Epidemiological study (observational study)

A pilot study on the reproductive risks of maternal exposure to magnetic fields from electronic article surveillance systems epidem.

By: Khan MW, Roivainen P, Herrala M, Tiikkaja M, Sallmén M, Hietanen M, Juutilainen J

Published in: Int J Radiat Biol 2018; 94 (10): 902-908

Aim of study (acc. to author)

A pilot study was conducted in Finland to assess the feasibility of a large-scale study on reproductive effects of occupational exposure to intermediate frequency magnetic fields among cashiers working near electronic article surveillance systems.

Endpoint/type of risk estimation

reproductive effects and pregnancy outcomes: miscarriage, reduced birth weight, smallness for gestational age and preterm birth

Exposure

- 8.2 MHz
- magnetic field
- static magnetic field
- low frequency
- intermediate frequency
- EAS/RFID
- occupational
- co-exposure

Assessment

measurement: magnetic field strength for extremely low frequency and intermediate frequency range and magnetic flux density for static magnetic field at the position of cashier’s seat in supermarkets with EAS systems, at the distance of 0.1 m from an EAS gate, at the center between two gates and in grocery stores without EAS systems

Exposure groups

Group	Description
Reference group 1	cashiers working in grocery stores without EAS-systems: unexposed
Group 2	cashiers working in supermarkets with EAS systems: exposed

Population

Group:
- women
- children in utero
Age: 18–40 years
Characteristics: cashiers of a large Finnish retail company
Observation period: 2008 - 2015
Study location: Finland
Data source: Finnish Medical Birth Register, Register for Health Care

Study size

Type	Value
Total	4,157

Other:

536 births and 38 miscarriages

Statistical analysis method:

linear regression
logistic regression

(adjustment:

mother: age at the beginning of pregnancy, number of previous deliveries, smoking during pregnancy; child: gender, gestational weeks

)

Results (acc. to author)

All magnetic fields measured were clearly below the ICNIRP occupational reference levels and the reference levels for the general public. Cashiers were found to be exposed to 8.2 MHz magnetic fields only when passing by the EAS gates at short distance. Static fields of about 0.1 mT were measured at cashier’s seat. Extremely low frequency magnetic fields were higher at stores without EAS devices compared to supermarkets with EAS devices.
No differences on the risk of miscarriage, reduced birth weight or preterm birth were observed between cashiers in different store types.
The authors concluded that any further studies should attempt to include study subjects working near EAS systems that produce stronger IF MFs at kHz frequencies. Exposure to ELF MFs should be assessed as a possible confounding factor.

Limitations (acc. to author)

A limitation of the study was lack of information about the exact duties of the workers, such as working hours as cashiers.

Study funded by

European Union (EU)/European Commission

Eskelinen T et al. (2016): Maternal exposure to extremely low frequency magnetic fields: Association with time to pregnancy and foetal growth
Roivainen P et al. (2014): Occupational exposure to intermediate frequency and extremely low frequency magnetic fields among personnel working near electronic article surveillance systems
Grajewski B et al. (1997): Work with video display terminals and the risk of reduced birthweight and preterm birth

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