Can drinking water standards be reliably derived from industrial TLVs?

Area of Science:

• Environmental Science
• Toxicology
• Public Health

Background:

• Drinking water standards are crucial for public health protection.
• Threshold Limit Values (TLVs) are occupational exposure guidelines that have been considered for adaptation to drinking water standards.
• Previous methodologies for deriving drinking water standards from TLVs exist, such as the one used for barium.

Purpose of the Study:

• To evaluate the accuracy and protective capacity of drinking water standards derived using the Threshold Limit Value (TLV) conversion methodology.
• To compare TLV-derived standards for specific contaminants against existing drinking water standards.

Main Methods:

• The study applied the TLV conversion methodology, identical to that used by Stokinger and Woodward for barium, to derive drinking water standards for arsenic, cadmium, chromium, lead, and fluoride.
• The protective factor of these TLV-derived standards was quantitatively compared to the protection offered by current drinking water standards.

Main Results:

• TLV-derived standards for arsenic, cadmium, chromium, and lead offer significantly less protection (6, 200, 60, and 10 times, respectively) compared to current standards.
• Conversely, the TLV-derived standard for fluoride offers approximately twice the protection of the current standard.
• The methodology's effectiveness varies significantly across different contaminants.

Conclusions:

• The TLV conversion methodology yields inconsistent levels of protection when applied to drinking water standards.
• Reliance on TLV conversion alone for setting drinking water standards is not advisable due to variable accuracy.
• TLV-derived values should be considered as one component of evidence within a comprehensive standard derivation process, not as a sole determinant, especially for contaminants like barium.