WV HB4949

Prohibits West Virginia state agencies from adopting rules on "chemicals of emerging concern" (including PFAS, microplastics, 1,4-Dioxane, and nanoscale materials) that are more stringent than federal regulations on the same topic

Requires that when no federal standard exists, state rules establishing numeric limits for these chemicals must be based on "best available science" and "weight of scientific evidence" as specifically defined in the bill

Mandates that rules protecting human health must establish a "direct causal link" between chemical exposure and "manifest bodily harm" — defined as presently existing, diagnosable physical disease or injury, not merely increased risk

Exempts rules required by federal law, rules less stringent than federal standards, rules repealing or weakening existing regulations, and emergency rules from these requirements

Applies to regulations covering drinking water, water pollution control, hazardous substances, contaminated site remediation, air quality, solid waste, and hazardous waste handling