Air quality in an animal facility: particulates, ammonia, and volatile organic compounds

Indoor Air Quality Considerations for Laboratory Animals in Wildfire-Impacted Regions-A Pilot Study

Wildfire events are increasing across the globe. The smoke generated as a result of this changing fire landscape is potentially more toxic than air pollution from other ambient sources, according to recent studies. This is especially concerning for populations of humans or animals that live downwind of areas that burn frequently, given that ambient exposure to wildfire smoke cannot be easily eliminated. We hypothesized that a significant indoor air pollution risk existed for laboratory animal facilities located proximal to fire-prone areas. Here, we measured real time continuous outdoor and indoor air quality for 28 days at a laboratory animal facility located in the Rocky Mountain region. We demonstrated that during a wildfire event, the indoor air quality of this animal facility is influenced by ambient smoke events. The daily average indoor fine particulate matter value in an animal room exceeded the Environmental Protection Agency's ambient annual standard 14% of the time and exceeded the World Health Organization's ambient annual guideline 71% of the time. We further show that specialized cage filtration systems are capable of mitigating air pollution penetrance and could improve an animal's microenvironment. The potential effects for laboratory animal physiology that occur in response to the exposure levels and durations measured in this study remain to be determined; yet, even acute wildfire exposure events have been previously correlated with significant differences in gene regulatory and metabolic processes in vivo. We believe these findings warrant consideration for indoor laboratory animal facility air quality monitoring and development of smoke exposure prevention and response protocols, especially among facilities located downwind of fire-prone landscapes.

Assessment of Indoor Air Quality for Group-Housed Macaques (Macaca spp.)

Indoor Air Quality (IAQ) is strongly associated with animal health and wellbeing. To identify possible problems of the indoor environment of macaques (Macaca spp.), we assessed the IAQ. The temperature (°C), relative humidity (%) and concentrations of inhalable dust (mg/m3), endotoxins (EU/m3), ammonia (ppm) and fungal aerosols were measured at stationary fixed locations in indoor enclosures of group-housed rhesus (Macaca mulatta) and cynomolgus macaques (Macaca fascicularis). In addition, the personal exposure of caretakers to inhalable dust and endotoxins was measured and evaluated. Furthermore, the air circulation was assessed with non-toxic smoke, and the number of times the macaques sneezed was recorded. The indoor temperature and relative humidity for both species were within comfortable ranges. The geometric mean (GM) ammonia, dust and endotoxin concentrations were 1.84 and 0.58 ppm, 0.07 and 0.07 mg/m3, and 24.8 and 6.44 EU/m3 in the rhesus and cynomolgus macaque units, respectively. The GM dust concentrations were significantly higher during the daytime than during the nighttime. Airborne fungi ranged between 425 and 1877 CFU/m3. Personal measurements on the caretakers showed GM dust and endotoxin concentrations of 4.2 mg/m3 and 439.0 EU/m3, respectively. The number of sneezes and the IAQ parameters were not correlated. The smoke test revealed a suboptimal air flow pattern. Although the dust, endotoxins and ammonia were revealed to be within accepted human threshold limit values (TLV), caretakers were exposed to dust and endotoxin levels exceeding existing occupational reference values.

Bedding-generated particulate matter: implications for rodent studies

OBJECTIVES

Rodents used in scientific research are typically housed in cages containing natural bedding materials. Despite extensive evidence of biological harm from inhaled particulate matter (PM), relatively little work has been performed to measure bedding-generated PM exposure in caged animals used in basic science research. Our objectives were to determine whether bedding-generated PM was present in significant concentrations in rodent cages and to identify the main factors affecting the accumulation and attenuation of bedding-generated PM inside cages.

MATERIALS AND METHODS

We measured PM2.5 concentrations in cages containing common bedding materials (pine, aspen, paper, and corncob) with filter top isolator absent or present on the cages. PM2.5 concentrations were monitored with rats inside cages as well as during artificial manipulation of the bedding (designed to simulate rodent activity).

RESULTS AND DISCUSSION

Upon rodent digging or mechanical/manual stirring, all four bedding materials produced significant increases in PM2.5 concentrations (as much as 100-200 µg/m3 PM2.5, 50- to 100-fold higher than during periods of no rodent activity), and concentrations in cages fitted with filter tops were an order of magnitude higher than in cages without filter tops. Elevated concentrations were sustained for longer durations in cages with filter tops (5-10 minutes) compared to cages with only bar lids (0-2 minutes).

CONCLUSIONS

These results indicate that standard laboratory housing conditions can expose rodents to substantial levels of PM2.5. Bedding-generated PM has potential implications as an environmental agent in rodent studies.

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.

Guidelines for Inspection of Companion and Commercial Animal Establishments

Various establishments exist in which animals are held for a variety of reasons. Historically, the management and inspection of animals in commerce and in private keeping have involved a considerable degree of arbitrary evaluation based on the personal experience of the vendor, keeper, advisor, or inspector. Accordingly, relevant protocols and standards are subject to considerable variation. Relatedly, diversity of traded and privately kept species generates significant challenges for those responsible for facility management and inspection alike. Animal welfare and public health and safety are constant and major concerns that require objective methodologies to monitor and control. This report focuses on establishments concerned with the boarding, breeding, storage, vending or handover of animals intended for human “companions” or “pets”, and aims to provide universal objective information for essential husbandry, inspection protocols and an allied inspection assessment tool for scoring establishments.

Individually ventilated cages cause chronic low-grade hypoxia impacting mice hematologically and behaviorally

Use of individually ventilated caging (IVC) systems for mouse-based laboratory investigation has dramatically increased. We found that without mice present, intra-cage oxygen concentration was comparable (21%) between IVC housing and ambient environment caging (AEC) that used wire top lids. However, when mice were housed 4-to-a-cage for 1week, intra-cage oxygen dropped to 20.5% in IVC housing as compared to 21% for AEC housing. IVC intra-cage humidity was also elevated relative to AEC housing. Mice raised in IVC housing as compared to mice raised in AEC housing had higher RBC mass, hematocrit and hemoglobin concentrations. They also had elevated platelet counts but lower white blood cell counts. IVC mice, relative to AEC mice, had increased saccharin preference and increased fluid consumption but similar locomotion, food intake, social exploration and novel object recognition when tested in an AEC environment. Taken together, these data indicate that ventilated caging systems can have a 0.5% reduction from ambient oxygen concentration that is coupled to mouse red blood cell indices indicative of chronic exposure to a hypoxia. Importantly, IVC housing can impact behavioral testing for depressive-like behavior.

Detection of mouse and rat urinary aeroallergens with an improved ELISA

BACKGROUND

Risk analysis of laboratory animal work presupposes allergen monitoring with sensitive methods. Commercial ELISA kits have recently become available for the detection of mouse (Mus m 1) and rat (Rat n 1) urinary allergen from settled dust samples and air samples with high allergen levels.

OBJECTIVE

Our aims were to enhance the sensitivities of the commercial ELISA kits for low aeroallergen levels (less than 1 ng/m(3)) and to test these methods with air samples collected from an animal facility.

METHODS

Personal and stationary air samples were collected from an animal facility during various tasks of laboratory animal work and from various premises of the animal facility.

RESULTS

The sensitivities of the ELISA assays were improved with a careful choice of analysis parameters and reagents. The detection limits of 0.1 ng/m(3) for Mus m 1 and 0.8 ng/m(3) for Rat n 1 were established. The sensitized assays enabled detection of mouse and rat aeroallergens also from premises in which animals or dirty cages were not present during sampling.

CONCLUSION

These sensitive assays will help to perform risk assessment in laboratory animal work. However, there remains a lack of standardized analytic procedures and occupational exposure limits for laboratory animal allergens.

Airborne endotoxin predicts symptoms in non-mouse-sensitized technicians and research scientists exposed to laboratory mice

Research scientists, laboratory technicians, and animal handlers who work with animals frequently report respiratory and skin symptoms from exposure to laboratory animals (LA). However, on the basis of prick skin tests or RASTs, only half are sensitized to LA. We hypothesized that aerosolized endotoxin from mouse work is responsible for symptoms in nonsensitized workers. We performed a cross-sectional study of 269/310 (87%) workers at a research institution. Subjects completed a questionnaire and underwent prick skin tests (n = 254) or RASTs (n = 16) for environmental and LA allergens. We measured airborne mouse allergen and endotoxin in the animal facility and in research laboratories. Of 212 workers not sensitized to mice, 34 (16%) reported symptoms compared with 26 (46%) of mouse-sensitized workers (p < 0.001). Symptomatic workers were more likely to be atopic, regardless of mouse sensitization status. Symptomatic non-mouse-sensitized workers spent more time performing animal experiments in the animal facility (p = 0.0001) and in their own laboratories (p < 0.0001) and had higher daily endotoxin exposure (p = 0.008) compared with asymptomatic coworkers. In a multivariate model, daily endotoxin exposure most strongly predicted symptoms to mice in non-mouse-sensitized workers (odds ratio = 30.8, p = 0.003). We conclude that airborne endotoxin is associated with respiratory symptoms to mice in non-mouse-sensitized scientists and technicians.

Controlling exposure to laboratory animal allergens

Laboratory animal allergy (LAA) is a significant occupational disease that may affect up to one third of personnel exposed to laboratory animals. Research has characterized the relative risks of exposure, in terms of intensity, frequency, and duration, associated with given tasks and work areas in the animal facility. Studies have shown that reduced exposure to animal allergens can reduce the incidence of LAA and relieve symptoms among affected workers. A combination of measures to eliminate or control allergen exposure, including engineering and administrative controls and personal protective equipment, have been integral components of effective LAA management programs. The author provides a comprehensive review of exposure control options, considerations, and " best practices" relative to laboratory animal allergen in the context of traditional industrial hygiene methods.

Control strategies for aeroallergens in an animal facility

BACKGROUND

Prevalence of the occupational disease laboratory animal allergy could be reduced if aeroallergen reduction strategies are identified.

OBJECTIVE

To reduce worker exposure to Mus m 1, an allergen from laboratory mice, the effect of filter cage tops, increased room ventilation, negatively pressurized ventilated cages, and ventilated cage-changing tables were evaluated.

METHODS

Aeroallergen was collected in the ambient air and in the breathing zone and quantified by using a competitive immunoassay.

RESULTS

When mice were housed in unventilated cages, ambient allergen was reduced from 5.1 ng/m3 with no cage top to 1.3 ng/m3 with a simple filter-sheet top and 0.8 ng/m3 with a fitted filter-bonnet top (P <. 05). Room ventilation was increased from 6 to 10, 15, and 20 air changes per hour and had little effect on aeroallergen levels and no impact on airborne particulate matter. When mice were housed in ventilated cages, ambient allergen was significantly reduced from 1. 1 ng/m3 at positive cage pressure to 0.3 ng/m3 at negative cage pressure (P <.05). Negative cage pressure combined with handling animals under a ventilated table reduced breathing zone allergen from 28 ng/m3 with neither control strategy in place to 9 ng/m3 (P <. 05). Use of a ventilated table controlled bacterial contamination, measured as colony forming units, found in negatively pressurized cages.

CONCLUSION

Three aeroallergen control strategies are use of filter cage tops, operation of negatively pressurized cages, and use of ventilated changing tables.