-dB hearing level). Of those with measured hearing loss, 10.8% were reported to have current hearing loss during the interview. CONCLUSIONS: This analysis indicates that 14.9% of US children have low-frequency or high-frequency hearing loss of at least 16-dB hearing level in 1 or both ears. Among children in elementary, middle, and high school, audiometric screening should include low-frequency and high-frequency testing to detect hearing loss.

Exposure of the US population to environmental tobacco smoke: the Third National Health and Nutrition Examination Survey, 1988 to 1991.

OBJECTIVE: To estimate the extent of exposure of the US population to environmental tobacco smoke and the contribution of the home and workplace environment to environmental tobacco smoke exposure. DESIGN: Nationally representative cross-sectional survey including questionnaire information from persons aged 2 months and older (n=16818) and measurements of serum cotinine (a metabolite of nicotine) from persons aged 4 years and older (n=10642). SETTING/PARTICIPANTS: Participants in the Third National Health and Nutrition Examination Survey, October 25, 1988, to October 21, 1991. RESULTS: Of US children aged 2 months to 11 years, 43% lived in a home with at least 1 smoker, and 37% of adult non-tobacco users lived in a home with at least 1 smoker or reported environmental tobacco smoke exposure at work. Serum cotinine levels indicated more widespread exposure to nictoine. Of non-tobacco users, 87.9% had detectable levels of serum cotinine. Both the number of smokers in the household and the hours exposed at work were significantly and independently associated (P<.001, multiple regression t test) with increased serum cotinine levels. Serum cotinine levels of children, non-Hispanic blacks, and males indicated that these groups had higher exposure to environmental tobacco smoke. Dietary variables showed no consistent association with serum cotinine levels, and dietary contribution to serum cotinine level, if any, appeared to be extremely small. CONCLUSIONS: The high proportion of the population with detectable serum cotinine levels indicates widespread exposure to environmental tobacco smoke in the US population. Both the home and workplace environments significantly contribute to environmental tobacco smoke exposure in the United States.

Blood lead levels in the US population. Phase 1 of the Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1991)

OBJECTIVE: To determine mean blood lead levels and their sociodemographic correlates in the US population. DESIGN: Nationally representative cross-sectional health examination survey that included measurements of venous blood lead. PARTICIPANTS: A total of 13,201 persons aged 1 year and older examined during phase 1 of the third National Health and Nutrition Examination Survey (1988 to 1991). RESULTS: The overall mean blood lead level for the US population was 0.14 mumol/L (2.8 micrograms/dL). Blood lead levels were consistently higher for younger children than for older children, for older adults than for younger adults, for males than for females, for blacks than for whites, and for central-city residents than for non-central-city residents. Other correlates of higher blood lead levels included low income, low educational attainment, and residence in the Northeast region of the United States. National estimates for children 1 to 5 years of age indicate that 8.9%, or approximately 1.7 million children, have blood lead levels 0.48 mumol/L (10 micrograms/dL) or greater. These levels are high enough to be of health concern under 1991 Centers for Disease Control and Prevention guidelines. CONCLUSIONS: The low overall mean blood lead levels demonstrate a major public health success in primary prevention efforts. However, exposure to lead at levels that may adversely affect the health of children remains a problem especially for those who are minority, urban, and from low-income families. Strategies to identify the most vulnerable risk groups are necessary to further reduce lead exposure in the United States.

The decline in blood lead levels in the United States. The National Health and Nutrition Examination Surveys (NHANES)

OBJECTIVE: To describe trends in blood lead levels for the US population and selected population subgroups during the time period between 1976 and 1991. DESIGN: Two nationally representative cross-sectional surveys and one cross-sectional survey representing Mexican Americans in the southwestern United States. SETTING/PARTICIPANTS: Participants in two national surveys that included blood lead measurements: the second National Health and Nutrition Examination Survey, 1976 to 1980 (n = 9832), and phase 1 of the third National Health and Nutrition Examination Survey, 1988 to 1991 (n = 12,119). Also, Mexican Americans participating in the Hispanic Health and Nutrition Examination Survey, 1982 to 1984 (n = 5682). RESULTS: The mean blood lead level of persons aged 1 to 74 years dropped 78%, from 0.62 to 0.14 mumol/L (12.8 to 2.8 micrograms/dL). Mean blood lead levels of children aged 1 to 5 years declined 77% (0.66 to 0.15 mumol/L [13.7 to 3.2 micrograms/dL]) for non-Hispanic white children and 72% (0.97 to 0.27 mumol/L [20.2 to 5.6 micrograms/dL]) for non-Hispanic black children. The prevalence of blood lead levels 0.48 mumol/L (10 micrograms/dL) or greater for children aged 1 to 5 years declined from 85.0% to 5.5% for non-Hispanic white children and from 97.7% to 20.6% for non-Hispanic black children. Similar declines were found in population subgroups defined by age, sex, race/ethnicity, income level, and urban status. Mexican Americans also showed similar declines in blood lead levels of a slightly smaller magnitude over a shorter time. CONCLUSIONS: The results demonstrate a substantial decline in blood lead levels of the entire US population and within selected subgroups of the population. The major cause of the observed decline in blood lead levels is most likely the removal of 99.8% of lead from gasoline and the removal of lead from soldered cans. Although these data indicate major progress in reducing lead exposure, they also show that the same sociodemographic factors continue to be associated with higher blood lead levels, including younger age, male sex, non-Hispanic black race/ethnicity, and low income level. Future efforts to remove other lead sources (eg, paint, dust, and soil) are needed but will be more difficult than removing lead from gasoline and soldered cans.

Apparent underreporting of cigarette consumption among Mexican American smokers.

To determine the accuracy of self-report of cigarette consumption among Mexican American smokers, we compared self-reported cigarette use and serum cotinine concentrations in a sample of 547 participants in the Hispanic Health and Nutrition Examination Survey (HHANES). We defined underreporting of cigarette use as a cotinine to cigarette-per-day ratio of greater than 0.142 microM/l which represented a substantial discrepancy between self-reported consumption and serum cotinine. Of the 98 men and 97 women who reported smoking one to nine cigarettes/day, 20.4 percent and 24.7 percent, respectively, underreported their cigarette consumption. Underreporting was less common among men and women smoking 10 to 19 cigarettes/day (8.3 percent and 10.8 percent, respectively) and 20 or more cigarettes/day (2.2 percent and 2.9 percent, respectively). Comparison of underreporters to other smokers by demographic characteristics within sex and cigarettes/day categories showed no differences. Differences in cotinine metabolism and extremely efficient smoking are alternative explanations that can not be ruled out with these data. We believe, however, that a proportion of Mexican American light smokers may underreport the quantity of cigarettes smoked per day, and may truly be moderate or heavy smokers.

A study of respiratory effects from exposure to 2.0 ppm formaldehyde in occupationally exposed workers.

It has been suggested that exposure to formaldehyde (FA) induces asthmatic symptomatology. We have previously studied healthy and asthmatic individuals and found that lung function was unaltered by controlled exposures to 2.0 ppm FA with and without mild exercise. Our present study extends these observations to a group of hospital laboratory workers routinely exposed to FA. Fifteen laboratory workers were exposed in double-blind, random sequence to 0 and 2 ppm FA for 40 min in an environmental chamber with temperature and relative humidity held constant at 23 degrees C and 50%, respectively. These exposures were repeated on two more occasions with a 10-min exercise regimen (450 kpm/min) after being in the chamber 5 min. In addition, a symptom diary and measurements of peak expiratory flow rate (PEFR) were recorded for 24 hr after exposure. Lung function remained unaltered for all 4 exposure days; e.g., mean FEV1.0 for the group did not change by more than 3% at any testing time on any exposure day. Also, there were no delayed obstructive changes as measured by PEFR recordings. Symptoms were mild and transient with unusual odor and eye irritation the most frequent complaint. No lower airway symptoms were reported. We conclude that this group of healthy laboratory workers did not experience any acute or delayed lung function changes from exposure to 2.0 ppm FA at rest and with exercise and that irritative symptoms were few.

Short interpregnancy interval: a risk factor for low birthweight.

In a prospective study of 1683 women delivering at Yale-New Haven Hospital during 1980 through 1982, those conceiving within 1-4 months of a prior live birth were at increased risk of delivering a low birthweight (less than 2500 gm) newborn (RR = 5.70, 95% Cl = 0.83, 39.75), as were those conceiving 5-8 months later (RR = 3.25, 95% Cl = 1.02, 10.34), when compared with women conceiving 9 or more months later. Adjustment was made for maternal age, ethnicity, preterm delivery or low birthweight of prior newborn, and cigarette smoking in pregnancy. Gestational age of the second delivery was not affected by interpregnancy interval. These results may explain earlier reports of increased perinatal mortality after short birth intervals.