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Electric and magnetic fields and health

index/glossary | EMFs At A Glance | EMF The Facts (pdf)
  • What are EMFs
    • Terminology – an introduction
    • Electric fields
    • Magnetic fields
    • Units for measuring EMFs
    • Measuring and calculating EMFs
      • “EMF Commercial”
    • Adding fields together
    • Radiofrequencies
    • Screening EMFs
  • Sources
    • Overhead power lines
      • Fields from specific power lines
        • 400 kV
        • 400 kV – specific cases
        • 275 kV
        • 132 kV
        • 66 kV
        • 33 kV
        • 11 kV
        • 400 V/230 V
        • Replacing a 132 kV line with a 400 kV line
      • Summaries of fields from all power lines
      • Factors affecting the field from a power line
        • Voltage
        • Current
        • Clearance
        • Height above ground
        • Conductor bundle
        • Phasing
        • Balance between circuits
        • Balance within circuit
        • Ground resistivity
        • Two parallel lines
      • Calculating and measuring fields from power lines
        • Geometries of power lines
        • Raw data
        • On-line calculator
      • Fields from power lines – more detail on the physics
        • Field lines from a power line
        • The direction of the field from a power line
        • Power law variations in the field from a power line
      • Statistics of power line fields
    • Underground power cables
      • Different types of underground cable
      • Fields from cables in tunnels
      • Gas Insulated Lines (GIL)
      • Underground cables with multiple conductors
      • Effect of height on fields from underground cables
      • Screening fields from underground cables
    • Low-voltage distribution
      • UK distribution wiring
      • USA distribution wiring
    • House wiring
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      • National Grid substations
        • Static Var Compensators
      • Sealing-end compounds
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        • Indoor substations
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      • EMFs from electric trains (UK)
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      • Smart meters
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    • Occupational exposures
      • Live-line work
      • Static Var Compensators
      • Occupational exposures on pylons
    • Field levels and exposures
      • Personal exposure
      • Other factors that vary with magnetic fields
      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
      • Screening fields from underground cables
      • EMF Reduction Devices
  • Known effects
    • Induced currents and fields
    • Microshocks
      • Control of microshocks in the UK
      • Microshocks from bicycles
      • Bees and microshocks
    • EMFs and medical devices
      • Standards relating to pacemakers and other AIMDs
    • Effects of EMFs on equipment
  • Research
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    • Epidemiology
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      • UKCCS
      • CCRG
      • French Geocap study
      • CEGB cohort
      • Imperial College study
  • Current evidence on health
    • Childhood leukaemia
      • Survival from childhood leukaemia
      • Childhood leukaemia and Downs
      • Childhood leukaemia and night-time exposure
      • The “contact current” hypothesis
    • Other health effects
    • Scientific review bodies
      • WHO
      • IARC
    • Electric fields and ions
    • Comparing EMFs to other issues
  • Exposure limits for people
    • Limits in the UK
    • Limits in the EU
    • Limits in the USA
    • Limits in the rest of the world
    • Limits from specific organisations
      • ICNIRP 1998
      • ICNIRP 2010
      • NRPB 1993
      • NRPB 2004
      • EU 2004
      • EU 2013
  • Policy
    • UK policy
      • Power lines and property – UK
    • Compliance with exposure limits
    • European EMF policy
    • Precaution
    • SAGE
      • SAGE First Interim Assessment
        • Government response to SAGE First Interim Assessment
      • SAGE Second Interim Assessment
        • Government response to SAGE Second Interim Assessment
        • SAGE Second Interim Assessment – the full list of recommendations
  • Finding out more
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    • Links
    • Literature
    • Contact us
  • Static fields
    • Static fields – the expert view
You are here: Home / Exposure limits for people / Compliance with exposure limits / Limits for pregnant women

Limits for pregnant women

Do any special exposure limits apply to pregnant women?

What does the science suggest?

The exposure limits for EMFs are designed to protect against the established effects of EMFs on the body, whereby EMFs induce currents and voltages that can interfere with nerves.  There is no established mechanism whereby either a pregnant woman or the baby she is carrying would be any more sensitive to these effects than any other adult.  The evidence on exposure to magnetic magnetic fields and pregnancy outcomes is broadly reassuring - see a summary of what the review bodies have said.

It is, of course, possible to speculate that the developing foetus may be more sensitive to these or other effects, but this is speculation.  On the other hand, there may be an entirely understandable wish to take an extra level of precaution when it comes to pregnancy.

What do the exposure limits say?

Many of the EMF exposure guidelines that have been published make no specific reference to pregnant women.  The issue is not mentioned explicitly in ICNIRP 1998, EU 1999, or ICES 2002.

NRPB 2004, the NRPB's most recent recommendations on exposure limits, does mention pregnant women but mainly in the context of radiofrequency (RF) EMFs.  For RF EMFs they suggest that the foetus may be more susceptible to heating effects than the adult is, so the public exposure limits (which are lower than the occupational limits) should apply to all pregnant women, to ensure excess heating does not occur.  Power-frequency EMFs do not cause heating, so this argument does not directly apply to power-frequency EMFs.

For power-frequency fields, they state:

The ad hoc expert group (NRPB, 2004) considered that such sensitive people [discussed in the previous sentences] should be adequately protected at lower induced electric field strengths, possibly about a factor of five lower than for normal adults. In addition, the group considered that this reduction factor would be adequate to protect the developing nervous system in utero, and in neonates and young children. It is concluded that a restriction of the induced electric field in the tissue of the CNS to less than 20 mV m–1 is adequate to protect these members of the population.

In a separate document (Documents of the NRPB 15-3, the reference given in the paragraph quoted above), they conclude:

Applied static electric fields also affect nerve growth and regeneration. In addition, static electric fields of typically 10–100 V m–1 have been reported to affect the development of the embryonic and neonatal nervous system; however, these processes are likely to be less sensitive to the effects of induced low frequency electric fields. Nevertheless, effects have been seen with applied static electric fields as low as 100 mV m–1 and at higher values of applied static electric fields which alternate slowly. These data indicate that a degree of caution is appropriate when considering the potential susceptibility of the developing nervous system, both in utero and in neonates and young children to weak induced time-varying electric fields.

ICNIRP 2010 does not specifically say anything about pregnant women in its actual recommended guidelines.  But in the "definitions" it does say:

"General public
The term General public refers to the entire population. It includes individuals of all ages, and of varying health status, and this will include particularly vulnerable groups or individuals such as the frail, elderly, pregnant workers, babies and young children."

This implies that pregnant women may be regarded as "particularly vulnerable".  But it doesn't specifically say how to treat pregnant women who are at work.

The 2011 Commission draft of the Directive on occupational exposures said:

"Where a worker has declared to her employer that she is pregnant then the requirements of Council Directive 92/85/EEC on the introduction of measures to encourage improvements in the safety and health at work of pregnant workers and workers who have recently given birth or are breastfeeding apply. The employer shall enable the worker to avoid having to enter areas where exposures exceeding the exposure limits for the general public given in Council Recommendation 1999/519/EC, or its subsequent revisions."

However, this was not present in the final adopted version of the Directive.

The UK Regulations that implement the EU Directive for occupational exposure define pregnant women as one of the groups of "workers at particular risk".  Employers are required to take specific account of these workers in their Risk Assessment (Regulation 8(2)(j)).  In their Guide to the Regulations, the HSE state (Section F):

Expectant mothers
As working with certain levels of EMFs could result in a greater risk to an expectant mother, you should encourage your workers to advise you in writing if they become pregnant. You may wish to take a practical approach and limit the exposure of expectant mothers to the public exposure limits. These are stated in Council Recommendation1999/519/EC, see Useful links ref2
If risks from EMFs are identified during pregnancy, you must take appropriate action to eliminate, reduce or control the risks; they must be included and managed as part of the general workplace risk assessment. You can find more general information on ‘Workers at particular risk – expectant mothers’ on the HSE website; see References and Further reading, New and expectant mothers; ref6.
Table 5 contains a non-exhaustive list of sources of EMF which may pose specific risks. You will need to consider these in addition to the information contained in Table 3; Sources of EMF which may pose a risk to workers.

What would be a sensible approach?

The various exposure guidelines all agree that there is no need for exposure limits for pregnant women any more restrictive than the limits that apply to all members of the public.  The public exposure limits are valid for pregnant women and their unborn babies.

When a pregnant woman is at work, the wording of the various existing exposure guidelines implies it is acceptable to continue to use the occupational guidelines, which are higher than the public guidelines.  But as a precautionary measure, it may be sensible to apply the public guidelines to pregnant women at work.

This is the approach taken by National Grid.

Latest news

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  • How has the reported risk for childhood leukaemia changed over time? February 11, 2019
  • Media stories about microshocks in children’s playground September 10, 2018
  • New studies on leukaemia and distance from power lines June 1, 2018
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Navigation
  • What are EMFs
    • Terminology – an introduction
    • Electric fields
    • Magnetic fields
    • Units for measuring EMFs
    • Measuring and calculating EMFs
      • “EMF Commercial”
    • Adding fields together
    • Radiofrequencies
    • Screening EMFs
  • Sources
    • Overhead power lines
      • Fields from specific power lines
        • 400 kV
        • 400 kV – specific cases
        • 275 kV
        • 132 kV
        • 66 kV
        • 33 kV
        • 11 kV
        • 400 V/230 V
        • Replacing a 132 kV line with a 400 kV line
      • Summaries of fields from all power lines
      • Factors affecting the field from a power line
        • Voltage
        • Current
        • Clearance
        • Height above ground
        • Conductor bundle
        • Phasing
        • Balance between circuits
        • Balance within circuit
        • Ground resistivity
        • Two parallel lines
      • Calculating and measuring fields from power lines
        • Geometries of power lines
        • Raw data
        • On-line calculator
      • Fields from power lines – more detail on the physics
        • Field lines from a power line
        • The direction of the field from a power line
        • Power law variations in the field from a power line
      • Statistics of power line fields
    • Underground power cables
      • Different types of underground cable
      • Fields from cables in tunnels
      • Gas Insulated Lines (GIL)
      • Underground cables with multiple conductors
      • Effect of height on fields from underground cables
      • Screening fields from underground cables
    • Low-voltage distribution
      • UK distribution wiring
      • USA distribution wiring
    • House wiring
    • Substations
      • National Grid substations
        • Static Var Compensators
      • Sealing-end compounds
      • Distribution substations
      • Final distribution substations
        • Indoor substations
    • Transport
      • EMFs from electric trains (UK)
      • EMFs from cars
    • Appliances
    • Electricity meters
      • Smart meters
      • Traditional meters
    • Occupational exposures
      • Live-line work
      • Static Var Compensators
      • Occupational exposures on pylons
    • Field levels and exposures
      • Personal exposure
      • Other factors that vary with magnetic fields
      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
      • Screening fields from underground cables
      • EMF Reduction Devices
  • Known effects
    • Induced currents and fields
    • Microshocks
      • Control of microshocks in the UK
      • Microshocks from bicycles
      • Bees and microshocks
    • EMFs and medical devices
      • Standards relating to pacemakers and other AIMDs
    • Effects of EMFs on equipment
  • Research
    • Types of research
    • Epidemiology
    • Animal and laboratory experiments
    • Mechanisms
    • Specific studies
      • UKCCS
      • CCRG
      • French Geocap study
      • CEGB cohort
      • Imperial College study
  • Current evidence on health
    • Childhood leukaemia
      • Survival from childhood leukaemia
      • Childhood leukaemia and Downs
      • Childhood leukaemia and night-time exposure
      • The “contact current” hypothesis
    • Other health effects
    • Scientific review bodies
      • WHO
      • IARC
    • Electric fields and ions
    • Comparing EMFs to other issues
  • Exposure limits for people
    • Limits in the UK
    • Limits in the EU
    • Limits in the USA
    • Limits in the rest of the world
    • Limits from specific organisations
      • ICNIRP 1998
      • ICNIRP 2010
      • NRPB 1993
      • NRPB 2004
      • EU 2004
      • EU 2013
  • Policy
    • UK policy
      • Power lines and property – UK
    • Compliance with exposure limits
    • European EMF policy
    • Precaution
    • SAGE
      • SAGE First Interim Assessment
        • Government response to SAGE First Interim Assessment
      • SAGE Second Interim Assessment
        • Government response to SAGE Second Interim Assessment
        • SAGE Second Interim Assessment – the full list of recommendations
  • Finding out more
    • EMF measurement and commercial services
    • Links
    • Literature
    • Contact us
  • Static fields
    • Static fields – the expert view