Dose Response Relations for Health Effects Caused by Office Dust

Dose Response Relations for Health Effects Caused by Office Dust.

The study is focused at the dose response relation for office dust and such office dust spiked with components from fungi known from damp buildings.

The first aim of this study is to investigate if dust causes objective changes such as changes of lung function, nasal geometry, inflammatory indicators in tears and nasal lavage, tear film stability and cells at exposure levels relevant to indoor air. The controlled exposure variable is air concentration of office dust spiked with Glucan to simulate a worse case scenario.

Aim 1: Confirm or support the causality between objective effects and exposures to dust spiked with Glucan with focus on inflammatory responses. This is done by negation of the hypothesis that no significant effects are found for the variables in question.

Aim 2 is to estimate the thresholds and slopes of the DR relation for effect measures which show effects of exposures. At best the study will supply for each variable a zero response to clean air and three non-zero responses to dust. Thresholds and slopes are estimated graphically by linear regression or by an accumulated response model.

Aim 3 is a confirmation that atopic persons and histamine sensitive persons in nasal provocation tests have different responses in the effect measures showing significant effects of exposures to dust spiked with Glucan. Risk group status is therefore included in the analyses of the main variables as explaining variable.

Potential additional aim 4: Chemical and biological characterization of the office dust used in the study.

Aim 4 is an investigation of dose response relations for explorative measures, which in previous investigations have showed indications of a dose response relation. For these no a priory hypotheses exists and the analyses must be arranged ad hoc. The explaining variables are exposure and risk group status.

One challenge in investigations of unspecific effects caused by mixed exposures is that few specific objective effects measures are available and subjective measures have to be introduced. Therefore there is a need for developments of new objective measures of health effects of air pollution. Some of these are related to new biomarkers of respiratory effects in a bio-sample taken as condensed exhaled breath.

Aim 5: Developments of new objective measures of health effects of air pollution. After the experiment it will be investigated by logistic regression if a sensitivity index can be established.

Study Overview

• Status: Completed
• Conditions: Discomfort Symptoms; Changed Lung Function
• Intervention / Treatment: Other: Office dust; Other: clean air

Detailed Description

The basic procedure is an exposure experiment in which human subjects are exposed to controlled variations of dust spiked with Glucan. Their responses are monitored before, after minutes and hours of exposure and later the same evening.

Two groups of subjects are selected in a pre-investigation using strict selection and exclusion criteria. The two groups are atopic persons and responders to Histamine in a RSM nasal provocation test.

The groups are exposed under controlled conditions in a climate chamber at IMA to office dust spiked with Glucan (same procedure and amount as in DAMOS) at clean air level (less than 20 micro-g/m3 (TSP) and at 150, 300 and 700 micro-g/m3 (TSP). In the pre-investigation and during the exposure sessions a number of personal characteristics are measured or registered to be used in the statistical analyses as explaining variables for the responses of the subjects.

The dust exposure will be characterized both though its size distribution and gravimetrically using up-to-date analytical instruments. To optimise the exposures several pilot studies are made. Only effects measures, which previously have shown clear indications of responses to dust exposures, are included in the study.

The timetable includes pre-investigations, two repetitions of the exposure design (run 1 and 2), analyses of the bio-samples, statistical analyses, and reporting.

The study includes a main study and several additional work-packages, which will be activated when funding become available.

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Phase 2; Phase 1

Contacts and Locations

Study Locations

• Denmark
  • Aarhus, Denmark, DK-8000
    • The Air Pollution Unit, Department of Environmental and Occupational Medicine, Institute of Public Health, The University of Aarhus.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 64 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• All in local area
• Nasal histamine responsive
• Grass allergic

Exclusion Criteria:

• Pregnancy
• House dust allergy
• Hyper-responding air ways, Disease

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Non-Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 2; Office dust with added glucan	Other: Office dust; airborne office dust spiked with glucan; Other Names: Glucan
Experimental: 1; Clean air exposures in climate chamber	Other: clean air; Clean air

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Lung Inflammation	during exposures

Secondary Outcome Measures

Outcome Measure	Time Frame
Lung function	during exposures
FEV	during exposures
FVC	during exposures
Acoustic rhinometry	during exposures
cytokine profile	during exposures
Peak expiratory flow	during exposures
inflammation and sensory symptoms	during exposures

Collaborators and Investigators

• Sponsor: University of Aarhus
• Collaborators: The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS); Service Branchens Arbejdsgiverforening i Danmark
• Investigators: Principal Investigator: Lars Mølhave, DMSc, Ph.D., The Air Pollution Unit, Department of Environmental and Occupational Medicine, Institute of Public Health, The University of Aarhus.

Study record dates

Study Major Dates

• Study Start: May 1, 2005
• Primary Completion (Actual): November 1, 2006
• Study Completion (Actual): November 1, 2006

Study Registration Dates

• First Submitted: September 1, 2005
• First Submitted That Met QC Criteria: September 1, 2005
• First Posted (Estimate): September 2, 2005

Study Record Updates

• Last Update Posted (Estimate): March 27, 2008
• Last Update Submitted That Met QC Criteria: March 26, 2008
• Last Verified: March 1, 2008

More Information

Terms related to this study

• Keywords: lung function; inflammation; perception; peak expiratory flow; dose-response; Office dust; Glucan
• Other Study ID Numbers: FORMAS 24.2/2003-0464; DORES2002