Mortality among workers exposed to ethylene oxide

Effect of Ethylene Oxide Exposure on Sleep Health: Using NHANES Data from 2015 to 2020

Background/Objectives: This study aims to investigate the effects of ethylene oxide (EO) exposure on sleep health, focusing on sleep duration and quality. Methods: The study analyzed data from the NHANES (National Health and Nutrition Examination Survey) 2015-2020 cycles, including 4268 participants aged 20 and older. EO exposure was measured using hemoglobin adducts of EO (HbEO), which serve as a reliable biomarker. Sleep health was assessed through self-reported questionnaires on sleep duration and quality. Participants were categorized based on sleep duration (<6 h, 6-9 h, >9 h) and symptoms of sleep disturbances. Statistical analyses employed survey-weighted logistic regression models to evaluate the associations between HbEO levels and sleep outcomes, adjusting for sociodemographic, health-related, and behavioral factors. Moreover, to examine whether the impact of ethylene oxide exposure on sleep quality and sleep duration varies by sociodemographic characteristics, stratified analyses were conducted based on gender, age, marital status, and employment type. Results: According to the results, higher EO exposure was associated with shorter sleep durations and increased likelihood of sleep disturbances. Moreover, according to sub-group analysis by sex, men with higher exposure to EO, were likely to have short sleep duration, and women with higher exposure to EO had higher risk of daytime sleepiness and sleep problems. Conclusions: The findings suggest that EO exposure may negatively impact sleep health, emphasizing the need for stricter EO exposure regulations and public health interventions to reduce associated risks.

Ethylene Oxide Hemoglobin Adducts in Cord Blood and Offspring's Size at Birth: The NewGeneris European Cohort Study

BACKGROUND

Prenatal ethylene oxide exposure may have adverse effects on fetal development. We examined the relationships between ethylene oxide hemoglobin (Hb) adduct levels and offspring's size at birth in a prospective European mother-child study.

METHODS

This study included 1106 singletons from the NewGeneris project (2006-2010) with ethylene oxide Hb adducts measured in cord blood. We examined the relationships between adduct levels and offspring's size at birth among all infants and separately among infants of nonsmokers, using linear regression models for birth weight and birth head circumference and logarithmic binomial regression models for small for gestational age. We examined potential interactions between CYP2E1 single nucleotide polymorphisms in cord blood and the effects of ethylene oxide Hb adduct levels on offspring birth size.

RESULTS

Higher quartiles of adduct levels as a measure of exposure were associated with decreasing birth weight and head circumference in the overall population. Compared to infants in the lowest quartile, those in the highest quartile exhibited lower birth weight (-70.73 g, 95% confidence interval = -141.16, -0.30) and reduced head circumference (-0.30 cm, 95% confidence interval = -0.58, -0.02). We observed similar, albeit less pronounced, patterns among infants of nonsmokers. There was no evidence of an association between ethylene oxide Hb adducts and risk of small for gestational age, nor consistent evidence of an interaction with CYP2E1 polymorphisms on the association between EO Hb adduct levels and offspring's size at birth.

CONCLUSION

Results suggest that higher ethylene oxide Hb adduct levels in cord blood are associated with a reduction in offspring birth size.

Innovative non-targeted screening approach using High-resolution mass spectrometry for the screening of organic chemicals and identification of specific tracers of soil and dust exposure in children

Environmental contamination through direct contact, ingestion and inhalation are common routes of children's exposure to chemicals, in which through indoor and outdoor activities associated with common hand-to-mouth, touching objects, and behavioral tendencies, children can be susceptible and vulnerable to organic contaminants in the environment. The objectives of this study were the screening and identification of a wide range of organic contaminants in indoor dust, soil, food, drinking water, and urine matrices (N = 439), prioritizing chemicals to assess children's environmental exposure, and selection of unique tracers of soil and dust ingestion in young children by non-targeted analysis (NTA) using Q-Exactive Orbitrap followed data processing by the Compound Discoverer (v3.3, SP2). Chemical features were first prioritized based on their predominant abundance (peak area>500,000), detection frequency (in >50% of the samples), available information on their uses and potential toxicological effects. Specific tracers of soil and dust exposure in children were selected in this study including Tripropyl citrate and 4-Dodecylbenzenesulfonic acid. The criteria for selection of the tracers were based on their higher abundance, detection frequency, unique functional uses, measurable amounts in urine (suitable biomarker), and with information on gastrointestinal absorption, metabolism, and excretion, and were further confirmed by authentic standards. We are proposing for the first time suitable unique tracers for dust ingestion by children.

Association between blood ethylene oxide levels and the prevalence of periodontitis: evidence from NHANES 2013-2014

BACKGROUND

The study aimed to establish a link between blood ethylene oxide (EO) levels and periodontitis, given the growing concern about EO's detrimental health effects.

MATERIALS AND METHODS

The study included 1006 adults from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) dataset. We assessed periodontitis prevalence across groups, used weighted binary logistic regression and restricted cubic spline fitting for HbEO-periodontitis association, and employed Receiver Operating Characteristic (ROC) curves for prediction.

RESULTS

In the periodontitis group, HbEO levels were significantly higher (40.57 vs. 28.87 pmol/g Hb, P < 0.001). The highest HbEO quartile showed increased periodontitis risk (OR = 2.88, 95% CI: 1.31, 6.31, P = 0.01). A "J"-shaped nonlinear HbEO-periodontitis relationship existed (NL-P value = 0.0116), with an inflection point at ln-HbEO = 2.96 (EO = 19.30 pmol/g Hb). Beyond this, ln-HbEO correlated with higher periodontitis risk. A predictive model incorporating sex, age, education, poverty income ratio, alcohol consumption, and HbEO had 69.9% sensitivity and 69.2% specificity. The model achieved an area under the ROC curve of 0.761.

CONCLUSIONS

These findings suggest a correlation between HbEO levels and an increased susceptibility to periodontitis.

Suitability of new and existing ambient ethylene oxide measurement techniques for cancer inhalation risk assessment

Ethylene oxide (EtO) is an industrial gas that was recently reassessed to pose significant additional cancer risk at low ambient concentrations. The objective of this study is to evaluate the capabilities of existing and novel techniques to measure ambient EtO at concentrations relevant for assessing cancer risk. We present the first comparison of background ambient EtO measurements between the standard offline TO-15 techniques and two new cavity ringdown spectroscopy (CRDS) instruments, the Picarro G2920 Ethylene Oxide Gas Analyzer and the Entanglement Technologies AROMA-ETO, at a site in Atlanta, GA. Then, we analyzed background EtO measured at EPA NATTS sites across the US. Finally, we used TO-15 measurement data to assess EtO cancer risk at three near-source sites. We find that the TO-15 method has low precision for collocated samples (NME ranges from 24% to 63%), and measurements made with TO-15 pressurized samplers are biased 27% low compared to those from TO-15 passive samplers. Both CRDS methods are biased low compared to TO-15 methods (88% and 31% low bias for Picarro and AROMA, respectively), and TO-15 methods observe a seasonal peak during summer (June to September) whereas Picarro observes no seasonal trend. From our near-source assessment, we find only one site with notable elevation in cancer risk prior to EtO controls installation. Our results suggest that measurement techniques need further development to accurately assess near-source EtO cancer risk. Because different techniques measure distinct EtO trends, EtO cancer risk studies that rely on current measurement capabilities should subtract simultaneous background observations from near-source observations measured by the same method to account for these real or artificial background trends.

A DFT and QTAIM insight into ethylene oxide adsorption on the surfaces of pure and metal-decorated inorganic fullerene-like nanoclusters

In this industrial era, the use of low-dimensional nanomaterials as gas sensors for environmental monitoring has received enormous interest. To develop an effective sensing method for ethylene oxide (EO), DFT computations are conducted using method ωB97X-D and B3LYP with 6-31G(d,p) basis set to evaluate the adsorption behavior of ethylene oxide gas on the surfaces of pristine, as well as Scandium and Titanium decorated B12N12, Al12N12, and Al12P12 nanocages. Several properties like structural, physical, and electronic are studied methodically to better understand the sensing behavior. Scandium-decorated aluminum phosphate and boron nitride nanocages were shown to perform better in terms of adsorption properties. The short recovery time observed in this study is beneficial for the repetitive use of the gas sensor. The Natural Bond Orbital and molecular electrostatic potential analysis demonstrated a substantial quantity of charge transfer from adsorbate to adsorbents. The bandgap alternation after adsorption shows an influence of adsorption on electronic properties. The interactions of adsorbate and adsorbents are further studied using the ultraviolet-visible predicted spectrum, and quantum theory of atoms in molecules all of which yielded promising findings.

Systematic review of the scientific evidence on ethylene oxide as a human carcinogen

Ethylene oxide is a highly reactive chemical primarily used as an intermediate in chemical production and as a sterilant of medical equipment and food products; it also is produced endogenously as a result of physiological processes. We conducted a systematic review of the potential carcinogenicity of inhaled ethylene oxide in humans using methods that adhere to PRIMSA guidelines and that incorporate aspects from the Institute of Medicine (IOM) (now the National Academy of Medicine) as well as several US Environmental Protection Agency (EPA) frameworks for systematic reviews. After a comprehensive literature search and selection process, study quality was evaluated following a method adapted from the EPA Toxic Substances Control Act (TSCA) framework. The literature screening and selection process identified 24 primary studies in animals or humans and more than 50 mechanistic studies. Integrating epidemiological, animal, and mechanistic literature on ethylene oxide and cancer according to the IOM framework yielded classifications of suggestive evidence of no association between ethylene oxide and stomach cancer, breast cancer and lymphohematopoietic malignancies at human relevant exposures. However, we acknowledge that there is additional uncertainty in the classification for lymphohematopoietic malignancies owing to a paucity of evidence for specific types of these tumors, each of which is a distinct disease entity of possibly unique etiology.

Ethylene oxide review: characterization of total exposure via endogenous and exogenous pathways and their implications to risk assessment and risk management

This review is intended to provide risk assessors and risk managers with a better understanding of issues associated with total exposures of human populations to ethylene oxide from endogenous and exogenous pathways. Biomonitoring of human populations and lab animals exposed to ethylene oxide has relied upon the detection of hemoglobin adducts such as 2-hydroxyethylvaline (HEV), which provides a useful measure of total exposure to ethylene oxide from all pathways. Recent biomonitoring data from CDC provide an excellent characterization of total exposure to ethylene oxide to the general U.S. population by demographic factors such as age, gender, and race as well as smoking habit, which might be comparable to previous measurements reported for humans and lab animals. The biochemical pathways including gastrointestinal (production by bacteria) and systemic (enzymatic production) pathways by which endogenous ethylene is generated and converted to ethylene oxide are described. The relative importance of endogenous pathways and exogenous pathways via ambient air or tobacco smoke was quantified based upon available data to characterize their relative importance to total exposure. Considerable variation was noted for HEV measurements in human populations, and important sources of variation for all pathways are discussed. Issues related to risk assessment and risk management of human populations exposed to ethylene oxide are provided within the context of characterizing total exposure, and data needs for supporting future risk assessment identified.

Associations between exposure to ethylene oxide, job termination, and cause-specific mortality risk

BACKGROUND

Previous analyses of mortality were conducted in a large cohort of ethylene oxide (EtO) exposed workers employed at 13 sterilization facilities throughout the U.S. and followed from the start of operation through 1998. Statistically significant elevated mortality was reported from hematopoietic cancer in men and breast cancer in women compared to the general population. Possible healthy worker survivor bias was not addressed.

METHODS

To examine survivor bias in this cohort, employment termination was analyzed with statistical models stratified on sex and race that included age, employment duration, and cumulative EtO exposure. To reduce survivor bias employment duration was included in Poisson regression model specifications for estimating standardized mortality ratios for several cancer outcomes.

RESULTS

Strong statistically significant effects of unlagged cumulative EtO exposure were observed on rate of employment termination, indicating potential healthy worker survivor effect bias. Adjustment for employment duration in analyses of mortality resulted in statistically significant and stronger associations between cumulative EtO exposure and lung cancer, female breast cancer and hematopoietic cancer. There was a striking reduction in nonmalignant respiratory disease mortality risk with increasing employment duration with a further (nonsignificant) reduction with cumulative EtO, suggesting that EtO itself is driving termination of workers with respiratory morbidity even though the average EtO exposures in this population were generally far below odor and acute irritancy thresholds.

CONCLUSIONS

Important survivor bias was present in this EtO cohort and may be present in many occupational settings involving irritant exposures.

Ethylene Oxide: Cancer Evidence Integration and Dose-Response Implications

The International Agency for Research on Cancer (IARC) and the United States Environmental Protection Agency (USEPA) classified ethylene oxide (EtO) as a known human carcinogen. Critically, both noted that the epidemiological evidence based on lymphoid and breast cancers was “limited,” but that the evidence in animal studies was “sufficient” and “extensive” (respectively) and that EtO is genotoxic. The USEPA derived one of the highest published inhalation unit risk (IUR) values (3 × 10⁻³ per [µg/m³ EtO]), based on results from 2 epidemiological studies. We performed focused reviews of the epidemiological and toxicological evidence on the carcinogenicity of EtO and considered the USEPA’s reliance on a genotoxic mode of action to establish EtO’s carcinogenicity and to determine likely dose–response patterns. Higher quality epidemiological studies demonstrated no increased risk of breast cancers or lymphohematopoietic malignancies (LHM). Similarly, toxicological studies and studies of early effect biomarkers in animals and humans provided no strong indication that EtO causes LHM or mammary cancers. Ultimately, animal data are inadequate to define the actual dose–response shape or predict tumor response at very low doses with any confidence. We conclude that the IARC and USEPA classification of EtO as a known human carcinogen overstates the underlying evidence and that the IUR derived by USEPA grossly overestimates risk.

Reevaluation of Historical Exposures to Ethylene Oxide Among U.S. Sterilization Workers in the National Institute of Occupational Safety and Health (NIOSH) Study Cohort

The 2016 U.S. Environmental Protection Agency (EPA) Integrated Risk Information System (IRIS) assessment for ethylene oxide (EO) estimated a 10⁻⁶ increased inhalation cancer risk of 0.1 parts per trillion, based on National Institute of Occupational Safety and Health (NIOSH) epidemiology studies of sterilization facility workers exposed to EO between 1938 and 1986. The worker exposure estimates were based on a NIOSH statistical regression (NSR) model “validated” with EO levels measured after 1978. Between 1938 and 1978, when EO data was unavailable, the NSR model predicts exposures lowest in 1938 increasing to peak levels in 1978. That increasing EO concentration trend arose, in part, because engineering/industrial-hygiene (E/IH) factors associated with evolving EO-sterilization equipment and operations before 1978 were not properly considered in the NSR model. To test the NSR model trend prediction, a new E/IH-based model was developed using historical data on EO kill concentrations, EO residue levels in sterilized materials, post-wash EO concentrations in a sterilization chamber, and information on facility characteristics and sterilizer operator practices from operators familiar with pre-1978 industry conditions. The E/IH 90th percentile of 8 h time-weighted average EO exposures (C₉₀) for highly exposed sterilizer operators was calibrated to match 1978 C₉₀ values from the NSR model. E/IH model C₉₀ exposures were estimated to decrease over time from levels 16 and were four-fold greater than NSR-estimated exposures for workers during 1938–1954 and 1955–1964. This E/IH modeled trend is opposite to that of NSR model predictions of exposures before 1978, suggesting that EPA’s exclusive reliance on the NIOSH cohort to estimate EO cancer risk should be re-examined.

Bronchioloalveolar lung tumors induced in “mice only” by non-genotoxic chemicals are not useful for quantitative assessment of pulmonary adenocarcinoma risk in humans

Chemicals classified as known human carcinogens by International Agency for Research on Cancer (IARC) show a low level of concordance between rodents and humans for induction of pulmonary carcinoma. Rats and mice exposed via inhalation for 2 years show a low level of concordance in both tumor development and organ site location. In 2-year inhalation studies using rats and mice, when pulmonary tumors are seen in only male or female mice or both, but not in either sex of rat, there is a high probability that the murine pulmonary tumor has been produced via Clara cell or club cell (CC) metabolism of the inhaled chemical to a cytotoxic metabolite. Cytotoxicity-induced mitogenesis increases mutagenesis via amplification of the background mutation rate. If the chemical being tested is also negative in the Ames Salmonella mutagenicity assay, and only mouse pulmonary tumors are induced, the probability that this pulmonary tumor is not relevant to human lung cancer risk goes even higher. Mice have a larger percentage of CCs in their distal airways than rats, and a much larger percentage than in humans. The CCs of mice have a much higher concentration of metabolic enzymes capable of metabolizing xenobiotics than CCs in either rats or humans. A principal threat to validity of extrapolating from the murine model lies in the unique capacity of murine CCs to metabolize a significant spectrum of xenobiotics which in turn produces toxicants not seen in rat or human pulmonary pathophysiology.

Effect of external electric field on the adsorption of ethylene oxide on pristine and Al-doped coronenes: A DFT study

The adsorption interactions between ethylene oxide (EO) molecule and pristine and aluminum-doped coronene (Al-coronene) were studied in the presence and absence of perpendicular external electric fields (EFs) with strengths [Formula: see text], [Formula: see text] and [Formula: see text] a.u. using density functional theory (DFT) calculations. The geometry optimizations and adsorption calculations were carried out by employing 6-31[Formula: see text]G** basis set. The changes in geometric and electronic structures after the adsorption were investigated to characterize the sensitivity of pristine and Al-coronene toward EO molecules. For all the studied systems, adsorption energies ([Formula: see text], band gap energy ([Formula: see text], Mulliken charge transfer, molecular electrostatic potential (MEP) and density of electron state (DOS) were calculated and discussed. According to the obtained results, the high impact of the applied EFs on the adsorption characteristics of EO molecules on the pristine and Al-doped coronenes showed that applying EF is a good strategy for enhancing the EO adsorption capability of the pristine and Al-doped coronenes, improving the potential application of coronene-based sensors for detection of EO in trace amounts.

Carcinogenicity of ethylene oxide: key findings and scientific issues

In support of the Integrated Risk Information System (IRIS), the U.S. Environmental Protection Agency (EPA) completed an evaluation of the inhalation carcinogenicity of ethylene oxide (EtO) in December 2016. This article reviews key findings and scientific issues regarding the carcinogenicity of EtO in EPA's Carcinogenicity Assessment. EPA's assessment critically reviewed and characterized epidemiologic, laboratory animal, and mechanistic studies pertaining to the human carcinogenicity of EtO, and addressed some key scientific issues such as the analysis of mechanistic data as part of the cancer hazard evaluation and to inform the quantitative risk assessment. The weight of evidence from the epidemiologic, laboratory animal, and mechanistic studies supports a conclusion that EtO is carcinogenic in humans, with the strongest human evidence linking EtO exposure to lymphoid and breast cancers. Analyses of the mechanistic data establish a key role for genotoxicity and mutagenicity in EtO-induced carcinogenicity and reveal little evidence supporting other mode-of-action hypotheses. In conclusion, EtO was found to be carcinogenic to humans by inhalation, posing a potential human health hazard for lymphoid and breast cancers.

Ethylene oxide as an occupational contact allergen - an underestimated problem?

Background: Ethylene oxide (EtO) is a volatile epoxy compound which is used to sterilize medical devices. EtO may cause irritant contact dermatitis, but only few cases of allergic contact dermatitis have been reported yet. Objectives: About 20 employees of a department for surgery developed eczematous skin reactions at the contact areas to wrist bands of surgical gowns which had been sterilized with EtO. Patch tests were performed to exclude contact allergy. Methods: Due to the volatility of EtO, patch tests were done with epichlorohydrin (0.1% pet., 1% pet.) which is an epoxy compound chemically related to EtO. Results: 7/8 patients and 4 healthy control persons showed non-allergic irritant reactions to 1.0% epichlorohydrin. 1.0% epichlorohydrin may have induced an iatrogenic sensitization in one of the control persons. None of the control persons reacted to 0.1% epichlorohydrin. Allergic contact dermatitis to EtO and a cross sensitization to epichlorohydrin was diagnosed in a nurse who showed an allergic crescendo patch test reaction to 0.1% epichlorohydrin. Conclusions: EtO can act as an occupational contact allergen in health personnel, a problem that may have been underestimated in the past due to methodological difficulties in patch testing. When allergic contact dermatitis to EtO is suspected, a patch test to 0.1% epichlorohydrin should be performed.

Chemical Exposures in the Workplace

Occupational health nurses need to be aware of the current science on breast cancer risks in the workplace because they are risk communicators for employees and their families. Occupational health nurses can serve as advocates for necessary research ultimately leading to risk reduction and prevention strategies in the workplace. Current research suggests exposure to organic solvents, metals, acid mists, sterilizing agents (ethylene oxide), some pesticides, light at night (shift work), and tobacco smoke increases breast cancer risk among women in occupational settings. Animal cancer bioassays conducted by the National Toxicology Program indicate more than 40 chemicals can induce mammary tumors, and most of these are still in production. A variety of occupations worldwide, including health care providers and metal, textile, dye, rubber, and plastic manufacturing workers, have been identified as having some evidence of higher breast cancer risk. Although some chemical exposures are suspected to affect breast cancer risk, estimates of or actual exposures to these chemicals in the workplace often have not been determined. Research needed to better identify breast cancer risks in occupational settings includes monitoring breast cancer incidence in occupations with exposures to suspected carcinogens, characterizing chemical exposures by job type and task, determining whether potential gender differences affect chemical exposures, and using molecular approaches to identify gene-environment interactions.

Misinterpretation of categorical rate ratios and inappropriate exposure-response model fitting can lead to biased estimates of risk: ethylene oxide case study

There are pitfalls associated with exposure-response modeling of human epidemiological data based on rate ratios (RRs). Exposure-response modeling is best based on individual data, when available, rather than being based on summary results of that data such as categorical RRs. Because the data for the controls (or the lowest exposure interval if there are not enough controls) are random and not known with certainty a priori, any exposure-response model fit to RRs should estimate the intercept rather than fixing it equal to one. Evaluation of a model's goodness-of-fit to the individual data should not be based on the assumption that summary RRs describe the true underlying exposure-response relationship. These pitfalls are illustrated by Monte Carlo simulation examples with known underlying models. That these pitfalls are a practical concern is illustrated by the need for U.S. EPA to reconsider its most recent evaluation of ethylene oxide. If they had avoided these pitfalls, their exposure-response modeling would have been in better agreement with the log-linear model fit to the individual data.

Effects of sterilization with hydrogen peroxide gas plasma, ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints

OBJECTIVE

To compare effects of sterilization with hydrogen peroxide gas plasma (HPGP), ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints.

SAMPLE

Samples of a 36.3-kg test nylon leader line, 57.8-kg test nylon fishing line, and 2-mm ultrahigh-molecular weight polyethylene (UHMWPE) were used.

PROCEDURES

In this in vitro study, samples of nylon leader line, fishing line, and UHMWPE sterilized by use of HPGP, ethylene oxide, and steam or unsterilized samples were used. Bacterial adherence on unsterilized and sterilized samples was tested with Staphylococcus epidermidis and Escherichia coli. Five samples were examined for each line type and sterilization condition, and final colony counts were obtained.

RESULTS

Bacterial adherence was significantly affected by method of sterilization for all 3 line types. For most of the samples, bacterial adherence was similar or lower when HPGP sterilization was used, compared with results for sterilization via ethylene oxide and steam, respectively. Bacterial adherence was significantly higher for UHMWPE, compared with adherence for the nylon line, regardless of the sterilization method used. Bacterial adherence was higher for nylon fishing line than for nylon leader line for S epidermidis after ethylene oxide sterilization and for E coli after HPGP and ethylene oxide sterilization.

CONCLUSIONS AND CLINICAL RELEVANCE

Effects of HPGP sterilization on bioadhesive properties of nylon and polyethylene lines compared favorably with those for ethylene oxide and steam sterilization. Also, nylon line may be a more suitable material than UHMWPE for suture prostheses on the basis of bacterial adherence properties.

Allografts in Anterior Cruciate Ligament Reconstruction

Usual allograft sources for anterior cruciate ligament (ACL) reconstruction are patellar ligament, Achilles tendon, tibialis anterior, and posterior. The advantages of the use of allograft include reduced donor-site morbidity, shorter operative time, smaller incisions, and no size restrictions. The disadvantages include increased cost, slower graft embodiment, and the risk of viral or bacterial infection, which may occur either by transmission from an infected donor or by contamination by the healthcare provider. Careful donor selection, aseptic graft procurement and processing, and tissue sterilization, by irradiation or proprietary chemical processing, are the three major steps of the graft preparation procedure. Successful allograft implantation depends on sterility, reduction of antigenicity, and preservation of the biomechanical properties of the graft. To date, reports on the clinical and functional outcomes of allograft compared to autograft ACL reconstruction are controversial. Overall, graft choice depends on surgeon and patient preference, since no graft can perfectly match the properties of the native ACL.

Cancer incidence and mortality in Swedish sterilant workers exposed to ethylene oxide: updated cohort study findings 1972-2006

Objectives:

To assess whether cancer incidence, mainly from lymphohaematopoietic tumours and breast cancer, and mortality were increased in a cohort of Swedish sterilant workers exposed to low levels of ethylene oxide (EtO), updated with 16 more years of follow up.

Methods:

The mortality and cancer incidence 1972–2006 experienced by a cohort of 2,171 male and female workers employed for at least one year in two plants producing medical equipment sterilised with EtO were investigated. Individual cumulative exposure to EtO was assessed by occupational hygienists. Cause-specific standardized rate ratios were calculated using the regional general population as a comparison for mortality (SMR) and cancer incidence (SIR). Internal Poisson-regression analyses were performed for selected causes.

Results:

The median cumulative exposure to EtO was 0.13 ppm-years. The overall cancer incidence was close to unity (SIR 0.94, 95% CI 0.82–1.08). Eighteen cases of lymphohaematopoietic cancer were observed (SIR 1.25, 95% CI 0.74–1.98). A healthy worker effect was indicated from a significantly decreased overall mortality and mortality from cardiovascular diseases. Internal analyses found significantly increased rate ratios for breast cancer for the two upper quartiles of cumulative exposure as compared to the lowest 50% of the cohort (IRR 2.76, 95% CI 1.20–6.33 and IRR 3.55, 95% CI 1.58–7.93).

Conclusions:

The findings from this updated study indicate limited or low risks for human cancer due to occupational exposure from ethylene oxide at the low cumulative exposure levels in this cohort. However a positive exposure-response relation with breast cancer was observed though.

Quantitative cancer risk assessment for ethylene oxide inhalation in occupational settings

The estimated occupational ethylene oxide (EO) exposure concentrations corresponding to specified extra risks are calculated for lymphoid mortality as the most appropriate endpoint, despite the lack of a statistically significant exposure-response relationship. These estimated concentrations are for occupational exposures--40 years of occupational inhalation exposure to EO from age 20 to age 60 years. The estimated occupational inhalation exposure concentrations (ppm) corresponding to specified extra risks of lymphoid mortality to age 70 years in a population of male and female EO workers are based on Cox proportional hazards models of the most recent updated epidemiology cohort mortality studies of EO workers and a standard life-table calculation. An occupational exposure at an inhalation concentration of 2.77 ppm EO is estimated to result in an extra risk of lymphoid mortality of 4 in 10,000 (0.0004) in the combined worker population of men and women from the two studies. The corresponding estimated concentration decreases slightly to 2.27 ppm when based on only the men in the updated cohorts combined. The difference in these estimates reflects the difference between combining all of the available data or focusing on only the men and excluding the women who did not show an increase in lymphoid mortality with EO inhalation exposure. The results of sensitivity analyses using other mortality endpoints (all lymphohematopoietic tissue cancers, leukemia) support the choice of lymphoid tumor mortality for estimation of extra risk.

Mechanical evaluation of hydrogen peroxide gas plasma sterilization of nylon lines used for extra-articular stabilization of the canine stifle joint

OBJECTIVE

To compare the effects of hydrogen peroxide gas plasma (HPGP) and ethylene oxide (EO) sterilizations on the mechanical properties of nylon lines used for stabilization of the canine stifle. Secondarily, to compare the performance of crimped and knotted lines.

STUDY DESIGN

In vitro mechanical evaluation.

SAMPLE POPULATION

Nonsterilized, EO- and HPGP-sterilized specimens of 36.3 kg test nylon leader line (NLL) and 57.8 kg test nylon fishing line (NFL).

METHODS

Single strands and looped specimens of NLL or NFL were positioned on a material testing machine. To create looped specimens, NLL were crimped using the Securos system, and NFL were knotted, as used clinically. Elongation (%) and ultimate load (N) variables were studied.

RESULTS

Elongation and ultimate load of NLL groups were not significantly different between EO and HPGP. For NFL, HPGP sterilization led to slightly greater elongation than EO in loops only. Ultimate load of NFL single strands was not significantly different between EO and HPGP, but was higher after HPGP compared with EO in NFL loops. All NLL groups had less elongation and ultimate load than NFL.

CONCLUSION

The effects of HPGP on NLL compared positively to EO, making HPGP an attractive alternative. As HPGP led to a slightly greater elongation of NFL than EO, the latter could be favored to sterilize NFL. Crimped NLL minimized elongation better than knotted NFL.

CLINICAL RELEVANCE

Sterilization with HPGP seems a good alternative to EO for NLL. EO may be a better choice for NFL; however, it is difficult to judge the clinical relevance of this result. Crimped NLL minimizes elongation and may help reducing the recurrence of stifle instability postoperatively.

A review of the molecular mechanisms of chemically induced neoplasia in rat and mouse models in National Toxicology Program bioassays and their relevance to human cancer

Tumor response in the B6C3F1 mouse, F344 rat, and other animal models following exposure to various compounds provides evidence that people exposed to these or similar compounds may be at risk for developing cancer. Although tumors in rodents and humans are often morphologically similar, underlying mechanisms of tumorigenesis are often unknown and may be different between the species. Therefore, the relevance of an animal tumor response to human health would be better determined if the molecular pathogenesis were understood. The underlying molecular mechanisms leading to carcinogenesis are complex and involve multiple genetic and epigenetic events and other factors. To address the molecular pathogenesis of environmental carcinogens, the authors examine rodent tumors (e.g., lung, colon, mammary gland, skin, brain, mesothelioma) for alterations in cancer genes and epigenetic events that are associated with human cancer. National Toxicology Program (NTP) studies have identified several genetic alterations in chemically induced rodent neoplasms that are important in human cancer. Identification of such alterations in rodent models of chemical carcinogenesis caused by exposure to environmental contaminants, occupational chemicals, and other compounds lends further support that they are of potential human health risk. These studies also emphasize the importance of molecular evaluation of chemically induced rodent tumors for providing greater public health significance for NTP evaluated compounds.

Emission characteristics of plastic syringes sterilized with ethylene oxide--a controlled study

OBJECTIVES

This study examined the emission characteristics of ethylene oxide (EO)-sterilized syringes under various environmental conditions, aiming to develop control strategies to minimize worker exposure.

METHODS

Experiments were performed in a facility in which temperature, relative humidity (RH), and air change rate (ACR) were controlled.

RESULTS

Analytical results indicate that the main effects of the four test variables on kinetic parameters were statistically significant (p < 0.05), except for the effect of the product on the decay rate constant, the effect of ACR on maximum EO concentration, and effect of RH on the area under the curve-days 1 and 2. The interactive effects among test variables were also evident, indicating complex emission behaviors. The mean EO emission factors during the days 1 and 2 and at the 48th hour for the 1- and 30-ml products were 2302, 1301, and 1031 mg/m(3)/h, and 871, 490, and 381 mg/m(3)/h, respectively. The times required for air EO concentrations from tested products to return to approximately 0 and 1 ppm (permissible limit) were 417 and 218 h, respectively.

CONCLUSIONS

Plastic content, temperature, RH, and ACR affected EO emissions. ACR is an achievable means of control; however, the aeration area/system should be isolated to ensure adequate ventilation is achieved.

Tissue processing: role of secondary sterilization techniques

Secondary sterilization of musculoskeletal allografts may use chemicals, radiation, or combinations of these. No sterilization techniques have been definitively proven to be more effective than others, and their biomechanical and biological effects on allograft tissue remain largely unknown. The current risk of an allograft infection appears to be much less than the risk of infection surrounding the surgical procedure itself. With appropriate donor screening, improved donor testing—including nucleic acid testing (NAT), and adherence to AATB standards—the risk of disease transmission or infections can be eliminated or substantially decreased.

Ethylene oxide sterilization in the medical-supply manufacturing industry: assessment and control of worker exposure

OBJECTIVE

In 2005, the Taiwan Institute of Occupational Safety and Health started an on-site consulting program for the medical supplies manufacturing industry, which use ethylene oxide (EO) as a sterilant, with the goal of enhancing occupational hygiene practices and controlling EO-related risks. This study presents EO exposure assessment results and examines the effectiveness of control measures.

METHODS

Detailed surveys, including exposure monitoring, were conducted at 10 factories. Airborne EO was collected using an HBr-coated charcoal tube and analyzed using GC/MS.

RESULTS

Sterilizer operators had an average short-term EO exposure level of 27.61 ppm during unloading; mean time-weighted average workshift exposure was 7.35 ppm. High EO concentrations were also present throughout the facilities. Specifically, mean EO concentrations in the aeration area, near the sterilizer and in the warehouse were 10.19, 5.75, and 8.78 ppm, respectively. These findings indicate that immediate controls are needed, and that EO emissions from sterilized products during storage cannot be overlooked. Worker short-term exposures during unloading was inversely correlated (p < 0.05) with the numbers of poststerilization purge cycle applied. The specific controls implemented and their usefulness is discussed.

CONCLUSION

Increasing the number of poststerilization purge cycles is a simple approach to eliminating extremely high exposure during unloading. Improvements to ventilation, particularly in the aeration area and warehouse, were also effective in minimizing worker exposures. Use of effective respirator is recommended until the EO exposure levels, averaging 3.41 ppm after the controls, fall below the permissible exposure limit.

Overview of Procurement, Processing, and Sterilization of Soft Tissue Allografts for Sports Medicine

Musculoskeletal allografts are commonly used in orthopedic surgery and have become increasingly popular. Their indications have widened as an alternatives to autografts. A tissue processing industry has secondarily evolved. An increasing number of accredited tissue banks are providing donor screening, procurement, processing, storage, and distribution of tissue. Multiple factors play a role for a graft to be successfully implanted: sterility, reduction of antigenicity, and preservation of its biologic and biomechanical properties. A rare but catastrophic complication that has raised concern is disease transmission. Controversies exist on which is the best way to produce a strong, disease-free graft. There is no current standard, but as allograft technology evolves, surgeons need to be aware of the regulations and policies surrounding allograft tissue procurement and processing to provide the best outcomes in transplanted patients.

The non-Hodgkin lymphomas: a review of the epidemiologic literature

The non-Hodgkin lymphomas (NHL) are a heterogeneous group of B-cell and T-cell neoplasms that arise primarily in the lymph nodes. NHL incidence rates in the US doubled between about 1970 and 1990, and stabilized during the 1990s. NHL accounts for approximately 3.4% of cancer deaths in the US. Although some of the observed patterns in NHL have been related to HIV/AIDS, these conditions cannot fully explain the magnitude of the changes; neither do changes in classification systems nor improved diagnostic capabilities. Studies of occupational and environmental exposures (e.g., pesticides, solvents) have produced no consistent pattern of significant positive associations. Inverse associations with ultraviolet radiation exposure and alcohol and fish intake, and positive associations with meat and saturated fat intake have been reported in several studies; additional studies are needed to confirm or refute these associations. Family history of NHL or other hematolympho-proliferative cancers and personal history of several autoimmune disorders are associated with increased risk of NHL, but are not likely to account for a large proportion of cases. HIV and other infectious agents, such as human herpesvirus 8 and Epstein-Barr, appear to be associated with differing types of NHL, such as some B-cell lymphomas. Future epidemiologic studies should evaluate associations by NHL type, enhance exposure information collected, and elucidate factors that may identify susceptible (or resistant) subpopulations because of genetic, immunologic or other characteristics. The extent to which the etiology of NHL types may differ is important to resolve in ongoing and future studies.

K-ras mutations in lung tumors and tumors from other organs are consistent with a common mechanism of ethylene oxide tumorigenesis in the B6C3F1 mouse

Ethylene oxide is a multisite carcinogen in rodents and classified as a human carcinogen by the National Toxicology Program. In 2-year mouse studies, ethylene oxide (EO) induced lung, Harderian gland (HG), and uterine neoplasms. We evaluated representative EO-induced and equivalent spontaneous neoplasms for K-ras mutations in codons 12, 13, and 61. K-ras mutations were identified in 100% (23/23) of the EO-induced lung neoplasms and 25% (27/108) of the spontaneous lung neoplasms. Codon 12 G to T transversions were common in EO-induced lung neoplasms (21/23) but infrequent in spontaneous lung neoplasms (1/108). K-ras mutations were found in 86% (18/21) of the EO-induced HG neoplasms and 7% (2/27) of the spontaneous HG neoplasms. Codon 13 G to C and codon 12 G to T transversions were predominant in the EO-induced HG neoplasms but absent in spontaneous HG neoplasms (0/27). K-ras mutations occurred in 83% (5/6) of the EO-induced uterine carcinomas and all were codon 13 C to T transitions. These data show a strong predilection for development of K-ras mutations in EO-induced lung, Harderian gland, and uterine neoplasms. This suggests that EO specifically targets the K-ras gene in multiple tissue types and that this event is a critical component of EO-induced tumorigenesis.

Multiple myeloma: A review of the epidemiologic literature

Multiple myeloma, a neoplasm of plasma cells, accounts for approximately approximately 15% of lymphatohematopoietic cancers (LHC) and 2% of all cancers in the US. Incidence rates increase with age, particularly after age 40, and are higher in men, particularly African American men. The etiology is unknown with no established lifestyle, occupational or environmental risk factors. Although several factors have been implicated as potentially etiologic, findings are inconsistent. We reviewed epidemiologic studies that evaluated lifestyle, dietary, occupational and environmental factors; immune function, family history and genetic factors; and the hypothesized precursor, monoclonal gammopathies of undetermined significance (MGUS). Because multiple myeloma is an uncommon disease, etiologic assessments can be difficult because of small numbers of cases in occupational cohort studies, and few subjects reporting exposure to specific agents in case-control studies. Elevated risks have been reported consistently among persons with a positive family history of LHC. A few studies have reported a relationship between obesity and multiple myeloma, and this may be a promising area of research. Factors underlying higher incidence rates of multiple myeloma in African Americans are not understood. The progression from MGUS to multiple myeloma has been reported in several studies; however, there are no established risk factors for MGUS. To improve our understanding of the causes of multiple myeloma, future research efforts should seek the causes of MGUS. More research is also needed on the genetic factors of multiple myeloma, given the strong familial clustering of the disease.

Increased genotoxic susceptibility of breast epithelial cells to ethylene oxide

This study was carried out with the aim of elucidating the organ-specific effects of ethylene oxide in comparison with the sensitivity of cells from different tissues. An increased incidence of leukemia and lymphoma has been observed in workers exposed to ethylene oxide. However, contradictory findings exist regarding its ability to induce other tumor types, such as breast cancer. We characterized the genotoxicity of ethylene oxide by means of the alkaline version of comet assay in in vitro systems, in order to investigate the hypothesized role of this substance in the development of breast cancer. For this study, we used primary and secondary cultures of lymphoblasts (well-known target cells of the genotoxicity of ethylene oxide), breast epithelial cells (hypothesized target), peripheral blood lymphocytes (cells commonly used in biomonitoring), and of keratinocytes and cervical epithelial cells. DNA damage was measured and expressed as tail DNA, tail length, and tail moment. In the concentration range 0-100 microM, ethylene oxide induced a dose-dependent increase of DNA damage in the investigated cell types without notable cytotoxicity. A statistically significant increase of DNA damage could be observed after treatment with 20 microM ethylene oxide in lymphoblasts (51% increase of tail moment over the background), breast epithelial cells (26% increase) and peripheral lymphocytes (71% increase). In keratinocytes (5% increase) and cervical epithelial cells (5% increase) significant DNA damage could not be detected at this dose, but at higher concentrations (50-100 microM), such an increase was observed. These results are indicative of an increased sensitivity of breast epithelial cells towards genotoxic insults of ethylene oxide. Our observations provide additional data to evaluate the hypothesis that exposure to ethylene oxide may play a role in breast cancer, and the findings may contribute to the development of screening tests for monitoring an early response to genotoxic insults in occupational settings.

Addressing nonlinearity in the exposure-response relationship for a genotoxic carcinogen: cancer potency estimates for ethylene oxide

Ethylene oxide (EO) has been identified as a carcinogen in laboratory animals. Although the precise mechanism of action is not known, tumors in animals exposed to EO are presumed to result from its genotoxicity. The overall weight of evidence for carcinogenicity from a large body of epidemiological data in the published literature remains limited. There is some evidence for an association between EO exposure and lympho/hematopoietic cancer mortality. Of these cancers, the evidence provided by two large cohorts with the longest follow-up is most consistent for leukemia. Together with what is known about human leukemia and EO at the molecular level, there is a body of evidence that supports a plausible mode of action for EO as a potential leukemogen. Based on a consideration of the mode of action, the events leading from EO exposure to the development of leukemia (and therefore risk) are expected to be proportional to the square of the dose. In support of this hypothesis, a quadratic dose-response model provided the best overall fit to the epidemiology data in the range of observation. Cancer dose-response assessments based on human and animal data are presented using three different assumptions for extrapolating to low doses: (1) risk is linearly proportionate to dose; (2) there is no appreciable risk at low doses (margin-of-exposure or reference dose approach); and (3) risk below the point of departure continues to be proportionate to the square of the dose. The weight of evidence for EO supports the use of a nonlinear assessment. Therefore, exposures to concentrations below 37 microg/m3 are not likely to pose an appreciable risk of leukemia in human populations. However, if quantitative estimates of risk at low doses are desired and the mode of action for EO is considered, these risks are best quantified using the quadratic estimates of cancer potency, which are approximately 3.2- to 32-fold lower, using alternative points of departure, than the linear estimates of cancer potency for EO. An approach is described for linking the selection of an appropriate point of departure to the confidence in the proposed mode of action. Despite high confidence in the proposed mode of action, a small linear component for the dose-response relationship at low concentrations cannot be ruled out conclusively. Accordingly, a unit risk value of 4.5 x 10(-8) (microg/m3)(-1) was derived for EO, with a range of unit risk values of 1.4 x 10(-8) to 1.4 x 10(-7) (microg/m3)(-1) reflecting the uncertainty associated with a theoretical linear term at low concentrations.

Long-term ethylene oxide exposure trends in US hospitals: relationship with OSHA regulatory and enforcement actions

OBJECTIVES

We assessed long-term trends in ethylene oxide (EtO) worker exposures for the purposes of exposure surveillance and evaluation of the impacts of the Occupational Safety and Health Administration (OSHA) 1984 and 1988 EtO standards.

METHODS

We obtained exposure data from a large commercial vendor and processor of EtO passive dosimeters. Personal samples (87,582 workshift [8-hr] and 46,097 short-term [15-min] samples) from 2265 US hospitals were analyzed for time trends from 1984 through 2001 and compared with OSHA enforcement data.

RESULTS

Exposures declined steadily for the first several years after the OSHA standards were set. Workshift exposures continued to taper off and have remained low and constant through 2001. However, since 1996, the probability of exceeding the short-term excursion limit has increased. This trend coincides with a decline in enforcement of the EtO standard.

CONCLUSIONS

Results indicate the need for renewed intervention efforts to preserve gains made following the passage and implementation of the 1984 and 1988 EtO standards.

Mortality of workers exposed to ethylene oxide: extended follow up of a British cohort

AIMS

To obtain further information about the risks of cancer associated with occupational exposure to ethylene oxide

METHODS

Follow up was extended by 13 years for a cohort of 2876 men and women with definite or potential exposure to ethylene oxide in the chemical industry or in hospital sterilising units. Subjects were traced through National Health Service and social security records, and their mortality was compared with that expected from rates in the national population by the person-years method.

RESULTS

Analysis was based on 565 deaths, of which 339 had occurred during the additional period of follow up. Mortality was close to or below expectation for all causes (565 deaths v 607.6 expected), all cancers (188 v 184.2), and for all specific categories of malignancy including stomach cancer (10 v 11.6), breast cancer (11 v 13.2), non-Hodgkin's lymphoma (7 v 4.8), and leukaemia (5 v 4.6). All five deaths from leukaemia occurred in the subset of subjects with greatest potential for exposure to ethylene oxide, but even in this group the excess of deaths was small (2.6 expected).

CONCLUSIONS

The balance of evidence from this and other epidemiological investigations indicates that any risk of human cancer from ethylene oxide is low, particularly at the levels of occupational exposure that have occurred in Britain over recent decades. This may reflect the capacity of human cells to repair DNA damage caused by the chemical, which is a potent genotoxin and animal carcinogen.

Laboratory and field validations of a solid-phase microextraction device for the determination of ethylene oxide

Laboratory and field evaluations were performed to validate a solid-phase microextraction (SPME) device that was used as a diffusive sampler. Hydrogen bromide (HBr) was loaded onto the carboxen-polydimethylsiloxane (CAR-PDMS) fiber for the determination of ethylene oxide (EtO) with on-fiber derivatization. For laboratory evaluations, known concentrations of ethylene oxide around the threshold limit values (TLV)/time-weighted average and specific relative humidities (RHs) were generated by syringe pumps in a dynamic generation system. The SPME diffusive samplers and the commercially available 3M 3551 passive monitors were placed side-by-side in an exposure chamber which was designed to allow measurement of face velocities, temperatures, exposing vapor concentrations, and RHs. Field validations with both SPME diffusive sampler and 3M 3551 passive monitors were also performed. The correlations between the results from both SPME device and 3M 3551 passive monitor were found to be linear (r > 0.9699) and consistent (slope approximately equal to 1.12 +/- 0.07). However, the variations of diffusion coefficients at different temperatures needs to be considered and the adjustment of sampling constant was a must when sampling at temperatures different from 25 degrees C.

Determination of ethylene oxide by solid-phase microextraction device with on-fiber derivatization

The solid-phase microextraction (SPME) device was used as a time-weighted average (TWA) sampler for ethylene oxide. Carboxen/polydimethylsiloxane (CAR/PDMS) fiber was used and hydrogen bromide (HBr) was loaded onto the fiber. The SPME fiber assembly was then inserted into PTFE tubing to improve the wearer's acceptance as a diffusive sampler. Known concentrations of ethylene oxide around the threshold limit values (TLVs)/time-weighted average and specific relative humidities (RHs) were generated by syringe pumps in a dynamic generation system. Ethylene oxide in gas bags were also generated. An exposure chamber was designed to allow measurement of face velocities, temperatures, exposing vapor concentrations, and RHs. Gas chromatography-mass spectrometry (GC-MS) was used for sample analysis. The appropriate adsorption time for SPME coating HBr was found to be 30 s and the desorption time for 2-bromothanol formed after sampling was determined to be 5 min. The experimental sampling constant of the sampler was found to be (2.96 +/- 0.09) x 10(-2) cm3/min, while face velocity (0-0.25 m/s) as well as RHs (10-80%) were not expected to have effects on the sampler.

Genotoxic effects of ethylene oxide, propylene oxide and epichlorohydrin in humans: update review (1990-2001)

Ethylene oxide (EtO), propylene oxide (PO) and epichlorohydrin (ECH) are important industrial chemicals widely used as intermediates for various synthetic products. EtO and PO are also environmental pollutants. In this review we summarize data published during the period 1990-2001 concerning both the genotoxic and carcinogenic effects of these epoxides in humans. The use of DNA and hemoglobin adducts as biomarkers of exposure and the role of polymorphism, as well as confounding factors, are discussed. We have also included recent in vitro data comprising genotoxic effects induced by EtO, PO and ECH in mammalian cells. The uncertainties regarding cancer risk estimation still persist, in spite of the large database collected.

Myeloma aetiology and epidemiology

Recently there have been substantial improvements in our understanding of the biology of myeloma. These findings have important implications for aetiological studies aimed at defining the causative factors for myeloma. Myeloma is closely related to monoclonal gammopathy of unknown significance (MGUS), which is now recognized to be very common in the older population. The epidemiology of these conditions is presented and discussed in the context of the genetic factors governing both the risk of developing MGUS or of transformation to myeloma. Biological studies support a role for aberrant class switch recombination early in the natural history of myeloma suggesting that factors in the environment may interact with this mechanism to increase myeloma risk. Case-control and cohort studies have identified several known and suspected environmental exposures. These exposures include high doses of ionizing radiation, and occupational exposure in the farming and petrochemical industries. The data supporting these associations are presented and discussed in the context of the molecular mechanisms underlying these exposures. In particular DNA damage occurring as a consequence could readily interact with the class switch recombination process to increase the risk of chromosomal translocations, oncogene deregulation and malignant transformation. A further hypothesis, which has been extensively investigated, is the role of chronic immune/antigenic stimulation and the risk of myeloma. This concept is difficult to explain in the context of our current immunological concepts. The data supporting the association and how molecular epidemiological studies using genetic variants in cytokine genes are allowing us to revisit this concept are discussed in detail.

[Mortality caused by cancer in Andalusia: trends and geographic distribution]

AIMS

To describe the evolution of mortality due to gastric cancer in Andalusia and the current geographic distribution of mortality.

DESIGN

Descriptive, population-based study.

SETTING

Andalusia (Southern Spain) during the period from 1975 to 1999.

PARTICIPANTS

Residents of the region of Andalusia.

MEASUREMENTS

Crude rates adjusted for age (interval 35-64 years) of potential years of life lost (1-70 years), and cumulative rates (0-74 years), for mortality due to gastric cancer from 1975 to 1999. Linear regression coefficients were calculated from the model that best fit mortality rates standardized across the study period. Age-adjusted rates were calculated for the five-year period from 1995 to 1999 for primary health care districts.

RESULTS

A sustained decrease in mortality (standardized rate per 100000 inhabitants) due to gastric cancer was seen in women (15.9 to 5.8) and men (33.9 to 14.5). The Sierra Norte (Seville province), Huelva and Córdoba districts, together with the Guadix district (Granada province), had the highest age-adjusted rates for the period from 1995 to 1999. Mortality rates were higher in men than in women throughout the period analyzed; the male:female ratio was consistently greater than 2.

CONCLUSIONS

Mortality due to gastric cancer decreased notably in Andalusia during the last quarter of the twentieth century, but the current geographic distribution of mortality rates varies across the region. Mortality rates in some primary health care districts were threefold as high as in other districts where mortality was low. Further analytical studies are needed to clarify the possible causes of these marked local differences.

Evaluating OSHA's ethylene oxide standard: exposure determinants in Massachusetts hospitals

OBJECTIVES

This study sought to identify determinants of workplace exposures to ethylene oxide to assess the effect of the Occupational Safety and Health Administration's (OSHA's) 1984 ethylene oxide standard.

METHODS

An in-depth survey of all hospitals in Massachusetts that used ethylene oxide from 1990 through 1992 (96% participation, N = 90) was conducted. Three types of exposure events were modeled with logistic regression: exceeding the 8-hour action level, exceeding the 15-minute excursion limit, and worker exposures during unmeasured accidental releases. Covariates were drawn from data representing an ecologic framework including direct and indirect potential exposure determinants.

RESULTS

After adjustment for frequencies of ethylene oxide use and exposure monitoring, a significant inverse relation was observed between exceeding the action level and the use of combined sterilizer-aerators, an engineering control technology developed after the passage of the OSHA standard. Conversely, the use of positive-pressure sterilizers that employ ethylene oxide gas mixtures was strongly related to both exceeding the excursion limit and the occurrence of accidental releases.

CONCLUSIONS

These findings provide evidence of a positive effect of OSHA's ethylene oxide standard and specific targets for future prevention and control efforts.

Stomach cancer-related mortality

In Japan stomach cancer remains the leading cause of cancer-related mortality. We analysed the annual mortality rate of stomach cancer in relation to age, gender and life expectancy in Japan between 1970 and 1995. The adjusted stomach cancer-related mortality rates decreased from 88.9 in 1970 to 45.4 per 100,000 in 1995 in males and from 46.5 to 18.5 per 100,000 in females. The male-female ratio for stomach cancer-related mortality in all ages was 1.9-2.5 during this 25-year period, and the mortality rate was higher in females than in males at young age. The negative contribution to life expectancy for stomach cancer in males was 0.65 years and 0.42 years in females, which is consistent with a higher mortality rate in males. This negative contribution was 41.8% of total cancer in 1970 and 39.4% in 1995 in males and 34.4% and 16.0%, respectively, in females. Our results demonstrated the need to take into consideration the characteristics of stomach cancer in young women and the effects of ageing when designing programmes aimed at prevention and control of this malignancy.