When oral Cannabis is ingested, there is a low (6%–20%) and variable oral bioavailability.[1,2] Peak plasma concentrations of delta-9-tetrahydrocannabinol (THC) occur after 1 to 6 hours and remain elevated with a terminal half-life of 20 to 30 hours. Taken by mouth, delta-9-THC is initially metabolized in the liver to 11-OH-THC, a potent psychoactive metabolite. Inhaled cannabinoids are rapidly absorbed into the bloodstream with a peak concentration in 2 to 10 minutes, declining rapidly for a period of 30 minutes and with less generation of the psychoactive 11-OH metabolite.
Most pro-hemp initiatives in the United States are now focused on defining and distinguishing between industrial hemp and marijuana. Some pro-hemp supporters would like to move the control of U.S. hemp production from the DEA to the USDA. Proponents of legalizing hemp also argue that new technology to distinguish THC levels both in the field and from the air will allow for adequate production enforcement.
Some studies state that while there is no proof for the gateway hypothesis,[252] young cannabis users should still be considered as a risk group for intervention programs.[253] Other findings indicate that hard drug users are likely to be poly-drug users, and that interventions must address the use of multiple drugs instead of a single hard drug.[254] Almost two-thirds of the poly drug users in the "2009/10 Scottish Crime and Justice Survey" used cannabis.[255]

Textile expert Elizabeth Wayland Barber summarizes the historical evidence that Cannabis sativa, "grew and was known in the Neolithic period all across the northern latitudes, from Europe (Germany, Switzerland, Austria, Romania, Ukraine) to East Asia (Tibet and China)," but, "textile use of Cannabis sativa does not surface for certain in the West until relatively late, namely the Iron Age."[107] "I strongly suspect, however, that what catapulted hemp to sudden fame and fortune as a cultigen and caused it to spread rapidly westwards in the first millennium B.C. was the spread of the habit of pot-smoking from somewhere in south-central Asia, where the drug-bearing variety of the plant originally occurred. The linguistic evidence strongly supports this theory, both as to time and direction of spread and as to cause."[108]
As noted above, hemp seed cake makes an excellent feed for animals. However, feeding entire plants is another matter, because the leaves are covered with the resin-producing glands. While deer, groundhogs, rabbits, and other mammals will nibble on hemp plants, mammals generally do not choose to eat hemp. Jain and Arora (1988) fed narcotic Cannabis refuse to cattle, and found that the animals “suffered variable degrees of depression and revealed incoordination in movement.” By contrast, Letniak et al. (2000) conducted an experimental trial of hemp as silage. No significant differences were found between yield of the hemp and of barley/oat silage fed to heifers, suggesting that fermenting hemp plants reduces possible harmful constituents.

Some of the research focuses that were explored in 2018 were: comparison of various agronomic factors on industrial hemp (planting dates, tillage regimens, range of soil fertility, etc.); hemp variety comparison for suitability to PA growing conditions; study of the effectiveness of potential herbicide products; comparison of hemp’s capability for weed suppression to other crops; surveying hemp crops for presence of arthropod and disease pests; evaluation of hemp’s performance for phytoremediation and land reclamation; study of hemp seed oil processing and marketability; development of industrial hemp products (using grain, stalks and flowers); genetic selection for desired hemp variety characteristics; and evaluations of hemp as an animal feed ingredient (cattle).  
This summary is reviewed regularly and updated as necessary by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).

With a hypothesis that chronic marijuana use produces adverse effects on the human endocrine and reproductive systems, the association between Cannabis use and incidence of testicular germ cell tumors (TGCTs) has been examined.[12-14] Three population-based case-control studies reported an association between Cannabis use and elevated risk of TGCTs, especially nonseminoma or mixed-histology tumors.[12-14] However, the sample sizes in these studies were inadequate to address Cannabis dose by addressing associations with respect to recency, frequency, and duration of use. In a study of 49,343 Swedish men aged 19 to 21 years enrolled in the military between 1969 and 1970, participants were asked once at the time of conscription about their use of Cannabis and were followed up for 42 years.[15] This study found no evidence of a significant relation between “ever” Cannabis use and the development of testicular cancer, but did find that “heavy” Cannabis use (more than 50 times in a lifetime) was associated with a 2.5-fold increased risk. Limitations of the study were that it relied on indirect assessment of Cannabis use; and no information was collected on Cannabis use after the conscription-assessment period or on whether the testicular cancers were seminoma or nonseminoma subtypes. These reports established the need for larger, well-powered, prospective studies, especially studies evaluating the role of endocannabinoid signaling and cannabinoid receptors in TGCTs.

Nevertheless, every bit of this ancient plant is useful and valuable, and not just for rope, but for textiles, auto parts, cosmetics, dynamite, supplements, food, and medicine. In ancient China, hemp seed was regarded as food for the lower classes, and in Europe, a peanut butter-like spread was made from the seeds, in both cases with the hulls intact.

The United Kingdom and Germany resumed commercial production in the 1990s. British production is mostly used as bedding for horses; other uses are under development. Companies in Canada, the UK, the United States, and Germany, among many others, process hemp seed into a growing range of food products and cosmetics; many traditional growing countries still continue to produce textile-grade fibre.

Elias Anderson, one of the owners of Going Green, said representatives from HempMedsPx approached him after Krenzler published the lab’s findings on his blog. “They were like, ‘What are we gonna do about it?’” Anderson recalled, “And I was like, ‘Nothing. We have standards, and I stand behind my test results.’” Still, the company’s representatives were insistent and advised Anderson to have Kenzler take down the lab’s findings. In an email to the New Republic, Hard, the Medical Marijuana, Inc. spokesman, contended that the sample of hemp oil that Going Green Labs tested had been “tampered with” by a competitor after Krenzler obtained it. “HempMedsPX, if anything, told the lab they cannot publish results from products [for which] they had no chain of custody tracked,” Hard said, “and if they did—that could prove to be very bad for the lab.” He also characterized Krenzler and Anderson as “haters” of Medical Marijuana, Inc., and suggested that much of the criticism of the company and its products comes from commercial competitors.
In Europe and Asia, hemp farming has been conducted for millennia. Although most countries ceased growing hemp after the second word war, some didn’t, including France, China, Russia, and Hungary, so that essential knowledge of how to grow and process hemp was maintained. When commercial hemp cultivation resumed in Canada in 1997, many farmers undertook to grow the crop without appreciating its suitability for their situation, or for the hazards of an undeveloped market. Hemp was often grown on farms with marginal incomes in the hopes that it was a savior from a downward financial spiral. The myth that hemp is a wonder crop that can be grown on any soil led some to cultivate on soils with a history of producing poor crops; of course, a poor crop was the result.
The DEA isn’t the only government agency scrutinizing CBD vendors. To fend off the FDA, hemp oil companies contend their wares are not drugs but “dietary supplements.” Despite the suggestive “meds” in the company’s name, HempMedsPx is careful to note on its web site, “Although some of our founders are medical professionals, we cannot make medical claims about the benefits of our products.” Others are not quite so nuanced in their marketing. The internet is flooded with CBD products claiming to treat everything from seizures to arthritis to skin conditions and other maladies.
Hemp crops are tall, have thick foliage, and can be planted densely, and thus can be grown as a smother crop to kill tough weeds.[45] Using hemp this way can help farmers avoid the use of herbicides, gain organic certification, and gain the benefits of crop rotation. However, due to the plant's rapid and dense growth characteristics, some jurisdictions consider hemp a prohibited and noxious weed, much like Scotch Broom.[citation needed]
As marijuana is legalized in more and more states, the wellness world has whipped itself into a frenzy over a non-intoxicating cannabis derivative called cannabidiol. CBD products can be found on the internet and in health-food stores, wellness catalogs and even bookstores. (A bookstore in downtown Boulder, Colorado, displays a case of CBD products between the cash register and the stacks of new releases.) Celebrities like Gwyneth Paltrow, disgraced cyclist1 Floyd Landis and former Denver Broncos quarterback Jake Plummer are all touting CBD products, and according to Bon Appétit, CBD-infused lattes have become “the wellness world’s new favorite drink.”

Cannabis is believed to be an aggravating factor in rare cases of arteritis, a serious condition that in some cases leads to amputation. Because 97% of case-reports also smoked tobacco, a formal association with cannabis could not be made. If cannabis arteritis turns out to be a distinct clinical entity, it might be the consequence of vasoconstrictor activity observed from delta-8-THC and delta-9-THC.[100] Other serious cardiovascular events including myocardial infarction, stroke,[101] sudden cardiac death, and cardiomyopathy have been reported to be temporally associated with cannabis use. Research in these events is complicated because cannabis is often used in conjunction with tobacco, and drugs such as alcohol and cocaine.[102] These putative effects can be taken in context of a wide range of cardiovascular phenomena regulated by the endocannabinoid system and an overall role of cannabis in causing decreased peripheral resistance and increased cardiac output, which potentially could pose a threat to those with cardiovascular disease.[103] There is some evidence from case reports that cannabis use may provoke fatal cardiovascular events in young people who have not been diagnosed with cardiovascular disease.[78] Smoking cannabis has also been shown to increase the risk of myocardial infarction by 4.8 times for the 60 minutes after consumption.[104]
Hemp, or industrial hemp (from Old English hænep),[1] typically found in the northern hemisphere, is a variety of the Cannabis sativa plant species that is grown specifically for the industrial uses of its derived products.[2] It is one of the fastest growing plants[3] and was one of the first plants to be spun into usable fiber 10,000 years ago.[4] It can be refined into a variety of commercial items including paper, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed.[5]