Estrogen, synaptic plasticity and hypothalamic reproductive aging.

Unlike primates who undergo ovarian failure and loss of sex steroids at the end of reproduction, aging rodents undergo constant vaginal estrus followed by constant diestrus and finally anestrus, which indicates the absence of responsive ovarian follicles. The latter state is analogous to menopause in women. The timing of the appearance of constant estrus is determined by many factors including estrogen exposure in the brain during development and the number of times that the animal gets pregnant. The chief site of this reproductive aging in rat brains is the arcuate nucleus of the hypothalamus. The transition from normal cycles to constant estrus parallels the females' gradually decreased ability to respond to administered estradiol with a cycle of inhibition followed by disinhibition of gonadotrophin-releasing hormone. Evidence has accumulated indicating this to be due to a loss of the rat's ability to respond to markedly elevated estradiol with the usual arcuate nucleus neuro-glial plasticity that supports the estrogen-induced gonadotrophin surge (EIGS). Just as male rats are not capable of an EIGS, aged females loose this ability through repeated EIGS. Experiments indicate that in male rats the hypothalamic synaptology that develops as a result of exposure to testicular androgens in the perinatal period (brain sexual differentiation) is a result of conversion of testosterone from the testes to estrogen in the brain and is therefore due to early estrogen exposure. Aging females appear to reach a synaptology similar to males and constant estrus as a result of repeated exposure to ovarian estrogens during their reproductive careers. The relative role of aging and hormonal factors remains unclear. Morphological evidence is presented that indicates the above effects of estrogen involve changes in hypothalamic arcuate nucleus neurons and glia, including changes in the organization of perikaryal membranes as well as arcuate nucleus synaptology and the load of peroxidase in the astroglia. A possible role for free radicals (reactive oxygen species) in hypothalamic reproductive aging has been proposed. Such a mechanism is supported by evidence that the anti-oxidant vitamin E delays the onset of constant estrus and the accumulation of glial peroxidase in aging female rats. However, since the synaptology and peroxidase load in constant estrus females is independent of the age at which the constant estrus occurs, it appears that the role of (repeated) estradiol exposure is more deterministic of hypothalamic failure than is aging, per se.

Surveillance of work-related asthma in selected U.S. states using surveillance guidelines for state health departments--California, Massachusetts, Michigan, and New Jersey, 1993-1995.

PROBLEM/CONDITION: Cases of work-related asthma (WRA) are sentinel health events that indicate the need for preventive intervention. WRA includes new-onset asthma caused by workplace exposure to sensitizers or irritants and preexisting asthma exacerbated by workplace exposures. REPORTING PERIOD: This report reviews cases of WRA identified by state health departments from January 1, 1993, through December 31, 1995, as well as follow-up investigations of cases and associated workplaces conducted through June 30, 1998. DESCRIPTION OF THE SYSTEMS: State-based surveillance and intervention programs for WRA are conducted in California, Massachusetts, Michigan, and New Jersey as part of the Sentinel Event Notification Systems for Occupational Risks (SENSOR) cooperative agreement program, initiated by CDC's National Institute for Occupational Safety and Health (NIOSH). RESULTS: From 1993 through 1995, a total of 1,101 cases of WRA were identified by SENSOR surveillance staff members in California, Massachusetts, Michigan, and New Jersey. Of these 1,101 cases, 19.1% were classified as work-aggravated asthma, and 80.9% were classified as new-onset asthma. Objective evidence substantiating asthma work-relatedness was documented in the medical records of 3.4% of WRA cases identified in the two states (Michigan and New Jersey) where medical records are routinely reviewed for this information. Indoor air pollutants, dusts, cleaning materials, lubricants (e.g., metalworking fluids), and diisocyanates were among the most frequently reported causes of WRA. In addition, a well-recognized cause of occupational asthma - natural rubber latex - was identified in a new setting, the healthcare industry. The most common industries associated with WRA cases included transportation equipment manufacturing (19.3%), health services (14.2%), and educational services (8.7%). Air sampling for agents known to induce occupational asthma was performed in Michigan for comparison with established federal time-weighted average exposure limits. Sixteen (13.4%) of 119 workplaces tested had airborne concentrations exceeding NIOSH recommended exposure limits (RELs); 11 (9.1%) of 121 workplaces had concentrations exceeding permissible exposure limits (PELs) of the Michigan Occupational Safety and Health Act (MIOSHA) program. INTERPRETATION: The surveillance data findings confirm well-recognized causes of asthma and have identified new putative causes (e.g., cleaning materials and metalworking fluids). Because the surveillance program depends on physicians' recognizing asthma work-relatedness and reporting diagnosed cases, the data are considered an underestimate of the magnitude of the WRA problem. The data also indicate that physicians are not commonly performing objective physiologic tests to substantiate a WRA diagnosis. Workplace findings suggest a need to evaluate existing exposure standards for specific agents known to induce occupational asthma (e.g., diisocyanates). Case-based surveillance can help improve the recognition, control, and prevention of WRA. The SENSOR model also provides a mechanism for workers and physicians to request workplace investigations aimed at primary prevention for other workers. PUBLIC HEALTH ACTION: NIOSH and state health department representatives are working to establish a long-term agenda for state-based surveillance of work-related conditions and hazards. The results from the SENSOR WRA programs described in this report support inclusion of WRA as a priority condition warranting surveillance at the state level.

Evolution of a state occupational lead exposure registry: 1986-1996.

In the first 11 full years of operation (January 1, 1986, through December 31, 1996) of an adult lead registry in New Jersey, 23,456 reports of occupational lead toxicity (blood lead level > or = 1.21 mumol/L) in 4,011 workers, involving 496 workplaces, were received. The majority of the reports and workers were from the manufacturing and construction industries. Over the 11 years, the annual numbers of reports and workers declined, although the annual numbers of involved workplaces remained stable, as did the number of newly identified workers and workplaces. The decline occurred primarily in the manufacturing industry; the construction industry experienced an increase in reports and reported workers. For all years combined, 36% of reported workers had at least one blood lead level equal to or greater than 1.93 mumol/L, although in the most recent years the percentage dropped overall and in both the manufacturing and construction industries.

Surveillance for silicosis, 1993--Illinois, Michigan, New Jersey, North Carolina, Ohio, Texas, and Wisconsin.

PROBLEM/CONDITION: Silicosis is an occupational respiratory disease caused by the inhalation of respirable dust containing crystalline silica. Public health surveillance programs to identify workers at risk for silicosis and target workplace-specific and other prevention efforts are currently being field-tested in seven U.S. states. REPORTING PERIOD COVERED: Confirmed cases ascertained by state health departments during the period January 1, 1993, through December 31, 1993; the cases and associated workplaces were followed through December 1994. DESCRIPTION OF SYSTEMS: As part of the Sentinel Event Notification System for Occupational Risks (SENSOR) program initiated by CDC's National Institute for Occupational Safety and Health (NIOSH), development of state-based surveillance and intervention programs for silicosis was initiated in 1987 in Michigan, New Jersey, Ohio, and Wisconsin and in 1992 in Illinois, North Carolina, and Texas. RESULTS: From January 1, 1993, through December 2, 1994, the SENSOR silicosis programs in Illinois, Michigan, New Jersey, North Carolina, Ohio, Texas, and Wisconsin confirmed 256 cases of silicosis that were initially ascertained in 1993. Overall, 185 (72%) were initially identified through review of hospital discharge data or through hospital reports of silicosis diagnoses; 188 (73%) were associated with silica exposure in manufacturing industries (e.g., foundries; stone, clay, glass, and concrete manufacturers; and industrial and commercial machinery manufacture). Overall, 42 (16%) cases were associated with silica exposure from sandblasting operations. Among the 193 confirmed cases for which information was available about duration of employment in jobs with potential exposure to silica, 37 (19%) were employed < or = 10 years in such jobs and 156 (81%) were employed > or = 11 years. A total of 192 primary workplaces associated with potentially hazardous silica exposures were identified for the 256 confirmed silicosis cases. Of these, nine (5%) workplaces were inspected by state health department (SHD) industrial hygienists, 19 (10%) were referred to the Occupational Safety and Health Administration (OSHA) for follow-up, and seven (4%) were routinely monitored by the Mine Safety and Health Administration. Of the 157 (82%) remaining workplaces, follow-up activities determined that 82 were no longer in operation, eight were no longer using silica, 18 were assigned a lower priority for follow-up, six were associated with building trades and could not be inspected because of the transient nature of work in the construction industry, and 43 workplaces were not inspected for other reasons. Fourteen (7%) of the 192 workplaces were inspected. At 10 of the 14 workplaces, airborne levels of crystalline silica were measured; in nine, silica levels exceeded the NIOSH-recommended exposure level of 0.05 mg/m, and in six, airborne silica levels also exceeded federal permissible exposure limits. ACTIONS TAKEN: Employee-specific and other preventive interventions have been initiated in response to reported cases. In addition, special silicosis prevention projects have been initiated in Michigan, New Jersey, North Carolina, Ohio, Texas, and Wisconsin. To facilitate the implementation of silicosis surveillance by other states, efforts are ongoing to identify and standardize core data needed by surveillance programs to describe cases and the workplaces where exposure occurred. These core variables will be incorporated into a user-friendly software system that states can use for data collection and reporting.

Risk of lung cancer among former chromium smelter workers.

Hexavalent chromium is a known carcinogen. Previous epidemiologic studies in the 1950s of United States workers from seven facilities producing chromium compounds from chromite ore have reported a markedly increased risk for dying from lung cancer. As part of a high risk notification project of workers from four of these facilities, a mortality study was performed. The cohort was assembled in 1990-1991 from the Social Security records of four former chromate producing facilities in northern New Jersey. The study subjects were known to have worked at these facilities some time between 1937 and 1971. Proportionate mortality and proportionate cancer mortality ratios (PCMR) were calculated. The overall risk for lung cancer was a PCMR of 1.51 (confidence limits [CL] 1.29-1.74) for white men and 1.34 (CL 1.00-1.75) for black men. These risks increased with increasing duration of employment and latency since time of first employment. The PCMR for greater than 20 years duration of work and more than 20 years since first exposure was 1.94 (CL 1.15-3.06) for white men and 3.08 (CL 1.13-6.71) for black men. The risk for lung cancer for white men remains elevated more than 20 years after exposure has ceased (PCMR, 1.29; CL 1.03-1.60). The PCMR for nasal cavity/sinus cancer was also found to be a significantly increased, 5.18 (CL 2.37-11.30). A cluster of bladder cancer was seen among black workers from one facility, (PCMR, 3.30; CL 1.42-6.51). Despite the cessation of exposure, former chromium workers remain at significantly increased risk of lung cancer. Although there have been case reports of nasal cavity/ sinus cancer in association with chromium exposure, this is the first epidemiologic study to report a significant increase in these cancers. Limitations in this study include lack of exposure data and lack of information on smoking habits. The lack of increase in other smoking-related diseases besides lung cancer indicates that the increase in lung cancer cannot be attributed to cigarette smoking. The ongoing elevated risk of lung cancer after cessation of exposure emphasizes the need for developing early detection texts for lung cancer.

Silicosis and workers' compensation in New Jersey.

The employer is expected to maintain responsibility for health care expenses and lost income that result from occupational injury and illness through the workers' compensation insurance system. However, financial support for individuals with occupational illnesses, especially those with long latency, is often from sources other than workers' compensation. Silicosis, a well defined, chronic, occupational lung disease, can be viewed as a sentinel for the inadequacy of the public policy to compensate workers for chronic occupational lung disease. Three hundred twenty-nine patients with confirmed silicosis were identified by the silicosis surveillance program in the New Jersey Department of Health using source data from 1979 through 1992. One hundred seventy-seven of these individuals provided information on the status of any compensation claims against their employer. Only 31% of these patients stated that a claim had been filed; 84% of those whose claims were settled were awarded payments. Severity of radiologic findings was not associated with the likelihood of filing a claim or with being awarded a payment; whereas, smoking was associated with these outcomes. The implications of these findings for the health care system are discussed.

A pilot study of take-home lead exposure in New Jersey.

Studies in various industries have found an association between worker exposure to lead and elevated blood lead levels in workers' children, but the magnitude of this problem is unknown. In an effort to characterize this problem further, a pilot study was undertaken to obtain blood lead levels of children of lead-exposed workers with elevated blood lead levels who had been reported by laboratories to the New Jersey Department of Health. Fifteen workers' families participated in this study, including 28 children. Thirty-two percent of the children were found to have blood lead levels > or = 10 micrograms/dl, the level of concern set by the Centers for Disease Control and Prevention for medical monitoring. This finding is in contrast to population-based data collected from the Third National Health and Nutrition Survey, where the overall prevalence of blood lead levels > or = 10 micrograms/dl was only 4.5%.

Mortality among persons with silicosis reported to disease surveillance systems in Michigan and New Jersey in the United States.

Michigan and New Jersey in the United States maintain silicosis disease registers. In 1988-1992, 372 cases of silicosis were confirmed in Michigan, and, in 1979-1992, 288 were confirmed in New Jersey. A proportionate mortality ratio (PMR) analysis was performed on data from 292 deceased silicotics. Increases in PMR values were found for nonmalignant respiratory disease (NMRD) and lung cancer. The PMR values for NMRD were statistically elevated in all the analyses. The overall proportionate cancer mortality ratio (PCMR) for lung cancer was 1.78 [95% confidence interval (95% CI) 1.22-2.61]. For patients having ever smoked cigarettes, the PCMR for lung cancer was 1.82 (95% CI 1.8-2.81). Never smoking silicotics had a lung cancer PCMR of 1.48 (95% CI 0.43-2.86). For those who had never applied for workers' compensation the corresponding PCMR was higher, 2.10 (95% CI 1.21-3.69), than for those who had applied, 1.45 (95% CI 0.70-2.99).

Surveillance for occupational asthma--Michigan and New Jersey, 1988-1992.

PROBLEM/CONDITION: A case of occupational asthma is a sentinel health event indicating a need for preventive intervention. REPORTING PERIOD COVERED: 1988-1992. DESCRIPTION OF SYSTEMS: As part of the Sentinel Event Notification System for Occupational Risks (SENSOR) Program, initiated by CDC's National Institute for Occupational Safety and Health in 1987, state-based surveillance and intervention programs for occupational asthma (OA) have been under development in Michigan and New Jersey. The initial 5-year projects in these states have been completed. RESULTS: From 1988 through 1992, the SENSOR programs in these states identified a total of 535 cases of occupational asthma and related conditions. Of these 535 cases, 328 cases met the SENSOR surveillance case definition for OA. In addition, 128 cases were classified as possible OA, 42 as reactive airways dysfunction syndrome, and 37 as occupationally aggravated asthma. In both Michigan and New Jersey, manufacturing was the industrial sector with the largest proportion of cases. In Michigan, > 40% of the case-patients worked in transportation equipment manufacturing. In New Jersey, 15% of case-patients worked in manufacturing of chemicals and allied products. Overall, isocyanates were the most frequently reported asthma-causing agents (19.4% of cases). Follow-up industrial hygiene sampling measured suspect agents at airborne concentrations generally below the permissible exposure limits established by the Occupational Safety and Health Administration. INTERPRETATION: In its first 5 years, the SENSOR system has led to the identification of previously unrecognized causes of occupational asthma. Overall findings indicate the need for more comprehensive control of such well-known occupational allergens as the isocyanates. In addition, SENSOR interventions have prompted improvements in protection for workers. ACTIONS TAKEN: Approaches to state-based surveillance and intervention for OA are being developed through newly funded 5-year SENSOR projects in four states (California, Massachusetts, Michigan, and New Jersey). The goal is to develop a model for effective state-based OA surveillance that can be applied by any state health department.

Silicosis surveillance--Michigan, New Jersey, Ohio, and Wisconsin, 1987-1990.

PROBLEM/CONDITION: Improved surveillance for silicosis is needed to target interventions to prevent this occupational lung disease caused by the inhalation of crystalline silica dust. REPORTING PERIOD COVERED: 1987-1990. DESCRIPTION OF SYSTEMS: State-based silicosis surveillance and intervention programs have been developed in Michigan, New Jersey, Ohio, and Wisconsin as part of the Sentinel Event Notification System for Occupational Risks (SENSOR) Program, initiated in 1987 by the National Institute for Occupational Safety and Health (NIOSH). RESULTS: From 1987 through 1990, the SENSOR program confirmed a total of 430 cases of silicosis reported from these four states. Overall, approximately 60% of these cases were in workers employed in primary metal industries, although the types of industries in which cases occurred varied by state. Some cases were attributable to relatively recent exposure, including new cases in seven persons first exposed since 1980 in New Jersey. Silicosis case reports have prompted measurement of respirable silica concentrations at 25 Michigan work sites, and 14 (56%) of these sites were found to have levels that exceeded the legally permissible exposure level. INTERPRETATION: The silicosis surveillance and intervention strategies piloted by state health departments in the NIOSH-funded SENSOR Program have demonstrated the feasibility and effectiveness of identifying specific silica-using work sites that need preventive intervention. ACTIONS TAKEN: On the basis of initial experience in these four states, NIOSH developed guidelines for state-based silicosis surveillance and awarded SENSOR cooperative agreements to three additional states where the applicability of these surveillance methods will be further evaluated.

High-risk notification of chromate and bichromate production workers.

A high-risk notification program is in progress for 4,862 former chromate and bichromate production workers. A previous mortality study of this cohort found a 29-fold increase in mortality for respiratory cancer. The increase was greater in black than white workers (80-fold vs. 15-fold). The cohort was compiled from Social Security Administration records. Notification was performed mainly using addresses on file with the Internal Revenue Service. At this time, 68% of the cohort has either been determined to have died or has been contacted. A description of the various steps of notification is included. This project has demonstrated that it is possible to perform high-risk notification in an economical manner even in the absence of employer personnel records or current addresses. The methodology used in this project is generalizable to other cohorts.

Asbestos disease risk communication conducted by the New Jersey Department of Health.

Since October 1985, the New Jersey Department of Health (NJDOH) has required hospitals to report all patients with a discharge diagnosis of asbestosis. As follow-up to a needs assessment survey of these patients, the NJDOH developed an educational packet including an information bulletin titled "Asbestos Disease: Medical and Legal Facts for Employees" and a pre-stamped postcard evaluation survey. The packet was sent to 1,418 patients reported by hospitals; 433 patients returned the evaluation questionnaire. The survey assessed attitudinal responses (were the materials helpful and easy to understand?) and behavioral responses (did the respondent plan on discussing the materials with a doctor or lawyer?) to the information in the packet. Of the postcard respondents, 85% found the materials helpful, and approximately half indicated that they would discuss the materials with a doctor or lawyer. Of the 33% who were proxy respondents, half appeared not to have understood that the materials had relevance to them as family members. Modifications to the protocol for the asbestos disease educational packet were made based on the evaluation data. Limitations of the evaluation survey and the value of process evaluations in risk communication projects are discussed.

Patterns of asbestosis in New Jersey.

Hospital discharge data from New Jersey were used to identify cases of asbestosis for the 8 years 1979-1986. Multiple admissions were deleted so that each individual was counted once at the time of his/her first hospitalization with an asbestosis diagnosis. White males had the highest age-adjusted average annual discharge rate of 19.3 cases/100,000 population, followed by black males (12.3 cases/100,000) and white females (1.2 cases/100,000). The discharge rate was positively associated with age in each race/sex category. The relationship between rates for black males and white males depended on age: under 65 years, the rates were almost equal, and at 65 years and older, the white rates were nearly twice the black rates. There were two areas of the state where the rates were highest: the north-central and southwest regions. These two areas represent manufacturing and shipbuilding applications of asbestos, respectively. During the years 1979-1986, the annual percentage increase in asbestosis rates was 20% for white males, 17% for black males, and 8% for white females. Continued surveillance will reveal when the rates for asbestosis stop increasing.

The use of portable peak flowmeters in the surveillance of occupational asthma.

The purpose of this study was to identify the strengths and limitations of using portable peak flowmeters to document suspected cases of occupational asthma that were reported to a statewide surveillance project. The New Jersey Department of Health conducts surveillance for occupational asthma as part of the federally sponsored Sentinel Event Notification System for Occupational Risks (SENSOR). Between May 1988 and January 1990, 70 cases were reported voluntarily by physicians. Subjects who were still employed in suspected work sites were requested to test themselves for at least 15 days, using portable peak flowmeters to generate serial measurements of their peak expiratory flow rate (PEFR). For each of the 14 subjects who were successfully tested, the PEFR data provided valuable information about their asthma-work association. However, a large number of subjects whose cases were reported (56) either could not be tested or were not successfully tested. The proportion of subjects completing the test would probably improve if it were conducted when their conditions were first diagnosed. Accordingly, the collection of serial peak flow measurements to document occupational asthma would best be initiated by the treating physician when the patient first sought care, rather than waiting until after the case was reported to the state health department.

The identification of occupational lung disease from hospital discharge data.

The Bureau of Labor Statistics-State Health Department Select Committee on Occupational Illnesses and Injuries conducted a study of hospital discharge records to determine their usefulness for identifying cases of occupational disease. Four states searched the diagnosis fields on computerized hospital discharge records for selected occupational lung diseases; pneumoconiosis, extrinsic allergic alveolitis, and respiratory conditions due to chemical fumes and vapors. The hospital discharge data identified more cases of pneumoconiosis than did the BLS data systems. Numerous cases of extrinsic allergic alveolitis and respiratory conditions due to chemical fumes and vapors were also identified. Patterns evidenced in the data were generally consistent with current knowledge of the diseases. The inclusion of industry and occupation on the hospital discharge record, further study of the quality of diagnosis coding, and the use of these data by additional states will enhance the usefulness of these data for occupational disease surveillance.