California pool and spa retailers are no strangers to Proposition 65, the state law requiring a generic warning in the store notifying customers that some products on display may contain potentially harmful chemicals.

If your business sells products containing any one of the approximately 900 chemicals that the state believes may cause cancer or birth defects, legally, you should have a sign in your store saying as much. The Golden State has mandated the warning since the late 1980s.

Come August, however, that warning will look a little different.

The Office of Environmental Health Hazard Assessment is revising the warning system to make it more specific and less easy to overlook. While intended to better protect merchants from lawsuits, the changes could complicate things for retailers.

The current rule doesn’t require manufacturers to specify the offending chemical in the product. The revised law will. It also changes the wording from “product contains” to “this product can expose you to …”. Example: WARNING: This product can expose you to chemicals including [name of chemical], which are known to the State of California to cause cancer.

If the product also contains an ingredient that could compromise reproductive health, that chemical will need to be identified on the label, too. The new requirements also will include a pictogram — an exclamation point inside a yellow triangle — along with this URL: www.P65Warnings.ca.gov.

Additionally, the way warnings are conveyed to your customers will change. Rather than a simple sign — typically displayed near the cash register — warning labels will be applied on the exterior of the product, its packaging or on a shelf display.

Here’s where things get complicated: Manufacturers have two options to comply with the new provisions. 1.) They can place the label on the product itself, or 2.) They can provide a notice to the seller indicating that the product requires a warning, along with the warning materials. Once the manufacturer sends the notice, it has satisfied its obligations under the regulation. Then the retailer becomes responsible for displaying the materials accordingly.

Option No. 2 has some retailers nervous.

“It does place an affirmative burden on the retailer to provide warnings in certain circumstances,” said Anthony Samson, a senior attorney and policy adviser at Arnold & Porter Kaye Scholer in Sacramento. “Retailers are not necessarily pleased with having to take on that burden at all.”

There is a third option. A statute in the law allows parties along the supply chain to enter into a written agreement with the retailer to allocate legal responsibility among themselves, so long as the consumer receives the warning “prior to exposure.” This agreement would supersede the regulation.

Just what such an agreement would look like is not yet known.

“I think the manufacturers and retailers are probably talking about that now,” Samson said.