Delayed Growth in Immature Male Rats Exposed to 900 MHz Radiofrequency.

The second generation of mobile communications (2G) was introduced in the 1990s with the GSM network (900 MHz). To date, exposure to 900 MHz mobile phone radiation is ubiquitous in both public and occupational settings. The 2G network has been shown to remain the primary source of brain penetration by radiofrequency electromagnetic fields during phone calls. The exposure limits are set at 0.08 W/kg for the general public (Pu) and 0.4 W/kg for occupational exposure (Oc). In both cases, there are particularly vulnerable groups, such as pregnant women, immature individuals (fetuses, newborns, children), and sick or elderly people. It is known that the skulls of fetuses and newborns provide less protection against the penetration of radiofrequency radiation than those of adults. Therefore, it can be assumed that the physiological and developmental protection provided by ICNIRP limits is less effective in vulnerable populations. This study aims to investigate how radiation exposure at public and occupational limits affects growth and development and to what extent these effects differ, using a rat model.

A total of 25 pregnant rats were divided into three groups: sham-exposed (n = 9), PuM (n = 8; whole-body SAR 0.08 W/kg), and OcM (n = 8; whole-body SAR 0.4 W/kg). The animals and their offspring were exposed to 900 MHz radiation from day 8 post-fertilization (prenatal) until day 17 after birth (postnatal) between 11:00 a.m. and 7:00 p.m. The field strengths were 30.2 V/m (PuM) and 67.5 V/m (OcM). At birth, the litters were reduced to three male and three female pups per litter. One pup of each sex was sacrificed on days 8, 17, and 43 after birth. General litter parameters (litter size, sex ratio, and number of stillbirths) were first analyzed. In addition, pup weight and size were documented from birth until day 43 postpartum. Each pup was examined daily to determine the timing of eye opening, incisor eruption, and ear unfolding. These events are considered developmental markers.

The study found no evidence of adverse effects of perinatal radiation exposure on general litter parameters (litter size, sex ratio, number of stillbirths) or on pup weight and size at birth. However, a statistically significant reduction in body weight was observed in OcM-exposed male pups (0.4 W/kg) from day 6, which persisted until the end of the experiment (day 43). Male pups in both exposed groups were also smaller, although this result did not reach statistical significance (p = 0.0557). However, the effects of 900 MHz exposure on early developmental markers were statistically significant. Eye opening and ear unfolding were observed earlier in both exposure groups and both sexes. Incisor eruption was significantly earlier only in the male pups of the PuM group.

This publication is the first to compare the effects of public and occupational exposure limits on the physical development of rats. The results suggest physical developmental defects (premature ear unfolding, early eye opening, reduced body weight), with occupational exposure limits causing a more pronounced phenotype. The observed phenotype may indicate a metabolic disorder with increased energy demand. The authors note that comparable developmental defects have been observed in newborn rats and mice with chemically disrupted serotonin and dopamine metabolism (Abu-Taweel, 2019; Cai et al., 2023). The neurotoxic effects of these chemicals are partly due to oxidative stress (Huang et al., 2008). (RH)

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"Premature eye opening and ear unfolding occurred at both field strengths and in both sexes."