Characteristics and Determinants of the Presence of Respiratory Symptoms among Sewage Workers in Malaysia

Background

The purpose of this study was to determine the relationships of PM 2.5 and H₂S exposure with the presence of work-related respiratory symptoms among sewage workers.

Methods

A cross-sectional study was conducted in eleven sewage plants located in the central region of Peninsular Malaysia. One hundred ninety-one sewage workers were assessed using the British Medical Research Council (BMRC) questionnaire. Area air sampling was performed in three different sewage plants to measure the following parameters: physical air quality and concentration of PM 2.5 and H₂S.

Result

Chronic cough (34.0%) was reported as the most common symptom, followed by chronic phlegm (26.2%), shortness of breath (7.9%), and chest tightness (3.7%). There were five significant determinants of the presence of respiratory symptoms among the sewage workers: shift work (AOR 23.50, 95% CI: 1.90–616.52), working at a sludge treatment facility (STF) (AOR 25.46, 95% CI: 2.06–314.29), a longer duration of working years (AOR 1,21, 95% CI: 1.01–1.44), individual cumulative exposure to PM 2.5 (AOR 9.01, 95% CI: 1.98–83.33), and individual cumulative exposure to H₂S (AOR 1.04, 95% CI: 1.01–1.07). The majority of STF and non-STF workers had higher exposure to PM 2.5 and H₂S concentrations in the air than office workers.

Conclusion

Sewage workers working at non-STFs or STFs reported a significantly higher prevalence of work-related respiratory symptoms and exposure to PM 2.5 and H₂S compared with office workers. Exposure-response relationships were also found in sewage workers' cumulative exposure to PM 2.5 and H₂S and the presence of respiratory symptoms.

Allergy to Mus m 1: Allergy to Mus m 1: A review of structural, and immunological features

The prevalence of allergies to pets has been increasing over the past decades. Some of the most important animal-derived allergens are members of the lipocalin protein family, which are found in dander, saliva, and urine. These allergens disperse effectively and are widely present in indoor environments. Exposure to high levels of mouse urinary protein (Mus m 1, hereinafter called 'mouse allergen') has been previously linked to sensitization to mouse, and indicators of asthma severity or control in some studies. To date, this is the only known mouse allergen registered in the IUIS database. This allergen is responsible for 27% of the total T cell response, confirming the dominant role it plays in mouse allergy. Mice have a worldwide distribution affecting both rural and urban areas; hence humans are frequently exposed to mouse-derived proteins. Additionally, exposure to mouse allergens has increased since they are more frequently being made pets, and in addition, exposure of laboratory animal care personnel to mice has been associated with a high risk of developing occupational allergies. Mus m 1 has been recognized as the main mouse allergen, and several studies suggest its clinical relevance. What makes Mus m 1 such an important allergen? In this review, we explored its structural, immunological, and clinical features.

Association of Endotoxin and Allergens with Respiratory and Skin Symptoms: A Descriptive Study in Laboratory Animal Workers

Background

In laboratory animal work, allergens are classically considered to play a prominent role in generation of respiratory and skin symptoms. However, recent development may have changed working conditions and require an updating of preventive measures.

Objective

In workers exposed to a range of animals besides laboratory mice and rats the relative role of endotoxin, irritants, and allergens in symptom generation was assessed for updating preventative measures and health surveillance.

Methods

Eligible workers were recruited from university units in which exposure to rats and/or mice, occurrence of respiratory and/or skin symptoms, and/or a history of animal bites had been reported. Exposure to endotoxin and rat and mouse allergen was assessed (71 half-day personal samples). 'Symptomatic' was defined by work-related ocular, nasal, respiratory, or skin symptoms. A concentration of specific IgE against rat or mouse (e87 and e88) ≥0.35 kU/l defined sensitization. Sensitivity analyses examined the effect of alternative exposure indicators and definitions of 'sensitized' and 'symptomatic'.

Results

From 302 eligible workers, 177 participated. There were 121 and 41 workers in the asymptomatic and non-sensitized and symptomatic but non-sensitized group, respectively. Eight subjects were symptomatic and sensitized. Six sensitized subjects were asymptomatic. One participant could not be assigned to a subgroup. Airborne endotoxin and allergen concentrations were mostly below 20 EU m-3 or the detection limit, respectively. Clinical history showed that irritants and sensitizers other than mouse/rat allergen or endotoxin were a major cause of symptoms. Results were sensitive to the selected exposure indicator and the definition of 'symptomatic'.

Conclusions

Health surveillance programs need to be adapted to include a larger range of allergens and pay more attention to irritants.

Can serum cytokine profile discriminate irritant-induced and allergen-induced symptoms? A cross-sectional study in workers mostly exposed to laboratory animals

BACKGROUND

In workers exposed mostly to laboratory animals (LA), symptoms may be due to irritants or allergens. Correct aetiological diagnosis is important for health surveillance.

OBJECTIVES

This study aims to test whether work-related (WR) allergen-induced symptoms are associated with a cytokine profile distinct from that due to irritants.

METHODS

In a cross-sectional study (n=114), WR respiratory and/or skin symptoms were assessed through a standardised clinical examination and sensitisation to rat and/or mouse allergen determined by serum immunoglobulin E. Serum cytokine concentrations were measured by multiplex assays. The predefined cytokine profiles 'sensitiser' (interleukin (IL)-4, IL-5, IL-13, eotaxin-1) and 'irritation' (IL-8, IL-17A, IL-17F, IL-22) were considered positive, when ≥3 concentrations exceeded the 95th percentile of the asymptomatic non-sensitised group. Results were examined by hierarchical clustering analyses (HCA) and multiple linear regression. Explorative analyses were carried out for nine additional cytokines. Exposure to allergens and endotoxin was assessed in a subpopulation.

RESULTS

The prevalence of the profile 'irritation' was comparable in 28 symptomatic non-sensitised workers and 71 asymptomatic non-sensitised workers. HCA showed that nearly all symptomatic non-sensitised workers were gathered in two subclusters, characterised by high IL-17A levels, but different IL-8 levels. Multiple linear regression identified drug consumption and current complaints as confounders. Sensitised subjects were too few (n=14) for testing the profile 'sensitiser'.

CONCLUSIONS

In this unselected population of LA workers, the profile 'irritation' did not prove to be a valuable health surveillance tool. Low power precluded assessment of the profile 'sensitiser'. The increased IL-17A concentration may originate from irritative constituents of organic dust.

A risk-based approach to reducing exposure of staff to laboratory animal allergens

Within the biomedical research industry, people who work with laboratory animals may be at risk of developing laboratory animal allergy, which can lead to occupational asthma. Under UK and EU laws, employers must prevent or adequately control exposure to any hazardous substance, which includes animal allergens, so far as reasonably practicable, for the protection of all people on the premises. This can be achieved in part by reviewing the risk of allergen exposure in specific areas of a facility and implementing appropriate infrastructure, environmental and performance controls to minimize that risk. The authors describe the approach used at their institution to stratify risk of allergen exposure in various areas of the animal facility and to implement appropriate controls. They also discuss their use of a monitoring program to evaluate allergen concentrations in low- and high-risk areas of the animal facility and explain how the monitoring results can be applied to determine which controls are needed to minimize risk of exposure and to provide a safe working environment.

Medical surveillance for prevention of occupational asthma

PURPOSE OF REVIEW

Because there is sufficient knowledge of its environmental determinants, occupational asthma is a disease that ought to be largely preventable; yet its incidence in many settings remains unacceptably high. Here we review one approach to prevention: the routine use of health surveillance in exposed workforces.

RECENT FINDINGS

Health surveillance is widely practised but there is little evidence that it is used strategically to reduce disease incidence. There are several barriers to the effective use of its various components, chiefly symptoms questionnaires and spirometry. Cost-benefit analyses may help to increase the uptake of industry-wide workplace interventions.

SUMMARY

The effective use of health surveillance for occupational asthma continues to be challenging and there remains relatively little published evidence that will encourage those involved to use it more efficiently. Useful advances could be made by greater collaboration between employers, employee organizations, legislators and researchers.

Laboratory animals and respiratory allergies: the prevalence of allergies among laboratory animal workers and the need for prophylaxis

OBJECTIVE

Subjects exposed to laboratory animals are at a heightened risk of developing respiratory and allergic diseases. These diseases can be prevented by simple measures such as the use of personal protective equipment. We report here the primary findings of the Laboratory Animals and Respiratory Allergies Study regarding the prevalence of allergic diseases among laboratory animal workers, the routine use of preventive measures in laboratories and animal facilities, and the need for prevention programs.

METHODS

Animal handlers and non-animal handlers from 2 Brazilian universities (University of São Paulo and State University of Campinas) answered specific questionnaires to assess work conditions and symptoms. These subjects also underwent spirometry, a bronchial challenge test with mannitol, and skin prick tests for 11 common allergens and 5 occupational allergens (rat, mouse, guinea pig, hamster, and rabbit).

RESULTS

Four hundred fifty-five animal handlers (32±10 years old [mean±SD], 209 men) and 387 non-animal handlers (33±11 years old, 121 men) were evaluated. Sensitization to occupational allergens was higher among animal handlers (16%) than non-animal handlers (3%, p<0.01). Accessibility to personal protective equipment was measured at 85% (median, considering 73 workplaces of the animal handler group). Nineteen percent of the animal handlers indicated that they wear a respirator at all times while handling animals or working in the animal room, and only 25% of the animal handlers had received an orientation about animal-induced allergies, asthma, or rhinitis.

CONCLUSION

In conclusion, our data indicate that preventive programs are necessary. We suggest providing individual advice to workers associated with institutional programs to promote a safer work environment.

Prevention of laboratory animal allergy in the United States: a national survey

OBJECTIVE

Respiratory allergy to laboratory animals is a common and preventable occupational health problem. This study documents current laboratory animal allergy (LAA) prevention programs in the United States.

METHODS

An online survey was e-mailed to designated institutional officials at laboratory animal facilities identified by the National Institutes of Health Office of Laboratory Animal Welfare.

RESULTS

A total of 198 organizations responded and more than 80% required the use of uniforms and gloves to control exposure. Respirators were required by 25% of organizations. Medical surveillance was mandated by 58% of organizations (70% for organizations with at least 100 employees working with animals). Work restriction practices varied. Only 25% of organizations reported knowing the prevalence (range: 0% to 75%) and 29% reported knowing the incidence of LAA (range: 0% to 18%).

CONCLUSIONS

There is broad variation in policy and practice to prevent LAA. An evidence-based consensus would ensure greater protection of workers.