Epidemiological study (observational study)

Health Effects of Electromagnetic Fields on Reproductive-Age Female Operators of Plastic Welding Machines in Fuzhou, China epidem.

By: Xu Y, Zhang X, Chen Y, Ren N, Lin W, Zhang Q

Published in: J Occup Environ Med 2016; 58 (2): 148-153

A cross-sectional study was conducted in China to investigate the health effects of electromagnetic fields among female operators of plastic welding machines in shoe factories.

Female workers were recruited from supermarkets near the factories as the unexposed control group.

reproductive effects and pregnancy outcomes: low birth weight, prematurity birth, spontaneous abortion, still birth
symptoms of discomfort: headaches, dizziness, lethargy, troubled with dreams, loss of memory, irritability, fatigue, night sweat, muscular aches, palpitation, anorexia, decreased libido, menstrual disorders, difficulties in concentration, anxiety
sleep disturbances: insomnia
serum hormone levels of follicle stimulating hormone, luteinizing hormone, prolactin, estradiol, progesterone and testosterone; gestational hypertension

Type of risk estimation:

measurement: measurements of electric field strength and magnetic field strength were performed in front of the plastic welding machines at three positions, including head, chest, and abdomen as well as in supermarkets at the most frequent working locations of the workers
calculation: cumulative exposure calculated as working duration (years) times exposure level (V/m)

Group	Description
Reference group 1	control group: not exposed
Group 2	factories with low exposure: < 150 V/m
Group 3	factories with high exposure: ≥ 150 V/m
Reference group 4	cumulative exposure level: 0 years-V/m
Group 5	cumulative exposure level: 0 - 499 years-V/m
Group 6	cumulative exposure level: 500 - 999 years-V/m
Group 7	cumulative exposure level: ≥ 1000 years-V/m

Group:
- women
Age: 18–40 years
Characteristics: female plastic welding machine workers of 5 shoemaking factories
Observation period: not stated
Study location: China (Fuzhou)
Exclusion criteria: working part-time, menopausal, pregnant or breastfeeding, smokers, oral contraceptives in the previous 12 months, history of pelvic inflammatory diseases, endometriosis, and/or major abdominal surgery

Type	Value
Total	529

Other:

180 female operators in shoe fabrics and 349 female workers in supermarkets

Statistical analysis method:

No electric fields were detectable in the supermarkets (≥ 1 V/m). The mean electric field strengths in the frequency range from 25 MHz to 30 MHz in the vicinity of the welding machines in the five factories ranged from 51.3 to 368.9 V/m and exceeded the national standard of 25 V/m. The levels of magnetic field strength ranged from 0.02 A/m to 0.06 A/m below the reference values.
The prevalence of neurovegetative symptoms increased with higher electric field exposures. The prevalence of menstrual disorder was 12.0% in the unexposed group, but was significantly increased in the low exposure group < 150 V/m (26.8%) and in the high exposure group ≥ 150 V/m (33.8%). In the groups with cumulative exposure, the prevalence of most neurovegetative symptoms and menstrual abnormalities increased with higher cumulative exposure. No significant associations between adverse reproductive outcomes and occupational exposure were observed among the female workers. Serum progesterone was significantly lower in the exposed groups compared to the control group.
The authors concluded that occupational exposure to electromagnetic fields of plastic welding machines in shoe factories was associated with adverse health effects, including subjective symptoms, menstrual disorder and low level of serum progesterone among female operators.

Chen Q et al. (2013): ECG changes in factory workers exposed to 27.2 MHz radiofrequency radiation
Wilen J et al. (2004): Electromagnetic field exposure and health among RF plastic sealer operators
Kolmodin-Hedman B et al. (1988): Health problems among operators of plastic welding machines and exposure to radiofrequency electromagnetic fields