# Prop 65 Exposure vs MADL Calculator > Source: https://netray.co/tools/prop-65-exposure-vs-madl-calculator > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer Compare the estimated daily exposure from your product with a Prop 65 safe harbor level and see the highest concentration that stays below it. ## Category compliance-legal ## Region United States ## Audience - Compliance engineer - Product safety - Regulatory affairs ## Tool **Kind:** calculator **Inputs:** #### Chemical concentration in product **Key:** conc **Type:** number **Default:** 2 **Min:** 0 **Step:** 0.1 **Unit:** ug/g **Help:** Concentration of the listed chemical in the product or material, micrograms per gram. #### Amount contacted or ingested per use **Key:** amount **Type:** number **Default:** 5 **Min:** 0 **Step:** 0.5 **Unit:** g **Help:** Mass of product a user ingests or that transfers to skin per use. #### Uses per day **Key:** uses **Type:** number **Default:** 1 **Min:** 0 **Step:** 1 **Unit:** per day #### Fraction transferred to the person **Key:** transfer **Type:** slider **Default:** 100 **Min:** 1 **Max:** 100 **Step:** 1 **Unit:** % **Help:** Use 100 for ingestion of the whole mass; lower values for dermal transfer from a wipe study. #### Safe harbor level (MADL or NSRL) **Key:** level **Type:** number **Default:** 0.5 **Min:** 0.0001 **Step:** 0.1 **Unit:** ug/day **Help:** Take the value for your chemical and route from the OEHHA safe harbor table. Lead reproductive MADL is 0.5 ug/day. **Outputs:** #### Estimated daily exposure **Key:** exposure **Expr:** conc * amount * uses * transfer / 100 **Format:** decimal **Primary:** true **Description:** Micrograms per day. #### Exposure as share of safe harbor level **Key:** pct **Expr:** exposure / level * 100 **Format:** percent #### Warning screen (1 = exposure above level) **Key:** over **Expr:** gt(exposure, level) **Format:** integer **Primary:** true #### Maximum concentration for no warning **Key:** max_conc **Expr:** level / (amount * uses * transfer / 100) **Format:** decimal **Description:** Micrograms per gram that keeps exposure at the level. #### Reduction needed **Key:** reduction **Expr:** max(0, 1 - level / exposure) * 100 **Format:** percent **Chart:** #### Daily exposure vs concentration **Type:** line **X:** conc **From:** 0 **To:** 10 **Steps:** 30 **Series:** - exposure **Disclaimer:** Prop 65 exposure assessment follows OEHHA regulations (Title 27 CCR section 25821 and related). Use the reasonably anticipated rate of exposure for the product and a qualified toxicologist for defensible claims. This tool is a screening aid, not legal advice. ## Content **Intro:** California Proposition 65 requires a clear and reasonable warning when a product exposes people to a listed chemical above the safe harbor level. This calculator does the exposure arithmetic so you can decide whether a warning, a reformulation or a better test is the next step. **Sections:** #### How to use it **Body:** Start with the analytical result for the chemical in the product. Enter the amount of product a person ingests or contacts per use and the number of uses per day. If the route is dermal, use a transfer fraction from a wipe or migration study; for ingestion leave it at 100%. Enter the safe harbor level for the chemical and the endpoint: a MADL for reproductive toxicity or an NSRL for cancer risk. The tool returns exposure, the share of the level and the highest concentration that avoids a warning. **Bullets:** - Use the OEHHA table for the current level - Pick the endpoint that gives the lower level if the chemical has both - Use the realistic upper-bound use pattern #### The method **Body:** Daily exposure equals concentration times mass per use times uses per day times the fraction that reaches the person. If that exposure is at or below the safe harbor level, a warning is not required for that chemical and route. The inverse gives the specification limit you can write into a purchase order: maximum concentration equals the level divided by the daily mass transferred. Safe harbor levels are not the only defence, but they are the most direct one. **Bullets:** - Exposure = conc x mass x uses x transfer - Max conc = level / daily mass transferred - Reduction = 1 - level / exposure #### Worked example **Body:** A product has 2 ug/g of lead and a user ingests 5 g once a day, so exposure is 10 ug/day against a lead reproductive MADL of 0.5 ug/day. That is 2,000% of the level and a warning would be needed. The maximum concentration would be 0.1 ug/g, a 95% reduction. The chart shows how steeply exposure rises with concentration, which helps when you negotiate a specification with a supplier. #### Common mistakes **Body:** Teams often use the level for the wrong route or endpoint, or copy a value from an old list. Another mistake is using average rather than reasonably anticipated use, or ignoring that a sold-in-California product can reach the state through a distributor. Keep the evidence, the date of the level you used and the use assumptions together in the technical file so you can defend the decision if a notice of violation arrives. **Cta:** Netray can help you attach test results and chemical specifications to the item records in your ERP so Prop 65 decisions are traceable by part number. **Faq:** #### What is a MADL? **Answer:** A maximum allowable dose level is the safe harbor level for chemicals that cause reproductive toxicity, given in micrograms per day. Exposure at or below the MADL does not require a Prop 65 warning for that chemical. #### What is an NSRL? **Answer:** A no significant risk level is the daily intake that is calculated to result in no more than one excess case of cancer in 100,000 individuals exposed over a 70 year lifetime. It is the cancer-endpoint equivalent of a MADL. #### Does a warning protect me from all claims? **Answer:** A compliant warning reduces the risk of a notice of violation for that exposure, but it must meet the content and delivery rules of the regulation. It is not a substitute for reducing exposure where that is possible. #### Where do I get the safe harbor value? **Answer:** OEHHA, California's Office of Environmental Health Hazard Assessment, publishes the MADL and NSRL tables on its Proposition 65 website. Use the current version and record the date you consulted it. ## Search terms prop 65 calculator, prop 65 exposure calculation, madl calculator, prop 65 safe harbor level, nsrl calculator, proposition 65 lead exposure, prop 65 warning needed, oehha exposure assessment --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json