The regulation if adopted would amend Title 27, California Code of Regulations, section 25705(b).
To develop the proposed NSRL for malathion, OEHHA relied on Volume 112 in the series of International Agency for Research on Cancer (IARC) Monographs on the Evaluation of Carcinogenic Risks to Humans entitled “Some Organophosphate Insecticides and Herbicides: Diazinon, Glyphosate, Malathion, Parathion, and Tetrachlorvinphos,” which summarizes the available data from rodent carcinogenicity studies of malathion, as well as other information relevant to the carcinogenic activity of the chemical. OEHHA notes in its announcement that the selected studies reviewed in the IARC monograph meet the criterion in Section 25703 as being sensitive scientific studies of sufficient quality for a cancer dose response assessment.
IARC risk assessments have caused controversy recently as the American Chemistry Council (ACC) has called for U.S. lawmakers to cut funding to the international research agency's studies until it reforms its practices, accusing it of "dubious and misleading" work in classifying potential carcinogens.
The trade association has also initiated what it calls a "campaign for accuracy in public health research." ACC contends the International Agency for Research on Cancer's (IARC) evaluations "have a significant impact on U.S. public policy" and should be based on "transparent, thorough assessment of the best available science."
IARC's assessments of whether such things as coffee, mobile phones, processed meat and the weedkiller glyphosate cause cancer have caused a great deal of controversy in recent years.
Malathion is an insecticide in the chemical family known as organophosphates. Products containing malathion are used outdoors to control a wide variety of insects in agricultural settings and around people's homes. Malathion has also been used in public health mosquito control and fruit fly eradication programs. Malathion may also be found in some special shampoos for treating lice. Malathion was first registered for use in the United States in 1956.
Products containing malathion may be liquids, dusts, wettable powders, or emulsions. There are thousands of products containing malathion registered for use in the United States.
Malathion kills insects by preventing their nervous system from working properly. When healthy nerves send signals to each other, a special chemical messenger travels from one nerve to another to continue the message. The nerve signal stops when an enzyme is released into the space between the nerves. Malathion binds to the enzyme and prevents the nerve signal from stopping. This causes the nerves to signal each other without stopping. The constant nerve signals make it so the insects can't move or breathe normally and they die.
People, pets and other animals can be affected the same way as insects if they are exposed to a high enough dose of malathion. About the same amount of malathion will be taken into the body whether you breathe it or you swallow it. Malathion is also readily absorbed by dermal contact, though the amount absorbed will depend on where the exposure occurs on the body. Malathion can become more toxic if it has been sitting for a long time, especially in a hot place.