BREAKTHROUGHS IN POPULATION CONTROL?
Most observers conclude that today's skyrocketing growth in human population is creating a serious underlying threat to the well-being of the world's natural and economic resources. Between 1990 and 2025, for instance, the number of people on the planet is expected to rise by 3.2 billion.1 And by the year 2000, it is projected that 1.7 billion people will be added to countries that can barely support their populations now, let alone create an economic climate to raise everyone out of poverty.
Whether neem can help reduce runaway population growth is uncertain. However, as noted earlier, exploratory research has indicated that certain neem ingredients have contraceptive properties. Thus it is possible that, given research attention, products from this tree could come into widespread use for the reduction of unwanted pregnancies. This could be an important breakthrough because perhaps 2 billion of the projected population increase before 2025 will occur in regions where neem can be grown.
Eventually, contraception could perhaps become the greatest of neem's contributions. Because of the importance of any breakthrough in this area, we reproduce in this appendix the abstracts of three recent research papers that point toward the possibility of neem providing cheap, widely available contraceptives for even the remotest regions of many of the already overpopulated nations.2
NEEM OIL FOR THE "MORNING AFTER"
Shakti N. Upadhyay, Charu Kaushic, and G.P. Talwar. 1990. Antifertility effects of neem (Azadirachta indica) oil by single intrauterine administration: a novel method for contraception. Proceedings of the Royal Society of London Series B: Biological Sciences 242:175-179.
A novel use of neem (Azadirachta indica) oil, a traditional plant product, for long-term and reversible blocking of fertility after a single intrauterine application is described. Female Wistar rats of proven fertility were given a single dose (100 µl) of neem oil by intrauterine route; control animals received the same volume of peanut oil. Whereas all control animals became pregnant and delivered normal litters, the rats treated with neem oil remained infertile for variable periods ranging from 107 to 180 days even after repeated matings with males of proven fertility. The block in fertility was, however, reversible, as half of the animals regained fertility and delivered normal litters by five months after treatment, without any apparent teratogenic effects. Unilateral administration of neem oil in the uterus blocked pregnancy only on the side of application, whereas the contralateral uterine horn treated with peanut oil had normally developing foetuses; no sign of implantation or foetal resorption was noted in the neem-oil-treated horn. The ovaries on both sides had 4-6 corpora lutea, indicating no effect of treatment on ovarian functions. The animals treated with neem oil showed a significant leukocytic infiltration in the uterine epithelium between days 3 and 5 post coitum, i.e., during the pre-implantation period. Intrauterine application of neem oil appears to induce a pre-implantation block in fertility; the possible mechanisms of the antifertility action are discussed.
NEEM OIL AS SPERMICIDE
Gp. Capt. K.C. Sinha and Lt. Col. S.S. Riar. 1985. Neem oil—an ideal contraceptive. Biological Memoirs 10(1 and 2):107-114.
Neem oil in vitro proved to be a strong spermicidal agent. Rhesus monkey and human spermatozoa became totally immotile within 30 seconds of contact with the undiluted oil.
In vivo studies in rats (20), rabbits (8), rhesus monkeys (14), and human volunteers (10) proved that neem oil applied intravaginally before sexual intercourse prevented pregnancy in all the species.
Neem oil has also been found to have anti-implantation/abortifacient effect in rats and rabbits if applied intravaginally on day 2 to day 7 of expected pregnancy. The minimum effective dose is 25 µl for rats. One month after the stoppage of neem oil application there was complete reversibility in fertility in these animals. It had no deleterious effect on the subsequent pregnancies and the offsprings.
Histopathological studies on rats' vagina, cervix, and uterus showed no ill effects of neem oil in these tissues. In contrast, nonyl-phenoxy polyethoxy ethanol, a popular vaginal contraceptive cream, showed signs of severe irritant reaction in these tissues. Radioisotope studies indicated that neem oil was not absorbed from the vagina; it thus ruled out its possible systemic effects.
Results of the present study indicate than neem oil is an "ideal" female contraceptive, being easily available, cheap, and nontoxic. Therefore, its mass acceptance is anticipated.
NEEM-LEAF EXTRACT TO REDUCE MALE FERTILITY
N.L. Sadre, Vibhavari Y. Deshpande, K.N. Mendulkar, and D.H. Nandal. 1983. Male antifertility activity of Azadirachta indica in different species. Pages 473-482 in H. Schmutterer and K.R.S. Ascher, eds. 1984. Natural Pesticides from the Neem Tree (Azadirachta indica A. Juss.) and other tropical plants. Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ), Eschborn, Germany.
Male antifertility activity of neem (Azadirachta indica A. Juss) was studied in mice, rats, rabbits, and guinea pigs by daily oral feeding of a cold-water extract of fresh green neem leaves. The infertility effect was seen in treated male rats, as there was a 66.7 percent reduction in fertility after 6 weeks, 80 percent after 9 weeks, and 100 percent after 11 weeks. There was no inhibition of spermatogenesis. During this period there was no decrease in body weight and no other manifestation of toxicity were observed. There was a marked decrease in the motility of spermatozoa. The infertility in rats was not associated with loss of libido or with impotence and the animals maintained normal mating behavior. The male antifertility activity was reversible in 4 to 6 weeks and the active principle from the extract was observed to be thermostable. Neem extract also shows reversible male antifertility activity in mice without inhibition of spermatogenesis. In guinea pigs and rabbits, however, it exhibited toxicity, as demonstrated by 66.6 percent and 74.9 percent mortality in guinea pigs and 80 percent and 90 percent mortality in rabbits at the end of 4 and 6 weeks, respectively.