Editor’s message: Communication applications and perception of microwave effect

According to publications on microwave conferences and journals, the interest in the field of not communication applications covers a wide range of topics, such as agriculture, biomedical, chemistry, dielectric properties, drying, energy, food, industrial and scale-up, modelling, ovens design, plasma, and solid state, among many others.

Non-thermal microwave effect is still a controversial issue, at least in terms of its justification, although there are many well supported reports of higher rate reactions with microwaves compared to conventional heating. Activation of different reaction mechanisms, and either volumetric or selective heating, more energy into the system, could provide an explanation to this observed effect. The two-step sintering process where temperature is increased above the sintering set point for a short time could be a sort of example of thermal issues involved. Therefore, it is essential for non-thermal studies to accurately know the temperature profile in the sample, which often is difficult, so that values are calculated, or estimated, though modelling. Despite this inconvenience, there are reports with results that seriously challenges thermal explanations, and that is why this field of microwave research is active.

However, some words regarding microwave effect have been taken, mostly in the internet and social networking, for claiming that microwaves are cause of illness, alter nutritional meal values, and have other effects against healthy life, including infertility. Even earlier than these generalized claims, safety has been an issue, regardless their impossibility due to nature of microwave energy being not energetical enough to break chemical bonding, and thermal regulation of mammals, to produce such consequences.

These topics have been studied as they have arisen, quite before the commercial internet and, of course, internet social networking, which penetration power made almost any subject interesting to a wide audience.

Regarding experiments to proof the effect of microwaves, there are some, even presented in fair science projects that although well prepared, have a scientific rigor accordingly to the student’s level. For instance, there is an experiment where plants were watered with water that was previously heated with microwaves and then left to cool down, against running water watering, with the comparation of the appearance of only two plants, they made conclusions about microwave effect.

For public interest, this becomes a matter of perception rather than science, social networks offer the chance to cast conclusions directly, without any proof, leading understanding to the general knowledge and common sense of the readers. Table 1 shows a roughly ranking of the number of pdf documents found in internet from a google search combining different words about the subject. The number changes each time that the search is conducted, but they are within the same range and ranking remains the same. Counting of documents cannot be taken as a measurement of interest directly, because their availability depends of factors related to popularity and accessibility. Despite this condition, it is noticeable that there is more literature regarding mobile phones than microwaves, connecting somehow the effect to the device.

Table 1. Number of pdf documents found in a google search with different words.

Ranking	Searched words (and)	Number of found documents
1	Mobile phone risk	228,000,000
2	Mobile phone cancer	232,000,000
3	Sun risk	182,000,000
4	Sun cancer	177,000,000
5	Microwave safety	38,800,000
6	Microwave food	45,800,000
7	Microwave chemistry	34,400,000
8	Microwave risk	25,100,000
9	Microwave synthesis	23,300,000
10	Microwave non-thermal	21,500,000
11	Microwave cancer	15,600,000
12	Microwave agriculture	14,700,000
13	Microwave nutrition	10,100,000
14	Microwave oven risk	8,160,000
15	Mobile phone infertility	8,020,000
16	Microwave drying	7,800,000
17	Microwave dangerous	5,750,000
18	Sun infertility	2,910,000
19	Radon cancer	1,750,000
20	Microwave infertility	446,000

It is difficult to evaluate the quality of each document posted on the internet, some might be serious reports, newspaper notes, and even brochures of miraculous products. ‘Microwave and risk’ is the 8^th in the proposed ranking, with food and chemistry, which are common microwave applications above, and other applications close. If the ranking is arbitrarily associated to public concern, mobile phones are of greater concern than microwave ovens, although that could come from the difference in the mobile phone and the household microwave oven market are not comparable. Currently, there is no direct evidence of microwave being the cause of illnesses, either directly or through meals exposed to them. A problem with health issues is that causes cannot be isolated as in a chemical reaction case. For instance, inexplicable cancer could come from environmental conditions, such as sun radiation with higher energy than microwaves, radon, and pollution. These conditions conform the antecedent to an effect, but an antecedent is not a cause by itself.

What it has been observed, thermal or not, is taken by engineers in their application designs. Any possible effect due to microwave exposition, regardless the applications, even communication ones as the mobile phones, is of the interest of microwaves experts that consider theoretical bases to build experiments to conclude about this matter.

Juan Antonio Aguilar Garib
Universidad Autónoma de Nuevo León
Facultad de Ingeniería Mecánica y Eléctrica
San Nicolás de los Garza, NL, México
[email protected]