Evaluation of Data Sources for Carbon Monoxide Poisoning Surveillance in New York City.

CONTEXT: Carbon monoxide (CO) exposure can be life-threatening. Suspected and confirmed cases of CO poisoning warranting health care in New York City (NYC) are reportable to the NYC Poison Control Center (PCC). OBJECTIVES: We evaluated 4 hospital-based sources of CO surveillance data to identify ways to improve data capture and reporting. DESIGN: Suspected and confirmed CO poisoning records from October 2015 through December 2016 were collected from the NYC emergency department (ED) syndromic surveillance system, New York State Statewide Planning and Research Cooperative System (SPARCS) ED billing data, NYC PCC calls made from hospitals, and the Electronic Clinical Laboratory Reporting System (ECLRS). Syndromic and SPARCS records were person- and visit-matched. SPARCS and ECLRS records were also matched to PCC records on combinations of name, demographic characteristics, and visit information. SETTING: Hospitals in NYC. PARTICIPANTS: Individuals who visited NYC hospitals for CO-related health effects. MAIN OUTCOME MEASURES: We assessed the validity of syndromic data, with SPARCS records as the gold standard. We matched SPARCS and ECLRS records to PCC records to analyze reporting rates by case characteristics. RESULTS: The sensitivity of syndromic surveillance was 60% (225 true-positives detected among 372 visit-matched SPARCS cases), and positive predictive value was 46%. Syndromic records often missed CO flags because of a nonspecific or absent International Classification of Diseases code in the diagnosis field. Only 15% of 428 SPARCS records (total includes 56 records not visit-matched to syndromic) and 16% of 199 ECLRS records were reported to PCC, with male sex and younger age associated with higher reporting. CONCLUSIONS: Mandatory reporting makes PCC useful for tracking CO poisoning in NYC, but incomplete reporting and challenges in distinguishing between confirmed and suspected cases limit its utility. Simultaneous tracking of the systems we evaluated can best reveal surveillance patterns.

Impact of a Municipal Policy Restricting Trans Fatty Acid Use in New York City Restaurants on Serum Trans Fatty Acid Levels in Adults.

OBJECTIVES: To estimate the impact of the 2006 policy restricting use of trans fatty acids (TFAs) in New York City restaurants on change in serum TFA concentrations in New York City adults. METHODS: Two cross-sectional population-based New York City Health and Nutrition Examination Surveys conducted in 2004 (n = 212) and 2013-2014 (n = 247) provided estimates of serum TFA exposure and average frequency of weekly restaurant meals. We estimated the geometric mean of the sum of serum TFAs by year and restaurant meal frequency by using linear regression. RESULTS: Among those who ate less than 1 restaurant meal per week, geometric mean of the sum of serum TFAs declined 51.1% (95% confidence interval [CI] = 42.7, 58.3)-from 44.6 (95% CI = 39.7, 50.1) to 21.8 (95% CI = 19.3, 24.5) micromoles per liter. The decline in the geometric mean was greater (P for interaction = .04) among those who ate 4 or more restaurant meals per week: 61.6% (95% CI = 55.8, 66.7) or from 54.6 (95% CI = 49.3, 60.5) to 21.0 (95% CI = 18.9, 23.3) micromoles per liter. CONCLUSIONS: New York City adult serum TFA concentrations declined between 2004 and 2014. The indication of greater decline in serum TFAs among those eating restaurant meals more frequently suggests that the municipal restriction on TFA use was effective in reducing TFA exposure. Public Health Implications. Local policies focused on restaurants can promote nutritional improvements.

Tracking Declines in Mercury Exposure in the New York City Adult Population, 2004-2014.

Mercury is a toxic metal that can be measured in human blood and urine. Population-based biomonitoring from 2004 guided New York City (NYC) Department of Health and Mental Hygiene (DOHMH) efforts to reduce exposures by educating the public about risks and benefits of fish consumption-a predominant source of exposure in the general population-and removing mercury-containing skin-lightening creams and other consumer products from the marketplace. We describe changes in exposures over the past decade in relation to these local public health actions and in the context of national changes by comparing mercury concentrations measured in blood (1201 specimens) and urine (1408 specimens) from the NYC Health and Nutrition Examination Survey (NYC HANES) 2013-2014 with measurements from NYC HANES 2004 and National Health and Nutrition Examination Surveys (NHANES) 2003-2004 and 2013-2014. We found that NYC adult blood and urine geometric mean mercury concentrations decreased 46% and 45%, respectively. Adult New Yorkers with blood mercury concentration ≥ 5 µg/L (the New York State reportable level) declined from 24.8% (95% CL = 22.2%, 27.7%) to 12.0% (95% CL = 10.1%, 14.3%). The decline in blood mercury in NYC was greater than the national decline, while the decline in urine mercury was similar. As in 2004, Asian New Yorkers had higher blood mercury concentrations than other racial/ethnic groups. Foreign-born adults of East or Southeast Asian origin had the highest prevalence of reportable levels (29.7%; 95% CL = 21.0%, 40.1%) across sociodemographic groups, and Asians generally were the most frequent fish consumers, eating on average 11 fish meals in the past month compared with 7 among other groups (p < 0.001). Fish consumption patterns were similar over time, and fish continues to be consumed more frequently in NYC than nationwide (24.7% of NYC adults ate fish ten or more times in the past 30 days vs. 14.7% nationally, p < 0.001). The findings are consistent with the hypothesis that blood mercury levels have declined in part because of local and national efforts to promote consumption of lower mercury fish. Local NYC efforts may have accelerated the reduction in exposure. Having "silver-colored fillings" on five or more teeth was associated with the highest 95th percentile for urine mercury (4.06 µg/L; 95% CL = 3.1, 5.9). An estimated 5.5% of the adult population (95% CL = 4.3%, 7.0%) reported using a skin-lightening cream in the past 30 days, but there was little evidence that use was associated with elevated urine mercury in 2013-14.

Declines in adult blood lead levels in New York City compared with the United States, 2004-2014.

OBJECTIVES: To assess changes in lead exposure in the New York City (NYC) adult population over a 10-year period and to contrast changes with national estimates, overall, and by socio-demographics and smoking status. METHODS: We used measurements of blood lead levels (BLLs) from NYC resident adults who participated in the NYC Health and Nutrition Examination Surveys (HANES) in 2004 and 2013-2014. We compared estimates of geometric means (GM), 95th percentiles, and prevalence of BLL ≥ 5 µg/dL overall and by subgroups over time, with adults who participated in the National HANES (NHANES) 2001-2004 and 2011-2014. RESULTS: The GM BLLs among NYC adults declined from 1.79 µg/dL in 2004 to 1.13 µg/dL in 2013-2014 (P < .0001). The declines over this period ranged from 30.1% to 43.2% across socio-demographic groups and smoking status (P < .0001 for all comparisons), and were slightly greater than declines observed nationally. The drop in prevalence of elevated BLLs (≥ 5 µg/dL) was also greater in NYC (4.8-0.5%), compared with NHANES (3.8-2.0%). By 2013-2014, NYC adults with lower annual family income (< $20,000) no longer had higher GM BLLs relative to those with higher incomes (≥ $75,000), a disparity improvement not observed nationally. Likewise, GM BLLs and 95th percentiles for non-Hispanic black adults in NYC were lower than GM BLLs for non-Hispanic white adults. Non-Hispanic Asian adults had the highest GM BLLs compared with other racial/ethnic groups, both in NYC in 2013-14 and nationally in 2011-2014 (1.37 µg/dL, P = .1048 and 1.22 µg/dL, P = .0004, respectively). CONCLUSION: The lessening of disparity in lead exposure across income groups and decreasing exposure at the high end of the distribution among non-Hispanic black and Asian adults in NYC suggest that regulatory and outreach efforts have effectively targeted these higher exposure risk groups. However, Asian adults still had the highest average BLL, suggesting a need for enhanced outreach to this group. Local surveillance remains an important tool to monitor BLLs of local populations and to inform initiatives to reduce exposures in those at highest risk.

Using Tracking Data to Promote Environmental Public Health Through Regulatory and Legislative Processes in New York City.

Legislation and regulation are powerful tools for decreasing health risks from environmental hazards. Legislation is enacted by an elected body, and regulations are issued by an agency in the executive branch delegated authority by the legislature to carry out enacted laws. The New York City (NYC) Environmental Public Health Tracking Program makes data and analytic findings available to policy makers to inform development of sound and effective environmental health legislation and regulation. Tracking data and associated science create awareness of environmental hazards and health impacts, guide strategies for mitigating hazards, and sustain support for effective law by documenting beneficial impacts on the environment and health. We describe how environmental and health surveillance data and analytic findings have informed legislation and regulations related to restaurant food safety and air pollution control in NYC. Using data to guide legislative and regulatory processes helps ensure that policy decisions and directions are based on objective evidence.

Impact of a letter-grade program on restaurant sanitary conditions and diner behavior in New York City.

OBJECTIVES: We evaluated the impact of the New York City restaurant letter-grading program on restaurant hygiene, food safety practices, and public awareness. METHODS: We analyzed data from 43,448 restaurants inspected between 2007 and 2013 to measure changes in inspection score and violation citations since program launch in July 2010. We used binomial regression to assess probability of scoring 0 to 13 points (A-range score). Two population-based random-digit-dial telephone surveys assessed public perceptions of the program. RESULTS: After we controlled for repeated restaurant observations, season of inspection, and chain restaurant status, the probability of scoring 0 to 13 points on an unannounced inspection increased 35% (95% confidence interval [CI]=31%, 40%) 3 years after compared with 3 years before grading. There were notable improvements in compliance with some specific requirements, including having a certified kitchen manager on site and being pest-free. More than 91% (95% CI=88%, 94%) of New Yorkers approved of the program and 88% (95% CI=85%, 92%) considered grades in dining decisions in 2012. CONCLUSIONS: Restaurant letter grading in New York City has resulted in improved sanitary conditions on unannounced inspection, suggesting that the program is an effective regulatory tool.

Using tracking infrastructure to support public health programs, policies, and emergency response in New York City.

OBJECTIVE: To describe how the New York City (NYC) Tracking Program has used nationally mandated Secure Portal infrastructure and staff analytical expertise to support programs and inform policy. SETTING: The NYC Health Department assesses, investigates, and acts on a wide range of environmental concerns to protect the health of New Yorkers. DESIGN: Specific examples of highly effective policies or initiatives that relied on the NYC Tracking Program are described, including restaurant sanitary grade posting, rat indexing, converting boilers to cleaner-burning fuels, reducing exposure to mercury from fish and contaminated products, and responding to Superstorm Sandy. CONCLUSIONS: The NYC Tracking Program supports the Health Department in using inspectional, administrative, and health data to guide operations. Tracking has also allowed internal and external partners to use these data to guide policy development.

Restaurant and Staff Characteristics Related to Practices that Could Contribute to Cross-Contamination.

Foodborne illness is a persistent public health concern in the U.S.; over 800 foodborne illness outbreaks are reported to the Centers for Disease Control and Prevention (CDC) annually. Most of these outbreaks (60%) are linked with restaurants. Contamination of food with foodborne pathogens during preparation and storage is a significant contributing factor to many of these outbreaks. The CDC's Environmental Health Specialists Network (EHS-Net) collected data to identify restaurant characteristics, policies, and practices associated with contamination prevention practices. Data collectors interviewed managers and conducted kitchen observations in 312 restaurants across six EHS-Net sites in five states. Data collectors observed at least one food worker action that could lead to contamination in 63.1% of restaurants. The most frequently observed action that could lead to contamination was bare-hand or dirty glove contact with ready-to-eat food (35.9%). The estimated mean number of observed potential contamination actions was greater in restaurants that were independently owned (does not share a name and operations with other restaurants), did not require managers to be certified in food safety, did not have workers trained in food safety, did not have a handwashing policy, did not have a policy minimizing bare-hand contact with ready-to-eat foods, and had a manager with more than two years of experience at their current restaurant. These results suggest that to improve contamination prevention, the foodservice industry and food safety officials can consider supporting and encouraging strong food safety training and policies, particularly concerning hand hygiene, and targeting interventions to independent restaurants.

Observed Potential Cross-Contamination in Retail Delicatessens.

ABSTRACT: Listeria monocytogenes is a persistent public health concern in the United States and is the third leading cause of death from foodborne illness. Cross-contamination of L. monocytogenes (between contaminated and uncontaminated equipment, food, and hands) is common in delicatessens and likely plays a role in the foodborne illness associated with retail deli meats. In 2012, the Centers for Disease Control and Prevention's Environmental Health Specialists Network conducted a study to describe deli characteristics related to cross-contamination with L. monocytogenes. The study included 298 retail delis in six state and local health departments' jurisdictions and assessed how well deli practices complied with the U.S. Food and Drug Administration Food Code provisions. Among delis observed using wet wiping cloths for cleaning, 23.6% did not store the cloths in a sanitizing solution between uses. Observed potential cross-contamination of raw meats and ready-to-eat foods during preparation (e.g., same knife used on raw meats and ready-to-eat foods, without cleaning in between) was present in 9.4% of delis. In 24.6% of delis with a cold storage unit, raw meats were not stored separately from ready-to-eat products in containers, bins, or trays. A proper food safety management plan can reduce gaps in cross-contamination prevention and should include adopting procedures to minimize food safety risks, instituting training with instruction and in-person demonstrations and certifying staff on those procedures, and monitoring to ensure the procedures are followed.

Mercury and polychlorinated biphenyls in Asian market fish: a response to results from mercury biomonitoring in New York City.

In 2004, the New York City (NYC) Health and Nutrition Examination Survey measured the highest blood mercury levels in Asian and foreign-born Chinese demographic groups. Fish consumption was the strongest predictor of exposure. The survey did not inquire about consumption of individual species, and subsequent visits to fish markets serving the Asian community suggested that many popular species lack contaminant data. Our objective was to supplement existing information on contaminants in commercial fish by collecting data on species present in markets serving the Asian community. We measured total mercury and the sum of 101 polychlorinated biphenyl (PCB) congeners in 282 individual specimens of 19 species or products from retail fish markets in Chinese neighborhoods in NYC. Species were selected based on their volume in the market, and an absence or insufficiency of national data on mercury levels. PCBs were measured because they are also contaminants of concern. All measurements were made on a wet weight basis on whole fillets (with skin) or products (drained of liquid). Mean mercury levels ranged from below the limit of detection (0.004microg/g) in tilapia to 0.229microg/g in tilefish. The highest mercury level (1.150microg/g) was measured in a tilefish specimen, and mercury levels in tilefish increased with the specimen size. Mean PCB levels ranged from 1ng/g in red snapper to 98ng/g in buffalo carp. The highest PCB levels were measured in a buffalo carp (469ng/g) and a yellow croaker (495ng/g). Species-specific differences in PCB levels accounted for only 6.3% of total variability, in contrast with 39.2% for mercury. Although we did not measure high mean mercury levels in the species we sampled, frequent consumption of fish with low to moderate levels can also elevate blood mercury. The data we collected can be used to guide fish consumption in Asian communities. However, risk-benefit trade-offs also need to be considered.

Cardiovascular Health Risk Behaviors by Occupation in the NYC Labor Force.

OBJECTIVE: We explored associations between occupation and cardiovascular disease (CVD) risk behaviors including: attempted weight loss, physical activity, smoking, and restaurant meal and sugary beverage consumption. METHODS: We used NYC Health and Nutrition Examination Survey 2013 to 2014 data, and coded free-text, occupational question responses using 2010 US Census Bureau Classification. CVD risk behaviors were compared across occupational categories, using regression to adjust for demographics. RESULTS: There were health behavior differences across occupational categories. Construction/transportation/maintenance workers smoked more and were less likely than management to attempt weight loss, service workers were less likely to eat restaurant-prepared meals, sales/office workers were less likely to be physically active (all P < 0.05). Adjusting for demographics, differences in health behaviors were reduced, but remained present. CONCLUSIONS: Knowledge of occupational disparities may aid chronic disease prevention by identifying populations for targeted interventions.

Retail Deli Characteristics Associated with Sanitizing Solution Concentrations.

ABSTRACT: Listeria monocytogenes is commonly found in retail delicatessen environments. Proper types and concentrations of sanitizers must be used to eliminate this pathogen from surfaces and reduce the consumer's risk for infection. In 2012, the Environmental Health Specialists Network of the Centers for Disease Control and Prevention completed a study on practices in retail delis that can help prevent cross-contamination and growth of L. monocytogenes. The present study focuses on the sanitizing solution used in delis, given its importance to cleaning and reducing pathogen contamination in retail food environments. We identified deli, manager, and worker characteristics associated with use of improper concentrations of sanitizing solution to wipe down food contact surfaces; 22.8% of sanitizing solutions used for wiping food contact surfaces were at improper concentrations. Independent delis were more likely to use improper concentrations of sanitizing solution, as were delis that sold fewer chubs (plastic tubes of meat) per week. Use of improper sanitizing solution concentrations was associated with required food safety training for managers; additional analyses suggest that this relationship is significant for independent but not chain delis. Cleaning and sanitizing must be emphasized in food safety efforts focused on independent and smaller delis.

Hot Weather Impacts on New York City Restaurant Food Safety Violations and Operations.

Previous studies have shown that higher ambient air temperature is associated with increased incidence of gastrointestinal illnesses, possibly as a result of leaving potentially hazardous food in the temperature danger zone for too long. However, little is known about the effect of hot weather on restaurant practices to maintain safe food temperatures. We examined hot weather impacts on restaurant food safety violations and operations in New York City using quantitative and qualitative methods. We used data from 64,661 inspections conducted among 29,614 restaurants during May to September, 2011 to 2015. We used Poisson time-series regression to estimate the cumulative relative risk (CRR) of temperature-related food safety violations across a range of daily maximum temperature (13 to 40°C [56 to 104°F]) over a lag of 0 to 3 days. We present CRRs for an increase in daily maximum temperature from the median (28°C [82°F]) to the 95th percentile (34°C [93°F]) values. Maximum temperature increased the risk of violations for cold food holding above 5°C (41°F) (CRR, 1.19; 95% CI, 1.14, 1.25) and insufficient refrigerated or hot holding equipment (CRR, 2.37; 95% CI, 2.02, 2.79). We also conducted focus groups among restaurant owners and managers to aid interpretation of findings and identify challenges or knowledge gaps that prevent hot weather preparedness. Focus group participants cited refrigeration issues as a common problem during hot weather. Participants expressed the need for more guidance on hot weather and power outages to be delivered concisely. Our findings suggest that hotter temperatures may compromise cold and hot food holding, possibly by straining refrigeration or other equipment. The findings have public health implications because holding potentially hazardous foods in the temperature danger zone allows foodborne pathogens to proliferate and increases risk for foodborne illness. Distribution of simple guidelines that can be easily accessed during emergencies could help restaurants respond better.

Asthma diagnosed after 11 September 2001 among rescue and recovery workers: findings from the World Trade Center Health Registry.

BACKGROUND: Studies have consistently documented declines in respiratory health after 11 September 2001 (9/11) among surviving first responders and other World Trade Center (WTC) rescue, recovery, and clean-up workers. OBJECTIVES: The goal of this study was to describe the risk of newly diagnosed asthma among WTC site workers and volunteers and to characterize its association with WTC site exposures. METHODS: We analyzed 2003-2004 interview data from the World Trade Center Health Registry for workers who did not have asthma before 9/11 (n = 25,748), estimating the risk of newly diagnosed asthma and its associations with WTC work history, including mask or respirator use. RESULTS: Newly diagnosed asthma was reported by 926 workers (3.6%). Earlier arrival and longer duration of work were significant risk factors, with independent dose responses (p < 0.001), as were exposure to the dust cloud and pile work. Among workers who arrived on 11 September, longer delays in the initial use of masks or respirators were associated with increased risk of asthma; adjusted odds ratios ranged from 1.63 [95% confidence interval (CI), 1.03-2.56) for 1 day of delay to 3.44 (95% CI, 1.43-8.25) for 16-40 weeks delay. CONCLUSIONS: The rate of self-reported newly diagnosed asthma was high in the study population and significantly associated with increased exposure to the WTC disaster site. Although we could not distinguish appropriate respiratory protection from inappropriate, we observed a moderate protective effect of mask or respirator use. The findings underscore the need for adequate and timely distribution of appropriate protective equipment and the enforcement of its use when other methods of controlling respiratory exposures are not feasible.

A biomonitoring study of lead, cadmium, and mercury in the blood of New York city adults.

OBJECTIVES: We assessed the extent of exposure to lead, cadmium, and mercury in the New York City (NYC) adult population. METHODS: We measured blood metal concentrations in a representative sample of 1,811 NYC residents as part of the NYC Health and Nutrition Examination Survey, 2004. RESULTS: The geometric mean blood mercury concentration was 2.73 microg/L [95% confidence interval (CI), 2.58-2.89]; blood lead concentration was 1.79 microg/dL (95% CI, 1.73-1.86); and blood cadmium concentration was 0.77 microg/L (95% CI, 0.75-0.80). Mercury levels were more than three times that of national levels. An estimated 24.8% (95% CI, 22.2-27.7%) of the NYC adult population had blood mercury concentration at or above the 5 microg/L New York State reportable level. Across racial/ethnic groups, the NYC Asian population, and the foreign-born Chinese in particular, had the highest concentrations of all three metals. Mercury levels were elevated 39% in the highest relative to the lowest income group (95% CI, 21-58%). Blood mercury concentrations in adults who reported consuming fish or shellfish 20 times or more in the last 30 days were 3.7 times the levels in those who reported no consumption (95% CI, 3.0-4.6); frequency of consumption explained some of the elevation in Asians and other subgroups. CONCLUSIONS: Higher than national blood mercury exposure in NYC adults indicates a need to educate New Yorkers about how to choose fish and seafood to maximize health benefits while minimizing potential risks from exposure to mercury. Local biomonitoring can provide valuable information about environmental exposures.

Breast cancer risk and drinking water contaminated by wastewater: a case control study.

BACKGROUND: Drinking water contaminated by wastewater is a potential source of exposure to mammary carcinogens and endocrine disrupting compounds from commercial products and excreted natural and pharmaceutical hormones. These contaminants are hypothesized to increase breast cancer risk. Cape Cod, Massachusetts, has a history of wastewater contamination in many, but not all, of its public water supplies; and the region has a history of higher breast cancer incidence that is unexplained by the population's age, in-migration, mammography use, or established breast cancer risk factors. We conducted a case-control study to investigate whether exposure to drinking water contaminated by wastewater increases the risk of breast cancer. METHODS: Participants were 824 Cape Cod women diagnosed with breast cancer in 1988-1995 and 745 controls who lived in homes served by public drinking water supplies and never lived in a home served by a Cape Cod private well. We assessed each woman's exposure yearly since 1972 at each of her Cape Cod addresses, using nitrate nitrogen (nitrate-N) levels measured in public wells and pumping volumes for the wells. Nitrate-N is an established wastewater indicator in the region. As an alternative drinking water quality indicator, we calculated the fraction of recharge zones in residential, commercial, and pesticide land use areas. RESULTS: After controlling for established breast cancer risk factors, mammography, and length of residence on Cape Cod, results showed no consistent association between breast cancer and average annual nitrate-N (OR = 1.8; 95% CI 0.6-5.0 for > or = 1.2 vs. < .3 mg/L), the sum of annual nitrate-N concentrations (OR = 0.9; 95% CI 0.6-1.5 for > or = 10 vs. 1 to < 10 mg/L), or the number of years exposed to nitrate-N over 1 mg/L (OR = 0.9; 95% CI 0.5-1.5 for > or = 8 vs. 0 years). Variation in exposure levels was limited, with 99% of women receiving some of their water from supplies with nitrate-N levels in excess of background. The total fraction of residential, commercial, and pesticide use land in recharge zones of public supply wells was associated with a small statistically unstable higher breast cancer incidence (OR = 1.4; 95% CI 0.8-2.4 for highest compared with lowest land use), but risk did not increase for increasing land use fractions. CONCLUSION: Results did not provide evidence of an association between breast cancer and drinking water contaminated by wastewater. The computer mapping methods used in this study to link routine measurements required by the Safe Drinking Water Act with interview data can enhance individual-level epidemiologic studies of multiple health outcomes, including diseases with substantial latency.

Periodontal health and oral mucosal lesions as related to occupational exposure to acid mists.

OBJECTIVES: The association between exposure to acid mists and periodontal changes and oral mucosal lesions was measured using data from an Oral Health Promotion Program in a large metal plant. The role of sociodemographic factors, lifestyle, and oral health behavior in relation to these outcomes was also examined. METHODS: This is a cross-sectional study of 665 active male workers who volunteered to participate in the oral health program. A job exposure matrix was constructed with industrial hygienist scores and job titles to estimate years of exposure to acid mists. Oral health outcomes were identified during standardized dental examinations. Unconditional logistic regression models were utilized in the analysis. RESULTS: Duration of exposure to acid mists exposure was positively associated with oral mucosal lesions among workers without lip sealing. Only age, low salaries and oral hygiene-related variables were associated with periodontal changes, and estimates varied according to lip sealing. CONCLUSIONS: Results suggest that long-term occupational exposure to acid mists is associated with oral mucosal lesions, and that absence of lip sealing may increase the intensity of exposure.

Time-related aspects of the healthy worker survivor effect.

PURPOSE: Health is important for continued employment and therefore continued accrual of occupational exposure; furthermore, steady employment can benefit health. Consequently, bias can occur in estimates of cumulative exposure-mortality associations. This has been called the healthy worker survivor effect (HWSE). The processes associated with the HWSE tend to lead to variation in mortality rates with time-since-termination of employment, most notably a peak in mortality shortly after termination of employment. We use simulations and an empirical example to demonstrate that time-since-termination can be a confounding factor in analyses of occupational-exposure-mortality associations. METHODS: Simulation data were generated for 20,000 workers followed for 40 years under a model of no effect of employment duration (a proxy for cumulative exposure) on mortality. Proportional hazards regression methods were used to quantify exposure-mortality associations and evaluate methods to control for the HWSE. Results were derived after 100 iterations of the simulation. Relationships between employment duration and mortality were also investigated in a cohort of 122,247 male utility workers with adjustments for time since termination. RESULTS: Simulation data show a peak in mortality rates in the first year after termination of employment which declined in magnitude with continued time since termination of employment; average employment duration also declined with time since termination of employment. This led to confounding of cumulative-exposure-mortality associations, with spurious evidence of a positive association between cumulative exposure and mortality in the post-termination period. Adjustment for time-since-termination eliminated this spurious association; in contrast, adjustment for a binary indicator of employment status led to positively-biased relative rate estimates. A similar pattern was observed in analyses of utility worker data. The log relative rate of all cancer mortality is -0.12+/-0.03 per decade of employment without adjustment for time-since-termination, and -0.01+/-0.03 with adjustment for time-since-termination of employment. CONCLUSIONS: The HWSE can lead to temporal variation in mortality rates that is correlated with cumulative exposure. Under these conditions, adjusting for time-since-termination of employment may reduce bias in estimates of cumulative-exposure-mortality trends more effectively than the commonly-used method of adjusting for a binary indicator of employment status.