Quarantine and serial testing for variants of SARS-CoV-2 with benefits of vaccination and boosting on consequent control of COVID-19.

Quarantine and serial testing strategies for a disease depend principally on its incubation period and infectiousness profile. In the context of COVID-19, these primary public health tools must be modulated with successive SARS CoV-2 variants of concern that dominate transmission. Our analysis shows that (1) vaccination status of an individual makes little difference to the determination of the appropriate quarantine duration of an infected case, whereas vaccination coverage of the population can have a substantial effect on this duration, (2) successive variants can challenge disease control efforts by their earlier and increased transmission in the disease time course relative to prior variants, and (3) sufficient vaccine boosting of a population substantially aids the suppression of local transmission through frequent serial testing. For instance, with Omicron, increasing immunity through vaccination and boosters-for instance with 100% of the population is fully immunized and at least 24% having received a third dose-can reduce quarantine durations by up to 2 d, as well as substantially aid in the repression of outbreaks through serial testing. Our analysis highlights the paramount importance of maintaining high population immunity, preferably by booster uptake, and the role of quarantine and testing to control the spread of SARS CoV-2.

Life-threatening heat-related illness with severe hyponatremia in an aluminum smelter worker.

Heat stress is a recognized occupational hazard in aluminum smelter pot rooms. This is the report of an unusual and complex case of heat-related illness in an aluminum smelter worker. The 34-year-old male US worker developed life-threatening heat-related illness in August 2018, on his first day back at work after a 7-day absence. The worker initially presented with bilateral hand then all-extremity cramping followed some hours later by a generalized seizure and acute mental status changes, including combativeness. Emergency room evaluation identified a serum sodium level of 114 mmol/L. Acute liver and kidney injury ensued along with profound rhabdomyolysis, with peak total creatinine phosphokinase level reaching over 125 000 units/L at 3 days post incident. Initial ventilatory support, careful fluid resuscitation, and electrolyte management were provided. Metabolic encephalopathy resolved. Complications included sepsis. After 5 days in the intensive care unit and eight additional days of inpatient management, observation, and the initiation of rehabilitation, the worker was discharged. Residual effects include polyneuropathy of upper and lower extremities and the postdischarge magnetic resonance imaging finding of a cerebellar lesion. Prevailing considerations in the differential diagnosis included exertional heat stroke and/or exertion-associated hyponatremia with encephalopathy.

Pneumococcal vaccination for welders: Global deployment within a multi-national corporation.

BACKGROUND: Lobar pneumonia is an occupational disease of welders. This is the first report of global deployment of a pneumococcal vaccination program for welders within a multi-national corporation. METHODS: Global webinars were conducted to introduce the program. Communication packages translated into all location languages were deployed. All employee welders who had not previously been vaccinated were offered a free single dose of pneumococcal polysaccharide vaccine (PPV23) by on-site location medical centers during normal working hours. Numbers of vaccinated welders were reported by each location each month. RESULTS: Twelve months after starting the program, 241 of 767 welders have been vaccinated (31%) across six countries. CONCLUSIONS: Global deployment of pneumococcal vaccination for welders can be successfully undertaken by a multi-national corporation. Adoption of this practice by corporations could reduce the incidence and mortality of pneumonia among welders globally.

Bladder cancer screening in aluminum smelter workers.

OBJECTIVE: To present results of a bladder cancer screening program conducted in 18 aluminum smelters in the United States from January 2000 to December 2010. METHODS: Data were collected on a cohort of workers with a history of working in coal tar pitch volatile exposed areas including urine analysis for conventional cytology and ImmunoCyt/uCyt+ assay. RESULTS: ImmunoCyt/uCyt+ and cytology in combination showed a sensitivity of 62.30%, a specificity of 92.60%, a negative predictive value of 99.90%, and a positive predictive value of 2.96%. Fourteen cases of bladder cancer were detected, and the standardized incidence ratio of bladder cancer was 1.18 (95% confidence interval, 0.65 to 1.99). Individuals who tested positive on either test who were later determined to be cancer free had undergone expensive and invasive tests. CONCLUSIONS: Evidence to support continued surveillance of this cohort has not been demonstrated.

Acoustic neuroma: potential risk factors and audiometric surveillance in the aluminium industry.

OBJECTIVES: To look for an association between acoustic neuroma (AN) and participation in a hearing conservation programme (HCP) and also for an association between AN and possible occupational risk factors in the aluminium industry. METHODS: We conducted a case-control analysis of a population of US aluminium production workers in 8 smelters and 43 other plants. Using insurance claims data, 97 cases of AN were identified between 1996 and 2009. Each was matched with four controls. Covariates included participation in a HCP, working in an aluminium smelter, working in an electrical job and hearing loss. RESULTS: In the bivariate analyses, covariates associated with AN were participation in the HCP (OR=1.72; 95% CI 1.09 to 2.69) and smelter work (OR=1.88; 95% CI 1.06 to 3.36). Electrical work was not significant (OR=1.60; 95% CI 0.65 to 3.94). Owing to high participation in the HCP in smelters, multivariate subanalyses were required. In the multivariate analyses, participation in the HCP was the only statistically significant risk factor for AN. In the multivariate analysis restricted to employees not working in a smelter, the OR was 1.81 (95% CI 1.04 to 3.17). Hearing loss, an indirect measure of in-ear noise dose, was not predictive of AN. CONCLUSIONS: Our results suggest the incidental detection of previously undiagnosed tumours in workers who participated in the company-sponsored HCP. The increased medical surveillance among this population of workers most likely introduced detection bias, leading to the identification of AN cases that would have otherwise remained undetected.

Bauxite mining and alumina refining: process description and occupational health risks.

OBJECTIVE: To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. METHODS: Review article. RESULTS: The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust, alumina dust, and caustic mist in contemporary best-practice bauxite mining and alumina refining operations have not been demonstrated to be associated with clinically significant decrements in lung function. Exposures to bauxite dust and alumina dust at such operations are also not associated with the incidence of cancer. CONCLUSIONS: A range of occupational health risks in bauxite mining and alumina refining require the maintenance of effective control measures.

Health risk assessments for alumina refineries.

OBJECTIVE: To describe contemporary air dispersion modeling and health risk assessment methodologies applied to alumina refineries and to summarize recent results. METHODS: Air dispersion models using emission source and meteorological data have been used to assess ground-level concentrations (GLCs) of refinery emissions. Short-term (1-hour and 24-hour average) GLCs and annual average GLCs have been used to assess acute health, chronic health, and incremental carcinogenic risks. RESULTS: The acute hazard index can exceed 1 close to refineries, but it is typically less than 1 at neighboring residential locations. The chronic hazard index is typically substantially less than 1. The incremental carcinogenic risk is typically less than 10(-6). CONCLUSIONS: The risks of acute health effects are adequately controlled, and the risks of chronic health effects and incremental carcinogenic risks are negligible around referenced alumina refineries.

Radiological assessment for bauxite mining and alumina refining.

OBJECTIVE: Two international benchmarks assess whether the mining and processing of ores containing Naturally Occurring Radioactive Material (NORM) require management under radiological regulations set by local jurisdictions. First, the 1 Bq/g benchmark for radionuclide head of chain activity concentration determines whether materials may be excluded from radiological regulation. Second, processes may be exempted from radiological regulation where occupational above-background exposures for members of the workforce do not exceed 1 mSv/year. This is also the upper-limit of exposure prescribed for members of the public. Alcoa of Australia Limited (Alcoa) has undertaken radiological evaluations of the mining and processing of bauxite from the Darling Range of Western Australia since the 1980s. Short-term monitoring projects have demonstrated that above-background exposures for workers do not exceed 1 mSv/year. A whole-of-year evaluation of above-background, occupational radiological doses for bauxite mining, alumina refining and residue operations was conducted during 2008/2009 as part of the Alcoa NORM Quality Assurance System (NQAS). The NQAS has been guided by publications from the International Commission on Radiological Protection (ICRP), the International Atomic Energy Agency (IAEA) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). The NQAS has been developed specifically in response to implementation of the Australian National Directory on Radiation Protection (NDRP). METHODS: Positional monitoring was undertaken to increase the accuracy of natural background levels required for correction of occupational exposures. This is important in view of the small increments in exposure that occur in bauxite mining, alumina refining and residue operations relative to natural background. Positional monitoring was also undertaken to assess the potential for exposure in operating locations. Personal monitoring was undertaken to characterise exposures in Similar Exposure Groups (SEGs). The monitoring was undertaken over 12 months, to provide annual average assessments of above-background doses, thereby reducing temporal variations, especially for radon exposures. The monitoring program concentrated on gamma and radon exposures, rather than gross alpha exposures, as past studies have shown that gross alpha exposures from inhalable dust for most of the workforce are small in comparison to combined gamma and radon exposures. RESULTS: The natural background determinations were consistent with data in the literature for localities near Alcoa's mining, refining and residue operations in Western Australia, and also with UNSCEAR global data. Within the mining operations, there was further consistency between the above-background dose estimates and the local geochemistry, with slight elevation of dose levels in mining pits. Conservative estimates of above-background levels for the workforce have been made using an assumption of 100% occupancy (1920 hours per year) for the SEGs considered. Total incremental composite doses for individuals were clearly less than 1.0 mSv/year when gamma, radon progeny and gross alpha exposures were considered. This is despite the activity concentration of some materials being slightly higher than the benchmark of 1 Bq/g. CONCLUSIONS: The results are consistent with previous monitoring and demonstrate compliance with the 1 mSv/year exemption level within mining, refining and residue operations. These results will be of value to bauxite mines and alumina refineries elsewhere in the world.

Occupational asthma in the aluminum smelters of Australia and New Zealand: 1991-2006.

OBJECTIVE: To examine the incidence of occupational asthma in the seven aluminum smelters of Australia and New Zealand from 1991 to 2006. METHODS: Incidence and exposure data were collected by survey from the smelters prospectively during the study period. RESULTS: The incidence of occupational asthma across all smelters combined was highest in 1992 at 9.46/1,000/year, declining to 0.36/1,000/year in 2006; a 96.2% reduction. The incidence of occupational asthma was correlated with geometric mean total fluoride concentration, measured as personal samples from employees undertaking anode changing (r(s) = 0.497, P < 0.001). CONCLUSIONS: The control of exposures, respiratory protection and pre-placement medical assessments undertaken during the study period seem to have contributed to the substantial decline in occupational asthma incidence.

Diphoterine for alkali chemical splashes to the skin at alumina refineries.

BACKGROUND: Diphoterine is a commercially available amphoteric, hypertonic, chelating solution used to decontaminate and irrigate chemical splashes. The aim of this study was to evaluate the implementation of Diphoterine at three alumina refineries. This is the largest case series reported to date. METHODS: One hundred eighty cases of alkali splashes to the skin were evaluated clinically. Two groups were compared; those who had applied Diphoterine first and those who had applied water first. RESULTS: There were no signs of chemical burn in 52.9% of the group who applied Diphoterine first compared with 21.4% of the group who applied water first. Only 7.9% of the group who applied Diphoterine first had blisters or more severe signs compared with 23.8% of the group who applied water first. The differences were statistically significant (P < 0.001). After implementation of Diphoterine the "first aid" injury rate for chemical burns fell 24.7% (95% CI 0.5­43.0%). CONCLUSIONS: Applying Diphoterine first was associated with significantly better outcomes following alkali skin splashes than applying water first.

Impact of a health promotion magazine on employee's health-knowledge.

BACKGROUND: Health promotion initiatives are an important element of occupational medicine practice but evaluating success is complex. The publishers of a quarterly health promotion magazine asked an aluminium smelting company if it would consider providing the magazine to its employees. AIMS: To evaluate the possible benefits to employees of receiving a health promotion magazine. METHODS: Three issues were distributed by post over a 9 month period to employees at an aluminium smelter. Pre- and post-distribution questionnaires were mailed to employees and their partners, asking questions about health knowledge and behaviour. Statistical analysis was undertaken using chi-square and Fisher's exact test. RESULTS: Overall 243 of 640 employees (38%) responded to the initial questionnaire and 129 (20%) to the final questionnaire. Pre-existing knowledge about preventive health issues was high; 61-100% of employees selected the correct answer to questions about diet, smoking and exercise. Following distribution of the magazines, there was an increase in employees' knowledge of sugars in 'fat-free' foods (P < 0.05), the benefits of fish oil (P < 0.01) and in how often health was considered when buying food (P < 0.05), as well as an increase in partners' knowledge of dietary fats (P < 0.001). Overall 84% of employees and 87% of their partners who returned the final questionnaire and indicated they had read the magazine showed enthusiasm for continued delivery. CONCLUSIONS: The results suggest that the pilot intervention was beneficial; however, the findings must be interpreted with caution given the modest response rates.

Air emissions from Wagerup alumina refinery and community symptoms: an environmental case study.

Commissioning of a liquor burner at Wagerup alumina refinery gave rise to complaints of malodor and irritation among employees. Subsequently, community members complained about odor and various health issues. Some employees and community members were diagnosed by general practitioners as having multiple chemical sensitivity. After implementation of emission controls, the situation improved; however, community concerns lingered. This paper describes this experience and summarizes several recent investigations including air dispersion modeling, health risk assessment, ambient air quality monitoring, and complaints analyses. It is concluded that refinery emissions currently present negligible risks of acute or chronic health effects including cancer. Communication of these findings has been generally well received, but modifying the perception of risk among some elements of the community has been difficult. Organizations need to effectively address both technical and perception of risk issues.

Heat illness in the U.S. mining industry.

BACKGROUND: Heat illness is relatively common in the underground metalliferous mines of South Africa and Australia. Little is known about heat illness in other forms of mining and there have been no studies of heat illness in the US mining industry. METHODS: Mine Safety and Health Administration (MSHA) accident, injury, illness, and employment data were used to study heat illness reported by the US mining industry from January 1, 1983 to December 31, 2001. RESULTS: Five hundred thirty eight cases of heat illness were reported. None of these cases were fatal. Four hundred twenty seven cases (79.4%) occurred in the summer months of June, July, and August. Incidence rates of heat illness in underground mining ranged from 0.00275/10(6) person-hours for coal, to 0.168/10(6) person-hours for metal, rate-ratio = 61.1 (P < 0.001). Incidence rates in surface mining ranged from 0.0265/10(6) person-hours for coal, to 0.0644/10(6) person-hours for stone, rate-ratio = 2.43 (P < 0.001). Incidence rates in mills/preparation plants ranged from 0.0255/10(6) person-hours for coal, to 0.417/10(6) person-hours for stone, rate-ratio = 16.4 (P < 0.001). CONCLUSIONS: Heat illness occurs most frequently in stone mills, metal mills, and underground metal mines. Preventive measures should target the summer months of June, July, and August.