By Jonathan Stempel

Jan 14 (Reuters) - Procter & Gamble PG.N and Colgate-Palmolive CL.N are among the defendants in six new lawsuits targeting the sale of toothpaste and mouth rinse for young children because the products contain fluoride, which can be harmful if swallowed.

Parents filed complaints on Monday in federal courts in Illinois and California over products such as Procter & Gamble's Kid's Crest toothpaste and several products sold under Colgate's namesake, Tom's of Maine and Hello brands.

Other challenged products include Perrigo's PRGO.N Firefly anti-cavity rinse and Sanofi's SASY.PA ACT Kids rinse.

The proposed class actions cite warnings from U.S. health regulators that fluoride-based toothpastes and rinses not be used by children under ages 2 and 6, respectively, and that the toothpastes be kept out of reach of children under age 6.

They also say the products are marketed as "candy-like" with bright colors, cartoon images and flavors such as Groovy Grape and Silly Strawberry. The color of one Kid's Crest product is shown changing to pink from blue as children brush.

Fluoride helps prevent cavities when applied topically to the teeth, but when ingested can pose "significant" risks to and even kill young children, according to the lawsuits.

Procter & Gamble, Colgate, Perrigo and Sanofi did not immediately respond to requests for comment.

The lawsuits, which seek various restitutions including compensatory and punitive damages, allege violations of various consumer protection laws.

Lawyers from Siri & Glimstad, which represents the parents, were not immediately available for comment on Tuesday.

The relationship between fluoride and human health has long been debated.

A study published in the journal JAMA Pediatrics last week linked higher fluoride exposures in children to lower IQ scores.

Robert F. Kennedy Jr, who is U.S. President-elect Donald Trump's pick to become secretary of health and human services, has questioned fluoride's safety and use in public water systems.

The Illinois cases are Gibson et al v Perrigo Co, Gurrola et al v Procter & Gamble Co, Harden et al v Colgate-Palmolive Co, and Gurrola et al v Chattem Inc, U.S. District Court, Northern District of Illinois, Nos. 25-00348, 25-00358, 25-00362 and 25-00366.

The California cases are Verbish et al v Colgate-Palmolive Co, U.S. District Court, Northern District of California, No. 25-00426; and Miller et al v Hello Products LLC, U.S. District Court, Southern District of California, No. 25-00071.

(Reporting by Jonathan Stempel in New York; Editing by Mark Porter)

((jon.stempel@thomsonreuters.com; +1 646 223 6317; Reuters Messaging: jon.stempel.thomsonreuters.com@reuters.net))