Assessing the role of social determinants of health in health disparities: The need for data on work

BACKGROUND

Work is a key social determinant of health. Without the collection of work-related information in public health data systems, the role of social determinants in creating and reinforcing health disparities cannot be fully assessed.

METHODS

The Centers for Disease Control and Prevention (CDC) maintains or supports a number of public health surveillance and health monitoring systems, including surveys, case-based disease and exposure systems, vital status records, and administrative data systems. We evaluated a convenience sample of these systems for inclusion of information in three work-related domains: employment status, industry and occupation, and working conditions.

RESULTS

While 12 of 39 data systems were identified as collecting work-related data, this information was often minimal (e.g., only employment status), restricted to a subset of respondents, or only gathered periodically. Information on working conditions was particularly sparse.

CONCLUSION

Historically, the limited and inconsistent collection of work-related information in public health data systems has hindered understanding of the role work plays in health disparities. Current CDC data modernization efforts present opportunities to enhance the identification and mitigation of health disparities by prioritizing inclusion of an expanded set of work-related data elements.

Work: A Social Determinant of Health Worth Capturing

Work is a recognized social determinant of health. This became most apparent during the COVID-19 pandemic. Workers, particularly those in certain industries and occupations, were at risk due to interaction with the public and close proximity to co-workers. The purpose of this study was to assess how states collected work and employment data on COVID-19 cases, characterizing the need for systematic collection of case-based specific work and employment data, including industry and occupation, of COVID-19 cases. A survey was distributed among state occupational health contacts and epidemiologists in all 50 states to assess current practices in state public health surveillance systems. Twenty-seven states collected some kind of work and employment information from COVID-19 cases. Most states (93%) collected industry and/or occupation information. More than half used text-only fields, a predefined reference or dropdown list, or both. Use of work and employment data included identifying high risk populations, prioritizing vaccination efforts, and assisting with reopening plans. Reported barriers to collecting industry and occupation data were lack of staffing, technology issues, and funding. Scientific understanding of work-related COVID-19 risk requires the systematic, case-based collection of specific work and employment data, including industry and occupation. While this alone does not necessarily indicate a clear workplace exposure, collection of these data elements can help to determine and further prevent workplace outbreaks, thereby ensuring the viability of the nation's critical infrastructure.

Exposure control practices for administering nitrous oxide: A survey of dentists, dental hygienists, and dental assistants

Engineering, administrative, and work practice controls have been recommended for many years to minimize exposure to nitrous oxide during dental procedures. To better understand the extent to which these exposure controls are used, the NIOSH Health and Safety Practices Survey of Healthcare Workers was conducted among members of professional practice organizations representing dentists, dental hygienists and dental assistants. The anonymous, modular, web-based survey was completed by 284 dental professionals in private practice who administered nitrous oxide to adult and/or pediatric patients in the seven days prior to the survey. Use of primary engineering controls (i.e., nasal scavenging mask and/or local exhaust ventilation (LEV) near the patient's mouth) was nearly universal, reported by 93% and 96% of respondents who administered to adult (A) and pediatric (P) patients, respectively. However, adherence to other recommended precautionary practices were lacking to varying degrees, and were essentially no different among those administering nitrous oxide to adult or pediatric patients. Examples of work practices which increase exposure risk, expressed as percent of respondents, included: not checking nitrous oxide equipment for leaks (41% A; 48% P); starting nitrous oxide gas flow before delivery mask or airway mask was applied to patient (13% A; 12% P); and not turning off nitrous oxide gas flow before turning off oxygen flow to the patient (8% A; 7% P). Absence of standard procedures to minimize worker exposure to nitrous oxide (13% of all respondents) and not being trained on safe handling and administration of nitrous oxide (3%) were examples of breaches of administrative controls which may also increase exposure risk. Successful management of nitrous oxide emissions should include properly fitted nasal scavenging masks, supplemental LEV (when nitrous oxide levels cannot be adequately controlled using nasal masks alone), adequate general ventilation, regular inspection of nitrous oxide delivery and scavenging equipment for leaks, availability of standard procedures to minimize exposure, periodic training, ambient air and exposure monitoring, and medical surveillance.

Secondhand smoke in the operating room? Precautionary practices lacking for surgical smoke

BACKGROUND

Consensus organizations, government bodies, and healthcare organization guidelines recommend that surgical smoke be evacuated at the source by local exhaust ventilation (LEV) (i.e., smoke evacuators or wall suctions with inline filters).

METHODS

Data are from NIOSH's Health and Safety Practices Survey of Healthcare Workers module on precautionary practices for surgical smoke.

RESULTS

Four thousand five hundred thirty-three survey respondents reported exposure to surgical smoke: 4,500 during electrosurgery; 1,392 during laser surgery procedures. Respondents were mainly nurses (56%) and anesthesiologists (21%). Only 14% of those exposed during electrosurgery reported LEV was always used during these procedures, while 47% reported use during laser surgery. Those reporting LEV was always used were also more likely to report training and employer standard procedures addressing the hazards of surgical smoke. Few respondents reported use of respiratory protection.

CONCLUSIONS

Study findings can be used to raise awareness of the marginal use of exposure controls and impediments for their use. Am. J. Ind. Med. 59:1020-1031, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

NIOSH national survey of long-haul truck drivers: Injury and safety

Approximately 1,701,500 people were employed as heavy and tractor-trailer truck drivers in the United States in 2012. The majority of them were long-haul truck drivers (LHTDs). There are limited data on occupational injury and safety in LHTDs, which prompted a targeted national survey. The National Institute of Occupational Safety and Health conducted a nationally representative survey of 1265 LHTDs at 32 truck stops across the contiguous United States in 2010. Data were collected on truck crashes, near misses, moving violations, work-related injuries, work environment, safety climate, driver training, job satisfaction, and driving behaviors. Results suggested that an estimated 2.6% of LHTDs reported a truck crash in 2010, 35% reported at least one crash while working as an LHTD, 24% reported at least one near miss in the previous 7 days, 17% reported at least one moving violation ticket and 4.7% reported a non-crash injury involving days away from work in the previous 12 months. The majority (68%) of non-crash injuries among company drivers were not reported to employers. An estimate of 73% of LHTDs (16% often and 58% sometimes) perceived their delivery schedules unrealistically tight; 24% often continued driving despite fatigue, bad weather, or heavy traffic because they needed to deliver or pick up a load at a given time; 4.5% often drove 10miles per hours or more over the speed limit; 6.0% never wore a seatbelt; 36% were often frustrated by other drivers on the road; 35% often had to wait for access to a loading dock; 37% reported being noncompliant with hours-of-service rules (10% often and 27% sometimes); 38% of LHTDs perceived their entry-level training inadequate; and 15% did not feel that safety of workers was a high priority with their management. This survey brings to light a number of important safety issues for further research and interventions, e.g., high prevalence of truck crashes, injury underreporting, unrealistically tight delivery schedules, noncompliance with hours-of-service rules, and inadequate entry-level training.

National Survey of US Long-Haul Truck Driver Health and Injury: health behaviors

OBJECTIVE

To compare selected health behaviors and body mass index (modifiable risk factors) of US long-haul truck drivers to the US working population by sex.

METHODS

The National Survey of US Long-Haul Truck Driver Health and Injury interviewed a nationally representative sample of long-haul truck drivers (n = 1265) at truck stops. Age-adjusted results were compared with national health surveys.

RESULTS

Compared with US workers, drivers had significantly higher body mass index, current cigarette use, and pack-years of smoking; lower prevalence of annual influenza vaccination; and generally lower alcohol consumption. Physical activity level was low for most drivers, and 25% had never had their cholesterol levels tested.

CONCLUSIONS

Working conditions common to long-haul trucking may create significant barriers to certain healthy behaviors; thus, transportation and health professionals should address the unique work environment when developing interventions for long-haul drivers.

Precautionary Practices of Respiratory Therapists and Other Health-Care Practitioners Who Administer Aerosolized Medications

BACKGROUND

Respiratory therapists (RTs) and other health-care workers are potentially exposed to a variety of aerosolized medications. The National Institute for Occupational Safety and Health (NIOSH) Health and Safety Practices Survey of Healthcare Workers describes current exposure control practices and barriers to using personal protective equipment during administration of selected aerosolized medications.

METHODS

An anonymous, multi-module, web-based survey was conducted among members of health-care professional practice organizations representing RTs, nurses, and other health-care practitioners. A module on aerosolized medications included submodules for antibiotics (amikacin, colistin, and tobramycin), pentamidine, and ribavirin.

RESULTS

The submodules on antibiotics, pentamidine, and ribavirin were completed by 321, 227, and 50 respondents, respectively, most of whom were RTs. The relatively low number of ribavirin respondents precluded meaningful interpretation of these data and may reflect the rare use of this drug. Consequently, analysis focused on pentamidine, classified by NIOSH as a hazardous drug, and the antibiotics amikacin, colistin, and tobramycin, which currently lack authoritative safe handling guidelines. Respondents who administered pentamidine were more likely to adhere to good work practices compared with those who administered the antibiotics. Examples included training received on safe handling procedures (75% vs 52%), availability of employer standard procedures (82% vs 55%), use of aerosol delivery devices equipped with an expiratory filter (96% vs 53%) or negative-pressure rooms (61% vs 20%), and always using respiratory protection (51% vs 13%).

CONCLUSIONS

Despite the availability of safe handling guidelines for pentamidine, implementation was not universal, placing workers, co-workers, and even family members at risk of exposure. Although the antibiotics included in this study lack authoritative safe handling guidelines, prudence dictates that appropriate exposure controls be used to minimize exposure to the antibiotics and other aerosolized medications. Employers and employees share responsibility for ensuring that precautionary measures are taken to keep exposures to all aerosolized medications as low as practicable.

Overview of the National Occupational Mortality Surveillance (NOMS) system: leukemia and acute myocardial infarction risk by industry and occupation in 30 US states 1985-1999, 2003-2004, and 2007

BACKGROUND

Cancer and chronic disease are leading causes of death in the US with an estimated cost of $46 billion.

METHODS

We analyzed 11 million cause-specific deaths of US workers age 18-64 years in 30 states during 1985-1999, 2003-2004, and 2007 by occupation, industry, race, gender, and Hispanic origin.

RESULTS

The highest significantly elevated proportionate leukemia mortality was observed in engineers, protective service, and advertising sales manager occupations and in banks/savings &loans/credit agencies, public safety, and public administration industries. The highest significantly elevated smoking-adjusted acute myocardial infarction mortality was noted in industrial and refractory machinery mechanics, farmers, mining machine operators, and agricultural worker occupations; and wholesale farm supplies, agricultural chemical, synthetic rubber, and agricultural crop industries.

CONCLUSIONS

Significantly elevated risks for acute myocardial infarction and leukemia were observed across several occupations and industries that confirm existing reports and add new information. Interested investigators can access the NOMS website at http://www.cdc.gov/niosh/topics/NOMS/.

Adherence to Precautionary Guidelines for Compounding Antineoplastic Drugs: A Survey of Nurses and Pharmacy Practitioners

Precautionary guidelines detailing standards of practice and equipment to eliminate or minimize exposure to antineoplastic drugs during handling activities have been available for nearly three decades. To evaluate practices for compounding antineoplastic drugs, the NIOSH Health and Safety Practices Survey of Healthcare Workers was conducted among members of professional practice organizations representing primarily oncology nurses, pharmacists, and pharmacy technicians. This national survey is the first in over 20 years to examine self-reported use of engineering, administrative, and work practice controls and PPE by pharmacy practitioners for minimizing exposure to antineoplastic drugs. The survey was completed by 241 nurses and 183 pharmacy practitioners who compounded antineoplastic drugs in the seven days prior to the survey. They reported: not always wearing two pairs of chemotherapy gloves (85%, 47%, respectively) or even a single pair (8%, 10%); not always using closed system drug-transfer devices (75%, 53%); not always wearing recommended gown (38%, 20%); I.V. lines sometimes/always primed with antineoplastic drug (19%, 30%); and not always using either a biological safety cabinet or isolator (9%, 15%). They also reported lack of: hazard awareness training (9%, 13%); safe handling procedures (20%, 11%); and medical surveillance programs (61%, 45%). Both employers and healthcare workers share responsibility for adhering to precautionary guidelines and other best practices. Employers can ensure that: workers are trained regularly; facility safe-handling procedures reflecting national guidelines are in place and support for their implementation is understood; engineering controls and PPE are available and workers know how to use them; and medical surveillance, exposure monitoring, and other administrative controls are in place. Workers can seek out training, understand and follow facility procedures, be role models for junior staff, ask questions, and report any safety concerns.

NIOSH health and safety practices survey of healthcare workers: training and awareness of employer safety procedures

BACKGROUND

The Health and Safety Practices Survey of Healthcare Workers describes current practices used to minimize chemical exposures and barriers to using recommended personal protective equipment for the following: antineoplastic drugs, anesthetic gases, high level disinfectants, surgical smoke, aerosolized medications (pentamidine, ribavirin, and antibiotics), and chemical sterilants.

METHODS

Twenty-one healthcare professional practice organizations collaborated with NIOSH to develop and implement the web-based survey.

RESULTS

Twelve thousand twenty-eight respondents included professional, technical, and support occupations which routinely come in contact with the targeted hazardous chemicals. Chemical-specific safe handling training was lowest for aerosolized antibiotics (52%, n = 316), and surgical smoke (57%, n = 4,747). Reported employer procedures for minimizing exposure was lowest for surgical smoke (32%, n = 4,746) and anesthetic gases (56%, n = 3,604).

CONCLUSIONS

Training and having procedures in place to minimize exposure to these chemicals is one indication of employer and worker safety awareness. Safe handling practices for use of these chemicals will be reported in subsequent papers.

Obesity and other risk factors: the national survey of U.S. long-haul truck driver health and injury

BACKGROUND

Drivers of heavy and tractor-trailer trucks accounted for 56% of all production and nonsupervisory employees in the truck transportation industry in 2011. There are limited data for illness and injury in long-haul truck drivers, which prompted a targeted national survey.

METHODS

Interviewers collected data during 2010 from 1,670 long-haul truck drivers at 32 truck stops across the 48 contiguous United States that were used to compute prevalence estimates for self-reported health conditions and risk factors.

RESULTS

Obesity (69% vs. 31%, P < 0.01) and current smoking (51% vs. 19%, P < 0.01) were twice as prevalent in long-haul truck drivers as in the 2010 U.S. adult working population. Sixty-one percent reported having two or more of the risk factors: hypertension, obesity, smoking, high cholesterol, no physical activity, 6 or fewer hours of sleep per 24-hr period.

CONCLUSION

Survey findings suggest a need for targeted interventions and continued surveillance for long-haul truck drivers.

Adherence to safe handling guidelines by health care workers who administer antineoplastic drugs

The toxicity of antineoplastic drugs is well documented. Many are known or suspected human carcinogens where no safe exposure level exists. Authoritative guidelines developed by professional practice organizations and federal agencies for the safe handling of these hazardous drugs have been available for nearly three decades. As a means of evaluating the extent of use of primary prevention practices such as engineering, administrative and work practice controls, personal protective equipment (PPE), and barriers to using PPE, the National Institute for Safety and Health (NIOSH) conducted a web survey of health care workers in 2011. The study population primarily included members of professional practice organizations representing health care occupations which routinely use or come in contact with selected chemical agents. All respondents who indicated that they administered antineoplastic drugs in the past week were eligible to complete a hazard module addressing self-reported health and safety practices on this topic. Most (98%) of the 2069 respondents of this module were nurses. Working primarily in hospitals, outpatient care centers, and physician offices, respondents reported that they had collectively administered over 90 specific antineoplastic drugs in the past week, with carboplatin, cyclophosphamide, and paclitaxel the most common. Examples of activities which increase exposure risk, expressed as percent of respondents, included: failure to wear nonabsorbent gown with closed front and tight cuffs (42%); intravenous (I.V.) tubing primed with antineoplastic drug by respondent (6%) or by pharmacy (12%); potentially contaminated clothing taken home (12%); spill or leak of antineoplastic drug during administration (12%); failure to wear chemotherapy gloves (12%); and lack of hazard awareness training (4%). The most common reason for not wearing gloves or gowns was "skin exposure was minimal"; 4% of respondents, however, reported skin contact during handling and administration. Despite the longstanding availability of safe handling guidance, recommended practices are not always followed, underscoring the importance of training and education for employers and workers.

Prevalence of dermatitis in the working population, United States, 2010 National Health Interview Survey

BACKGROUND

Prevalence patterns of dermatitis among workers offer clues about risk factors and targets for prevention, but population-based estimates of the burden of dermatitis among US workers are lacking.

METHODS

Data from an occupational health supplement to the 2010 National Health Interview Survey (NHIS-OHS) were used to estimate the prevalence of dermatitis overall and by demographic characteristics and industry and occupation (I&O) of current/recent employment.

RESULTS

Data were available for 27,157 adults, including 17,524 current/recent workers. The overall prevalence rate of dermatitis among current/recent workers was 9.8% (range among I&O groups: 5.5-15.4%), representing approximately 15.2 million workers with dermatitis. The highest prevalence rates were among I&O groups related to health care. Overall, 5.6% of dermatitis cases among workers (9.2% among healthcare workers) were attributed to work by health professionals.

CONCLUSIONS

Dermatitis affected over 15 million US workers in 2010, and its prevalence varied by demographic characteristics and industry and occupation of employment. The prevalence rate of work-related dermatitis based on the NHIS-OHS was approximately 100-fold higher than incidence rates based on the Bureau of Labor Statistics' Survey of Occupational Illness and Injury.

Prevalence and work-relatedness of carpal tunnel syndrome in the working population, United States, 2010 National Health Interview Survey

BACKGROUND

Patterns of prevalence and work-relatedness of carpal tunnel syndrome (CTS) among workers offer clues about risk factors and targets for prevention.

METHODS

Data from an occupational health supplement to the 2010 National Health Interview Survey were used to estimate the prevalence of self-reported clinician-diagnosed CTS overall and by demographic characteristics. The proportion of these cases self-reported to have been attributed to work by clinicians was also examined overall and by demographic characteristics. In addition, the distribution of industry and occupation (I&O) categories to which work-related cases of CTS were attributed was compared to the distribution of I&O categories of employment among current/recent workers.

RESULTS

Data were available for 27,157 adults, including 17,524 current/recent workers. The overall lifetime prevalence of clinician-diagnosed CTS among current/recent workers was 6.7%. The 12-month prevalence was 3.1%, representing approximately 4.8 million workers with current CTS; 67.1% of these cases were attributed to work by clinicians, with overrepresentation of certain I&O categories.

CONCLUSIONS

CTS affected almost 5 million U.S. workers in 2010, with prevalence varying by demographic characteristics and I&O.

Documenting occupational history: the value to patients, payers, and researchers

Recording patient work history is vital to identifying work-related injuries and illnesses. As electronic health records become widespread, this is an important time to ensure occupational health data elements are included in EHR standards.

Paternal occupational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin and birth outcomes of offspring: birth weight, preterm delivery, and birth defects

Agent Orange is a phenoxy herbicide that was contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We studied pregnancy outcomes among wives of male chemical workers who were highly exposed to chemicals contaminated with TCDD and among wives of nonexposed neighborhood referents. For exposed pregnancies, we estimated serum TCDD concentration at the time of conception using a pharmacokinetic model. The mean TCDD concentration for workers' births was 254 pg/g lipid (range, 3-16,340 pg/g). The mean referent concentration of 6 pg/g was assigned to pregnancies fathered by workers before exposure. A total of 1,117 live singleton births of 217 referent wives and 176 worker wives were included. Only full-term births were included in the birth weight analysis (greater than or equal to 37 weeks of gestation). Mean birth weight among full-term babies was similar among referents' babies (n = 604), preexposure workers' babies (n = 221), and exposed workers' babies (n = 292) (3,420, 3,347, and 3,442 g, respectively). Neither continuous nor categorical TCDD concentration had an effect on birth weight for term infants after adjustment for infant sex, mother's education, parity, prenatal cigarette smoking, and gestation length. An analysis to estimate potential direct exposure of the wives during periods of workers' exposure yielded a nonstatistically significant increase in infant birth weight of 130 g in the highest exposure group (TCDD concentration > 254 pg/g) compared with referents (p = 0.09). Mothers' reports of preterm delivery showed a somewhat protective association with paternal TCDD (log) concentration (odds ratio = 0.8; 95% confidence interval, 0.6-1.1). We also include descriptive information on reported birth defects. Because the estimated TCDD concentrations in this population were much higher than in other studies, the results indicate that TCDD is unlikely to increase the risk of low birth weight or preterm delivery through a paternal mechanism. Key words: birth defects, birth weight, congenital anomalies, dioxin, occupation, paternal exposure, preterm birth, TCDD.

Information dissemination and use: critical components in occupational safety and health

BACKGROUND

Information dissemination is a mandated, but understudied, requirement of occupational and environmental health laws and voluntary initiatives. Research is needed on the factors that enhance and limit the development, transfer, and use of occupational safety and health information (OSH). Contemporary changes in the workforce, workplaces, and the nature of work will require new emphasis on the dissemination of information to foster prevention.

METHODS

Legislative and regulatory requirements and voluntary initiatives for dissemination of OSH information were identified and assessed. Literature on information dissemination was reviewed to identify important issues and useful approaches.

RESULTS

More than 20 sections of laws and regulations were identified that mandated dissemination of occupational and environmental safety and health information. A four-stage approach for tracking dissemination and considering the flow of information was delineated. Special areas of dissemination were identified: the information needs of the changing workforce, new and young workers; small businesses; and workers with difficulty in understanding or reading English.

CONCLUSIONS

We offer a framework for dissemination of OSH information and underscore the need to focus on the extent to which decision-makers and others receive and use such information. More solid data are also needed on current investments in disseminating, diffusing and applying OSH information and on the utility of that information. Am. J. Ind. Med. 44:515-531, 2003. Published 2003 Wiley-Liss, Inc.

Spontaneous abortion, sex ratio, and paternal occupational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin

There is conflicting research regarding an association between fetal death and paternal exposure to Agent Orange, a phenoxy herbicide widely used in Vietnam that was contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Men who worked in the U.S. factories that produced Agent Orange were exposed to TCDD at levels hundreds of times higher than TCDD levels in the general population. Wives of TCDD-exposed chemical workers and wives of nonexposed neighborhood referents were interviewed to determine reproductive history. Paternal serum TCDD level at time of conception was estimated for each pregnancy using serum samples taken in 1987. Estimated TCDD levels of workers during or after exposure were high (median, 254 ppt; range, 3-16,340 ppt) compared to referent levels (median, 6 ppt; range, 2-19 ppt). No association between paternal TCDD level at the time of conception and spontaneous abortion was observed among pregnancies fathered by workers with TCDD levels of < 20 ppt [odds ratio (OR) = 0.77; 95% confidence interval (CI), 0.48-1.22], 20 to < 255 ppt (OR = 0.81; 95% CI, 0.40-1.63), 255 to < 1,120, (OR = 0.69; 95% CI, 0.30-1.58), and >or= 1,120 ppt (OR = 0.95; 95% CI, 0.42-2.17) compared to pregnancies fathered by referents. The sex ratio [males/(males + females)] of offspring also did not differ by TCDD exposure (0.53 and 0.54 among workers and referents, respectively). We did not find an association between paternal serum TCDD level and spontaneous abortion or sex ratio of offspring in this population. The estimated TCDD levels in this exposed worker population were much higher than in other studies, providing additional evidence that paternal TCDD exposure does not increase the risk of spontaneous abortion at levels above those observed in the general population. The study could not evaluate the effect of father's childhood or prenatal TCDD exposure on subsequent sex ratio.

Major changes in human ocular UV protection with age

PURPOSE

Age-dependent human lens coloration may be explained by the binding of UV filters to crystallins. It has been proposed that glutathione may compete for reaction with UV filter degradation products and therefore protect crystallins from modification. To understand this process, UV filters were quantified together with oxidized and reduced glutathione in human lenses of varying age.

METHODS

Lens tissues were homogenized in ethanol to extract the UV filters. Metabolites were quantified by HPLC and correlations between them in the nuclear and cortical regions of the lens were examined.

RESULTS

The concentrations of the UV filters 3-hydroxykynurenine, kynurenine, and 3-hydroxykynurenine glucoside decreased linearly with age, with slightly lower levels in the nucleus than the cortex. 4-(2-Amino-3-hydroxyphenyl)-4-oxobutanoic acid glucoside was found in higher levels in the nucleus than the cortex and decreased slowly in both regions with age. Glutathionyl-3-hydroxykynurenine glucoside was present in higher concentrations in the nucleus, barely detectable in young lenses, but increased significantly after age 50. Reduced glutathione levels were lower in the nucleus and decreased in both regions with age, yet oxidized glutathione increased in the nucleus but remained constant in the cortex.

CONCLUSIONS

Results are consistent with a predominantly nuclear origin for both 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid glucoside and glutathionyl-3-hydroxykynurenine glucoside. This is in accord with their proposed mechanism of formation, which involves an initial deamination of 3-hydroxykynurenine glucoside. This process is more pronounced in older lenses, possibly because of the barrier to diffusion. The barrier may also explain the increase in nuclear oxidized glutathione that is observed with age.

A retrospective job exposure matrix for estimating exposure to 2,3,7, 8-tetrachlorodibenzo-p-dioxin

BACKGROUND

A job exposure matrix was developed to estimate the 2,3, 7,8-tetrachlorodibenzo-p-dioxin exposure of 3,538 workers who produced 2,4,5-trichlorophenol and its derivatives.

METHODS

Daily TCDD exposure scores that were plant, process, and period specific were estimated for each job title as the product of 1) the concentration of TCDD (microg/g); 2) a qualitative factor to account for the extent of worker contact and 3) time exposed to TCDD contamination. Daily scores were summed to compute individual cumulative TCDD exposure scores.

RESULTS

Daily TCDD exposure scores ranged from 0.001 to 1,250. Cumulative TCDD scores ranged from 0.002 to 1,559,430. The 393 workers with records of chloracne in the TCDD exposure cohort (11%) had markedly higher cumulative scores than those with no record of chloracne (a median score of 11,546 vs. 77).

CONCLUSIONS

The cumulative TCDD exposure scores incorporate both duration and level of exposure, and permit the relative ranking of worker exposures for the evaluation of exposure-response relationships between TCDD exposure and mortality in an updated cohort study analysis.

Review and update of the results of the NIOSH medical study of workers exposed to chemicals contaminated with 2,3,7,8-tetrachlorodibenzodioxin

In 1987, the National Institute for Occupational Safety and Health conducted a cross-sectional medical study to examine the long-term health effects of occupational exposure to chemicals and materials contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This study compared living workers employed more than 15 years earlier in the production of sodium trichlorophenol (NaTCP), and 2,4,5-trichlorophenoxyacetic ester (2,4,5-T ester) with an unexposed comparison group. Health status of the worker and comparison populations was collected through a comprehensive set of standardized interviews and medical examinations. Lipid adjusted serum TCDD levels were also measured. Workers had a statistically significantly elevated mean serum lipid-adjusted TCDD level (workers = 220 pg per g of lipid [range = not detected-3,400 pg per g of lipid], and referents 7 pg per g of lipid [range not detected-20 pg per g of lipid], P < 0.001). Compared to a community-based referent population, the prevalence of chronic bronchitis, chronic obstructive pulmonary disease, peripheral neuropathy, depression, cardiovascular outcomes (myocardial infarction, angina, cardiac arrhythmias, hypertension, and abnormal peripheral arterial flow), abnormal porphyrin levels, and abnormal ventilatory function parameters FEV1.0, FVC, or FEV1.0/FVC% in workers, was not statistically significantly different. In contrast, relationships were observed between serum 2,3,7,8-TCDD levels and the enzyme gamma-glutamyltransferase (GGT), the reproductive hormones serum testosterone, luteinizing, and follicle-stimulating hormones, and abnormal high-density lipoprotein concentration, counts of CD3/Ta1 cells (helper lymphocytes), and fasting serum glucose levels. Current diagnosis of chloracne was associated with the highest levels of serum 2,3,7,8-TCDD. Analysis of other endpoints continues.

Human health effects after exposure to 2,3,7,8-TCDD

In 1949, the first descriptions of human exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD)-contaminated chemicals were reported after a trichlorophenol reactor explosion in Nitro, West Virginia, USA. Reported non-cancer health effects included a range of conditions affecting most systems. Additional reports of the health consequences of exposure continued through the remainder of the century. The majority of effects have been reported among highly exposed groups including occupational populations, such as chemical production workers, pesticide applicators, and individuals who handled or were exposed to materials treated with 2,3,7,8-TCDD-contaminated pesticides, and among residents of communities contaminated with tainted waste oil (Missouri, USA) and industrial effluent (Seveso, Italy). For only six exposed populations were biological measurements of 2,3,7,8-TCDD-contaminated collected and used to examine the relationship between non-cancer health effects and exposure. Of the many non-cancer health effects thought to be associated with 2,3,7,8-TCDD exposure, only chloracne, elevations in GGT and triglyceride levels, and alterations in FSH and LH were related to serum 2,3,7,8-TCDD levels. Mortality from cardiovascular diseases also appeared to be elevated among cohorts of exposed chemical workers and Seveso residents. Continued surveillance of the health of exposed populations will be useful in identifying the long-term effects of both high and low 2,3,7,8-TCDD exposure.

Age-related changes in the kinetics of water transport in normal human lenses

Magnetic resonance microscopy (MRM) has been used to study the kinetics of water transport in human eye lenses. Fresh lenses obtained from the Queensland Eye Bank were incubated at 34.5 degrees C in artificial aqueous humour (AAH) containing nutrients and metabolites similar to those that are present in vivo. MR images were acquired over approximately a 20 hr period following replacement of H(2)O based AAH with deuterium oxide (D(2)O) based AAH. NMR signal intensity from the lenses decreased with time corresponding to a decrease in concentration of H(2)O within the lenses. A statistically significant correlation (P<0.001) was found between the rate of NMR signal loss from the lens nuclei and increasing age of the lenses. The results show that as lenses age, there is a reduction in the rate at which water and presumably also water soluble low molecular weight metabolites, can enter the cells of the lens nucleus via the epithelium and cortex. A decrease in the rate of transport of water, nutrients and anti-oxidants (e.g. glutathione) would be expected to lead to progressive oxidative damage to lenses with age, and may ultimately contribute to presbyopia and senile nuclear cataract.

Evaluation of diabetes mellitus, serum glucose, and thyroid function among United States workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

OBJECTIVE

Some studies suggest that exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) may affect glucose metabolism and thyroid function. To further assess the relation between exposure to TCDD and endocrine function, data from the largest morbidity study of industrial workers exposed to TCDD were examined.

METHODS

A cross sectional study of workers employed > 15 years earlier in the manufacture of 2,4,5-trichlorophenol or one of its derivatives at two United States chemical plants was conducted. The referent group consisted of people with no occupational exposure to phenoxy herbicides and were recruited from the neighbourhoods where the workers lived.

RESULTS

A total of 281 workers and 260 unexposed referents participated. The mean current serum lipid adjusted TCDD concentration among workers was 220 pg/g lipid, and among referents was 7 pg/g lipid (p < 0.05). The half life extrapolated TCDD concentrations (the estimated TCDD concentration when occupational exposure to TCDD stopped) among workers averaged 1900 pg/g lipid (range: not detected--30,000 pg/g lipid). Overall, the prevalence of diabetes mellitus was not significantly different between the workers and referents. Also, there was not a significant positive trend between prevalence of diabetes and increasing serum TCDD concentration. However, diabetes was found in six of 10 (60%) workers with current serum TCDD concentrations > 1500 pg/g lipid. After excluding subjects being treated for diabetes, workers in the group with the highest half life extrapolated TCDD concentrations had a significantly increased adjusted mean serum glucose concentration compared with referents (p = 0.03). Workers were also found to have a significantly higher adjusted mean free thyroxine index compared with referents (p = 0.02), especially among workers in the group with the highest half life extrapolated TCDD concentrations. However, no evidence was found that workers exposed to TCDD were at increased risk of thyroid disease.

CONCLUSIONS

These findings provide modest evidence that exposure to TCDD may affect thyroid function and glucose metabolism.

An impediment to glutathione diffusion in older normal human lenses: a possible precondition for nuclear cataract

Human age-related nuclear cataract is associated with progressive and widespread oxidation of proteins, particularly in the centre of the lens. The reasons for the onset of cataract and why this disease should take place only in the lenses of older individuals remain unclear. However, a common feature of nuclear cataract is the low concentration of reduced glutathione (GSH) in the centre of the lens. GSH is the principal lenticular antioxidant of the lens and it is synthesized and regenerated in the lens cortex. In this study we investigated the diffusion of glutathione within the human lens as a function of age. Normal human lenses were incubated in artificial aqueous humor containing [35S]cysteine and the label was metabolically incorporated into GSH. After 48-h incubation, lenses were sectioned and phosphorimaging was used to determine the distribution of 35S label. In young lenses, label appeared to diffuse uniformly throughout the whole lens. By contrast, in lenses over the age of 30, very little 35S had penetrated to the centre of the lens. A distinct zonal pattern of label distribution was noted in the older lenses after 48 h incubation, which had dimensions of approximately 7.2 mm (diameter) by 2.8 mm (axial). In some older lenses this pattern was noticeable even after 96-h incubation. Thus a barrier to the diffusion of GSH was observed in older normal lenses which was not present in younger lenses. Furthermore, the internal zone thus delineated has dimensions that coincide with those of the coloured and sclerotic zone present in nuclear cataract lenses. Since nuclear cataract is a disease of the elderly, and maintenance of GSH is known to be vital for lens clarity, we propose that the development of a barrier to the movement of GSH from its site of synthesis and regeneration in the cortex, into the nucleus in older normal lenses, may over time allow oxidative modification of protein to take place in the nucleus, resulting ultimately in nuclear cataract.

Immunological markers among workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

OBJECTIVES

To examine the association of immune cell number and function with occupational exposure to substances contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

METHODS

A cross sectional medical survey. The exposed participants were employed at two chemical plants between 1951 and 1972 in the manufacture of 2,4,5-trichlorophenate and its derivatives. The reference group consisted of people with no occupational exposure to phenoxy herbicides who lived within the communities of the workers. Data from a total of 259 workers and 243 unexposed referents were included in the analysis of immune function. Laboratory tests for immune status included enumeration of circulating leukocyte and lymphocyte populations, proliferative responses of circulating lymphocytes to mitogens and antigens, and serum concentrations of the major immunoglobulins and complement factor C3.

RESULTS

The workers had substantial exposure to substances contaminated with TCDD, as indicated by a lipid adjusted mean serum TCDD concentration of 229 ppt compared with a mean of 6 ppt in the unexposed referents. Workers were divided into categories based on their serum TCDD concentration. For all categories except the lowest, with values of serum TCDD comparable with the unexposed referents, there were increased odds of having lower counts of CD26 cells (activated T cells) (odds ratio (OR) 1.0, 95% confidence interval (95% CI) 0.5 to 1.8 for TCDD < 20 ppt; OR 1.6, 95% CI 0.8 to 3.2 for TCDD 20-51 ppt; OR 2.7, 95% CI 1.4 to 5.1 for TCDD 52-125 ppt; OR 2.6, 95% CI 1.4 to 4.9 for TCDD 125-297 ppt; OR 2.4, 95% CI 1.3 to 4.6 for TCDD 298-3389 ppt). A less consistent finding was decreased spontaneous proliferation of cultured lymphocytes. However, increases were found in proliferation of lymphocytes in response to concanavalin and pokeweed in workers in the high TCDD category. Age, cigarette smoking, and alcohol were significant predictors of several immunological outcomes.

CONCLUSIONS

Associations between serum TCDD concentration and both a decrease in circulating CD26 cells and decreased spontaneous background proliferation were the major findings of this study. These results are unlikely to be of clinical importance but may reflect limited evidence for an association between immunological changes in workers and high serum concentrations of TCDD, or chance findings resulting from the evaluation of multiple immunological variables.

Evaluation of cardiovascular outcomes among U.S. workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

Some animal studies and some human studies suggest that exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) may be associated with adverse effects on the cardiovascular system. As part of a cross-sectional medical study comparing workers employed 15 years earlier in the manufacture of 2,4,5-trichlorophenol or one of its derivatives at two U.S. chemical plants with an unexposed comparison group, we examined the association between TCDD exposure and various cardiovascular outcomes. A total of 281 workers and 260 unexposed referents participated. The workers had substantial exposure to TCDD, as demonstrated by significantly elevated mean serum TCDD concentration of 220 pg/g of lipid, compared with 7 pg/g of lipid among the referents. No significant association was found between TCDD exposure and any of the cardiovascular outcomes including myocardial infarction, angina, cardiac arrhythmias, hypertension, and abnormal peripheral arterial flow. Although our study had sufficient statistical power to detect an elevated risk for cardiac arrhythmias, hypertension, and abnormal peripheral arterial flow, it had low power (approximately 50%) to detect an elevated risk for myocardial infarction and angina. Our review of the literature suggests that our negative findings are consistent with those from other cross-sectional medical studies. Although several mortality studies of TCDD-exposed cohorts found significantly increased risks for cardiovascular disease mortality, similar increased risks were not observed in other mortality studies. The data available do not provide definitive conclusions but indicate that further examination of the association between TCDD exposure and cardiovascular disease should be pursued.

Proportionate mortality among unionized construction ironworkers

This report presents the results of proportionate mortality ratios (PMR) and proportionate cancer mortality ratios (PCMR) among 13,301 members of the International Union of Bridge, Structural, and Ornamental Ironworkers who had been members for a minimum of 1 year, were actively paying dues into the death beneficiary fund, and had died between 1984-1991. Using the United States proportionate mortality rates as the comparison population, statistically significant elevated risks, using 95% confidence intervals (CI), were observed for several types of injuries: falls (N = 259, PMR = 3.57, CI = 3.15-4.03), transportation injuries (N = 363, PMR = 1.22, CI = 1.10-1.35), and other types of injuries (N = 225, PMR = 1.63, CI = 1.43-1.86). The deaths due to falls were significantly elevated for each 10-year age group under age 60 (PMR > 7.00) and for those workers with < 20 years in the union (PMR > 6.00). Elevated mortality risks were also observed for all malignant neoplasms combined (N = 3,682, PMR = 1.09, CI = 1.06-1.13) as well as for site-specific malignant neoplasms of the lung (N = 1,523, PMR = 1.28, CI = 1.21-1.35), pleural mesothelioma (N = 7, PMR = 1.67, CI = 0.67-3.44) and "other and unspecified sites" (N = 307, PMR = 1.29, CI = 1.15-1.44). The category "pneumoconiosis and other respiratory diseases" was also significantly elevated (N = 690, PMR = 1.11, CI = 1.03-1.20); in this category, deaths due to asbestosis had the greatest elevated risk (N = 10, PMR = 3.56, CI = 1.70-6.54). No elevation in risk was found for kidney cancer or for chronic nephritis which were of interest because of Ironworkers' potential exposure to lead. The present study underscores the importance of fall protection and other injury prevention efforts in the construction industry, as well as the need to control airborne exposures to asbestos, welding fumes and other respirable disease hazards.

Tradeswomen's perspectives on occupational health and safety: a qualitative investigation

Qualitative research methods were used to determine the health and safety concerns of women employed in the construction trades. Major categories of concern were identified, including: 1) exposure to chemical and physical agents; 2) injuries from lifting/bending/ twisting, falling, and lacerations; 3) lack of proper education and training; and 4) the health and safety risks related specifically to tradeswomen. Many of the issues identified by the workers are amenable to change through either engineering, behavioral, or administrative interventions.

Evaluation of serum lipid concentrations among U.S. workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

2,3,7,8-Tetrachlorodibenzo-p-dioxin alters lipid metabolism in animals; however, evidence for such an effect in humans is conflicting. This conflict was addressed using data from a cross-sectional medical study conducted between 1987 and 1988. The exposed participants had been employed at least 15 y earlier in the manufacture of 2,4,5-trichlorophenol or one of its derivatives at two chemical plants in the United States. A total of 281 workers and 260 unexposed referents participated. Workers had substantial exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin, evidenced by a median serum 2,3,7,8-tetrachlorodibenzo-p-dioxin concentration of 406.6 femtograms/gram of serum (fg/g serum), compared with 36.9 fg/g serum among the referents. A slight association between triglyceride concentration and serum 2,3,7,8-tetrachlorodibenzo-p-dioxin concentration was found (p = .05). Over the range of observed 2,3,7,8-tetrachlorodibenzo-p-dioxin values (i.e., 37-19000 fg/g serum), triglyceride concentration increased only about 0.4 mmol/I. No association was found between an abnormally elevated triglyceride (i.e., > 2.82 mmol/I) concentration and serum 2,3,7,8-tetrachlorodibenzo-p-dioxin concentration. An association was also found between serum 2,3,7,8-tetrachlorodibenzo-p-dioxin concentration and an abnormal high-density lipoprotein concentration (p = .09). in summary, there was evidence of an effect on lipid metabolism in a group of workers with high serum 2,3,7,8-tetrachlorodibenzo-p-dioxin concentrations. The influence of serum 2,3,7,8-tetrachlorodibenzo-p-dioxin on lipid concentrations, however, was small, compared with the influence of other factors.

Proportionate mortality among construction laborers

This report presents the results of proportionate mortality ratio (PMR) analyses and proportionate cancer mortality ratio (PCMR) analyses among the 11,685 members of the Laborers' International Union of North America (LIUNA), who died between 1985-1988, using U.S. proportionate mortality rates as the comparison population. Statistically significant elevated mortality risks were observed for all malignant neoplasms (N = 3285, PMR = 1.13, CI = 1.09-1.17), as well as for site-specific neoplasms of the lung (N = 1208, PCMR = 1.06, CI = 1.00-1.12), stomach (N = 170, PCMR = 1.44, CI = 1.23-1.68), and thyroid gland (N = 10, PCMR = 2.24, CI = 1.07-4.12). The PCMRs for these malignant neoplasms were elevated among both white and non-white males, regardless of length of union membership, in most 10-year categories of age at death above 40 and for the three largest LIUNA regions examined. The study also observed 20 mesothelioma deaths, which indicated that some LIUNA members had been previously exposed to asbestos. Statistically significant elevated risks were also observed for deaths from transportation injuries (N = 448, PMR = 1.37, CI = 1.25-1.51), falls (N = 85, PMR = 1.34, CI = 1.07-1.66), and other types of injuries (N = 245, PMR = 1.61, CI = 1.42-1.83). The deaths due to injuries were most often observed among those members who had the shortest amount of time within the union, were younger, and first entered the union after 1955. This is the first study that has examined the general mortality experience limited to construction laborers only (Bureau of Census code 869).

Ethical considerations, confidentiality issues, rights of human subjects, and uses of monitoring data in research and regulation

Biomarkers are potentially powerful tools for use in research and regulation. Their derivation from biologic specimens collected from human subjects does, however, present many ethical implications. Ethical issues are relevant in almost each facet of human biomarker research studies: design, identification and recruitment of subjects, handling and use of the data, and interpretation and communication of results. Researchers also face a number of dilemmas when considering the use of human biologic specimens and new biomarkers. The mere fact that such markers are the result of measurements in human specimens gives the appearance of being more accurate than traditional sources of information such as questionnaires or environmental monitoring; yet, this may not always be the case. The meaning of the results of biomarker studies may be unclear because the purpose of the study is usually for research rather than clinical purposes. There generally are no established normal ranges for biomarkers and the interpretation of findings are often difficult. Researchers may not communicate these results to subjects or consider followup action because the task may be too difficult or undefined, or the reaction of the subject cannot be anticipated. A wide range of practices in this regard exists among researchers. Many questions remain unanswered about the use of biologic specimens. These include questions of ownership and access to specimens. Related to this is the question of whether specimens collected for one research purpose can be used for an entirely different research purpose. This is still an open question.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of P-450 in workers exposed to dioxin

OBJECTIVES

To examine the effects of occupational exposure to substances contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on cytochrome P-4501A2 activity in a cross sectional medical survey.

METHODS

The exposed workers had been employed at two chemical plants > 15 years earlier in the manufacture of 2,4, 5-trichlorophenol and its derivatives. The control group consisted of people with no occupational exposure to phenoxy herbicides and who lived within the communities of the exposed workers. A total of 58 workers and 125 unexposed controls participated in the analysis. Cytochrome P-450 activity was assessed with test that measures caffeine metabolites in the urine. A ratio of metabolites of caffeine (CMR) constituted a measure of P-4501A2 activity.

RESULTS

Compared with the control group in multivariate logistic regression, raised non-significant associations were found for three of four categories of TCDD in exposed workers (TCDD < 20 pg/g, odds ratio (OR) 1.7, 95% confidence interval (95% CI) 0.6 to 5.0, TCDD 20-66, OR 0.3, 95% CI 0.0 to 1.7; TCDD 67-147, OR 2.3, 95% CI 0.6 to 8.8; TCDD > or = 148, OR 3.1, 95% CI 0.8 to 12.5). We found a strongly significant association of CMR and urinary cotinine, a measure of smoking, and urinary free ethanol. We found weak non-significant associations between P-4501A2 activity and increased serum TCDD among workers.

CONCLUSIONS

The absence of an association between serum TCDD and cytochrome P-4501A2 may be due to the size of the study, insensitivity of the CMR to assess cytochrome P-4501A2 activity, or inadequate levels of exposure, although these were among the highest in human groups tested.

Evaluation of porphyria cutanea tarda in U.S. workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

A cross-sectional medical study was performed to evaluate whether occupational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-contaminated substances is associated with porphyria cutanea tarda or porphyrinuria. The exposed participants were employed more than 15 years earlier in the manufacture of sodium trichlorophenol and its derivatives. The referent group consisted of individuals with no occupational exposure to phenoxy herbicides. A total of 281 workers and 260 referents participated. The pattern of urinary porphyrin excretion for each participant was assessed to determine if symptomatic or subclinical porphyria cutanea tarda was present. None of the participants were found to have symptomatic porphyria cutanea tarda. No difference was found between workers and referents in the prevalence of subclinical porphyria cutanea tarda (odds ratio [OR] = 0.93, 95% confidence interval [CI] 0.19, 4.54). There were also no differences in the risk between workers and referents for an out-of-range urinary uroporphyrin or coproporphyrin concentration. In conclusion, this study did not find an elevated risk for porphyria cutanea tarda or porphyrinuria among workers with high serum TCDD levels. Our review of the literature indicates that there is insufficient evidence available to convincingly support or refute an association in humans between TCDD exposure and porphyria cutanea tarda or porphyrinuria.

Total serum testosterone and gonadotropins in workers exposed to dioxin

Human reproductive endocrine data may be an important source of epidemiologic information in regard to the toxic potential of 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin). The association of serum dioxin with total serum testosterone, luteinizing hormone, and follicle-stimulating hormone was examined in 248 chemical production workers from New Jersey and Missouri plants and 231 nonexposed neighborhood referents who participated in a medical evaluation in 1987. In linear regression analyses, current serum dioxin was positively and significantly related to luteinizing hormone and follicle-stimulating hormone and inversely related to total testosterone after adjustment for potential confounders (p < 0.05). These trends were also apparent in logistic regression analyses, in which the authors examined the odds ratios of high luteinizing hormone (> 28 IU/liter), high follicle-stimulating hormone (> 31 IU/liter), and low testosterone (< 10.4 nmol/liter) by serum dioxin quartiles. There was a greater prevalence of high luteinizing hormone among workers in the second (odds ratio (OR) = 1.9, 95% confidence interval (CI) 0.7-5.5), third (OR = 2.5, 95% CI 0.9-7.3), and fourth (OR = 1.9, 95% CI 0.7-5.0) quartiles of serum dioxin compared with referents. For follicle-stimulating hormone, the authors observed a greater prevalence of high follicle-stimulating hormone among workers in the fourth quartile (OR = 2.0, 95% CI 0.7-5.6) compared with referents. Similarly, the prevalence of low testosterone was two to four times greater among workers in the second (OR = 3.9, 95% CI 1.3-11.3), third (OR = 2.7, 95% CI 0.9-8.2), and fourth quartiles (OR = 2.1, 95% CI 0.8-5.8) than among referents. The trends observed in these data offer human evidence of alterations in male reproductive hormone levels associated with dioxin exposure. The results support the animal literature in which dioxin-related effects have been observed on the hypothalamic-pituitary-Leydig-cell axis and on testosterone synthesis.

Knowledge of medical history information among proxy respondents for deceased study subjects

Proxy respondents were interviewed for 96 decedents in an occupational cohort. A second respondent was interviewed for 59 decedents. Medical records were reviewed to validate questionnaire information. The percentage of respondents who answered "don't know" (non-response) to questions about medical condition ranged from 5% (cancer and heart disease) to 17% (ulcers). Non-response rates were lowest among spouses, intermediate among children, parents, and siblings, and highest among other relatives and friends. Among 41-55 pairs, depending on the condition, agreement between paired respondents was excellent (kappa > 0.75) for ulcers, cancer, diabetes, and lung disease. A higher percentage of medical records was obtained for decedents with spouse respondents and for decedents with more recent dates of death. Sixty percent or more of the medical records were obtained for patients with cancer (n = 30), heart disease (n = 26), stroke (n = 9), and liver disease (n = 10). The positive predictive value of the proxy respondent information for these conditions was 93, 81, 78, and 60%, respectively.

Peripheral neuropathy after occupational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

Reports of human exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) describe signs and symptoms consistent with exposure-related peripheral neuropathy. In a cross-sectional study, prevalence of peripheral neuropathy was measured in 265 workers exposed 15 years earlier to chemicals contaminated with TCDD and in 244 unexposed, age-, race-, gender- and community-matched comparisons. Cases of peripheral neuropathy were defined from examination, electrophysiologic and quantitative sensory tests, and symptoms. Exposure was assessed by measuring lipid-adjusted serum TCDD levels. The mean serum TCDD level for workers (220 parts per trillion (ppt)) was significantly higher than for referents (7 ppt) (p < .0001). Thirty-two percent of both worker and referent groups met the case definition for peripheral neuropathy. In the logistic regression analyses, serum TCDD level was not related to peripheral neuropathy. These data suggest that despite continued high serum TCDD levels, peripheral neuropathy is not a long-term sequela of high exposure to TCDD-contaminated chemicals. However, the study cannot preclude the occurrence and subsequent resolution of acute effects caused by high exposure, as experienced in Seveso and possibly by some workers, while exposed to high levels of TCDD-contaminated substances.

Hepatic and gastrointestinal effects in an occupational cohort exposed to 2,3,7,8-tetrachlorodibenzo-para-dioxin

OBJECTIVE

To examine the effect of occupational exposure to substances contaminated with 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) on the liver and gastrointestinal system.

DESIGN

A medical survey.

PARTICIPANTS

The exposed participants were employed at two chemical plants more than 15 years earlier in the manufacture of sodium trichlorophenol and its derivatives. The reference group consisted of individuals with no occupational exposure to phenoxy herbicides and who lived within the communities of the workers. A total of 281 workers and 260 unexposed referents participated in the medical study.

MEASUREMENTS AND MAIN RESULTS

The workers had substantial exposure to substances contaminated with TCDD, as evidenced by a mean serum TCDD level, lipid adjusted, of 220 pg per gram of lipid compared with a mean of 7 pg per gram of lipid in the referents. Compared with the unexposed reference group, workers had a statistically significantly elevated risk for an out-of-range gamma-glutamyltransferase (GGT) level (odds ratio, 2.27; 95% confidence interval, 1.17 to 4.39 [unadjusted for confounders]). In multivariate analyses run with logistic regression, a statistically significant interaction was found between TCDD exposure and lifetime alcohol consumption, indicating that the elevated risk for an out-of-range GGT was confined to those workers with a history of alcohol consumption and that the risk among the alcohol-consuming workers for an out-of-range GGT increased with increasing TCDD level. No difference was found between workers and referents for any of the other liver and gastrointestinal outcomes of interest.

CONCLUSIONS

This study found no evidence of an elevated risk for clinical hepatic or gastrointestinal disease in a group of workers with high exposure to TCDD. However, TCDD-exposed workers with a history of sufficient alcohol consumption were found to have a statistically significantly elevated risk for an out-of-range GGT compared with referents.

Evaluation of chronic bronchitis, chronic obstructive pulmonary disease, and ventilatory function among workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is produced as an undesirable contaminant in the manufacture of 2,4,5-trichlorophenol (TCP) and its derivatives. There is considerable concern about the health effects that may be associated with exposure to TCDD-contaminated substances. A cross-sectional medical study that included a comprehensive medical history, medical examination, and measurement of pulmonary function was conducted on workers employed more than 15 yr earlier in the manufacture of NaTCP and its derivatives at two chemical plants. The workers had substantial exposure to substances contaminated with TCDD, as evidenced by a mean serum TCDD level, lipid adjusted, of 200 ppt compared with a mean of 7 ppt in the unexposed reference group. The comparison group consisted of individuals with no occupational exposure to phenoxy herbicides who lived in the same communities as the workers. A total of 281 workers and 260 unexposed referents participated in the medical examination. Logistic and linear regression analyses, which contained categorical and continuous measures of TCDD exposure, were performed to control for important confounders, including cigarette and alcohol consumption. No difference was found between workers and referents in the risk for chronic bronchitis or COPD. Analysis of the ventilatory function data revealed no association between history of exposure to substances contaminated with TCDD and the forced expiratory volume at one second (FEV1), forced vital capacity (FVC), or the ratio of FEV1 to FVC (FEV1/FVC%).

Cancer mortality in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

BACKGROUND

In both animal and epidemiologic studies, exposure to dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD) has been associated with an increased risk of cancer.

METHODS

We conducted a retrospective cohort study of mortality among the 5172 workers at 12 plants in the United States that produced chemicals contaminated with TCDD. Occupational exposure was documented by reviewing job descriptions and by measuring TCDD in serum from a sample of 253 workers. Causes of death were taken from death certificates.

RESULTS

Mortality from several cancers previously associated with TCDD (stomach, liver, and nasal cancers, Hodgkin's disease, and non-Hodgkin's lymphoma) was not significantly elevated in this cohort. Mortality from soft-tissue sarcoma was increased, but not significantly (4 deaths; standardized mortality ratio [SMR], 338; 95 percent confidence interval, 92 to 865). In the subcohort of 1520 workers with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency, however, mortality was significantly increased for soft-tissue sarcoma (3 deaths; SMR, 922; 95 percent confidence interval, 190 to 2695) and for cancers of the respiratory system (SMR, 142; 95 percent confidence interval, 103 to 192). Mortality from all cancers combined was slightly but significantly elevated in the overall cohort (SMR, 115; 95 percent confidence interval, 102 to 130) and was higher in the subcohort with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency (SMR, 146; 95 percent confidence interval, 121 to 176).

CONCLUSIONS

This study of mortality among workers with occupational exposure to TCDD does not confirm the high relative risks reported for many cancers in previous studies. Conclusions about an increase in the risk of soft-tissue sarcoma are limited by small numbers and misclassification on death certificates. Excess mortality from all cancers combined, cancers of the respiratory tract, and soft-tissue sarcoma may result from exposure to TCDD, although we cannot exclude the possible contribution of factors such as smoking and occupational exposure to other chemicals.

Chloracne associated with employment in the production of pentachlorophenol

To evaluate the association between exposure to pentachlorophenol (PCP) and the occurrence of chloracne, we studied the medical and personnel records for individuals employed in the manufacturing of PCP. Forty-seven cases of chloracne were identified among 648 workers (7.0%) assigned to PCP production at a single plant between 1953 and 1978. The annual incidence rate varied considerably, ranging from 0 (in 1953) to 1.46 (in 1978). No linear trend in the risk of chloracne was observed with the duration of employment in the pentachlorophenol department. Workers with a documented episode of direct skin contact with PCP had a significantly increased risk of chloracne compared with workers who did not have a documented episode of direct skin contact (cumulative incidence ratio = 4.6; 95% confidence interval 2.6-8.1). Our results confirm that chloracne is associated with exposure to PCP contaminated with hexachlorinated, heptachlorinated, and octachlorinated dibenzo-p-dioxins and dibenzofurans.

Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

Review of employment and chemical production records at a Missouri chemical plant and of questionnaires with self-reported occupational exposure to 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2,3,7,8-TCDD) for 16 Missouri workers has explained the wide diversity of 2,3,7,8-TCDD levels previously reported in the workers' adipose tissue (3.5-750 ppt on whole-weight basis). We show that the highest exposures reported to date in the United States occurred in a group of nine production workers who made products contaminated with 2,3,7,8-TCDD. The nine workers had adipose tissue levels with a mean of 246 ppt and a range of 42 to 750 ppt. Seven persons who worked at the same chemical company, but not in the 2,3,7,8-TCDD-contaminated process, had a mean of 8.7 ppt and a range of 3.5 to 25.8 ppt. We also report serum levels of 2,3,7,8-TCDD in these individuals. The adipose tissue from a subset of four production workers with elevated levels of 2,3,7,8-TCDD and seven Missouri residents with normal 2,3,7,8-TCDD levels was also analyzed for other isomers of the PCDDs and PCDFs. The mean adipose tissue level of 2,3,7,8-TCDD in the subset of production workers was 45 times higher than the mean level in the unexposed Missouri residents, but similar levels of the other PCDDs and PCDFs were found in both groups.

An investigation of mortality from cancer and other causes of death among workers employed at an east Texas chemical plant

The cause-specific mortality of 2,510 males employed at an east Texas chemical plant was examined in a historical prospective study to evaluate a suspected increase in deaths from multiple myeloma and brain cancer. Potential exposures from chemicals, either used in manufacturing processes or produced during the study period 1952-1977, included the fuel additive tetraethyl lead, ethylene dibromide and dichloride, inorganic lead, and vinyl chloride monomer. Overall mortality for all workers (156 observed vs. 211.14 expected) and for workers first employed between 1952 and 1959 (131 observed vs. 167.33 expected) when tetraethyl lead was the single major product was lower than expected when compared to the United States general population. There were no significant increases in mortality from malignancies or other causes of death. The deficits may be due to the small number of total deaths, and the low power for detecting excess risk of mortality from multiple myeloma (Z1-beta = 27, alpha = .05), brain cancer (Z1-beta = 31, alpha = .05), or other rare causes of death; lack of complete workplace exposure data for production workers; and the absence of historical measurements on the extent of environmental exposure to tetraethyl lead and other chemicals.