How long is someone contagious after catching the flu?
We have heard a lot about the bad flu season and the importance of staying home while you have the flu to avoid infecting others. But we haven't heard too much about how to know when you are no longer likely to infect others with the flu. What if symptoms are lessened, you have been fever-free for 24 hours, and you go back to work or school-are you still possibly contagious? According to the CDC, the answer is "yes." The CDC says that most healthy adults are contagious for a day before the symptoms begin and for about 5-7 days after becoming sick. So while your symptoms may only last three to five days, you may be contagious for a couple of days after that. Young children and those with weakened immune symptoms may be contagious for a longer time.
Read more at the CDC: https://www.cdc.gov/flu/
More on the study about health effects of cell phone radiation
Last week, the NIH's National Toxicology Program (NTP) released the latest results from the third phase of a study on the cancer risks of cell phone radiation. The latest results, part of a larger $25 million project commissioned by the FDA, will be the topic of a peer-review assessment conducted by the NTP in March 2018. The FDA issued a press release about the study, citing some results that suggest there is not much to worry about, along with other concerning findings that beg for more research to be done. The concerning part of the study was that male rats exposed to whole-body non-ionizing radiation (with a lower frequency EMF but higher power than used in today's 4G cell phones) developed cancerous tumors (called malignant schwannoma) in their hearts while the control group did not. And the rate of these tumors increased with the increase in the radio frequency radiation.
Some background on non-ionizing radiation and electromagnetic radiation:
Non-ionizing radiation is a type of electromagnetic radiation that does not cause changes to the electrons of atoms of the molecules of the matter it passes through. Ionizing radiation does cause such changes and includes gamma rays, x-rays, and the high-frequency ultraviolet part of the electromagnetic spectrum. Non-ionizing radiation includes visible light, infrared, microwaves, and radio waves. Cell phone radiation is non-ionizing, and may fall within the radio wave or microwave spectrum. For non-ionizing radiation, there may be "thermal" (heat-related) or "nonthermal" effects.
Electromagnetic fields (EMFs) are "invisible lines of force created whenever electricity is generated or used. EMFs are produced by power lines, electric wiring, and electric equipment like cell phones and appliances. The frequency of EMFs is measured in hertz (Hz, or cycles per second)." (definition from Inspectopedia.com/emf/)
Hertz measurements, from lowest frequency to highest frequency:
| 1Hz | 1 cycle per second |
| 1MHz | 1 million cycle per second |
| 1GHz | 1 billion cycles per second |
The first generation (1G) of analog cell phone signals emitted far less cycles per second than current phones, having EMFs only in the 800-900 MHz range. Today, most cell phones are either 3G (third generation) or fourth-generation (4G-LTE). Each subsequent generation of cell phones offers higher frequency EMFs, and faster download speed of data.They may use a range of the operating frequencies, with a lower and upper range. Here is a breakdown of various frequencies for examples of applications in the non-ionizing spectrum:
| Application | Operating Frequency |
|---|---|
| Radio & TV | 145KHz - 850MHz |
| Cell Phone 2G | 800MHz-1900 MHz |
| Cell Phone 3G | 850MHz-2100 MHz |
| Microwave oven | 2.4 GHz |
| Cell phone 4G-LTE | 600MHz-5.7 GHz |
| Cell phone 5G | 24 GHz (proposed by FCC) |
Scientists and industry constituents are interpreting the NTP study results differently, with some calling the results alarming and others saying that the study demonstrates that cell phones don't pose a risk to humans. Here are some issues that might be discussed at the March peer-review meeting:
- The lab part of the study shows data from more than six years ago when cell phone EMF was at a lower frequency. In fact, smart phones have only been available for less than ten years. The discussion of the study mentions the need to test for the current 4G EMF level, but why not go ahead and test at the GHz level since that is what future generations of cell phone networks will be using?
- Since cell phones are not the only EMFs that people are exposed to today, (smart meters, wi-fi setups, cell phone towers, uninsulated electrical wiring, are just some more examples), are studies planned that attempt to replicate cumulative exposure from all sources to see if there are harmful effects?
- Children's brains absorb EMFs at a higher rate than adult brains, as their skulls are thinner and their brain tissues are more absorbent. Children have only very recently become frequent users of these devices. What are the implications of the study for safety recommendations on children's use of cell phones and other wireless devices?
The NTP invites the public to comment (deadline March 12, 2018) and/or to attend or view the scientific peer review meeting (deadline March 28 to sign up to attend or view the webcast). Use this link to do either, and also to download a copy of the NTP report.
https://ntp.niehs.nih.gov/about/org/sep/trpanel/meetings/index.html
Link to American Cancer Society's page on radio frequency radiation.