Cosmic ray

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Cosmic ray flux versus particle energy

Cosmic rays are immensely high-energy radiation, mainly originating outside the Solar System.^[1] They may produce showers of secondary particles that penetrate and impact the Earth's atmosphere and sometimes even reach the surface. Composed primarily of high-energy protons and atomic nuclei, they are of mysterious origin. Data from the Fermi space telescope (2013)^[2] have been interpreted as evidence that a significant fraction of primary cosmic rays originate from the supernovae of massive stars.^[3] However, this is not thought to be their only source. Active galactic nuclei probably also produce cosmic rays.

The term ray is a historical accident, as cosmic rays were at first, and wrongly, thought to be mostly electromagnetic radiation. In common scientific usage^[4] high-energy particles with intrinsic mass are known as "cosmic" rays, and photons, which are quanta of electromagnetic radiation (and so have no intrinsic mass) are known by their common names, such as "gamma rays" or "X-rays", depending on their frequencies.

Cosmic rays attract great interest practically, due to the damage they inflict on microelectronics and life outside the protection of an atmosphere and magnetic field, and scientifically, because the energies of the most energetic ultra-high-energy cosmic rays (UHECRs) have been observed to approach 3 × 10²⁰ eV,^[5] about 40 million times the energy of particles accelerated by the Large Hadron Collider.^[6] At 50 J,^[7] the highest-energy ultra-high-energy cosmic rays have energies comparable to the kinetic energy of a 90-kilometre-per-hour (56 mph) baseball. As a result of these discoveries, there has been interest in investigating cosmic rays of even greater energies.^[8] Most cosmic rays, however, do not have such extreme energies; the energy distribution of cosmic rays peaks at 0.3 gigaelectronvolts (4.8×10⁻¹¹ J).^[9]

Of primary cosmic rays, which originate outside of Earth's atmosphere, about 99% are the nuclei (stripped of their electron shells) of well-known atoms, and about 1% are solitary electrons (similar to beta particles). Of the nuclei, about 90% are simple protons, i. e. hydrogen nuclei; 9% are alpha particles, and 1% are the nuclei of heavier elements, called HZE ions.^[10] A very small fraction are stable particles of antimatter, such as positrons or antiprotons. The precise nature of this remaining fraction is an area of active research. An active search from Earth orbit for anti-alpha particles has failed to detect them.

History

After the discovery of radioactivity by Henri Becquerel and Marie Curie in 1896, it was generally believed that atmospheric electricity, ionization of the air, was caused only by radiation from radioactive elements in the ground or the radioactive gases or isotopes of radon they produce. Measurements of ionization rates at increasing heights above the ground during the decade from 1900 to 1910 showed a decrease that could be explained as due to absorption of the ionizing radiation by the intervening air.

Discovery

In 1909 Theodor Wulf developed an electrometer, a device to measure the rate of ion production inside a hermetically sealed container, and used it to show higher levels of radiation at the top of the Eiffel Tower than at its base. However, his paper published in Physikalische Zeitschrift was not widely accepted. In 1911 Domenico Pacini observed simultaneous variations of the rate of ionization over a lake, over the sea, and at a depth of 3 meters from the surface. Pacini concluded from the decrease of radioactivity underwater that a certain part of the ionization must be due to sources other than the radioactivity of the Earth.^[11]

Pacini makes a measurement in 1910.

Then, in 1912, Victor Hess carried three enhanced-accuracy Wulf electrometers^[12] to an altitude of 5300 meters in a free balloon flight. He found the ionization rate increased approximately fourfold over the rate at ground level.^[12] Hess also ruled out the Sun as the radiation's source by making a balloon ascent during a near-total eclipse. With the moon blocking much of the Sun's visible radiation, Hess still measured rising radiation at rising altitudes.^[12] He concluded "The results of my observation are best explained by the assumption that a radiation of very great penetrating power enters our atmosphere from above." In 1913–1914, Werner Kolhörster confirmed Victor Hess' earlier results by measuring the increased ionization rate at an altitude of 9 km.

Increase of ionization with altitude as measured by Hess in 1912 (left) and by Kolhörster (right)

Hess received the Nobel Prize in Physics in 1936 for his discovery.^[13][14]

The Hess balloon flight took place on 7 August 1912. By sheer coincidence, exactly 100 years later on 7 August 2012, the Mars Science Laboratory rover used its Radiation Assessment Detector (RAD) instrument to begin measuring the radiation levels on another planet for the first time. On 31 May 2013, NASA scientists reported that a possible manned mission to Mars may involve a greater radiation risk than previously believed, based on the amount of energetic particle radiation detected by the RAD on the Mars Science Laboratory while traveling from the Earth to Mars in 2011-2012.^[15][16][17]

Hess lands after his balloon flight in 1912.

Identification

In the 1920s the term "cosmic rays" was coined by Robert Millikan who made measurements of ionization due to cosmic rays from deep under water to high altitudes and around the globe. Millikan believed that his measurements proved that the primary cosmic rays were gamma rays, i.e., energetic photons. And he proposed a theory that they were produced in interstellar space as by-products of the fusion of hydrogen atoms into the heavier elements, and that secondary electrons were produced in the atmosphere by Compton scattering of gamma rays. But then, in 1927, J. Clay found evidence,^[18] later confirmed in many experiments, of a variation of cosmic ray intensity with latitude, which indicated that the primary cosmic rays are deflected by the geomagnetic field and must therefore be charged particles, not photons. In 1929, Bothe and Kolhörster discovered charged cosmic-ray particles that could penetrate 4.1 cm of gold.^[19] Charged particles of such high energy could not possibly be produced by photons from Millikan's proposed interstellar fusion process.

In 1930, Bruno Rossi predicted a difference between the intensities of cosmic rays arriving from the east and the west that depends upon the charge of the primary particles - the so-called "east-west effect."^[20] Three independent experiments^[21][22][23] found that the intensity is, in fact, greater from the west, proving that most primaries are positive. During the years from 1930 to 1945, a wide variety of investigations confirmed that the primary cosmic rays are mostly protons, and the secondary radiation produced in the atmosphere is primarily electrons, photons and muons. In 1948, observations with nuclear emulsions carried by balloons to near the top of the atmosphere showed that approximately 10% of the primaries are helium nuclei (alpha particles) and 1% are heavier nuclei of the elements such as carbon, iron, and lead.^[24][24]

During a test of his equipment for measuring the east-west effect, Rossi observed that the rate of near-simultaneous discharges of two widely separated Geiger counters was larger than the expected accidental rate. In his report on the experiment, Rossi wrote "... it seems that once in a while the recording equipment is struck by very extensive showers of particles, which causes coincidences between the counters, even placed at large distances from one another."^[23] In 1937 Pierre Auger, unaware of Rossi's earlier report, detected the same phenomenon and investigated it in some detail. He concluded that high-energy primary cosmic-ray particles interact with air nuclei high in the atmosphere, initiating a cascade of secondary interactions that ultimately yield a shower of electrons, and photons that reach ground level.

Soviet physicist Sergey Vernov was the first to use radiosondes to perform cosmic ray readings with an instrument carried to high altitude by a balloon. On 1 April 1935, he took measurements at heights up to 13.6 kilometers using a pair of Geiger counters in an anti-coincidence circuit to avoid counting secondary ray showers.^[25][26]

Homi J. Bhabha derived an expression for the probability of scattering positrons by electrons, a process now known as Bhabha scattering. His classic paper, jointly with Walter Heitler, published in 1937 described how primary cosmic rays from space interact with the upper atmosphere to produce particles observed at the ground level. Bhabha and Heitler explained the cosmic ray shower formation by the cascade production of gamma rays and positive and negative electron pairs.

Energy distribution

Measurements of the energy and arrival directions of the ultra-high energy primary cosmic rays by the techniques of "density sampling" and "fast timing" of extensive air showers were first carried out in 1954 by members of the Rossi Cosmic Ray Group at the Massachusetts Institute of Technology.^[27] The experiment employed eleven scintillation detectors arranged within a circle 460 meters in diameter on the grounds of the Agassiz Station of the Harvard College Observatory. From that work, and from many other experiments carried out all over the world, the energy spectrum of the primary cosmic rays is now known to extend beyond 10²⁰ eV. A huge air shower experiment called the Auger Project is currently operated at a site on the pampas of Argentina by an international consortium of physicists, led by James Cronin, winner of the 1980 Nobel Prize in Physics from the University of Chicago, and Alan Watson of the University of Leeds. Their aim is to explore the properties and arrival directions of the very highest-energy primary cosmic rays.^[28] The results are expected to have important implications for particle physics and cosmology, due to a theoretical Greisen–Zatsepin–Kuzmin limit to the energies of cosmic rays from long distances (about 160 million light years) which occurs above 10²⁰ eV because of interactions with the remnant photons from the big bang origin of the universe.

High-energy gamma rays (>50 MeV photons) were finally discovered in the primary cosmic radiation by an MIT experiment carried on the OSO-3 satellite in 1967.^[29] Components of both galactic and extra-galactic origins were separately identified at intensities much less than 1% of the primary charged particles. Since then, numerous satellite gamma-ray observatories have mapped the gamma-ray sky. The most recent is the Fermi Observatory, which has produced a map showing a narrow band of gamma ray intensity produced in discrete and diffuse sources in our galaxy, and numerous point-like extra-galactic sources distributed over the celestial sphere.

Sources of cosmic rays

Early speculation on the sources of cosmic rays included a 1934 proposal by Baade and Zwicky suggesting cosmic rays originating from supernovae.^[30] A 1948 proposal by Horace W. Babcock suggested that magnetic variable stars could be a source of cosmic rays.^[31] Subsequently in 1951, Y. Sekido et al. identified the Crab Nebula as a source of cosmic rays.^[32] Since then, a wide variety of potential sources for cosmic rays began to surface, including supernovae, active galactic nuclei, quasars, and gamma-ray bursts.^[33]

Sources of Ionizing Radiation in Interplanetary Space.

Later experiments have helped to identify the sources of cosmic rays with greater certainty. In 2009, a paper presented at the International Cosmic Ray Conference (ICRC) by scientists at the Pierre Auger Observatory showed ultra-high energy cosmic rays (UHECRs) originating from a location in the sky very close to the radio galaxy Centaurus A, although the authors specifically stated that further investigation would be required to confirm Cen A as a source of cosmic rays.^[34] However, no correlation was found between the incidence of gamma-ray bursts and cosmic rays, causing the authors to set a lower limit of 10⁻⁶ erg cm⁻² on the flux of 1 GeV-1 TeV cosmic rays from gamma-ray bursts.^[35]

In 2009, supernovae were said to have been "pinned down" as a source of cosmic rays, a discovery made by a group using data from the Very Large Telescope.^[36] This analysis, however, was disputed in 2011 with data from PAMELA, which revealed that "spectral shapes of [hydrogen and helium nuclei] are different and cannot be described well by a single power law", suggesting a more complex process of cosmic ray formation.^[37] In February 2013, though, research analyzing data from Fermi revealed through an observation of neutral pion decay that supernovae were indeed a source of cosmic rays, with each explosion producing roughly 3 × 10⁴² - 3 × 10⁴³ J of cosmic rays.^[2][3] However, supernovae do not produce all cosmic rays, and the proportion of cosmic rays that they do produce is a question which cannot be answered without further study.^[38]

Types

Primary cosmic particle collides with a molecule of atmosphere.

Cosmic rays originate as primary cosmic rays, which are those originally produced in various astrophysical processes. Primary cosmic rays are composed primarily of protons and alpha particles (99%), with a small amount of heavier nuclei (~1%) and an extremely minute proportion of positrons and antiprotons.^[10] Secondary cosmic rays, caused by a decay of primary cosmic rays as they impact an atmosphere, include neutrons, pions, positrons, and muons. Of these four, the latter three were first detected in cosmic rays.

Primary cosmic rays

Primary cosmic rays primarily originate from outside the Solar System and sometimes even the Milky Way. When they interact with Earth's atmosphere, they are converted to secondary particles. The mass ratio of helium to hydrogen nuclei, 28%, is similar to the primordial elemental abundance ratio of these elements, 24%.^[39] The remaining fraction is made up of the other heavier nuclei that are nuclear synthesis end products, products of the Big Bang,^{[citation needed]} primarily lithium, beryllium, and boron. These nuclei appear in cosmic rays in much greater abundance (~1%) than in the solar atmosphere, where they are only about 10⁻¹¹ as abundant as helium. Cosmic rays made up of charged nuclei heavier than helium are called HZE ions. Due to the high charge and heavy nature of HZE ions, their contribution to an astronaut's radiation dose in space is significant even though they are relatively scarce.

This abundance difference is a result of the way secondary cosmic rays are formed. Carbon and oxygen nuclei collide with interstellar matter to form lithium, beryllium and boron in a process termed cosmic ray spallation. Spallation is also responsible for the abundances of scandium, titanium, vanadium, and manganese ions in cosmic rays produced by collisions of iron and nickel nuclei with interstellar matter.^[40]

Primary cosmic ray antimatter

Satellite experiments have found evidence of positrons and a few antiprotons in primary cosmic rays, amounting to less than 1% of the particles in primary cosmic rays. These do not appear to be the products of large amounts of antimatter from the Big Bang, or indeed complex antimatter in the universe. Rather, they appear to consist of only these two elementary particles, newly made in energetic processes.
Preliminary results from the presently operating Alpha Magnetic Spectrometer (AMS-02) on board the International Space Station show that positrons in the cosmic rays arrive with no directionality, and with energies that range from 10 GeV to 250 GeV. In September, 2014, new results with almost twice as much data were presented in a talk at CERN and published in Physical Review Letters.^[41][42] A new measurement of positron fraction up to 500 GeV was reported, showing that positron fraction peaks at a maximum of about 16% of total electron+positron events, around an energy of 275 ± 32 GeV. At higher energies, up to 500 GeV, the ratio of positrons to electrons begins to fall again. The absolute flux of positrons also begins to fall before 500 GeV, but peaks at energies far higher than electron energies, which peak about 10 GeV.^[43] These results on interpretation have been suggested to be due to positron production in annihilation events of massive dark matter particles.^[44]

Cosmic ray antiprotons also have a much higher energy than their normal-matter counterparts (protons). They arrive at Earth with a characteristic energy maximum of 2 GeV, indicating their production in a fundamentally different process from cosmic ray protons, which on average have only one-sixth of the energy.^[45]

There is no evidence of complex antimatter atomic nuclei, such as antihelium nuclei (i.e., anti-alpha particles), in cosmic rays. These are actively being searched for. A prototype of the AMS-02 designated AMS-01, was flown into space aboard the Space Shuttle Discovery on STS-91 in June 1998. By not detecting any antihelium at all, the AMS-01 established an upper limit of 1.1×10⁻⁶ for the antihelium to helium flux ratio.^[46]

The moon in cosmic rays

The Moon's cosmic ray shadow, as seen in secondary muons detected 700 m below ground, at the Soudan 2 detector

The moon as seen by the Compton Gamma Ray Observatory, in gamma rays with energies greater than 20 MeV. These are produced by cosmic ray bombardment on its surface.^[47]

Secondary cosmic rays

When cosmic rays enter the Earth's atmosphere they collide with molecules, mainly oxygen and nitrogen. The interaction produces a cascade of lighter particles, a so-called air shower secondary radiation that rains down, including x-rays, muons, protons, alpha particles, pions, electrons, and neutrons.^[48] All of the produced particles stay within about one degree of the primary particle's path.

Typical particles produced in such collisions are neutrons and charged mesons such as positive or negative pions and kaons. Some of these subsequently decay into muons, which are able to reach the surface of the Earth, and even penetrate for some distance into shallow mines. The muons can be easily detected by many types of particle detectors, such as cloud chambers, bubble chambers or scintillation detectors. The observation of a secondary shower of particles in multiple detectors at the same time is an indication that all of the particles came from that event.

Cosmic rays impacting other planetary bodies in the Solar System are detected indirectly by observing high energy gamma ray emissions by gamma-ray telescope. These are distinguished from radioactive decay processes by their higher energies above  about 10 MeV.

Cosmic-ray flux

An overview of the space environment shows the relationship between the solar activity and galactic cosmic rays.^[49]

The flux of incoming cosmic rays at the upper atmosphere is dependent on the solar wind, the Earth's magnetic field, and the energy of the cosmic rays. At distances of ~94 AU from the Sun, the solar wind undergoes a transition, called the termination shock, from supersonic to subsonic speeds. The region between the termination shock and the heliopause acts as a barrier to cosmic rays, decreasing the flux at lower energies (≤ 1 GeV) by about 90%. However, the strength of the solar wind is not constant, and hence it has been observed that cosmic ray flux is correlated with solar activity.

In addition, the Earth's magnetic field acts to deflect cosmic rays from its surface, giving rise to the observation that the flux is apparently dependent on latitude, longitude, and azimuth angle. The magnetic field lines deflect the cosmic rays towards the poles, giving rise to the aurorae.

The combined effects of all of the factors mentioned contribute to the flux of cosmic rays at Earth's surface. For 1 GeV particles, the rate of arrival is about 10,000 per square meter per second. At 1 TeV the rate is 1 particle per square meter per second. At 10 PeV there are only a few particles per square meter per year. Particles above 10 EeV arrive only at a rate of about one particle per square kilometer per year, and above 100 EeV at a rate of about one particle per square kilometer per century.^[50]

In the past, it was believed that the cosmic ray flux remained fairly constant over time. However, recent research suggests 1.5 to 2-fold millennium-timescale changes in the cosmic ray flux in the past forty thousand years.^[51]

The magnitude of the energy of cosmic ray flux in interstellar space is very comparable to that of other deep space energies: cosmic ray energy density averages about one electron-volt per cubic centimeter of interstellar space, or ~1 eV/cm³, which is comparable to the energy density of visible starlight at 0.3 eV/cm³, the galactic magnetic field energy density (assumed 3 microgauss) which is ~0.25 eV/cm³, or the cosmic microwave background (CMB) radiation energy density at ~ 0.25 eV/cm³.^[52]

Detection methods

The VERITAS array of air Cherenkov telescopes.

There are several ground-based methods of detecting cosmic rays currently in use. The first detection method is called the air Cherenkov telescope, designed to detect low-energy (<200 a="" analyzing="" by="" cosmic="" ev="" href="http://en.wikipedia.org/wiki/Cherenkov_radiation" means="" nbsp="" of="" rays="" their="" title="Cherenkov radiation">Cherenkov radiation
, which for cosmic rays are gamma rays emitted as they travel faster than the speed of light in their medium, the atmosphere.^[53] While these telescopes are extremely good at distinguishing between background radiation and that of cosmic-ray origin, they can only function well on clear nights without the Moon shining, and have very small fields of view and are only active for a few percent of the time. Another Cherenkov telescope uses water as a medium through which particles pass and produce Cherenkov radiation to make them detectable.^[54]

Comparison of Radiation Doses - includes the amount detected on the trip from Earth to Mars by the RAD on the MSL (2011 - 2013).^[15][16][17]

Extensive air shower (EAS) arrays, a second detection method, measure the charged particles which pass through them. EAS arrays measure much higher-energy cosmic rays than air Cherenkov telescopes, and can observe a broad area of the sky and can be active about 90% of the time. However, they are less able to segregate background effects from cosmic rays than can air Cherenkov telescopes. EAS arrays employ plastic scintillators in order to detect particles.

Another method was developed by Robert Fleischer, P. Buford Price, and Robert M. Walker for use in high-altitude balloons.^[55] In this method, sheets of clear plastic, like 0.25 mm Lexan polycarbonate, are stacked together and exposed directly to cosmic rays in space or high altitude. The nuclear charge causes chemical bond breaking or ionization in the plastic. At the top of the plastic stack the ionization is less, due to the high cosmic ray speed. As the cosmic ray speed decreases due to deceleration in the stack, the ionization increases along the path. The resulting plastic sheets are "etched" or slowly dissolved in warm caustic sodium hydroxide solution, that removes the surface material at a slow, known rate. The caustic sodium hydroxide dissolves the plastic at a faster rate along the path of the ionized plastic. The net result is a conical etch pit in the plastic. The etch pits are measured under a high-power microscope (typically 1600x oil-immersion), and the etch rate is plotted as a function of the depth in the stacked plastic.

This technique yields a unique curve for each atomic nucleus from 1 to 92, allowing identification of both the charge and energy of the cosmic ray that traverses the plastic stack. The more extensive the ionization along the path, the higher the charge. In addition to its uses for cosmic-ray detection, the technique is also used to detect nuclei created as products of nuclear fission.

A fourth method involves the use of cloud chambers^[56] to detect the secondary muons created when a pion decays. Cloud chambers in particular can be built from widely available materials and can be constructed even in a high-school laboratory. A fifth method, involving bubble chambers, can be used to detect cosmic ray particles.^[57]

Another method detects the light from nitrogen fluorescence caused by the excitation of nitrogen in the atmosphere by the shower of particles moving through the atmosphere. This method allows for accurate detection of the direction from which the cosmic ray came.^[58]

Finally, the CMOS devices in pervasive smartphone cameras have been proposed as a practical distributed network to detect air showers from ultra-high energy cosmic rays (UHECRs) which is at least comparable with that of conventional cosmic ray detectors.^[59] The app, which is currently in beta and accepting applications, is CRAYFIS (Cosmic RAYs Found In Smartphones).^[60][61]

Effects

Changes in atmospheric chemistry

Cosmic rays ionize the nitrogen and oxygen molecules in the atmosphere, which leads to a number of chemical reactions. One of the reactions results in ozone depletion. Cosmic rays are also responsible for the continuous production of a number of unstable isotopes in the Earth's atmosphere, such as carbon-14, via the reaction:

n + ¹⁴N → p + ¹⁴C

Cosmic rays kept the level of carbon-14^[62] in the atmosphere roughly constant (70 tons) for at least the past 100,000 years, until the beginning of above-ground nuclear weapons testing in the early 1950s. This is an important fact used in radiocarbon dating used in archaeology.

Reaction products of primary cosmic rays, radioisotope half-lifetime, and production reaction.^[63]

• Tritium (12.3 years): 14N(n, 3H)12C (Spallation)
• Beryllium-7 (53.3 days)
• Beryllium-10 (1.39 million years): 14N(n,p α)10Be (Spallation)
• Carbon-14 (5730 years): 14N(n, p)14C (Neutron activation)
• Sodium-22 (2.6 years)
• Sodium-24 (15 hours)
• Magnesium-28 (20.9 hours)
• Silicon-31 (2.6 hours)
• Silicon-32 (101 years)
• Phosphorus-32 (14.3 days)
• Sulfur-35 (87.5 days)
• Sulfur-38 (2.8 hours)
• Chlorine-34 m (32 minutes)
• Chlorine-36 (300,000 years)
• Chlorine-38 (37.2 minutes)
• Chlorine-39 (56 minutes)
• Argon-39 (269 years)
• Krypton-85 (10.7 years)

Role in ambient radiation

Cosmic rays constitute a fraction of the annual radiation exposure of human beings on the Earth, averaging 0.39 mSv out of a total of 3 mSv per year (13% of total background) for the Earth's population. However, the background radiation from cosmic rays increases with altitude, from 0.3 mSv per year for sea-level areas to 1.0 mSv per year for higher-altitude cities, raising cosmic radiation exposure to a quarter of total background radiation exposure for populations of said cities. Airline crews flying long distance high-altitude routes can be exposed to 2.2 mSv of extra radiation each year due to cosmic rays, nearly doubling their total ionizing radiation exposure.

Average annual radiation exposure (millisieverts)

Radiation		UNSCEAR[64][65]		Princeton[66]	Wa State[67]	MEXT[68]
Type	Source	World average	Typical range	USA	USA	Japan	Remark
Natural	Air	1.26	0.2-10.0a	2.29	2.00	0.40	Primarily from Radon, (a)depends on indoor accumulation of radon gas.
	Internal	0.29	0.2-1.0b	0.16	0.40	0.40	Mainly from radioisotopes in food (40K, 14C, etc.) (b)depends on diet.
	Terrestrial	0.48	0.3-1.0c	0.19	0.29	0.40	(c)Depends on soil composition and building material of structures.
	Cosmic	0.39	0.3-1.0d	0.31	0.26	0.30	(d)Generally increases with elevation.
	Subtotal	2.40	1.0-13.0	2.95	2.95	1.50
Artificial	Medical	0.60	0.03-2.0	3.00	0.53	2.30
	Fallout	0.007	0 - 1+	-	-	0.01	Peaked in 1963 with a spike in 1986; still high near nuclear test and accident sites. For the United States, fallout is incorporated into other categories.
	others	0.0052	0-20	0.25	0.13	0.001	Average annual occupational exposure is 0.7 mSv; mining workers have higher exposure. Populations near nuclear plants have an additional ~0.02 mSv of exposure annually.
	Subtotal	0.6	0 to tens	3.25	0.66	2.311
Total		3.00	0 to tens	6.20	3.61	3.81

Figures are for the time before the Fukushima Daiichi nuclear disaster. Human-made values by UNSCEAR are from the Japanese National Institute of Radiological Sciences, which summarized the UNSCEAR data.

Effect on electronics

Cosmic rays have sufficient energy to alter the states of circuit components in electronic integrated circuits, causing transient errors to occur, such as corrupted data in electronic memory devices, or incorrect performance of CPUs, often referred to as "soft errors" (not to be confused with software errors caused by programming mistakes/bugs). This has been a problem in extremely high-altitude electronics, such as in satellites, but with transistors becoming smaller and smaller, this is becoming an increasing concern in ground-level electronics as well.^[69] Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month.^[70] To alleviate this problem, the Intel Corporation has proposed a cosmic ray detector that could be integrated into future high-density microprocessors, allowing the processor to repeat the last command following a cosmic-ray event.^[71]

Cosmic rays are suspected as a possible cause of an in-flight incident in 2008 where an Airbus A330 airliner of Qantas twice plunged hundreds of feet after an unexplained malfunction in its flight control system. Many passengers and crew members were injured, some seriously. After this incident, the accident investigators determined that the airliner's flight control system had received a data spike that could not be explained, and that all systems were in perfect working order. This has prompted a software upgrade to all A330 and A340 airliners, worldwide, so that any data spikes in this system are filtered out electronically.^[72]

Significance to space travel

Galactic cosmic rays are one of the most important barriers standing in the way of plans for interplanetary travel by crewed spacecraft. Cosmic rays also pose a threat to electronics placed aboard outgoing probes. In 2010, a malfunction aboard the Voyager 2 space probe was credited to a single flipped bit, probably caused by a cosmic ray. Strategies such as physical or magnetic shielding for spacecraft have been considered in order to minimize the damage to electronics and human beings caused by cosmic rays.^[73][74]

Role in lightning

Cosmic rays have been implicated in the triggering of electrical breakdown in lightning. It has been proposed that essentially all lightning is triggered through a relativistic process, "runaway breakdown", seeded by cosmic ray secondaries. Subsequent development of the lightning discharge then occurs through "conventional breakdown" mechanisms.^[75]

Postulated role in climate change

The neutrality of this section is disputed. Relevant discussion may be found on the talk page. Please do not remove this message until the dispute is resolved. (February 2014)

A role of cosmic rays directly or via solar-induced modulations in climate change was suggested by Edward P. Ney in 1959^[76] and by Robert E. Dickinson in 1975.^[77] Despite the opinion of over 97% of climate scientists against this notion,^[78] the idea has been revived in recent years, most notably by Henrik Svensmark, who has argued that because solar variations modulate the cosmic ray flux on Earth, they would consequently affect the rate of cloud formation and hence the climate.^[79] Nevertheless, it has been noted by climate scientists actively publishing in the field^[who?] that Svensmark has inconsistently altered data on most of his published work on the subject, an example being adjustment of cloud data that understates error in lower cloud data, but not in high cloud data.^[80]

The 2007 IPCC synthesis report, however, strongly attributes a major role in the ongoing global warming to human-produced gases such as carbon dioxide, nitrous oxide, and halocarbons, and has stated that models including natural forcings only (including aerosol forcings, which cosmic rays are considered by some to contribute to) would result in far less warming than has actually been observed or predicted in models including anthropogenic forcings.^[81]

Svensmark, being one of several scientists outspokenly opposed to the mainstream scientific assessment of global warming, has found eminence among the popular culture movement that denies the scientific consensus. Despite this, Svensmark's work exaggerating the magnitude of the effect of GCR on global warming continues to be refuted in the mainstream science.^[82] For instance, a November 2013 study showed that less than 14 percent of global warming since the 1950s could be attributed to cosmic ray rate, and while the models showed a small correlation every 22 years, the cosmic ray rate did not match the changes in temperature, indicating that it was not a causal relationship.^[83]

Stop worrying, the bees are doing just fine, thank you.

Bee experts shred ‘Harvard’ neonics-Colony Collapse Disorder study, upbraid journalists for ‘activist science’

Jon Entine | December 19, 2014 | Genetic Literacy Project

3966

Chensheng Lu was in his element last month, delivering an impassioned speech before a green group at Harvard Law School. The School of Public Health professor was lecturing on his favorite topic–his only subject these days, as it has become his obsession: why he believes bees around the world are in crisis.

Lu is convinced, unequivocally, that a popular pesticide hailed by many scientists as a less toxic replacement for farm chemicals proven to be far more dangerous to humans and the environment is actually a killer in its own right.
“We demonstrated that neonicotinoids are highly likely to be responsible for triggering Colony Collapse Disorder in bee hives,” claimed Lu. The future of our food system and public health, he said, hangs in the balance.

Lu is the Dr. Doom of bees. According to the nutritionist — but not clear to most other experts in the field — colony collapse disorder (CCD), which first emerged in 2006, can be directly linked to “neonics,” as the now controversial class of pesticides is often called, and also to genetically modified crops. Phased in during the 1990s, neonics are most often used by farmers to control unwanted crop pests. They are coated on seeds, which then produce plants that systemically fight pests.

To many environmental activists, the pesticide does more harm than good, and they’ve found their champion in Chensheng Lu. It’s been a busy fall for the professor, jetting back and forth between Boston and Washington, with forays around the United States to talk to adoring audiences. He presents himself as the defender of bees, and this fiery message has transformed a once obscure academic into a global “green” rock star, feted at events like last month’s lunch talk at Harvard.

The sudden abandoning of hives by honey bees known as Colony Collapse Disorder has emerged as one of the hottest science mysteries in recent years. Lu has authored two extremely controversial papers on CCD: one in 2012 and a second published this past spring. He and his two beekeeper colleagues – there were no entomologists on his tiny research team – contend that neonicotinoids present a mortal threat to bees. Not only that, Lu claims, neonics endanger humans as well, accelerating Parkinson’s Disease.

Lu reached folk hero status among environmentalists last May when the Harvard School of Public Health launched a promotional campaign touting his latest, controversial research: “Study strengthens link between neonicotinoids and collapse of honey bee colonies,” the press release claimed. Before the study was even circulated, stories in some mainstream publications including Forbes ran the release with only a pretense of a rewrite.

The story exploded on the Internet. Many environmental and tabloid journalists painted an alarmist picture based on Lu’s research: “New Harvard Study Proves Why The Bees Are All Disappearing,” “Harvard University scientists have proved that two widely used neonicotinoids harm honeybee colonies,” and “Neonicotinoid Insecticide Impairs Winterization Leading to Bee Colony Collapse: Harvard Study” are three of hundreds of blog posts and articles.

Behind the headlines

Although public opinion has coalesced around the belief that the bee death mystery is settled, the vast majority of scientists who study bees for a living disagree–vehemently.

How could a “Harvard study” and a sizable slice of the nation’s press get this story so wrong?.

The buzz that followed the publication of Lu’s latest study is a classic example of how dicey science can combine with sloppy reporting to create a ‘false narrative’–a storyline with a strong bias that is compelling, but wrong. It’s how simplistic ideas get rooted in the public consciousness. And it’s how ideology-driven science threatens to wreak public policy havoc.

Bees are important to our food supply. They help pollinate roughly one-third of crop species in the US, including many fruits, vegetables, nuts and livestock feed such as alfalfa and clover. That’s why the mystery of CCD is so troubling.

One of the central problems with Lu’s central conclusion–and much of the reporting–is that despite the colony problems that erupted in 2006, the global bee population has remained remarkably stable since the widespread adoption of neonics in the late 1990s. The United Nations reports that the number of hives has actually risen over the past 15 years, to more than 80 million colonies, a record, as neonics usage has soared.

Country by country statistics are even more revealing. Beehives are up over the past two decades in Europe, where advocacy campaigns against neonics prompted the EU to impose a two-year moratorium beginning this year on the use of three neonics. 
Last February, the government of Australia, where neonics are used extensively, reaffirmed that “honeybee populations are not in decline despite the increased use of [neonicotinoids] in agriculture and horticulture since the mid-1990s.” Its central finding was just the opposite of what many in the media have reported: The APVMA (Australian equivalent of the EPA) concluded, “[T]he introduction of the neonicotinoids has led to an overall reduction in the risks to the agricultural environment from the application of insecticides.”
According to statistics Canada honey bee colonies have increased from 521,000 in 1995 to 672,000 in 2013, a record. North American managed beehive numbers have held stable over the last two decades. Sources: USDA and Statistics Canada

So how did the narrative that the world faces a beepocalypse become settled wisdom? The media have widely conflated two parallel but different phenomena: Bee deaths related to CCD and bees dying from other causes.

Bee health took a sharp hit in the 1980s and has been struggling during the winter months for decades coinciding with the global spread of the parasitical Varroa destructor mite and the sub-lethal effects of miticides used to control the parasite. But these overwinter losses, while troubling, haven’t translated into declines in the overall bee population because bees reproduce rapidly in warmer months.

The bee health issue erupted into the public consciousness in 2006, when bee die-offs mysteriously spiked–in California to as high as 80%.

GMOs and cell Phones did it?

The event was dubbed CCD by a team of entomologists because of the unique characteristics of the deaths: the unusual abandonment of hives by the oldest bees leaving behind larvae, the queen and food stores.

Advocacy groups originally pointed to cell phones and genetically modified crops as the likely culprits, and some fringe organizations, like the fringe activist group the Organic Consumers Association, still do. But CCD gradually subsided.

Dennis van Engelsdorp, a University of Maryland entomologist who was part of the research team that named CCD, has written to me that there has not been a single field CCD incident in the last three years, except cases linked to the Nosema fungus. Confusing the picture, overwinter bee deaths also increased in the years after the CCD scare, reaching 30% or more in the US and in some European countries. Confounding doomsayers, losses plummeted to 21.9% over the winter of 2011-2012, jumped again during the following year’s frigid weather, then settled back into the low 20s.

In some states, like North Dakota, which is the largest honey producer in the US, the number of bee colonies has hit an all-time high.

The recent trend in Europe is also encouraging. In April, the EU released a report called Epilobee that surveyed bee health in 2012-2013. Seventy-five percent of bees suffered overwinter losses of 15% or less, a level considered well within the acceptable range in the US. Only countries in Europe’s far north, home to 5% of the bee population, and which suffered through a bitter winter, experienced losses of more than 20%.

In short, most entomologists scoff at media references to a beemageddon.

But that’s exactly what Lu claims.

Hyping the “Harvard” studies

Mother Jones, in its coverage led by food reporter Tom Philpott, has been particularly myopic in its promotion of Lu’s controversial views and the scientifically dubious claim that neonics is the prime driver of bee deaths. It’s run more than a dozen articles about the alleged mortal threat posed by neonics. Upon the release of Lu’s most recent study, Philpott titled his article, “Did Scientists Just Solve the Bee Collapse Mystery?”

There were no “scientists” behind the Lu study, of course–only Lu himself. But rather than seeking out views of established experts in the field, he had Lu and only Lu answer the question he posed.

“[C]oming on the heels of a similar [study] he published in 2012, the CCD mystery has been solved,” he wrote. Philpott now unqualifiedly, and incorrectly say mainstream entomologists, refers to neonics as “bee killer chemicals.”

Who is Chensheng (Alex) Lu, the Dr. Doom of honey bees? He is an environmental researcher with the Harvard School of Public Health with no formal training in entomology. His two bee papers are “Harvard studies” only in the sense that the only scientist who conducted the studies has a Harvard faculty appointment; his co-authors are local beekeepers. Both studies appeared in one of the most obscure science journals in the world, a marginal Italian journal.

Lu emerged out of academic obscurity two years ago with the publication of his first study on bee deaths. He promoted a simple explanation, the kind that energizes activists: A new class of pesticides, promoted by large chemical companies as a safer alternative to older chemicals, was a hidden killer.

“I kind of ask myself,” Lu told Wired in 2012. “Is this the repeat of Silent Spring? What else do we need to prove that it’s the pesticides causing Colony Collapse Disorder?”

The second coming of Silent Spring? Almost from the day his first study was published, Lu was making grandiose claims. By his own admission, he is the definition of an activist scientist. He is on the board of The Organic Center, an arm of the multi-million dollar Organic Trade Association, a lobby group with strong financial interest in disparaging conventional agriculture, synthetic pesticides and neonics in particular–a conflict of interest that Lu never acknowledges and to my knowledge no other journalist has reported.

Earlier this month, OTA announced it is partnering with Lu to tout the benefits of organics, including promoting the dangers of neonics.

Many of the world’s top scientists have challenged his research. Dennis vanEngelsdorp called Lu’s first study “an embarrassment” while Scott Black, executive director of the bee-hugging Xerces Society for
Invertebrate Conservation, characterized it as fatally flawed, both in its design and conclusions.
University of Illinois entomologist May Berenbaum, who chaired the National Academy of Sciences 2007 National Research council study on the Status of Pollinators in North America called it “effectively worthless” to serious researchers. “The experimental design and statistical analysis are just not reliable,” she said.

Beekeepers have been skeptical as well. Lu’s findings contradicted what they witnessed in the fields. If neonics were a mystery killer, then not using them should translate into healthier bee stocks; but that’s not what has happened.

“In places where neonicotinoid pesticides have been banned, such as France and Italy, there’s no evidence that honeybee populations have rebounded,” noted Hannah Nordhaus, beekeeper and author of the bestseller The Beekeepers’ Lament.

Lu has been defiant since the stinging expert rejection of his first paper. He sees the fingerprints of a Big Ag conspiracy of chemical companies, USDA and entomologists who he believes are ignoring the dangers to bees. Those are damning charges if true, but Lu had yet to present any evidence to back them up–until the publication of his newest paper last May.

Lu monitored 18 hives, a small number for such a complex study, comparing two different pesticides in different locations. He fed bees high fructose corn syrup laced with two neonics, imidacloprid and clothianidin, for 13 weeks. It was an odd choice because bees in fields usually only feed for as few as two weeks. Six of the 12 colonies fed neonics eventually ended up showing substantial deaths over the winter, as did one of the six control colonies.

According to Lu and his beekeeper co-authors, this proved that neonics cause CCD.

To seasoned observers of the bee controversy, the “new” study looked like more of the same. “Lu’s sample sizes are astonishingly small,” May Berenbaum told me, ticking off a litany of problems. “He never tested for the presence of pathogens, so his conclusions dismissing other likely causes don’t follow from his data. The whole study just doesn’t hold together. And I’m not being a fusspot here. It’s unfortunate this was presented as a Harvard paper because it gives this credibility that it doesn’t deserve.”

Twitter lit up with critical comments, starting with Nordhaus: 
Many other critical posts followed, including by Brian Ames, a prominent apple grower, artisanal honeymaker and beekeeper: 

Even rudimentary digging by reporters would have turned up the revealing fact, unreported by the adulatory environmental press, that first study was rejected by Nature, as Lu himself has acknowledged, before ending up in the Bulletin of Insectology, a marginal “pay for play” publication that is known to publish research often rejected by mainstream peer-reviewed journals.

(The Bulletin of Insectology has an “impact factor” (IF) of 0.375, which means that the average paper from that journal is cited by another journal approximately once every three years; in contrast, Nature, which rejected Lu’s first paper, has an IF of 51).

The second study faced the same fate. Unable to get his work published by credible journals, Lu returned to the same publication that put out his first piece–perhaps the only journal in the world that would publish it.

“Anyone at this point in time who wishes to make a contribution to the study of potential effects of neonicotinoids on honey bees–or any other aspect of honey bee health–and publishes this data in the extremely obscure journal Bulletin of Insectology is very hard to take seriously,” Colorado State University entomologist Whitney Cranshaw emailed me.

A week does not go by without one advocacy group or government official or activist scientist making sensational claims about the supposed catastrophic dangers that neonics supposedly present.

In November, for example, advertisements began appearing across Ontario in Canada warning, “neonic pesticides hurt our bees and us,” one of them accompanied by a young boy gazing sadly at a dead bee. 

They were placed by a fringe advocacy group, the Canadian Association of Physicians for the Environment; its primary funder is David Suzuki, a once prominent but now long retired geneticist who more recently has become known for rants against GMO foods.

That kind of hyperbole, scientists say, obscures the complex story of what’s really happening to bees and why–and the risks of advocacy groups and activist journalists driving science and agricultural regulations into a policy ditch.

Which brings us back to the curious case of Alex Lu.

Although Lu’s most recent paper, published last spring, was not clear on this point, the nutritionist has publicly maintained that neonic seed treatments are the driving cause of CCD. Let’s be clear. Neonics are an appropriate subject for serious research. They are neurotoxic pesticides. Because they rely on a complex set of behaviors, bees exposed to high volumes could conceivably become drunk and ill. Scientists are and should continue to examine this chemical and all agricultural chemicals.

But the emphasis of many popular articles, and Lu’s study, is way out of whack with the potential dangers that scientists believe are presented by neonics. The pesticide is applied to seeds sparingly — only about 1-3 ppb is commonly found in pollen or nectar after application, levels way below safety concerns. Plants grown from a treated seed often need no further insecticidal treatment, unlike many competing chemicals. And in contrast to earlier generation insecticides that required multiple applications, when infestations are severe a single additional spraying generally suffices.

Lu steadfastly claims that bees that died in his studies were fed field realistic levels doses–statements echoed uncritically by reporters without, it turns out, cross checking with beekeepers or entomologists. “Chensheng Lu and his team treated 12 colonies with tiny levels of neonics,” Mother Jones maintained.

Tiny?

As Randy Oliver, a well known beekeeper, wrote on his Scientific Beekeeping blog, Lu fed his test colonies a pesticide brew of about 135 parts per billion (ppb). That’s 100 times higher then the 1-3 ppb commonly found in pollen or nectar, a level far below safety concerns. Rather than citing the chemicals’ ppb, some reporters touted the physical size of the dose, a worthless measurement. Lu also fed bees every week for 13 straight weeks when the real world application is just a few weeks at most.

“It’s hard to imagine anyone even reviewed this paper,” Oliver concluded.

What’s remarkable, numerous scientists and beekeepers told me, is that Lu’s bees didn’t just keel over in the first few weeks after sucking down what amounted to a lethal cocktail every day.

“It’s surprising those colonies lasted so long given the stratospheric quantities of insecticide [Lu] pumped into them for 13 weeks,” wrote Jonathan Getty on Bee-L Chat, a discussion forum for bee experts. “Lu has convincingly demonstrated, again, as in his previous study … that a high dose of an insecticide will kill an insect. Has anyone learned anything from all this? Looks like junk science at its worst.”

There was also scant evidence to back up Lu’s central claim that he had solved the mystery of CCD. “His description of the hives just didn’t show that,” University of Maryland entomologist Dennis vanEngelsdorp told me. Bee die offs, he said, have occurred mysteriously and periodically since at least the mid-19th century but became the focus of widespread public concern only in 2006. It’s clear that what Lu observed–bee deaths–“was not CCD. Looks like a typical bee colony death over the winter–which often includes bees abandoning the hive–but it’s a slow dwindle not a sudden collapse.”

Joe Ballenger, an entomologist writing for the independent sustainability site Biology Fortified, outlined how little Lu appears to know about CCD. “There are very important differences between the colonies Lu poisoned with insecticide and those which have been affected by CCD,” Ballenger wrote. “Despite these differences, Lu claims he has replicated CCD. However, his data demonstrates that he did not replicate CCD.”

Ballenger drew up a chart of Lu’s mistakes: 

Are there any prominent entomologists who endorse Lu’s findings? I couldn’t find any. Mother Jones quoted Jeffrey Pettis, an entomologist and research leader at USDA’s Beltsville’s Bee Laboratory, as appearing to be supportive. “Pettis told me that he thought Lu’s study ‘adds to the list’ of studies showing that pesticides pose a significant threat to honeybees,” Tom Philpott wrote.
I emailed Pettis about that quote:

I was trying to be diplomatic when I talked to Philpott but the Lu study should not have been published. It is not good science. I was trying to say that it adds to the list that pesticides and bees don’t mix but it is not a paper that shows that neonics cause problems simply because it was poorly replicated with high dosages used.

So what was going on in the hives that Lu monitored? The bee deaths that Lu found suggest a quite different cause, said vanEngelsdorp; the bees appear to have been killed by Lu himself–entirely expected if hives are overdosed during a frigid winter.

Are there potential advantages to using neonics to control pest infestations?

A telling fact emerges when you view the landscape of studies on neonics: on the whole, those done in a laboratory or that use unrealistic high doses (e.g. Lu’s studies) raise precautionary concerns. In contrast, field observations show few if any serious problems.

The latest example? Four Canadian scientists led by Cynthia D. Scott Dupree, an environmental biologist at the University of Guelph, undertook a large-scale study of honey bee exposure to one neonic, clothianidin, which is applied as a seed treatment. The study was centered in southern Ontario, which advocacy groups have contended has been particularly hard hit by neonic-related bee deaths.

Designed in cooperation with the U.S. Environmental Protection Agency and Health Canada, it was industry funded, but executed under Good Laboratory Practice Standards.

The scientists observed bees foraging heavily on the canola. As numerous other studies have suggested, they found, “Although various laboratory studies have reported sublethal effects in individual honey bees exposed to low doses of neonicotinoid insecticides, the results of the present study suggest that foraging on clothianidin seed-treated crops, under realistic conditions, poses low risk to honey bee colonies.”

Assertions by entomologists that neonics play a limited role in bee health infuriates some environmentalists convinced this mystery is solved: Let’s just ban neonics, they say, and move on.

“For its part, the pesticide industry is doing its best to shroud the phenomenon in uncertainty,” Mother Jones wrote in its article hyping the Lu study, “promoting a ‘multifactorial’ explanation that points the finger at mites, viruses, and ‘many other factors, but not…the use of insecticides,’ as neonic producer Bayer puts it in its ‘Honey Bee Health’ pamphlet.”

But it’s not Bayer making those claims, as Philpott seemed to suggest; it’s independent and government scientists. Noting the complexity of the phenomenon, the US Department of Agriculture and the Environmental Protection Agency took a cautious, science-based approach to the emerging controversy three years ago, commissioning a broad-based assessment of the evidence. This panel, reflecting views by most beekeepers and academic experts, concluded that neonics were unlikely to be the major driver of bee deaths.

Rather, the experts identified a complex set of causes likely linked to a surge in pathogens, such as Varroa mites that feed on the bodily fluids of bees and which first surfaced in the U.S. in the 1980s and began infesting beehives in California in 1993; and Nosema, a common parasite that invades their intestinal tracts; and the use and perhaps misuse of miticides to control them. Other issues include the stress put on bees by large commercial beekeepers, particularly to service the agri-business demand for bees needed for the California almond crop in late winter before bees normally repopulate, as well as climate change and breeding issues.

Few experts or practitioners believe banning neonics or GMOs would improve bee health and could in fact result in farmers going back to spraying insecticides known to harm pollinators and humans.

“If we took pesticides out of the equation tomorrow, I think there’s no doubt we would have reduced colony losses,” vanEngelsdorp told me. “But even without pesticides, we’d still be seeing significant losses–losses that are unsustainable.”

Neonics present in corn dust at planting have been shown definitively to contribute to bee mortality, but that’s a result of faulty formulation, scientists have concluded. When used properly, there is intriguing evidence that neonics may actually improved bee health in some circumstances. Hints can be found, ironically, in Alex Lu’s own data, of all places.

Lu’s 2012 paper raises red flags because he used two separate dosing regimens as the experiment progressed, noted Richard Cowles, a prominent entomologist with the state of Connecticut, in an email to me. During the first four weeks of his study, the bees were fed concentrations of imidacloprid that, as it turns out, were in fact field realistic. At three weeks into testing using these concentrations, the health of the bee colonies was positively correlated with exposure to imidacloprid, as measured by the number of capped brood cells. In other words, the bees appeared healthier.

“Rather than continue the experiment with these concentrations, Dr. Lu inexplicably increased the dosages for the last nine weeks of feeding-by 40 times,” Cowles told me.

Why?

Cowles couldn’t get an answer from Lu and neither could I. This is one of the many questions that I had hoped to put to Lu in an interview. He at first agreed by email but then stopped communicating. I contacted him again and also reached out to the Harvard School of Public Health, but got no reply. Entomologists have volunteered as to what they thought might have been going on when Lu changed feeding tactics.

“Dr. Lu probably was trying to hide the fact that he observed an unexpected result contrary to his expectations, which led to him increase the dosages to poison the bees,” Cowles, emailed me. “Whether this sub-lethal effect is actually therapeutic to honey bees is a very interesting question, and one that I’d like to investigate.”

In other words, Lu’s data suggests the opposite of his stated conclusion–bees appear to do fine when exposed to field realistic doses and even increasingly higher amounts of neonics, but ultimately succumb to astronomical levels.

This is not the first time a neonic study has shown that bee health might improve when crops are treated with new generation insecticides. In a 2013 PLOS ONE study, a team led by vanEngelsdorp and Jeffrey Pettis studied the real world impact of 35 pesticides including three neonics–acetamiprid, imidacloprid and thiacloprid–by examining hives from seven major crops. Intriguingly, bee health improved although the results would need to be confirmed with follow up research. This study remains the only lab research to date that has evaluated how real world pollen-pesticide blends affect honey bee health.

The researchers found a striking reduction in the risk from Nosema infection when neonics were used, bee health improved. Why would that be? It seems neonics may suppress the parasite associated with the disease. vanEngelsdorp and Pettis are not yet sure this is a real effect; good science requires that results be confirmed in multiple studies. That said, the intriguing but startling finding directly challenges the belief that neonics pose an unusually unique danger to bees.

What is the future for bees, neonics and agriculture?

Are there replacement insecticides if neonics should be banned? Sure. Those based on pyrethroids and organophosphates some of which are more toxic to bees and humans, are not as effective as neonics for many uses–and are not in the political crosshairs.

That’s not slowed demands for an immediate ban. Advocacy groups recently widened the scope of their concerns, claiming neonics could have an unknown environmental impact, and waterways are being polluted. But evidence for that is scant. A US Geological Society study published in July found the highest levels detected were at least 40 times lower than benchmarks established by EPA to be protective of aquatic life, and most were up to 1,000 times below that level.

What would happen if U.S. officials do institute sharp restrictions, as the White House may be contemplating?

Neonics are not only important to major row crops such as corn, soy and canola, they also remain the most effective weapon against Asian psyllid, an insect that spreads the deadly virus that threatens America’s citrus crop. They are the key pesticide keeping in check whitefly infestations, which could otherwise devastate winter vegetables. They are the primary insecticide used to counter leafhoppers in the grape-growing Northwest as well as thrips in cotton and water weevil in rice. They’ve been hugely successful in combating aphids and beetles in potatoes.

I found scant support among entomologists for the two-year precautionary moratorium adopted by European politicians in the wake of near hysterical media reports in 2012 and 2013, many generated by coverage of Lu’s research. That ban looks like a textbook case of “shooting before you aim,” resulting in unintended but predictable consequences. As Matt Ridley reported in November in The Times of London:

All across southeast Britain this autumn, crops of oilseed rape are dying because of infestation by flea beetles. The direct cause of the problem is the two-year ban on pesticides called neonicotinoids brought in by the EU over British objections at the tail end of last year. … Farmers in Germany, the EU’s largest producer of rape, are also reporting widespread damage. Since rape is one of the main flower crops, providing huge amounts of pollen and nectar for bees, this will hurt wild bee numbers as well as farmers’ livelihoods.

There are now growing concerns that Lu’s studies will carry weight with politicians facing pressure to “do something”. That’s what happened in late November in Ontario, where the government has proposed to restrict the sale of corn and soybean seeds treated with neonics to farmers by 80 percent over the next two years.

The very same week, Health Canada issued a report after a long investigation that found bee mortality, which was not an issue until 2012, dropped 70 percent over last winter.

Activists are trying to jack up political pressure in the United States, perhaps concerned as signs that a temporary global surge in bee deaths appears over, undercutting their campaign. In September, a coalition of environmental groups co-wrote a letter signed by 60 Congressional Democrats urging the EPA to restrict neonicotinoid use citing Lu’s work in arguing that “native pollinators” have “suffered alarming declines.”

Those calls send chills down the back of entomologists concerned that Lu’s claims that he has solved the mystery of the beemageddon that doesn’t actually exist will have a bullying impact on public policy.

“Lu’s work is clearly biased, sensational,” said Richard Cowles. “It is horrendously incompetent. This is just hogwash. We will all pay a price for bad research.”

May Berenbaum was appointed this past summer to chair a National Academy of Sciences study on the health of pollinators ordered by the White House. I asked her if there is anything of value in Lu’s study to guide scientists and regulators? Do neonicotinoids threaten the health of this beleaguered arthropod?

Berenbaum paused. A dedicated environmentalist, she is known for her understated fairness.

“I’m no fan of pesticides and they are overused in agriculture, but you won’t find any confirmation of that in this study.”

Science is not a set of results; it is a method. If the method is wrong, the results are useless. The uncomfortably high number of bee deaths eludes the kind of definitive but potentially reckless conclusion that could result in precipitous regulations.

“This is a really complex issue with no quick and easy solutions,” Berenbaum said. “I can’t imagine a situation in which I would cite the findings of this paper as rigorous and reliable. This is just not good science.”

Jon Entine, executive director of the Genetic Literacy Project, is a Senior Fellow at the World Food Center Institute for Food and Agricultural Literacy, University of California-Davis and at the Center for Health and Risk Communication, George Mason University. Follow @JonEntine on Twitter.