Exposure assessment for power frequency electric and magnetic fields.

Abstract

Over the past decade considerable data have been collected on electric and magnetic fields in occupational environments. These data have taken the form of area measurements, source characterizations, and personal exposure measurements. Occupational EMF levels are highly variable in space and time. Exposures associated with these fields exhibit similar large variations during a day, between days, and between individuals within a group. The distribution of exposure measures is skewed over several decades with only a few values occurring at the maximum field levels. The skewness of exposure measures implies that large sample sizes may be required for assessments and that multiple statistical descriptors are preferred to describe individual and group exposures. Except for the relatively few occupational settings where high voltage sources are prevalent, electric fields encountered in the workplace are probably similar to residential exposures. Consequently, high electric field exposures are essentially limited to utility environments and occupations. Within the electric utility industry, it is definitely possible to identify occupations with high electric field exposures relative to those of office workers or other groups. The highly exposed utility occupations are linemen, substation operators, and utility electricians. The distribution of electric field exposures in the utility worker population is very skewed even within a given occupation. As with electric fields, magnetic fields in the workplace appear to be comparable with residential levels, unless a clearly defined high-current source is present. Since high-current sources are more prevalent than high-voltage sources, environments with relatively high magnetic field exposures encompass a more diverse set of occupations than do those with high electric fields. Within the electric utility industry, it is possible to identify occupational environments with high magnetic field exposure relative to the office environment. Utility job categories with the highest exposures are generation facility workers, substation operators, utility linemen, and utility electricians. There are also higher exposures among traditional "electrical worker" job categories. Outside the electrical utility industry, potential sources of high occupational magnetic field exposures at ELF are induction furnaces, welding machines, electrical transportation systems, and electrical distribution vaults. However, the use of low power electrical equipment such as small motors in close proximity to workers and possibly for long periods of time could also lead to high exposure situations. Handheld survey instruments are available to perform area measurements of electric and magnetic fields at power frequencies but not aat all frequencies within the ELF range. Sophisticated personal computer-based instruments are available to characterize areas and sources across the entire frequency range.(ABSTRACT TRUNCATED AT 400 WORDS)

AI evidence extraction

Main findings

The paper summarizes occupational power-frequency electric and magnetic field measurement data, noting that exposures are highly variable in space and time and that exposure distributions are strongly skewed, implying large sample sizes and multiple statistical descriptors may be needed. It states that workplace electric and magnetic field levels are often comparable to residential levels unless high-voltage (electric fields) or high-current (magnetic fields) sources are present, and identifies several utility and other job categories with relatively higher exposures.

Outcomes measured

• Exposure levels and variability of power-frequency electric fields
• Exposure levels and variability of power-frequency magnetic fields
• Exposure measurement approaches (area, source characterization, personal measurements)
• Identification of occupations/environments with higher ELF exposures

Limitations

• No quantitative exposure values or sample sizes are provided in the abstract.
• Abstract is truncated, limiting available details.
• Review/summary nature of the article limits inference about specific measurement protocols or representativeness from the abstract alone.

Suggested hubs

• occupational-exposure (0.95)
  Focuses on assessment of occupational power-frequency electric and magnetic field exposures and identifies higher-exposure job categories.

{
    "study_type": "review",
    "exposure": {
        "band": "ELF",
        "source": "occupational",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Workers in occupational environments (including electric utility workers and other occupations)",
    "sample_size": null,
    "outcomes": [
        "Exposure levels and variability of power-frequency electric fields",
        "Exposure levels and variability of power-frequency magnetic fields",
        "Exposure measurement approaches (area, source characterization, personal measurements)",
        "Identification of occupations/environments with higher ELF exposures"
    ],
    "main_findings": "The paper summarizes occupational power-frequency electric and magnetic field measurement data, noting that exposures are highly variable in space and time and that exposure distributions are strongly skewed, implying large sample sizes and multiple statistical descriptors may be needed. It states that workplace electric and magnetic field levels are often comparable to residential levels unless high-voltage (electric fields) or high-current (magnetic fields) sources are present, and identifies several utility and other job categories with relatively higher exposures.",
    "effect_direction": "unclear",
    "limitations": [
        "No quantitative exposure values or sample sizes are provided in the abstract.",
        "Abstract is truncated, limiting available details.",
        "Review/summary nature of the article limits inference about specific measurement protocols or representativeness from the abstract alone."
    ],
    "evidence_strength": "insufficient",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "power frequency",
        "ELF",
        "occupational exposure",
        "electric fields",
        "magnetic fields",
        "exposure assessment",
        "utility workers",
        "linemen",
        "substation operators",
        "electricians",
        "generation facility workers",
        "welding machines",
        "induction furnaces",
        "electrical transportation systems",
        "area measurements",
        "personal exposure measurements"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.9499999999999999555910790149937383830547332763671875,
            "reason": "Focuses on assessment of occupational power-frequency electric and magnetic field exposures and identifies higher-exposure job categories."
        }
    ]
}

Comments

Log in to comment.

No comments yet.