Monitoring of people and workers exposure to the electric, magnetic and electromagnetic fields in an Italian national cancer Institute

The physiotherapy department (12x3m) includes an open space, where cyclettes and tapis roulant are positioned, and n. 4 boxes where the devices for specific therapies (Table 1) can be placed on demand. Broad band electric field measurements, carried out in the open space, with all the equipments working in operating conditions, have supplied values lower than the sensitivity of the electric field probe (1,0 V/m). In table 2 and 3 are reported the results of the magnetic induction (B(μT)) measurements respectively near the tapis roulant (Fig. 1) and specific equipments, conveniently placed in one box (Fig. 2). B(μT) levels are generally lower than 1 μT, with few exceptions, near the tapis roulant (4,5 μT), and near the press-therapy equipment, where a maximum B(μT) level of 1,6 μT has been registered. Effective electric field (E_eff(V/m)) levels lower than 2,3 V/m have been registered near the equipment for ultrasound therapy. Further measurements, performed near the head of the Laser Power Diode, have provided E_eff(V/m) measurements in the range 1,0 -3,0 V/m.

The rehabilitation area consists of: the reception, the press-therapy room and a medical office. In particular, in the press-therapy room, two equipments for the arms Lymphatic Drainage are placed. The duration of this therapeutic treatment varies from 2 hours up to 4 hours and is generally performed for four patients at the same time. The B(μT) levels, measured in the points reported in Fig. 3, are reported in Table 4.

During the treatments, the B(μT) levels detected near the patients are lower than 1 μT. Around the equipments, in positions where only the staff could eventually stay, B(μT) levels between 1,1 and 5,0 μT have been registered. Higher levels (up to 80 μT) have been obtained near the air compressors and the electronics of the equipments, in the positions reported in Table 4. Additional measurements, performed at a height of about 10 cm from the floor, have provided B(μT) levels lower than 1,4 μT. Further investigations, carried out in the contiguous rooms, during the equipments standard working conditions, provided B(μT) values between 0,1 and 0,2 μT.

The intensive care division consists of an open space, where three patients' beds and two monitoring workplaces are located, and three rooms. In Table 5, the results of the B(μT) measurements in the open space (Fig. 4) near the sources listed in Table 1, are reported; the magnetic induction measurements, carried out at a height of 1,0 m and 1,9 m from the floor, near the electric panel and near the intensive care staff workplaces, are lower than 1,9 μT. Magnetic field background measurements in the open space provided B(μT) levels equal to 70 nT. The high frequencies E_eff(V/m) values, measured near a patient's bed, resulted lower than 1,0 V/m. In Table 5, the results of the B(μT) measurements around a bed (Fig. 5) are reported. The B(μT) levels close to the patients are lower than 1 μT, while levels up to 7,0 μT have been detected at 1 m from the bed, at a distance of few centimetres from the volumetric and syringe infusion pumps. Higher B(μT) levels (equal to 14 μT) have been measured at the bottom of the bed near the engine of the anti-bedsore mattress.

In the surgical room (6x12 m), an operating table and two trolleys equipped with ventilators and electric scalpels are placed. B(μT) measurements, performed with the equipments in working conditions, without patients, provided levels of about 50 nT, comparable with the background. Levels up to 24,0 μT have been measured near the electric power of the electric scalpels, at 20 cm from the floor. Broad band E_eff(V/m) measurements, with all the equipments in working conditions, resulted close to the sensitivity of the electric field probe (1,0 V/m).

High frequencies E_eff(V/m) measurements near the MR and into the gate room during the sequences activation, showed levels lower than 1,0 V/m.

Further investigations have been performed in other departments where the indoor DECT base stations for wireless communication are placed. These apparatus are generally located in the passageways, on the wall at a height of 2 m from the floor. High frequencies E_eff(V/m) measurements have been carried out at a height of 1,0 m and 1,9 m from the floor close to the DECT systems. The E_eff(V/m) levels within 1 m from the equipments, at a height of 1,9 m are comprised between 1,0 and 1,3 V/m.

Further investigations have been carried out outside the NCI. In a radius of about 300 m a radiobase station for cellular communications is placed on the roof of a building. In the distance of a few km from the NCI, a tower with several broadcasting systems for radio, TV, and cellular radiobase stations is located. Investigations with the broad and the narrow band tools in the external area of the NCI show that these sources don't give a significant contribution to the electromagnetic field background in the area. Additional investigations inside the NCI, in particular in the physiotherapy division, allowed to detect a weak electric field at the frequency of 1,9 GHz produced by a radiobase station for the cellular networks (Fig. 6).

In Italy, people exposure to the ef-mf-emf is defined by two decrees [8, 9] in terms of three levels: (i) limits, levels that haven't to be exceeded in any circumstances for the protection from short terms effects; (ii) attention levels that have not to be exceeded into gambling areas, schools and buildings where people stay for more than 4 hours, as a precaution from the potential risks on health due to long time exposition; (iii) quality targets, levels to achieve in a long period in order to minimize people exposure. The respective levels for the protection of people exposure at high and low frequencies are reported in Tables 7 and 8.

The European recommendation [11] establishes basic restrictions and reference levels for limiting exposure. Basic restrictions are restrictions on exposure to time-varying electric, magnetic, and electromagnetic fields which are based directly on established health effects and biological considerations. Depending upon the frequency of the field, the physical quantities used to specify these restrictions are magnetic flux density (B), current density (J), specific energy absorption rate (SAR), and power density (S). The reference levels are electric field strength (E), magnetic field strength (H), B, and S. Reference levels and basic restrictions have been developed following a thorough review of all published scientific literature. The criteria applied in the course of the review were designed to evaluate the credibility of the various reported findings; only established effects were used as a basis for the proposed exposure restrictions. Induction of cancer from long-term electromagnetic fields exposure was not considered. However, since there are safety factors of about 50 between the threshold values for acute effects and the basis restrictions, this recommendation implicitly covers also possible long-term effects in the whole frequency range. The respective levels are reported in Table 9.

The directive 2004/40/EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from electromagnetic fields, has been issued in the European Official Journal on May 25, 2004, together with its recent application in the Italian regulation [13]. It introduces measures protecting workers from the risks associated with emf, owing to their effects on the health and safety. The long-term effects, including possible carcinogenic effects due to exposure to time-varying ef-mf-emf for which there is no conclusive scientific evidence establishing a causal relationship, are not addressed. Exposure limit values and action values have been defined. The former are based directly on established health effects and biological considerations and compliance with these limits ensures that workers exposed to emf are protected against all known adverse health effects. The action values refer to the magnitude of directly measurable parameters, provided in terms of E, H, B and S; the observance with these values ensure compliance with the relevant exposure limit. Action values are obtained from the exposure limit values according to the rationale used by the International Commission on Non-ionising Radiation Protection (ICNIRP) in its guidelines on limiting exposure to non-ionising radiation [13].

For the health staff in the NCI, the exposure levels are in agreement with the recommendations fixed by the international standards. However, for the health staff, the more restrictive Italian people long term exposure levels have been established as investigation levels. The results of the monitoring in the working areas frequented by patients and accompanies, near the equipments reported in Table 1 show a variability of the B(μT) measurements between 0,01 and 80 μT. The global statistical distribution of the B(μT) levels shows that most of the measurements are in the range 0,05<B = 0,5 μT, with 25% of the levels registered in the surgical room, 9% in the press-therapy room and 15% in the physiotherapy division. The 89% of the B(μT) levels measured near electric and electronic devices used in diagnostics and in medical cures, in positions normally occupied by the patients during the treatments are within 3 μT, while 8% are within 10 μT. Only 3% of the measurements is higher than this level but within the restrictive limits imposed by the Italian law to regulate the exposure of the public to the mf. The last levels have been measured typically near the engine of the tools and near the electric power of the instrumentations in areas where the presence of the population is not scheduled. In order to minimize or reduce exposures, it is then sufficient to set the area around the devices, with the indications to the staff not to stay close to the devices in their operative conditions.

The exposure conditions of the patients for the extremely low frequencies and the emf in the intensive care are in accordance with the measurements carried out by Petrucci [14]. The results show that the type of equipments, their number and also their orientation respect to the patient is important to minimize mf levels; in general, a collection of equipments should be avoided and a safety distance have to be adopted to avoid unnecessary exposures.

About the possible electromagnetic interference (EMI) with electronic equipments by radio waves coming from outside the hospital, we find E_eff(V/m) sensibly lower than the values registered by Hanada et others [15]. However, measurements of the electromagnetic environment should be performed by each hospital specially in urban areas [16] where some sources could potentially induce strong electric field intensity causing malfunctions.