While art lovers and collectors prefer chromolithographic plates that are easy to recognize, the market is flooded with "decorative posters", reproductions of images at low prices
Carcinogenesis 25:24872495 Shin VY, Wu WK, Chu KM, Wong HP, Lam EK, Tai EK, Koo MW, Cho CH (2005) Nicotine induces cyclooxygenase-2 and vascular endothelial growth factor receptor-2 in association with tumor-associated invasion and angiogenesis in gastric cancer
Another problem has been the introduction of non-native herbivores like cattle, sheep, rabbits, and goats, which now compete with wallabies for grasses, leaves, herbs, and other plants
Combining these two approaches, there are also reports of people using formaldehyde or embalming fluid as an agent for adding PCP to cigarettes