Frumkin, 2ePart 1: Methods and ParadigmsChapter 4: Exposure Assessment, Industrial Hygiene, and Environmental Management

Industrial Hygiene

Industrial hygiene has been defined as the science and art devoted to the anticipation, recognition, evaluation, and control of those environmental factors or stresses arising in or from the workplace that may cause sickness, impaired health and well - being, or significant discomfort among workers or among citizens of the community.

Industrial Hygiene

Industrial hygienists seek to recognize occupational hazards, to evaluate these hazards visual or instrumental monitoring of a site, and to control is the risk to health and safety through administrative or engineering measures.

Anticipation

Industrial hygienists anticipate a variety of hazards, including safety hazards (e.g. emergency exits, slippery surfaces, etc.), health hazards, which include physical hazards (e.g. high noise, extreme temperatures) and chemical hazards (e.g. mercury, chlorine gas, and environmental hazards (potential threats to the local people and ecosystems).

Recognition

Once the industrial hygienist has anticipated the potential hazards associated with a facility, the next step is recognition of the actual hazards.

The initial recognition phase is usually accomplished during a site visit or walk-through, a visual inspection of the facility. Herein, the hygienist also identifies subgroups

within the work environment that may be exposed to particular hazards that other groups are not.

Evaluation

Industrial hygienists next evaluate the level of exposure at the site through a variety of methods.

The hygienist may choose to measure exposures in a part of the workplace (area sampling), in the immediate vicinity of individual workers (personal sampling), or even in the bodies of individual workers (biological sampling).

Population Sampling for Exposure Evaluation

Hygienists may evaluate a population in many different ways.

In a small population, they may use a census to evaluate all members; in a larger population a representative sample can be used.

At times, they use a convenience sample (taking volunteers or those with a particular complaint), though this type is subject to bias.

Exposure Evaluation Instruments

Direct reading instruments are useful for measuring many physical hazards, such as temperature, noise, and radiation. They provide objective measures of potential exposure.

Sample collection instruments are used instead of direct reading instruments when multiple airborne pollutants are present or further analysis on samples is desirable. Active sampling uses a pump or another active device to

obtain a sample, whereas passive sampling requires an absorbing medium that removes the compound of interest from the air.

Control

The final component of the industrial hygiene paradigm is control of the hazards.

Industrial hygienists use several approaches to modify the workplace environment: Substitution (replacing a hazardous material or process with a less hazardous one), isolation (containing or limiting access to the hazardous process), and ventilation (introducing fresh or cool air into an environment so as to reduce the effects of exposure).

Protective devices and personal protective equipment minimize hazards.

Administrative strategies, such as rotating workers through dangerous jobs limit an individual’s aggregate exposure.

Exposure Science

Exposure science focuses on quantifying the contaminant exposures people experience as they go about their daily activities, evaluating factors that influence these exposures, and exploring new and innovative measurement methods designed to quantify exposure and effect.

Exposure assessment is one aspect of exposure science, is concerned with the quantification of exposures in both occupational and environmental settings.

Exposure Variables Magnitude, frequency, and duration of exposure

determine the effects of exposure on the body.

Experiencing acute exposure (brief, high magnitude exposure) can have different effects than chronic exposure (long-term, repeated, low magnitude exposure) or subchronic exposures (may occur over intermediate time scales, often weeks or months, and also may be episodic and recurring).

Exposure can occur through the skin (dermal), through inhalation, or through ingestion.

Exposure Assessment Methods

Imputing or modeling exposures

Measuring environmental exposures

Measuring personal exposures

Measuring biomarkers

Imputing or modeling exposures

To impute exposures, scientists use indirect exposure assessment methods that either forgo direct measurements of the exposures of interest or employ partial data.

Another method uses exposure scenarios, wherein exposure of individuals is estimated from activity patterns.

Measuring Environmental Exposure

May also use direct measurement of exposure, for example, the computerized monitoring of air and water pollution that occurs in cities.

Measuring Personal Exposure

Personal exposure assessment involves outfitting an individual with a monitor that measures exposures during daily activities, exactly as is done in the workplace.

Aggregate and Cumulative Exposure Assessment

In aggregate exposure scientists consider simultaneously all routes and pathways that may have been involved in an exposure to a single compound.

Scientists also study cumulative exposure, that is the accumulation of exposure to various potentially hazardous compounds.

Measuring Biomarkers

When measuring biomarkers of exposure, scientists sample biological material, such as exhaled breath, urine, blood, feces, or hair, for contaminants of interest.

These samples may be analyzed for the contaminant itself, called the parent compound, a metabolite, or a biological response known to reflect exposure.

Using Biomarkers

Using biomarkers to detect exposure is particularly effective because if a biomarker is present, scientists can be sure that exposure has occurred.

Biomarkers have the disadvantage of not giving information of the specific pathway of exposure. Furthermore, sometimes it is difficult to tell from a biomarker which compound precisely caused the problem at hand.

Assessment of Ingestion and Dermal Exposure

Exposure due to ingestion is studied by analyzing the foods that people consume.

Dermal exposure is studied by having individuals wear special patches that pick up chemicals that are absorbed into the skin or by testing the skin of cadavers.