Legaliseringsguiden, genomgång av ... - PDF Archive

kopplingen mellan ventrikelseptumdefekter (hjärtfel med ofullständig kammarvägg)
hos nyfödda och mödrarnas livsstil bland annat i fråga om rökning av marijuana.
Bakgrunden var att man under de gångna 30 åren sett en signifikant ökning av denna
missbildning i USA. För cannabisrökande mödrar var risken att föda ett missbildat
barn fördubblad. Risken ökade med rökningens intensitet.
Missbildningar på grund av cannabisorsakade kromosomskador
Missbildningar kan också framkallas på annat sätt än genom toxisk påverkan direkt
på fostret. Gifter med förmåga att påverka arvsanlagen kan genom att skada an lagen
hos någon av föräldrarna framkalla missbildningar på genetisk väg. Man har inte
kunnat visa att THC har sådana egenskaper och risken har avvisats i flera
forskningsöversikter (Marijuana and Health, 1982; Hollister, 1986; Hall, et al., 1994).
— Jan Ramström, Folkhälsoinstitutet - Skador av hasch och marijuana [28]
Hall skriver i sin rapport från 1994 om svårigheterna att identifiera faktorer som ger falska svar:
The animal evidence indicates that in sufficient dosage cannabis can "produce
resorption, growth retardation, and malformations" in mice, rats, rabbits, and
hamsters (Bloch, 1983, p406). Growth esorption and growth retardation have been
more consistently reported than birth malformations (Abel, 1985). There are also
several caveats on the evidence that cannabis increases rates of malformations. The
doses required to reliably produce malformations have been very high (Abel, 1985),
and such effects have been observed more often after the administration of crude
marijuana extract than pure THC, suggesting that other cannabinoids may be
involved in producing any teratogenic effects. There have also been doubts expressed
about whether these teratogenic effects can be directly attributed to THC. Some have
argued, for example, that the malformations may be a consequence of reduced
nutrition caused by the aversive properties of the large doses of cannabis used in
these studies (Abel, 1985; Bloch, 1983).
“
Hollister (1986) has also discounted the animal research data, arguing that "virtually
every drug that has ever been studied for dysmorphogenic effects has been found to
have them if the doses are high enough, if enough species are tested, or if treatment
is prolonged" (p4). Similar views have been expressed by Abel (1985) and by Bloch
(1983), who concluded that THC was unlikely to be teratogenic in humans because
"the few reports of teratogenicity in rodents and rabbits indicate that cannabinoids
are, at most, weakly teratogenic in these species" (p416).
...
Even when large sample sizes have been obtained, there are difficulties in
interpreting any associations found between adverse pregnancy outcomes and
cannabis use. Cannabis users are more likely to use tobacco, alcohol and other illicit
drugs during their pregnancy. They also differ from non-users in social class,
education, nutrition, and other factors which predict an increased risk of
experiencing an adverse outcome of pregnancy (Fried, 1980, 1982; National
Academy of Science, 1982; Tennes et al, 1985). These sources of confounding make it
difficult to unequivocally attribute any relationship between reproductive outcomes
and cannabis use to cannabis use per se, rather than to other drug use, or other
variables correlated with cannabis use, such as poor maternal nutrition, and lack of
prenatal care. Sophisticated forms of statistical control provide the only way of
assessing to what degree this may be the case, but its application is limited by the
small number of cannabis smokers identified in most studies.
Given these difficulties, and the marked variation between studies in the proportion
of women who report cannabis use during pregnancy, the degree of agreement
between the small number of studies is more impressive than the disagreement that
seems at first sight to such be a feature of this literature. There is reasonable
consistency (although not unanimity) in the finding that cannabis use in pregnancy is
associated with foetal growth retardation, as shown by reduced birth weight (e.g.
”
442