The DREAM method has two major parts. The first part, the inventory, includes a structured questionnaire designed to collect data on six levels: company, department, agent, job, tasks and exposure module. The second part, evaluation, involves assessmentof the potential dermal exposure for each task using the following equation:
Skin-P TASK = Σ Skin-P BP (A)
where: Skin-PTASK = Potential dermal exposure/task
Skin-PBP = Potential dermal exposure/body part
The potential skin exposure for each task is estimated as sum of potential skin exposure for 9 body parts: head, hands, upper arms, lower arms, torso front, torso back, lower body part, lower legs, and feet. The potential exposure for each body part is estimated as sum of the three major exposure routes: emission, deposition and transfer as follows:
Skin-P BP = E BP + D BP + T BP (B)
where: EBP = exposure/body part through emission
DBP = exposure/body part through deposition
TBP = exposure/body part through transfer
The exposure potential for each route is estimated using the following equations:
where: P = exposure probability
I = exposure intensity
EI = intrinsic emission
ER = exposure route factor
The main elements of the last set equations (C) are the probability (P) and the intensity (I) of exposure. The probability is assigned a value of 0, 1, 3, or 10 based on the frequency of the occurrence of exposure route. The intensity is also categorized in four categories and assigned values between 0, 1, 3, or 10. The intensity of emission and deposition is defined as amount of the agent on clothing and for transfer is defined as contaminated level of the surface. Another element in these equations is the “intrinsic emission” that accounts for physical and chemical properties of agents. For more details on how the intensity, probability and intrinsic emission values are assigned the reader can refer to the DREAM method.
Using these equations, we estimated the potential total body skin exposure per task (Skin-P TASK ) for a set of common cleaning tasks: toilet bowl cleaning, sink cleaning, mirror cleaning, floor cleaning with traditional method and floor cleaning with microfiber mops. In the paper we present step by step estimations for two cleaning tasks. Based on the value of the Skin-P TASK , cleaning tasks were classified in different exposure categories as defined by DREAM: “no exposure”, “low exposure”, “moderate exposure”, and “extremely high exposure”. Additionally, body parts with the highest potential for dermal exposures were identified by comparing the DREAM estimates for different body parts.
Ingredients of concern in cleaning product
The major product lines used for common cleaning tasks included general purpose cleaners, glass cleaners, washroom cleaners, and floor finishing products. Examples of products and their ingredients are given in Additional file 1. A list of chemical ingredients identified from MSDSs is given in Additional file 2. The most frequent ingredients (that occurred in more than three products) are highlighted in bold in Additional file 2.
Ingredients of concern identified based on the previously expanded criteria, included: quaternary ammonium chlorides or “quats”, glycol ethers such as 2-butoxyethanol, ethanolamine, several alcohols such as benzyl alcohol, ammonia and several phenols. Additional file 3 presents a summary of ingredients’ chemical and physical properties, health effects of their inhalation and dermal exposures, and the purpose of the application in cleaning product.
Description of common cleaning tasks in hospitals
Common cleaning tasks identified included: preparation of cleaning solutions, floor cleaning, window cleaning, mirror cleaning, toilet bowl cleaning, sink cleaning, and floor finishing tasks (buffing, waxing and stripping).
Preparation of cleaning solutions
Cleaning solutions were prepared in the preparation room and were later transported to each floor using a cart. In most of the cases, solutions were prepared using an automated dispensing system. Concentrated cleaning product were diluted to the ready to use (RTU) form at a certain dilution rate. The dilution rate differed from one product to another; for example the dilution rate was higher for floor cleaners (rate = 3 gallon/min) than for glass cleaners (rate = 1 gallon/min). Only floor finishing products such as floor strippers were prepared by manual mixing.
Floor cleaning tasks
Two methods of floor cleaning were observed: a) wet mop cleaning and b) microfiber mop cleaning. The traditional method involved dipping the mop into a bucket filled with cleaning solution. The second involved the use of the microfiber cloths that were soaked by hand in cleaning solution, used attached to a handle, and send to laundry after one room was cleaned. Floor cleaning was performed daily and its duration varied by the size of the room. For example, patient room cleaning required about 5–10 minutes and hallway floor cleaning required several hours.
Window/mirror/glass cleaning tasks
During these tasks the product was sprayed and then wiped with paper towels. The frequency of window cleaning was lower compared to other tasks. Windows were cleaned as needed and mostly in the main areas or hallways with glass doors. Bathroom mirrors were cleaned daily using glass cleaners.
Bathroom cleaning tasks
Bathroom cleaning involved several cleaning tasks such as: sink cleaning, mirror cleaning, toilet bowl cleaning, and floor cleaning and required application of many products, specific for each task. For mirror and sink cleaning the product was sprayed and wiped with paper towels. During toilet bowl cleaning the product was sprayed into the toilet bowl, followed by brushing with a toilet cleaning brush. In general, bathrooms were cleaned two times per day. The average cleaning time varied from 10–15 minutes.
Floor finishing tasks (stripping, waxing, buffing)
During stripping the floor stripper was applied and left to reside on the floor for about 10 minutes. Then the old floor finish and the residue of the stripper were removed by using a stripping and a wet vacuum machine. Floor waxing was performed after stripping by mopping the protective coat on the floor. After waxing the floor was left for about 20–40 minutes to dry, depending on the indoor air temperature and humidity. Fans were usually used to speed up this drying process. Floor stripping was performed twice a year and in cases when floors were worn or scratched. Floor buffing was needed more frequently, and was performed by spraying the solution and finishing the localized area with a buffing machine.