by requiring user education and the locking up of paraquat stores. when a 2011 south korean law completely banned paraquat in the country, death by pesticide plummeted 46%, contributing to the decrease of the overall suicide rate. the indiscriminate paraquat murders, which occurred in japan in 1985, were carried out using paraquat as a poison. paraquat was used in the uk in 1981 by a woman who poisoned her husband. steven david catlin killed two of his wives and his adoptive mother with paraquat between 1976 and 1984. parkinson's disease in 2011, a us national institutes of health study showed a link between paraquat use and parkinson's disease in farm workers. a co-author of the paper said that paraquat increases production of certain oxygen derivatives that may harm cellular structures, and that people who used paraquat, or other pesticides with a similar mechanism of action, were more likely to develop parkinson's. paraquat-induced toxicity in rats has also been linked to parkinson's-like neurological degenerative mechanisms. a study by researchers at the buck institute for research on aging showed a connection between exposure to paraquat and iron in infancy and mid-life parkinson's in laboratory mice. a 2013 meta-analysis published in neurology found that "exposure to paraquat ... was associated with about a 2-fold increase in risk" of parkinson's disease. paraquat is structurally similar to mpp+, a known fast-acting inducer of parkinson's disease in primate brains. the chloride of mpp+ was sold under the trade name cyperquat. paraquat also induces oxidative stress in invertebrates such as drosophila melanogaster. paraquat-fed flies suffer early-onset mortality and significant increases in superoxide dismutase activity. while in 2022 uk farmers were calling for a ban on the uk production of paraquat, a bbc article stated that "there is no scientific consensus and many conflicting studies on any possible association between paraquat and parkinson's"; in the usa a class action lawsuit against syngenta is ongoing; the company rejects the claims but has paid £187.5 million into a settlement fund.